TFile.cxx

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// @(#)root/io:$Id: 3a19890259ad6443ee313e090166614971ad4296 $
// Author: Rene Brun   28/11/94
 
/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
/**
\file TFile.cxx
\class TFile
\ingroup IO
\brief A ROOT file is an on-disk file, usually with extension .root, that stores objects in a file-system-like logical structure, possibly including subdirectory hierarchies.
\note See also \ref IO
\note See also \ref rootio (or `io/doc/TFile` folder in your codebase)
 
<details>
<summary>ROOT file data format specification</summary>
 
A ROOT file is composed of a header, followed by consecutive data records
(`TKey` instances) with a well defined format.
 
The first data record starts at byte fBEGIN (currently set to kBEGIN).
Bytes 1->kBEGIN contain the file description, when fVersion >= 1000000
it is a large file (> 2 GB) and the offsets will be 8 bytes long and
fUnits will be set to 8:
 
Byte Range      | Record Name | Description
----------------|-------------|------------
1->4            | "root"      | Root file identifier
5->8            | fVersion    | File format version
9->12           | fBEGIN      | Pointer to first data record
13->16 [13->20] | fEND        | Pointer to first free word at the EOF
17->20 [21->28] | fSeekFree   | Pointer to FREE data record
21->24 [29->32] | fNbytesFree | Number of bytes in FREE data record
25->28 [33->36] | nfree       | Number of free data records
29->32 [37->40] | fNbytesName | Number of bytes in TNamed at creation time
33->33 [41->41] | fUnits      | Number of bytes for file pointers
34->37 [42->45] | fCompress   | Compression level and algorithm
38->41 [46->53] | fSeekInfo   | Pointer to TStreamerInfo record
42->45 [54->57] | fNbytesInfo | Number of bytes in TStreamerInfo record
46->63 [58->75] | fUUID       | Universal Unique ID
 
For the purpose of magic bytes in the context of ROOT files' MIME definition,
the following additional requirements are introduced:
- The value of `fBEGIN` is fixed at 100.
- The four bytes starting at position 96 are reserved and must be 0.
If any changes to this need to be made, `media-types@iana.org` needs to be
notified in accordance with RFC 6838.
 
The key structure is as follows; if a key is located past the 32 bit file
limit (> 2 GB) then some fields will be 8 instead of 4 bytes (see parts marked
with square brackets below):
 
Byte Range      | Member Name | Description
----------------|-----------|--------------
1->4            | Nbytes    | Length of compressed object (in bytes)
5->6            | Version   | TKey version identifier
7->10           | ObjLen    | Length of uncompressed object
11->14          | Datime    | Date and time when object was written to file
15->16          | KeyLen    | Length of the key structure (in bytes)
17->18          | Cycle     | Cycle of key
19->22 [19->26] | SeekKey   | Pointer to record itself (consistency check)
23->26 [27->34] | SeekPdir  | Pointer to directory header
27->27 [35->35] | lname     | Number of bytes in the class name
28->.. [36->..] | ClassName | Object Class Name
..->..          | lname     | Number of bytes in the object name
..->..          | Name      | lName bytes with the name of the object
..->..          | lTitle    | Number of bytes in the object title
..->..          | Title     | Title of the object
----->          | DATA      | Data bytes associated to the object
 
Begin_Macro
../../../tutorials/io/file.C
End_Macro
 
The structure of a directory is shown in TDirectoryFile::TDirectoryFile
</details>
*/
 
#include <ROOT/RConfig.hxx>
 
#ifdef R__LINUX
// for posix_fadvise
#ifndef _XOPEN_SOURCE
#define _XOPEN_SOURCE 600
#endif
#endif
#include <fcntl.h>
#include <errno.h>
#include <sys/stat.h>
#ifndef WIN32
#include <unistd.h>
#ifndef R__FBSD
#include <sys/xattr.h>
#endif
#else
#   define ssize_t int
#   include <io.h>
#   include <sys/types.h>
#endif
 
#include "Bytes.h"
#include "Compression.h"
#include "RConfigure.h"
#include "Strlen.h"
#include "strlcpy.h"
#include "snprintf.h"
#include "TArrayC.h"
#include "TBuffer.h"
#include "TClass.h"
#include "TClassEdit.h"
#include "TClassTable.h"
#include "TDatime.h"
#include "TError.h"
#include "TFile.h"
#include "TFileCacheRead.h"
#include "TFileCacheWrite.h"
#include "TFree.h"
#include "TInterpreter.h"
#include "TKey.h"
#include "TMakeProject.h"
#include "TPluginManager.h"
#include "TProcessUUID.h"
#include "TRegexp.h"
#include "TPRegexp.h"
#include "TROOT.h"
#include "TStreamerInfo.h"
#include "TStreamerElement.h"
#include "TSystem.h"
#include "TTimeStamp.h"
#include "TVirtualPerfStats.h"
#include "TArchiveFile.h"
#include "TEnv.h"
#include "TVirtualMonitoring.h"
#include "TVirtualMutex.h"
#include "TMap.h"
#include "TMathBase.h"
#include "TObjString.h"
#include "TStopwatch.h"
#include "compiledata.h"
#include <cmath>
#include <iostream>
#include <set>
#include "TSchemaRule.h"
#include "TSchemaRuleSet.h"
#include "TThreadSlots.h"
#include "TGlobal.h"
#include "ROOT/RConcurrentHashColl.hxx"
#include <memory>
#include <inttypes.h>
 
#ifdef R__FBSD
#include <sys/extattr.h>
#endif
 
using std::sqrt;
 
std::atomic<Long64_t> TFile::fgBytesRead{0};
std::atomic<Long64_t> TFile::fgBytesWrite{0};
std::atomic<Long64_t> TFile::fgFileCounter{0};
std::atomic<Int_t>    TFile::fgReadCalls{0};
Int_t    TFile::fgReadaheadSize = 256000;
Bool_t   TFile::fgReadInfo = kTRUE;
TList   *TFile::fgAsyncOpenRequests = nullptr;
TString  TFile::fgCacheFileDir;
Bool_t   TFile::fgCacheFileForce = kFALSE;
Bool_t   TFile::fgCacheFileDisconnected = kTRUE;
UInt_t   TFile::fgOpenTimeout = TFile::kEternalTimeout;
Bool_t   TFile::fgOnlyStaged = kFALSE;
ROOT::Internal::RConcurrentHashColl TFile::fgTsSIHashes;
 
#ifdef R__MACOSX
/* On macOS getxattr takes two extra arguments that should be set to 0 */
#define getxattr(path, name, value, size) getxattr(path, name, value, size, 0u, 0)
#endif
#ifdef R__FBSD
#define getxattr(path, name, value, size) extattr_get_file(path, EXTATTR_NAMESPACE_USER, name, value, size)
#endif
 
const Int_t kBEGIN = 100;
 
ClassImp(TFile);
 
//*-*x17 macros/layout_file
// Needed to add the "fake" global gFile to the list of globals.
namespace {
static struct AddPseudoGlobals {
AddPseudoGlobals() {
   // User "gCling" as synonym for "libCore static initialization has happened".
   // This code here must not trigger it.
   TGlobalMappedFunction::MakeFunctor("gFile", "TFile*", TFile::CurrentFile);
}
} gAddPseudoGlobals;
}
////////////////////////////////////////////////////////////////////////////////
/// File default Constructor.
 
TFile::TFile() : TDirectoryFile(), fCompress(ROOT::RCompressionSetting::EAlgorithm::kUseGlobal)
{
   fCacheReadMap    = new TMap();
   SetBit(kBinaryFile, kTRUE);
 
   if (gDebug)
      Info("TFile", "default ctor");
}
 
////////////////////////////////////////////////////////////////////////////////
/// Opens or creates a local ROOT file.
///
/// \param[in] fname1 The name of the file
/// \param[in] option Specifies the mode in which the file is opened
/// \param[in] ftitle The title of the file
/// \param[in] compress Specifies the compression algorithm and level
///
/// It is recommended to specify fname1 as "<file>.root". The suffix ".root"
/// will be used by object browsers to automatically identify the file as
/// a ROOT file. If the constructor fails in any way IsZombie() will
/// return true. Use IsOpen() to check if the file is (still) open.
/// To open non-local files use the static TFile::Open() method, that
/// will take care of opening the files using the correct remote file
/// access plugin.
///
/// Option | Description
/// -------|------------
/// NEW or CREATE                     | Create a new file and open it for writing, if the file already exists the file is not opened.
/// RECREATE                          | Create a new file, if the file already exists it will be overwritten.
/// UPDATE                            | Open an existing file for writing. If no file exists, it is created.
/// READ                              | Open an existing file for reading (default).
/// NET                               | Used by derived remote file access classes, not a user callable option.
/// WEB                               | Used by derived remote http access class, not a user callable option.
/// READ_WITHOUT_GLOBALREGISTRATION   | Used by TTreeProcessorMT, not a user callable option.
///
/// If option = "" (default), READ is assumed.
/// \note Even in READ mode, if the file is the current directory `cd()`, and you create e.g. a new histogram in your code,
/// the histogram will be appended (but not written) to this directory, and automatically deleted when closing the file.
/// To avoid this behavior, call hist->SetDirectory(nullptr); after creating it.
///
/// The file can be specified as a URL of the form:
///
///     file:///user/rdm/bla.root or file:/user/rdm/bla.root
///
/// The file can also be a member of an archive, in which case it is
/// specified as:
///
///     multi.zip#file.root or multi.zip#0
///
/// which will open file.root which is a member of the file multi.zip
/// archive or member 1 from the archive. For more on archive file
/// support see the TArchiveFile class.
/// TFile and its remote access plugins can also be used to open any
/// file, i.e. also non ROOT files, using:
///
///     file.tar?filetype=raw
///
/// This is convenient because the many remote file access plugins allow
/// easy access to/from the many different mass storage systems.
/// The title of the file (ftitle) will be shown by the ROOT browsers.
/// A ROOT file (like a Unix file system) may contain objects and
/// directories. There are no restrictions for the number of levels
/// of directories.
/// A ROOT file is designed such that one can write in the file in pure
/// sequential mode (case of BATCH jobs). In this case, the file may be
/// read sequentially again without using the file index written
/// at the end of the file. In case of a job crash, all the information
/// on the file is therefore protected.
/// A ROOT file can be used interactively. In this case, one has the
/// possibility to delete existing objects and add new ones.
/// When an object is deleted from the file, the freed space is added
/// into the FREE linked list (fFree). The FREE list consists of a chain
/// of consecutive free segments on the file. At the same time, the first
/// 4 bytes of the freed record on the file are overwritten by GAPSIZE
/// where GAPSIZE = -(Number of bytes occupied by the record).
/// Option compress is used to specify the compression level and algorithm:
///
///     compress = 100 * algorithm + level
///
/// Level | Explanation
/// ------|-------------
/// 0   | objects written to this file will not be compressed.
/// 1   | minimal compression level but fast.
/// ... | ....
/// 9   | maximal compression level but slower and might use more memory.
/// (For the currently supported algorithms, the maximum level is 9)
/// If compress is negative it indicates the compression level is not set yet.
/// The enumeration ROOT::RCompressionSetting::EAlgorithm associates each
/// algorithm with a number. There is a utility function to help
/// to set the value of compress. For example,
///     ROOT::CompressionSettings(ROOT::kLZMA, 1)
/// will build an integer which will set the compression to use
/// the LZMA algorithm and compression level 1.  These are defined
/// in the header file <em>Compression.h</em>.
/// Note that the compression settings may be changed at any time.
/// The new compression settings will only apply to branches created
/// or attached after the setting is changed and other objects written
/// after the setting is changed.
/// In case the file does not exist or is not a valid ROOT file,
/// it is made a Zombie. One can detect this situation with a code like:
/// ~~~{.cpp}
/// TFile f("file.root");
/// if (f.IsZombie()) {
///    std::cout << "Error opening file" << std::endl;
///    exit(-1);
/// }
/// ~~~
/// If you open a file instead with TFile::Open("file.root") use rather
/// the following code as a nullptr is returned.
/// ~~~{.cpp}
/// TFile* f = TFile::Open("file.root");
/// if (!f) {
///    std::cout << "Error opening file" << std::endl;
///    exit(-1);
/// }
/// ~~~
/// When opening the file, the system checks the validity of this directory.
/// If something wrong is detected, an automatic Recovery is performed. In
/// this case, the file is scanned sequentially reading all logical blocks
/// and attempting to rebuild a correct directory (see TFile::Recover).
/// One can disable the automatic recovery procedure when reading one
/// or more files by setting the environment variable "TFile.Recover: 0"
/// in the system.rootrc file.
///
/// A bit `TFile::kReproducible` can be enabled specifying
/// the `"reproducible"` url option when creating the file:
/// ~~~{.cpp}
///   TFile *f = TFile::Open("name.root?reproducible","RECREATE","File title");
/// ~~~
/// Unlike regular `TFile`s, the content of such file has reproducible binary
/// content when writing exactly same data. This achieved by writing pre-defined
/// values for creation and modification date of TKey/TDirectory objects and
/// null value for TUUID objects inside TFile. As drawback, TRef objects stored
/// in such file cannot be read correctly.
///
/// In case the name of the file is not reproducible either (in case of
/// creating temporary filenames) a value can be passed to the reproducible
/// option to replace the name stored in the file.
/// ~~~{.cpp}
///   TFile *f = TFile::Open("tmpname.root?reproducible=fixedname","RECREATE","File title");
/// ~~~
 
TFile::TFile(const char *fname1, Option_t *option, const char *ftitle, Int_t compress)
           : TDirectoryFile(), fCompress(compress), fUrl(fname1,kTRUE)
{
   if (!gROOT)
      ::Fatal("TFile::TFile", "ROOT system not initialized");
 
   auto zombify = [this] {
      // error in file opening occurred, make this object a zombie
      if (fGlobalRegistration) {
         R__LOCKGUARD(gROOTMutex);
         gROOT->GetListOfClosedObjects()->Add(this);
      }
      MakeZombie();
      gDirectory = gROOT;
   };
 
   fOption = option;
   fOption.ToUpper();
 
   if (strlen(fUrl.GetProtocol()) != 0 && strcmp(fUrl.GetProtocol(), "file") != 0 && !fOption.BeginsWith("NET") &&
       !fOption.BeginsWith("WEB")) {
      Error("TFile",
            "please use TFile::Open to access remote files:\n\tauto f = std::unique_ptr<TFile>{TFile::Open(\"%s\")};",
            fname1);
      zombify();
      return;
   }
 
   // store name without the options as name and title
   TString sfname1 = fname1;
   if (sfname1.Index("?") != kNPOS) {
      TString s = sfname1(0, sfname1.Index("?"));
      SetName(s);
      fNoAnchorInName = kTRUE;
   } else
      SetName(fname1);
 
   SetTitle(ftitle);
 
   // accept also URL like "file:..." syntax
   fname1 = fUrl.GetFile();
 
   // if option contains filetype=raw then go into raw file mode
   if (strstr(fUrl.GetOptions(), "filetype=raw"))
      fIsRootFile = kFALSE;
 
   // if option contains filetype=pcm then go into ROOT PCM file mode
   if (strstr(fUrl.GetOptions(), "filetype=pcm"))
      fIsPcmFile = kTRUE;
 
   if (fUrl.HasOption("reproducible"))
      SetBit(kReproducible);
 
   // We are opening synchronously
   fAsyncOpenStatus = kAOSNotAsync;
 
   BuildDirectoryFile(this, nullptr);
 
   fVersion      = gROOT->GetVersionInt();  //ROOT version in integer format
   fUnits        = 4;
   fCacheReadMap = new TMap();
   SetBit(kBinaryFile, kTRUE);
 
   if (fIsRootFile && !fIsPcmFile && fOption != "NEW" && fOption != "CREATE"
       && fOption != "RECREATE") {
      // If !gPluginMgr then we are at startup and cannot handle plugins
      // as TArchiveFile yet.
      fArchive = gPluginMgr ? TArchiveFile::Open(fUrl.GetUrl(), this) : nullptr;
      if (fArchive) {
         fname1 = fArchive->GetArchiveName();
         // if no archive member is specified then this TFile is just used
         // to read the archive contents
         if (!strlen(fArchive->GetMemberName()))
            fIsArchive = kTRUE;
      }
   }
 
   if (fOption.Contains("_WITHOUT_GLOBALREGISTRATION")) {
      fOption = fOption.ReplaceAll("_WITHOUT_GLOBALREGISTRATION", "");
      fGlobalRegistration = false;
      if (fList) {
         fList->UseRWLock(false);
      }
   }
 
   if (fOption == "NET")
      return;
 
   if (fOption == "WEB") {
      fOption = "READ";
      fWritable = kFALSE;
      return;
   }
 
   if (fOption == "NEW")
      fOption = "CREATE";
 
   Bool_t create   = (fOption == "CREATE") ? kTRUE : kFALSE;
   Bool_t recreate = (fOption == "RECREATE") ? kTRUE : kFALSE;
   Bool_t update   = (fOption == "UPDATE") ? kTRUE : kFALSE;
   Bool_t read     = (fOption == "READ") ? kTRUE : kFALSE;
   if (!create && !recreate && !update && !read) {
      read    = kTRUE;
      fOption = "READ";
   }
 
   Bool_t devnull = kFALSE;
 
   if (!fname1 || !fname1[0]) {
      Error("TFile", "file name is not specified");
      zombify();
      return;
   }
 
   // support dumping to /dev/null on UNIX
   if (!strcmp(fname1, "/dev/null") &&
       !gSystem->AccessPathName(fname1, kWritePermission)) {
      devnull  = kTRUE;
      create   = kTRUE;
      recreate = kFALSE;
      update   = kFALSE;
      read     = kFALSE;
      fOption  = "CREATE";
      SetBit(kDevNull);
   }
 
   TString fname(fname1);
   if (!gSystem->ExpandPathName(fname)) {
      SetName(fname.Data());
      fRealName = GetName();
      if (!gSystem->IsAbsoluteFileName(fRealName)) {
         gSystem->PrependPathName(gSystem->WorkingDirectory(),fRealName);
      }
      fname = fRealName.Data();
   } else {
      Error("TFile", "error expanding path %s", fname1);
      zombify();
      return;
   }
 
   // If the user supplied a value to the option take it as the name to set for
   // the file instead of the actual filename
   if (TestBit(kReproducible)) {
      if(auto name=fUrl.GetValueFromOptions("reproducible")) {
         SetName(name);
      }
   }
 
   if (recreate) {
      if (!gSystem->AccessPathName(fname.Data(), kFileExists)) {
         if (gSystem->Unlink(fname.Data()) != 0) {
            SysError("TFile", "could not delete %s (errno: %d)",
                     fname.Data(), gSystem->GetErrno());
            zombify();
            return;
         }
      }
      recreate = kFALSE;
      create   = kTRUE;
      fOption  = "CREATE";
   }
   if (create && !devnull && !gSystem->AccessPathName(fname.Data(), kFileExists)) {
      Error("TFile", "file %s already exists", fname.Data());
      zombify();
      return;
   }
   if (update) {
      if (gSystem->AccessPathName(fname.Data(), kFileExists)) {
         update = kFALSE;
         create = kTRUE;
      }
      if (update && gSystem->AccessPathName(fname.Data(), kWritePermission)) {
         Error("TFile", "no write permission, could not open file %s", fname.Data());
         zombify();
         return;
      }
   }
   if (read) {
      if (gSystem->AccessPathName(fname.Data(), kFileExists)) {
         Error("TFile", "file %s does not exist", fname.Data());
         zombify();
         return;
      }
      if (gSystem->AccessPathName(fname.Data(), kReadPermission)) {
         Error("TFile", "no read permission, could not open file %s", fname.Data());
         zombify();
         return;
      }
   }
 
   // Connect to file system stream
   if (create || update) {
#ifndef WIN32
      fD = TFile::SysOpen(fname.Data(), O_RDWR | O_CREAT, 0644);
#else
      fD = TFile::SysOpen(fname.Data(), O_RDWR | O_CREAT | O_BINARY, S_IREAD | S_IWRITE);
#endif
      if (fD == -1) {
         SysError("TFile", "file %s can not be opened", fname.Data());
         zombify();
         return;
      }
      fWritable = kTRUE;
   } else {
#ifndef WIN32
      fD = TFile::SysOpen(fname.Data(), O_RDONLY, 0644);
#else
      fD = TFile::SysOpen(fname.Data(), O_RDONLY | O_BINARY, S_IREAD | S_IWRITE);
#endif
      if (fD == -1) {
         SysError("TFile", "file %s can not be opened for reading", fname.Data());
         zombify();
         return;
      }
      fWritable = kFALSE;
   }
 
   // calling virtual methods from constructor not a good idea, but it is how code was developed
   TFile::Init(create);                        // NOLINT: silence clang-tidy warnings
}
 
////////////////////////////////////////////////////////////////////////////////
/// File destructor.
 
TFile::~TFile()
{
   Close();                                    // NOLINT: silence clang-tidy warnings
 
   // In case where the TFile is still open at 'tear-down' time the order of operation will be
   // call Close("nodelete")
   // then later call delete TFile
   // which means that at this point we might still have object held and those
   // might requires a 'valid' TFile object in their desctructor (for example,
   // TTree call's GetReadCache which expects a non-null fCacheReadMap).
   // So delete the objects (if any) now.
 
   if (fList)
      fList->Delete("slow");
 
   SafeDelete(fAsyncHandle);
   SafeDelete(fCacheRead);
   SafeDelete(fCacheReadMap);
   SafeDelete(fCacheWrite);
   SafeDelete(fProcessIDs);
   SafeDelete(fFree);
   SafeDelete(fArchive);
   SafeDelete(fInfoCache);
   SafeDelete(fOpenPhases);
 
   if (fGlobalRegistration) {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfClosedObjects()->Remove(this);
      gROOT->GetUUIDs()->RemoveUUID(GetUniqueID());
   }
 
   if (IsOnHeap()) {
      // Delete object from CINT symbol table so it can not be used anymore.
      // CINT object are always on the heap.
      gInterpreter->ResetGlobalVar(this);
   }
 
   if (gDebug)
      Info("~TFile", "dtor called for %s [%zx]", GetName(),(size_t)this);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Initialize a TFile object.
///
/// \param[in] create Create a new file.
///
/// TFile implementations providing asynchronous open functionality need to
/// override this method to run the appropriate checks before calling this
/// standard initialization part. See TNetXNGFile::Init for an example.
 
void TFile::Init(Bool_t create)
{
   if (fInitDone)
      // Already called once
      return;
   fInitDone = kTRUE;
 
   if (!fIsRootFile) {
      gDirectory = gROOT;
      return;
   }
 
   if (fArchive) {
      if (fOption != "READ") {
         Error("Init", "archive %s can only be opened in read mode", GetName());
         delete fArchive;
         fArchive = nullptr;
         fIsArchive = kFALSE;
         goto zombie;
      }
 
      fArchive->OpenArchive();
 
      if (fIsArchive) return;
 
      // Make sure the anchor is in the name
      if (!fNoAnchorInName)
         if (!strchr(GetName(),'#'))
            SetName(TString::Format("%s#%s", GetName(), fArchive->GetMemberName()));
 
      if (fArchive->SetCurrentMember() != -1)
         fArchiveOffset = fArchive->GetMemberFilePosition();
      else {
         Error("Init", "member %s not found in archive %s",
               fArchive->GetMemberName(), fArchive->GetArchiveName());
         delete fArchive;
         fArchive = nullptr;
         fIsArchive = kFALSE;
         goto zombie;
      }
   }
 
   Int_t nfree;
   fBEGIN = (Long64_t)kBEGIN;    //First used word in file following the file header
 
   // make newly opened file the current file and directory
   cd();
 
   if (create) {
      //*-*---------------NEW file
      fFree        = new TList;
      fEND         = fBEGIN;    //Pointer to end of file
      new TFree(fFree, fBEGIN, Long64_t(kStartBigFile));  //Create new free list
 
      //*-* -------------Check if we need to enable forward compatible with version
      //*-* -------------prior to v6.30
      if (gEnv->GetValue("TFile.v630forwardCompatibility", 0) == 1)
         SetBit(k630forwardCompatibility);
 
      //*-* Write Directory info
      Int_t namelen= TNamed::Sizeof();
      Int_t nbytes = namelen + TDirectoryFile::Sizeof();
      TKey *key    = new TKey(fName, fTitle, IsA(), nbytes, this);
      fNbytesName  = key->GetKeylen() + namelen;
      fSeekDir     = key->GetSeekKey();
      fSeekFree    = 0;
      fNbytesFree  = 0;
      WriteHeader();
      char *buffer = key->GetBuffer();
      TNamed::FillBuffer(buffer);
      TDirectoryFile::FillBuffer(buffer);
      key->WriteFile();
      delete key;
   } else {
      //*-*----------------UPDATE
      //char *header = new char[kBEGIN];
      char *header = new char[kBEGIN+200];
      Seek(0);                                 // NOLINT: silence clang-tidy warnings
      //ReadBuffer(header, kBEGIN);
      if (ReadBuffer(header, kBEGIN+200)) {    // NOLINT: silence clang-tidy warnings
         // ReadBuffer returns kTRUE in case of failure.
         Error("Init","%s failed to read the file type data.",
               GetName());
         delete [] header;
         goto zombie;
      }
 
      // make sure this is a ROOT file
      if (strncmp(header, "root", 4)) {
         Error("Init", "%s not a ROOT file", GetName());
         delete [] header;
         goto zombie;
      }
 
      char *buffer = header + 4;    // skip the "root" file identifier
      frombuf(buffer, &fVersion);
      Int_t headerLength;
      frombuf(buffer, &headerLength);
      fBEGIN = (Long64_t)headerLength;
      if (fVersion < 1000000) { //small file
         Int_t send,sfree,sinfo;
         frombuf(buffer, &send);         fEND     = (Long64_t)send;
         frombuf(buffer, &sfree);        fSeekFree= (Long64_t)sfree;
         frombuf(buffer, &fNbytesFree);
         frombuf(buffer, &nfree);
         frombuf(buffer, &fNbytesName);
         frombuf(buffer, &fUnits );
         frombuf(buffer, &fCompress);
         frombuf(buffer, &sinfo);        fSeekInfo = (Long64_t)sinfo;
         frombuf(buffer, &fNbytesInfo);
      } else { // new format to support large files
         frombuf(buffer, &fEND);
         frombuf(buffer, &fSeekFree);
         frombuf(buffer, &fNbytesFree);
         frombuf(buffer, &nfree);
         frombuf(buffer, &fNbytesName);
         frombuf(buffer, &fUnits );
         frombuf(buffer, &fCompress);
         frombuf(buffer, &fSeekInfo);
         frombuf(buffer, &fNbytesInfo);
      }
      if (fBEGIN < 0 || fBEGIN > fEND) {
         // humm fBEGIN is wrong ....
         Error("Init","file %s has an incorrect header length (%lld) or incorrect end of file length (%lld)",
               GetName(),fBEGIN,fEND);
         delete [] header;
         goto zombie;
      }
      fSeekDir = fBEGIN;
      //*-*-------------Read Free segments structure if file is writable
      if (fWritable) {
         fFree = new TList;
         if (fSeekFree > fBEGIN) {
            ReadFree();                        // NOLINT: silence clang-tidy warnings
         } else {
            Warning("Init","file %s probably not closed, cannot read free segments",GetName());
         }
      }
      //*-*-------------Read directory info
      // buffer_keyloc is the start of the key record.
      char *buffer_keyloc = nullptr;
 
      Int_t nbytes = fNbytesName + TDirectoryFile::Sizeof();
      if ( (nbytes + fBEGIN) > fEND) {
         // humm fBEGIN is wrong ....
         Error("Init","file %s has an incorrect header length (%lld) or incorrect end of file length (%lld)",
              GetName(),fBEGIN+nbytes,fEND);
         delete [] header;
         goto zombie;
      }
      if (nbytes+fBEGIN > kBEGIN+200) {
         delete [] header;
         header       = new char[nbytes];
         buffer       = header;
         Seek(fBEGIN);                         // NOLINT: silence clang-tidy warnings
         if (ReadBuffer(buffer,nbytes)) {      // NOLINT: silence clang-tidy warnings
            // ReadBuffer returns kTRUE in case of failure.
            Error("Init","%s failed to read the file header information at %lld (size=%d)",
                  GetName(),fBEGIN,nbytes);
            delete [] header;
            goto zombie;
         }
         buffer = header+fNbytesName;
         buffer_keyloc = header;
      } else {
         buffer = header+fBEGIN+fNbytesName;
         buffer_keyloc = header+fBEGIN;
      }
      Version_t version,versiondir;
      frombuf(buffer,&version); versiondir = version%1000;
      fDatimeC.ReadBuffer(buffer);
      fDatimeM.ReadBuffer(buffer);
      frombuf(buffer, &fNbytesKeys);
      frombuf(buffer, &fNbytesName);
      if (version > 1000) {
         frombuf(buffer, &fSeekDir);
         frombuf(buffer, &fSeekParent);
         frombuf(buffer, &fSeekKeys);
      } else {
         Int_t sdir,sparent,skeys;
         frombuf(buffer, &sdir);    fSeekDir    = (Long64_t)sdir;
         frombuf(buffer, &sparent); fSeekParent = (Long64_t)sparent;
         frombuf(buffer, &skeys);   fSeekKeys   = (Long64_t)skeys;
      }
      if (versiondir > 1) fUUID.ReadBuffer(buffer);
 
      //*-*---------read TKey::FillBuffer info
      buffer_keyloc += sizeof(Int_t); // Skip NBytes;
      Version_t keyversion;
      frombuf(buffer_keyloc, &keyversion);
      // Skip ObjLen, DateTime, KeyLen, Cycle, SeekKey, SeekPdir
      if (keyversion > 1000) {
         // Large files
         buffer_keyloc += 2*sizeof(Int_t)+2*sizeof(Short_t)+2*sizeof(Long64_t);
      } else {
         buffer_keyloc += 2*sizeof(Int_t)+2*sizeof(Short_t)+2*sizeof(Int_t);
      }
      TString cname;
      cname.ReadBuffer(buffer_keyloc);
      cname.ReadBuffer(buffer_keyloc); // fName.ReadBuffer(buffer); file may have been renamed
      fTitle.ReadBuffer(buffer_keyloc);
      delete [] header;
      if (fNbytesName < 10 || fNbytesName > 10000) {
         Error("Init","cannot read directory info of file %s", GetName());
         goto zombie;
      }
 
      //*-* -------------Check if file is truncated
      Long64_t size;
      if ((size = GetSize()) == -1) {          // NOLINT: silence clang-tidy warnings
         Error("Init", "cannot stat the file %s", GetName());
         goto zombie;
      }
 
      //*-* -------------Check if, in case of inconsistencies, we are requested to
      //*-* -------------attempt recovering the file
      Bool_t tryrecover = (gEnv->GetValue("TFile.Recover", 1) == 1) ? kTRUE : kFALSE;
 
      //*-* -------------Check if we need to enable forward compatible with version
      //*-* -------------prior to v6.30
      if (gEnv->GetValue("TFile.v630forwardCompatibility", 0) == 1)
         SetBit(k630forwardCompatibility);
 
      //*-* -------------Read keys of the top directory
      if (fSeekKeys > fBEGIN && fEND <= size) {
         //normal case. Recover only if file has no keys
         TDirectoryFile::ReadKeys(kFALSE);
         gDirectory = this;
         if (!GetNkeys()) {
            if (tryrecover) {
               Recover();                      // NOLINT: silence clang-tidy warnings
            } else {
               Error("Init", "file %s has no keys", GetName());
               goto zombie;
            }
         }
      } else if ((fBEGIN+nbytes == fEND) && (fEND == size)) {
         //the file might be open by another process and nothing written to the file yet
         Warning("Init","file %s has no keys", GetName());
         gDirectory = this;
      } else {
         //something had been written to the file. Trailer is missing, must recover
         if (fEND > size) {
            if (tryrecover) {
               Error("Init","file %s is truncated at %lld bytes: should be %lld, "
                     "trying to recover", GetName(), size, fEND);
            } else {
               Error("Init","file %s is truncated at %lld bytes: should be %lld",
                     GetName(), size, fEND);
               goto zombie;
            }
         } else {
            if (tryrecover) {
               Warning("Init","file %s probably not closed, "
                       "trying to recover", GetName());
            } else {
               Warning("Init","file %s probably not closed", GetName());
               goto zombie;
            }
         }
         Int_t nrecov = Recover();             // NOLINT: silence clang-tidy warnings
         if (nrecov) {
            Warning("Init", "successfully recovered %d keys", nrecov);
         } else {
            Warning("Init", "no keys recovered, file has been made a Zombie");
            goto zombie;
         }
      }
   }
 
   if (fGlobalRegistration) {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfFiles()->Add(this);
      gROOT->GetUUIDs()->AddUUID(fUUID, this);
   }
 
   // Create StreamerInfo index
   {
      Int_t lenIndex = gROOT->GetListOfStreamerInfo()->GetSize()+1;
      if (lenIndex < 5000) lenIndex = 5000;
      fClassIndex = new TArrayC(lenIndex);
      if (fgReadInfo) {
         if (fSeekInfo > fBEGIN) {
            ReadStreamerInfo();                // NOLINT: silence clang-tidy warnings
            if (IsZombie()) {
               R__LOCKGUARD(gROOTMutex);
               gROOT->GetListOfFiles()->Remove(this);
               goto zombie;
            }
         } else if (fVersion != gROOT->GetVersionInt() && fVersion > 30000) {
            // Don't complain about missing streamer info for empty files.
            if (fKeys->GetSize()) {
               // #14068: we take into account the different way of expressing the version
               const auto separator = fVersion < 63200 ? "/" : ".";
               const auto thisVersion = gROOT->GetVersionInt();
               const auto msg = "no StreamerInfo found in %s therefore preventing schema evolution when reading this file. "
                                "The file was produced with ROOT version %d.%02d%s%02d, "
                                "while the current version is %d.%02d.%02d";
               Warning("Init", msg,
                       GetName(),
                       fVersion / 10000, (fVersion / 100) % (100), separator, fVersion  % 100,
                       thisVersion / 10000, (thisVersion / 100) % (100), thisVersion  % 100);
            }
         }
      }
   }
 
   // Count number of TProcessIDs in this file
   {
      TIter next(fKeys);
      TKey *key;
      while ((key = (TKey*)next())) {
         if (!strcmp(key->GetClassName(),"TProcessID")) fNProcessIDs++;
      }
      fProcessIDs = new TObjArray(fNProcessIDs+1);
   }
 
   return;
 
zombie:
   if (fGlobalRegistration) {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfClosedObjects()->Add(this);
   }
   // error in file opening occurred, make this object a zombie
   fWritable = kFALSE;
   MakeZombie();
   gDirectory = gROOT;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Close a file.
///
/// \param[in] option If option == "R", all TProcessIDs referenced by this file are deleted.
///
/// Calling TFile::Close("R") might be necessary in case one reads a long list
/// of files having TRef, writing some of the referenced objects or TRef
/// to a new file. If the TRef or referenced objects of the file being closed
/// will not be referenced again, it is possible to minimize the size
/// of the TProcessID data structures in memory by forcing a delete of
/// the unused TProcessID.
 
void TFile::Close(Option_t *option)
{
   TString opt = option;
 
   opt.ToLower();
 
   if (!IsOpen()) return;
 
   if (fIsArchive || !fIsRootFile) {
      FlushWriteCache();
      SysClose(fD);
      fD = -1;
 
      if (gMonitoringWriter)
         gMonitoringWriter->SendFileCloseEvent(this);
 
      return;
   }
 
   if (IsWritable()) {
      WriteStreamerInfo();
   }
 
   // Finish any concurrent I/O operations before we close the file handles.
   if (fCacheRead) fCacheRead->Close();
   {
      TIter iter(fCacheReadMap);
      TObject *key = nullptr;
      while ((key = iter()) != nullptr) {
         TFileCacheRead *cache = dynamic_cast<TFileCacheRead *>(fCacheReadMap->GetValue(key));
         cache->Close();
      }
   }
 
   // Delete all supported directories structures from memory
   // If gDirectory points to this object or any of the nested
   // TDirectoryFile, TDirectoryFile::Close will induce the proper cd.
   fMustFlush = kFALSE; // Make sure there is only one Flush.
   TDirectoryFile::Close(option);
 
   if (IsWritable()) {
      TFree *f1 = (TFree*)fFree->First();
      if (f1) {
         WriteFree();       //*-*- Write free segments linked list
         WriteHeader();     //*-*- Now write file header ; this forces a Flush/fsync
      } else {
         Flush();
      }
   }
   fMustFlush = kTRUE;
 
   FlushWriteCache();
 
   if (gMonitoringWriter)
      gMonitoringWriter->SendFileCloseEvent(this);
 
   delete fClassIndex;
   fClassIndex = nullptr;
 
   // Delete free segments from free list (but don't delete list header)
   if (fFree) {
      fFree->Delete();
   }
 
   if (IsOpen()) {
      SysClose(fD);
      fD = -1;
   }
 
   fWritable = kFALSE;
 
   // delete the TProcessIDs
   TList pidDeleted;
   TIter next(fProcessIDs);
   TProcessID *pid;
   while ((pid = (TProcessID*)next())) {
      if (!pid->DecrementCount()) {
         if (pid != TProcessID::GetSessionProcessID()) pidDeleted.Add(pid);
      } else if(opt.Contains("r")) {
         pid->Clear();
      }
   }
   pidDeleted.Delete();
 
   if (!IsZombie() && fGlobalRegistration) {
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfFiles()->Remove(this);
      gROOT->GetListOfBrowsers()->RecursiveRemove(this);
      gROOT->GetListOfClosedObjects()->Add(this);
   } else {
      // If we are a zombie, we are already in the list of closed objects.
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Creates key for object and converts data to buffer.
 
TKey* TFile::CreateKey(TDirectory* mother, const TObject* obj, const char* name, Int_t bufsize)
{
   return new TKey(obj, name, bufsize, mother);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Creates key for object and converts data to buffer.
 
TKey* TFile::CreateKey(TDirectory* mother, const void* obj, const TClass* cl, const char* name, Int_t bufsize)
{
   return new TKey(obj, cl, name, bufsize, mother);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the current ROOT file if any.
///
/// Note that if 'cd' has been called on a TDirectory that does not belong to a file,
/// gFile will be unchanged and still points to the file of the previous current
/// directory that was a file.
 
TFile *&TFile::CurrentFile()
{
   static TFile *currentFile = nullptr;
   if (!gThreadTsd)
      return currentFile;
   else
      return *(TFile**)(*gThreadTsd)(&currentFile,ROOT::kFileThreadSlot);
}
 
////////////////////////////////////////////////////////////////////////////////
/// \copydoc TDirectoryFile::Delete
 
void TFile::Delete(const char *namecycle)
{
   if (gDebug)
      Info("Delete", "deleting name = %s", namecycle);
 
   TDirectoryFile::Delete(namecycle);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Fill Graphics Structure and Paint.
///
/// Loop on all objects (memory or file) and all subdirectories.
 
void TFile::Draw(Option_t *option)
{
   GetList()->R__FOR_EACH(TObject,Draw)(option);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Draw map of objects in this file. The map drawing is handled by TFileDrawMap.
/// Once the map is drawn, turn on the TCanvas option "View->Event Statusbar". Then, when
/// moving the mouse in the canvas, the "Event Status" panels shows the object corresponding
/// to the mouse position.
///
/// Example:
/// ~~~{.cpp}
///   auto f = new TFile("myfile.root");
///   f->DrawMap();
/// ~~~
 
void TFile::DrawMap(const char *keys, Option_t *option)
{
   TPluginHandler *h;
   if ((h = gROOT->GetPluginManager()->FindHandler("TFileDrawMap"))) {
      if (h->LoadPlugin() == -1)
         return;
      h->ExecPlugin(3, this, keys, option);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Synchronize a file's in-memory and on-disk states.
 
void TFile::Flush()
{
   if (IsOpen() && fWritable) {
      FlushWriteCache();
      if (SysSync(fD) < 0) {
         // Write the system error only once for this file
         SetBit(kWriteError); SetWritable(kFALSE);
         SysError("Flush", "error flushing file %s", GetName());
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Flush the write cache if active.
///
/// Return kTRUE in case of error
 
Bool_t TFile::FlushWriteCache()
{
   if (fCacheWrite && IsOpen() && fWritable)
      return fCacheWrite->Flush();
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Encode file output buffer.
///
/// The file output buffer contains only the FREE data record.
 
void TFile::FillBuffer(char *&buffer)
{
   Version_t version = TFile::Class_Version();
   tobuf(buffer, version);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the best buffer size of objects on this file.
///
/// The best buffer size is estimated based on the current mean value
/// and standard deviation of all objects written so far to this file.
/// Returns mean value + one standard deviation.
 
Int_t TFile::GetBestBuffer() const
{
   if (!fWritten) return TBuffer::kInitialSize;
   Double_t mean = fSumBuffer/fWritten;
   Double_t rms2 = TMath::Abs(fSum2Buffer/fSumBuffer -mean*mean);
   Double_t result = mean + sqrt(rms2);
   if (result >= (double)std::numeric_limits<Int_t>::max()) {
      return std::numeric_limits<Int_t>::max() -1;
   } else {
      return (Int_t)result;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the file compression factor.
///
/// Add total number of compressed/uncompressed bytes for each key.
/// Returns the ratio of the two.
 
Float_t TFile::GetCompressionFactor()
{
   Short_t  keylen;
   UInt_t   datime;
   Int_t    nbytes, objlen, nwh = 64;
   char    *header = new char[fBEGIN];
   char    *buffer;
   Long64_t   idcur = fBEGIN;
   Float_t comp,uncomp;
   comp = uncomp = fBEGIN;
 
   while (idcur < fEND-100) {
      Seek(idcur);
      if (ReadBuffer(header, nwh)) {
         // ReadBuffer returns kTRUE in case of failure.
//         Error("GetCompressionFactor","%s failed to read the key header information at %lld (size=%d).",
//               GetName(),idcur,nwh);
         break;
      }
      buffer=header;
      frombuf(buffer, &nbytes);
      if (nbytes < 0) {
         idcur -= nbytes;
         Seek(idcur);
         continue;
      }
      if (nbytes == 0) break; //this may happen when the file is corrupted
      Version_t versionkey;
      frombuf(buffer, &versionkey);
      frombuf(buffer, &objlen);
      frombuf(buffer, &datime);
      frombuf(buffer, &keylen);
      if (!objlen) objlen = nbytes-keylen;
      comp   += nbytes;
      uncomp += keylen + objlen;
      idcur  += nbytes;
   }
   delete [] header;
   return uncomp/comp;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method returning errno.
 
Int_t TFile::GetErrno() const
{
   return TSystem::GetErrno();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method resetting the errno.
 
void TFile::ResetErrno() const
{
   TSystem::ResetErrno();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return a pointer to the current read cache.
 
TFileCacheRead *TFile::GetCacheRead(const TObject* tree) const
{
   if (!tree) {
      if (!fCacheRead && fCacheReadMap->GetSize() == 1) {
         TIter next(fCacheReadMap);
         return (TFileCacheRead *)fCacheReadMap->GetValue(next());
      }
      return fCacheRead;
   }
   TFileCacheRead *cache = (TFileCacheRead *)fCacheReadMap->GetValue(tree);
   if (!cache) return fCacheRead;
   return cache;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return a pointer to the current write cache.
 
TFileCacheWrite *TFile::GetCacheWrite() const
{
   return fCacheWrite;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read the logical record header starting at a certain postion.
///
/// \param[in] buf pointer to buffer
/// \param[in] first read offset
/// \param[in] maxbytes Bytes which are read into buf.
/// \param[out] nbytes Number of bytes in record if negative, this is a deleted
/// record if 0, cannot read record, wrong value of argument first
/// \param[out] objlen Uncompressed object size
/// \param[out] keylen Length of logical record header
///
/// The function reads nread bytes
/// where nread is the minimum of maxbytes and the number of bytes
/// before the end of file. The function returns nread.
/// Note that the arguments objlen and keylen are returned only
/// if maxbytes >=16
 
Int_t TFile::GetRecordHeader(char *buf, Long64_t first, Int_t maxbytes, Int_t &nbytes, Int_t &objlen, Int_t &keylen)
{
   nbytes = 0;
   objlen = 0;
   keylen = 0;
   if (first < fBEGIN) return 0;
   if (first > fEND)   return 0;
   Seek(first);
   Int_t nread = maxbytes;
   if (first+maxbytes > fEND) nread = fEND-maxbytes;
   if (nread < 4) {
      Warning("GetRecordHeader","%s: parameter maxbytes = %d must be >= 4",
              GetName(), nread);
      return nread;
   }
   if (ReadBuffer(buf,nread)) {
      // ReadBuffer return kTRUE in case of failure.
      Warning("GetRecordHeader","%s: failed to read header data (maxbytes = %d)",
              GetName(), nread);
      return nread;
   }
   Version_t versionkey;
   Short_t  klen;
   UInt_t   datime;
   Int_t    nb,olen;
   char *buffer = buf;
   frombuf(buffer,&nb);
   nbytes = nb;
   if (nb < 0) return nread;
   //   const Int_t headerSize = Int_t(sizeof(nb) +sizeof(versionkey) +sizeof(olen) +sizeof(datime) +sizeof(klen));
   const Int_t headerSize = 16;
   if (nread < headerSize) return nread;
   frombuf(buffer, &versionkey);
   frombuf(buffer, &olen);
   frombuf(buffer, &datime);
   frombuf(buffer, &klen);
   if (!olen) olen = nbytes-klen;
   objlen = olen;
   keylen = klen;
   return nread;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the current file size. Returns -1 in case the file could not
/// be stat'ed.
 
Long64_t TFile::GetSize() const
{
   Long64_t size;
 
   if (fArchive && fArchive->GetMember()) {
      size = fArchive->GetMember()->GetDecompressedSize();
   } else {
      Long_t id, flags, modtime;
      if (const_cast<TFile*>(this)->SysStat(fD, &id, &size, &flags, &modtime)) {  // NOLINT: silence clang-tidy warnings
         Error("GetSize", "cannot stat the file %s", GetName());
         return -1;
      }
   }
   return size;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the cached list of StreamerInfos used in this file.
 
const TList *TFile::GetStreamerInfoCache()
{
   return fInfoCache ?  fInfoCache : (fInfoCache=GetStreamerInfoList());
}
 
////////////////////////////////////////////////////////////////////////////////
/// See documentation of GetStreamerInfoList for more details.
/// This is an internal method which returns the list of streamer infos and also
/// information about the success of the operation.
 
TFile::InfoListRet TFile::GetStreamerInfoListImpl(bool lookupSICache)
{
   ROOT::Internal::RConcurrentHashColl::HashValue hash;
 
   if (fIsPcmFile) return {nullptr, 1, hash}; // No schema evolution for ROOT PCM files.
 
   TList *list = nullptr;
   if (fSeekInfo) {
      TDirectory::TContext ctxt(this); // gFile and gDirectory used in ReadObj
      auto key = std::make_unique<TKey>(this);
      std::vector<char> buffer(fNbytesInfo+1);
      auto buf = buffer.data();
      Seek(fSeekInfo);                         // NOLINT: silence clang-tidy warnings
      if (ReadBuffer(buf,fNbytesInfo)) {       // NOLINT: silence clang-tidy warnings
         // ReadBuffer returns kTRUE in case of failure.
         Warning("GetRecordHeader","%s: failed to read the StreamerInfo data from disk.",
                 GetName());
         return {nullptr, 1, hash};
      }
 
      if (lookupSICache) {
         // key data must be excluded from the hash, otherwise the timestamp will
         // always lead to unique hashes for each file
         hash = fgTsSIHashes.Hash(buf + key->GetKeylen(), fNbytesInfo - key->GetKeylen());
         auto si_uids = fgTsSIHashes.Find(hash);
         if (si_uids) {
            if (gDebug > 0)
               Info("GetStreamerInfo", "The streamer info record for file %s has already been treated, skipping it.", GetName());
            for(auto uid : *si_uids)
               fClassIndex->fArray[uid] = 1;
            return {nullptr, 0, hash};
         }
      }
      key->ReadKeyBuffer(buf);
      list = dynamic_cast<TList*>(key->ReadObjWithBuffer(buffer.data()));
      if (list) list->SetOwner();
   } else {
      list = (TList*)Get("StreamerInfo"); //for versions 2.26 (never released)
   }
 
   if (!list) {
      Info("GetStreamerInfoList", "cannot find the StreamerInfo record in file %s",
           GetName());
      return {nullptr, 1, hash};
   }
 
   return {list, 0, hash};
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read the list of TStreamerInfo objects written to this file.
///
/// The function returns a TList. It is the user's responsibility
/// to delete the list created by this function.
///
/// Note the list, in addition to TStreamerInfo object, contains sometimes
/// a TList named 'listOfRules' and containing the schema evolution rules
/// related to the file's content.
///
/// Using the list, one can access additional information, e.g.:
/// ~~~{.cpp}
/// TFile f("myfile.root");
/// auto list = f.GetStreamerInfoList();
/// auto info = dynamic_cast<TStreamerInfo*>(list->FindObject("MyClass"));
/// if (info) auto classversionid = info->GetClassVersion();
/// delete list;
/// ~~~
///
 
TList *TFile::GetStreamerInfoList()
{
   return GetStreamerInfoListImpl(/*lookupSICache*/ false).fList;
}
 
////////////////////////////////////////////////////////////////////////////////
/// List file contents.
///
/// Indentation is used to identify the file tree.
/// Subdirectories are listed first, then objects in memory,
/// then objects on the file.
 
void TFile::ls(Option_t *option) const
{
   TROOT::IndentLevel();
   std::cout <<ClassName()<<"**\t\t"<<GetName()<<"\t"<<GetTitle()<<std::endl;
   TROOT::IncreaseDirLevel();
   TDirectoryFile::ls(option);
   TROOT::DecreaseDirLevel();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns kTRUE in case file is open and kFALSE if file is not open.
 
Bool_t TFile::IsOpen() const
{
   return fD == -1 ? kFALSE : kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Mark unused bytes on the file.
///
/// The list of free segments is in the fFree linked list.
/// When an object is deleted from the file, the freed space is added
/// into the FREE linked list (fFree). The FREE list consists of a chain
/// of consecutive free segments on the file. At the same time, the first
/// 4 bytes of the freed record on the file are overwritten by GAPSIZE
/// where GAPSIZE = -(Number of bytes occupied by the record).
 
void TFile::MakeFree(Long64_t first, Long64_t last)
{
   TFree *f1      = (TFree*)fFree->First();
   if (!f1) return;
   TFree *newfree = f1->AddFree(fFree,first,last);
   if(!newfree) return;
   Long64_t nfirst = newfree->GetFirst();
   Long64_t nlast  = newfree->GetLast();
   Long64_t nbytesl= nlast-nfirst+1;
   if (nbytesl > 2000000000) nbytesl = 2000000000;
   Int_t nbytes    = -Int_t (nbytesl);
   char buffer[sizeof(Int_t)];
   char *pbuffer = buffer;
   tobuf(pbuffer, nbytes);
   if (last == fEND-1) fEND = nfirst;
   Seek(nfirst);
   // We could not update the meta data for this block on the file.
   // This is not fatal as this only means that we won't get it 'right'
   // if we ever need to Recover the file before the block is actually
   // (attempted to be reused.
   // coverity[unchecked_value]
   WriteBuffer(buffer, sizeof(buffer));
   if (fMustFlush) Flush();
}
 
////////////////////////////////////////////////////////////////////////////////
/// List the contents of a file sequentially.
/// For each logical record found, it prints:
///
///     Date/Time  Record_Adress Logical_Record_Length  ClassName  CompressionFactor
///
/// Example of output
///
///     20010404/150437  At:64        N=150       TFile
///     20010404/150440  At:214       N=28326     TBasket        CX =  1.13
///     20010404/150440  At:28540     N=29616     TBasket        CX =  1.08
///     20010404/150440  At:58156     N=29640     TBasket        CX =  1.08
///     20010404/150440  At:87796     N=29076     TBasket        CX =  1.10
///     20010404/150440  At:116872    N=10151     TBasket        CX =  3.15
///     20010404/150441  At:127023    N=28341     TBasket        CX =  1.13
///     20010404/150441  At:155364    N=29594     TBasket        CX =  1.08
///     20010404/150441  At:184958    N=29616     TBasket        CX =  1.08
///     20010404/150441  At:214574    N=29075     TBasket        CX =  1.10
///     20010404/150441  At:243649    N=9583      TBasket        CX =  3.34
///     20010404/150442  At:253232    N=28324     TBasket        CX =  1.13
///     20010404/150442  At:281556    N=29641     TBasket        CX =  1.08
///     20010404/150442  At:311197    N=29633     TBasket        CX =  1.08
///     20010404/150442  At:340830    N=29091     TBasket        CX =  1.10
///     20010404/150442  At:369921    N=10341     TBasket        CX =  3.09
///     20010404/150442  At:380262    N=509       TH1F           CX =  1.93
///     20010404/150442  At:380771    N=1769      TH2F           CX =  4.32
///     20010404/150442  At:382540    N=1849      TProfile       CX =  1.65
///     20010404/150442  At:384389    N=18434     TNtuple        CX =  4.51
///     20010404/150442  At:402823    N=307       KeysList
///     20010404/150443  At:403130    N=4548      StreamerInfo   CX =  3.65
///     20010404/150443  At:407678    N=86        FreeSegments
///     20010404/150443  At:407764    N=1         END
///
/// If the parameter opt contains "forComp", the Date/Time is omitted
/// and the decompressed size is also printed.
///
///    Record_Adress Logical_Record_Length  Key_Length Object_Record_Length ClassName  CompressionFactor
///
/// If the parameter opt contains "extended", the name and title of the keys are added:
///     20200820/155031  At:100      N=180       TFile                      name: hsimple.root      title: Demo ROOT file with histograms
///     220200820/155032  At:280      N=28880     TBasket        CX =  1.11  name: random            title: ntuple
///     220200820/155032  At:29160    N=29761     TBasket        CX =  1.08  name: px                title: ntuple
///     220200820/155032  At:58921    N=29725     TBasket        CX =  1.08  name: py                title: ntuple
///     220200820/155032  At:88646    N=29209     TBasket        CX =  1.10  name: pz                title: ntuple
///     220200820/155032  At:117855   N=10197     TBasket        CX =  3.14  name: i                 title: ntuple
///     ...
///     20200820/155032  At:405110   N=808       TNtuple        CX =  3.53  name: ntuple            title: Demo ntuple
///     20200820/155706  At:405918   N=307       KeysList                   name: hsimple.root      title: Demo ROOT file with histograms
///     20200820/155032  At:406225   N=8556      StreamerInfo   CX =  3.42  name: StreamerInfo      title: Doubly linked list
///     20200820/155708  At:414781   N=86        FreeSegments               name: hsimple.root      title: Demo ROOT file with histograms
///     20200820/155708  At:414867   N=1         END
///
/// Note: The combined size of the classname, name and title is truncated to 476 characters (a little more for regular keys of small files)
///
 
 
void TFile::Map(Option_t *opt)
{
   TString options(opt);
   options.ToLower();
   const bool forComp = options.Contains("forcomp");
   const bool extended = options.Contains("extended");
 
   const unsigned char nDigits = std::log10(fEND) + 1;
 
   std::optional<ROOT::Detail::TKeyMapNode> lastNode;
   const auto tkeyInfos = WalkTKeys();
   for (const auto &key : tkeyInfos) {
      lastNode = key;
      switch (key.fType) {
      case ROOT::Detail::TKeyMapNode::kError:
         Printf("Address = %" PRIu64 "\tNbytes = %u\t=====E R R O R=======", key.fAddr, key.fLen);
         break;
 
      case ROOT::Detail::TKeyMapNode::kGap:
         Printf("Address = %" PRIu64 "\tNbytes = %d\t=====G A P===========", key.fAddr, -key.fLen);
         break;
 
      case ROOT::Detail::TKeyMapNode::kKey:
         TString extrainfo;
         if (extended)
            extrainfo.Form(" name: %-16s  title: %s", key.fKeyName.c_str(), key.fKeyTitle.c_str());
 
         if (forComp) {
            // Printing to help compare two files.
            if (key.fObjLen != static_cast<Int_t>(key.fLen) - key.fKeyLen) {
               Float_t cx = static_cast<float>(key.fObjLen + key.fKeyLen) / key.fLen;
               Printf("At:%-*" PRIu64 "  N=%-8u K=%-3d O=%-8d  %-14s CX = %5.2f %s", nDigits + 1, key.fAddr, key.fLen,
                      key.fKeyLen, key.fObjLen, key.fClassName.c_str(), cx, extrainfo.Data());
            } else {
               Printf("At:%-*" PRIu64 "  N=%-8u K=%-3d O=%-8d  %-14s CX =  1    %s", nDigits + 1, key.fAddr, key.fLen,
                      key.fKeyLen, key.fObjLen, key.fClassName.c_str(), extrainfo.Data());
            }
         } else {
            Int_t date, time;
            TDatime::GetDateTime(key.fDatime, date, time);
            if (key.fObjLen != static_cast<Int_t>(key.fLen) - key.fKeyLen) {
               Float_t cx = static_cast<float>(key.fObjLen + key.fKeyLen) / key.fLen;
               Printf("%d/%06d  At:%-*" PRIu64 "  N=%-8u  %-14s CX = %5.2f %s", date, time, nDigits + 1, key.fAddr,
                      key.fLen, key.fClassName.c_str(), cx, extrainfo.Data());
            } else {
               Printf("%d/%06d  At:%-*" PRIu64 "  N=%-8u  %-14s            %s", date, time, nDigits + 1, key.fAddr,
                      key.fLen, key.fClassName.c_str(), extrainfo.Data());
            }
         }
      }
   }
 
   if (!forComp) {
      Int_t datime = lastNode ? lastNode->fDatime : 0;
      Int_t date, time;
      TDatime::GetDateTime(datime, date, time);
      Printf("%d/%06d  At:%-*lld  N=%-8d  %-14s", date, time, nDigits + 1, fEND, 1, "END");
   } else {
      Printf("At:%-*lld  N=%-8d K=    O=          %-14s", nDigits + 1, fEND, 1, "END");
   }
}
 
ROOT::Detail::TKeyMapIterable TFile::WalkTKeys()
{
   return ROOT::Detail::TKeyMapIterable(this);
}
 
ROOT::Detail::TKeyMapIterable::TIterator::TIterator(TFile *file, std::uint64_t addr) : fFile(file), fCurAddr(addr)
{
   if (addr == 0)
      fCurAddr = fFile->fBEGIN;
   Advance();
}
 
std::optional<ROOT::Detail::TKeyMapNode> ROOT::Detail::TKeyMapIterable::TIterator::Next()
{
   static constexpr int headerSize = 512;
 
   const std::uint64_t idcur = fCurAddr;
   const std::uint64_t end = fFile->fEND;
   if (idcur >= end)
      return std::nullopt;
 
   fFile->Seek(idcur);
   auto nread = headerSize;
   if (idcur + nread >= end)
      nread = end - idcur - 1;
 
   char header[headerSize];
   if (fFile->ReadBuffer(header, nread)) {
      // ReadBuffer returns kTRUE in case of failure.
      auto node = ROOT::Detail::TKeyMapNode{idcur, ROOT::Detail::TKeyMapNode::kError};
      fCurAddr = end;
      return node;
   }
 
   char *buffer = header;
   Int_t nbytes;
   frombuf(buffer, &nbytes);
   if (!nbytes) {
      auto node = ROOT::Detail::TKeyMapNode{idcur, ROOT::Detail::TKeyMapNode::kError};
      fCurAddr = end;
      return node;
   }
 
   if (nbytes < 0) {
      // free slot
      auto node =
         ROOT::Detail::TKeyMapNode{idcur, ROOT::Detail::TKeyMapNode::kGap, static_cast<std::uint32_t>(-nbytes)};
      fCurAddr -= nbytes;
      return node;
   }
 
   auto node = ROOT::Detail::TKeyMapNode{idcur, ROOT::Detail::TKeyMapNode::kKey, static_cast<std::uint32_t>(nbytes)};
   frombuf(buffer, &node.fKeyVersion);
   frombuf(buffer, &node.fObjLen);
   frombuf(buffer, &node.fDatime);
   frombuf(buffer, &node.fKeyLen);
   frombuf(buffer, &node.fCycle);
   if (node.fKeyVersion > 1000) {
      frombuf(buffer, &node.fSeekKey);
      frombuf(buffer, &node.fSeekPdir);
   } else {
      Int_t skey, sdir;
      frombuf(buffer, &skey);
      frombuf(buffer, &sdir);
      node.fSeekKey = static_cast<Long64_t>(skey);
      node.fSeekPdir = static_cast<Long64_t>(sdir);
   }
 
   const auto readString = [&buffer, &header](bool skipCheck = false) {
      std::uint8_t stringLenShort;
      std::uint32_t stringLen;
      if (!skipCheck && ((buffer - header) >= headerSize)) {
         stringLen = 0;
      } else {
         frombuf(buffer, &stringLenShort);
         if (stringLenShort == 0xFF)
            frombuf(buffer, &stringLen);
         else
            stringLen = stringLenShort;
 
         if ((buffer - header) + stringLen > headerSize)
            stringLen = headerSize - (buffer - header);
      }
 
      std::string str;
      if (stringLen)
         str = std::string(buffer, stringLen);
      buffer += stringLen;
 
      return str;
   };
 
   node.fClassName = readString(true);
 
   if (idcur == static_cast<std::uint64_t>(fFile->fSeekFree))
      node.fClassName = "FreeSegments";
   else if (idcur == static_cast<std::uint64_t>(fFile->fSeekInfo))
      node.fClassName = "StreamerInfo";
   else if (idcur == static_cast<std::uint64_t>(fFile->fSeekKeys))
      node.fClassName = "KeysList";
 
   node.fKeyName = readString();
   node.fKeyTitle = readString();
 
   fCurAddr += nbytes;
 
   return node;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Paint all objects in the file.
 
void TFile::Paint(Option_t *option)
{
   GetList()->R__FOR_EACH(TObject,Paint)(option);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Print all objects in the file.
 
void TFile::Print(Option_t *option) const
{
   Printf("TFile: name=%s, title=%s, option=%s", GetName(), GetTitle(), GetOption());
   GetList()->R__FOR_EACH(TObject,Print)(option);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read a buffer from the file at the offset 'pos' in the file.
///
/// Returns kTRUE in case of failure.
/// Compared to ReadBuffer(char*, Int_t), this routine does _not_
/// change the cursor on the physical file representation (fD)
/// if the data is in this TFile's cache.
 
Bool_t TFile::ReadBuffer(char *buf, Long64_t pos, Int_t len)
{
   if (IsOpen()) {
 
      SetOffset(pos);
 
      Int_t st;
      Double_t start = 0;
      if (gPerfStats) start = TTimeStamp();
 
      if ((st = ReadBufferViaCache(buf, len))) {
         if (st == 2)
            return kTRUE;
         return kFALSE;
      }
 
      Seek(pos);
      ssize_t siz;
 
      while ((siz = SysRead(fD, buf, len)) < 0 && GetErrno() == EINTR)
         ResetErrno();
 
      if (siz < 0) {
         SysError("ReadBuffer", "error reading from file %s", GetName());
         return kTRUE;
      }
      if (siz != len) {
         Error("ReadBuffer", "error reading all requested bytes from file %s, got %ld of %d",
               GetName(), (Long_t)siz, len);
         return kTRUE;
      }
      fBytesRead  += siz;
      fgBytesRead += siz;
      fReadCalls++;
      fgReadCalls++;
 
      if (gMonitoringWriter)
         gMonitoringWriter->SendFileReadProgress(this);
      if (gPerfStats) {
         gPerfStats->FileReadEvent(this, len, start);
      }
      return kFALSE;
   }
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read a buffer from the file. This is the basic low level read operation.
/// Returns kTRUE in case of failure.
 
Bool_t TFile::ReadBuffer(char *buf, Int_t len)
{
   if (IsOpen()) {
 
      Int_t st;
      if ((st = ReadBufferViaCache(buf, len))) {
         if (st == 2)
            return kTRUE;
         return kFALSE;
      }
 
      ssize_t siz;
      Double_t start = 0;
 
      if (gPerfStats) start = TTimeStamp();
 
      while ((siz = SysRead(fD, buf, len)) < 0 && GetErrno() == EINTR)
         ResetErrno();
 
      if (siz < 0) {
         SysError("ReadBuffer", "error reading from file %s", GetName());
         return kTRUE;
      }
      if (siz != len) {
         Error("ReadBuffer", "error reading all requested bytes from file %s, got %ld of %d",
               GetName(), (Long_t)siz, len);
         return kTRUE;
      }
      fBytesRead  += siz;
      fgBytesRead += siz;
      fReadCalls++;
      fgReadCalls++;
 
      if (gMonitoringWriter)
         gMonitoringWriter->SendFileReadProgress(this);
      if (gPerfStats) {
         gPerfStats->FileReadEvent(this, len, start);
      }
      return kFALSE;
   }
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read the nbuf blocks described in arrays pos and len.
///
/// The value pos[i] is the seek position of block i of length len[i].
/// Note that for nbuf=1, this call is equivalent to TFile::ReafBuffer.
/// This function is overloaded by TNetFile, TWebFile, etc.
/// Returns kTRUE in case of failure.
 
Bool_t TFile::ReadBuffers(char *buf, Long64_t *pos, Int_t *len, Int_t nbuf)
{
   // called with buf=0, from TFileCacheRead to pass list of readahead buffers
   if (!buf) {
      for (Int_t j = 0; j < nbuf; j++) {
         if (ReadBufferAsync(pos[j], len[j])) {
             return kTRUE;
         }
      }
      return kFALSE;
   }
 
   Int_t k = 0;
   Bool_t result = kTRUE;
   TFileCacheRead *old = fCacheRead;
   fCacheRead = nullptr;
   Long64_t curbegin = pos[0];
   Long64_t cur;
   char *buf2 = nullptr;
   Int_t i = 0, n = 0;
   while (i < nbuf) {
      cur = pos[i]+len[i];
      Bool_t bigRead = kTRUE;
      if (cur -curbegin < fgReadaheadSize) {n++; i++; bigRead = kFALSE;}
      if (bigRead || (i>=nbuf)) {
         if (n == 0) {
            //if the block to read is about the same size as the read-ahead buffer
            //we read the block directly
            Seek(pos[i]);
            result = ReadBuffer(&buf[k], len[i]);
            if (result) break;
            k += len[i];
            i++;
         } else {
            //otherwise we read all blocks that fit in the read-ahead buffer
            Seek(curbegin);
            if (!buf2) buf2 = new char[fgReadaheadSize];
            //we read ahead
            Long64_t nahead = pos[i-1]+len[i-1]-curbegin;
            result = ReadBuffer(buf2, nahead);
            if (result) break;
            //now copy from the read-ahead buffer to the cache
            Int_t kold = k;
            for (Int_t j=0;j<n;j++) {
               memcpy(&buf[k],&buf2[pos[i-n+j]-curbegin],len[i-n+j]);
               k += len[i-n+j];
            }
            Int_t nok = k-kold;
            Long64_t extra = nahead-nok;
            fBytesReadExtra += extra;
            fBytesRead      -= extra;
            fgBytesRead     -= extra;
            n = 0;
         }
         curbegin = i < nbuf ? pos[i] : 0;
      }
   }
   if (buf2) delete [] buf2;
   fCacheRead = old;
   return result;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read buffer via cache.
///
/// Returns 0 if the requested block is not in the cache, 1 in case read via
/// cache was successful, 2 in case read via cache failed.
 
Int_t TFile::ReadBufferViaCache(char *buf, Int_t len)
{
   Long64_t off = GetRelOffset();
   if (fCacheRead) {
      Int_t st = fCacheRead->ReadBuffer(buf, off, len);
      if (st < 0)
         return 2;  // failure reading
      else if (st == 1) {
         // fOffset might have been changed via TFileCacheRead::ReadBuffer(), reset it
         SetOffset(off + len);
         return 1;
      }
      // fOffset might have been changed via TFileCacheRead::ReadBuffer(), reset it
      Seek(off);
   } else {
      // if write cache is active check if data still in write cache
      if (fWritable && fCacheWrite) {
         if (fCacheWrite->ReadBuffer(buf, off, len) == 0) {
            SetOffset(off + len);
            return 1;
         }
         // fOffset might have been changed via TFileCacheWrite::ReadBuffer(), reset it
         SetOffset(off);
      }
   }
 
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read the FREE linked list.
///
/// Every file has a linked list (fFree) of free segments.
/// This linked list has been written on the file via WriteFree
/// as a single data record.
 
void TFile::ReadFree()
{
   // Avoid problem with file corruption.
   if (fNbytesFree < 0 || fNbytesFree > fEND) {
      fNbytesFree = 0;
      return;
   }
   TKey *headerfree = new TKey(fSeekFree, fNbytesFree, this);
   headerfree->ReadFile();
   char *buffer = headerfree->GetBuffer();
   headerfree->ReadKeyBuffer(buffer);
   buffer = headerfree->GetBuffer();
   while (1) {
      TFree *afree = new TFree();
      afree->ReadBuffer(buffer);
      fFree->Add(afree);
      if (afree->GetLast() > fEND) break;
   }
   delete headerfree;
}
 
////////////////////////////////////////////////////////////////////////////////
/// The TProcessID with number pidf is read from this file.
///
/// If the object is not already entered in the gROOT list, it is added.
 
TProcessID  *TFile::ReadProcessID(UShort_t pidf)
{
   TProcessID *pid = nullptr;
   TObjArray *pids = GetListOfProcessIDs();
   if (pidf < pids->GetSize()) pid = (TProcessID *)pids->UncheckedAt(pidf);
   if (pid) {
      pid->CheckInit();
      return pid;
   }
 
   //check if fProcessIDs[uid] is set in file
   //if not set, read the process uid from file
   char pidname[32];
   snprintf(pidname,32,"ProcessID%d",pidf);
   pid = (TProcessID *)Get(pidname);
   if (gDebug > 0) {
      printf("ReadProcessID, name=%s, file=%s, pid=%zx\n",pidname,GetName(),(size_t)pid);
   }
   if (!pid) {
      //file->Error("ReadProcessID","Cannot find %s in file %s",pidname,file->GetName());
      return pid;
   }
 
   //check that a similar pid is not already registered in fgPIDs
   TObjArray *pidslist = TProcessID::GetPIDs();
   TIter next(pidslist);
   TProcessID *p;
   bool found = false;
 
   {
      R__READ_LOCKGUARD(ROOT::gCoreMutex);
      while ((p = (TProcessID*)next())) {
         if (!strcmp(p->GetTitle(),pid->GetTitle())) {
            found = true;
            break;
         }
      }
   }
 
   if (found) {
      delete pid;
      pids->AddAtAndExpand(p,pidf);
      p->IncrementCount();
      return p;
   }
 
   pids->AddAtAndExpand(pid,pidf);
   pid->IncrementCount();
 
   {
      R__WRITE_LOCKGUARD(ROOT::gCoreMutex);
      pidslist->Add(pid);
      Int_t ind = pidslist->IndexOf(pid);
      pid->SetUniqueID((UInt_t)ind);
   }
 
   return pid;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Attempt to recover file if not correctly closed
///
/// The function returns the number of keys that have been recovered.
/// If no keys can be recovered, the file will be declared Zombie by
/// the calling function. This function is automatically called when
/// opening a file.
/// If the file is open in read only mode, the file is not modified.
/// If open in update mode and the function finds something to recover,
/// a new directory header is written to the file. When opening the file gain
/// no message from Recover will be reported.
/// If keys have been recovered, the file is usable and you can safely
/// read the corresponding objects.
/// If the file is not usable (a zombie), you can test for this case
/// with code like:
///
/// ~~~{.cpp}
/// TFile f("myfile.root");
/// if (f.IsZombie()) {<actions to take if file is unusable>}
/// ~~~
///
/// If the file has been recovered, the bit kRecovered is set in the TFile object in memory.
/// You can test if the file has been recovered with
///
///     if (f.TestBit(TFile::kRecovered)) {... the file has been recovered}
///
/// When writing TTrees to a file, it is important to save the Tree header
/// at regular intervals (see TTree::AutoSave). If a file containing a Tree
/// is recovered, the last Tree header written to the file will be used.
/// In this case all the entries in all the branches written before writing
/// the header are valid entries.
/// One can disable the automatic recovery procedure by setting
///
///     TFile.Recover 0
///
/// in the <em>system.rootrc</em> file.
 
Int_t TFile::Recover()
{
   Short_t  keylen,cycle;
   UInt_t   datime;
   Int_t    nbytes,date,time,objlen,nwheader;
   Long64_t seekkey,seekpdir;
   char     header[1024];
   char    *buffer, *bufread;
   char     nwhc;
   Long64_t idcur = fBEGIN;
 
   Long64_t size;
   if ((size = GetSize()) == -1) {             // NOLINT: silence clang-tidy warnings
      Error("Recover", "cannot stat the file %s", GetName());
      return 0;
   }
 
   fEND = Long64_t(size);
 
   if (fWritable && !fFree) fFree  = new TList;
 
   TKey *key;
   Int_t nrecov = 0;
   nwheader = 1024;
   Int_t nread = nwheader;
 
   while (idcur < fEND) {
      Seek(idcur);                             // NOLINT: silence clang-tidy warnings
      if (idcur+nread >= fEND) nread = fEND-idcur-1;
      if (ReadBuffer(header, nread)) {         // NOLINT: silence clang-tidy warnings
         // ReadBuffer returns kTRUE in case of failure.
         Error("Recover","%s: failed to read the key data from disk at %lld.",
               GetName(),idcur);
         break;
      }
      buffer  = header;
      bufread = header;
      frombuf(buffer, &nbytes);
      if (!nbytes) {
         Error("Recover","Address = %lld\tNbytes = %d\t=====E R R O R=======", idcur, nbytes);
         break;
      }
      if (nbytes < 0) {
         idcur -= nbytes;
         if (fWritable) new TFree(fFree,idcur,idcur-nbytes-1);
         Seek(idcur);
         continue;
      }
      Version_t versionkey;
      frombuf(buffer, &versionkey);
      frombuf(buffer, &objlen);
      frombuf(buffer, &datime);
      frombuf(buffer, &keylen);
      frombuf(buffer, &cycle);
      if (versionkey > 1000) {
         frombuf(buffer, &seekkey);
         frombuf(buffer, &seekpdir);
      } else {
         Int_t skey,sdir;
         frombuf(buffer, &skey);  seekkey  = (Long64_t)skey;
         frombuf(buffer, &sdir);  seekpdir = (Long64_t)sdir;
      }
      frombuf(buffer, &nwhc);
      char *classname = nullptr;
      if (nwhc <= 0 || nwhc > 100) break;
      classname = new char[nwhc+1];
      int i, nwhci = nwhc;
      for (i = 0;i < nwhc; i++) frombuf(buffer, &classname[i]);
      classname[nwhci] = '\0';
      TDatime::GetDateTime(datime, date, time);
      TClass *tclass = TClass::GetClass(classname);
      if (seekpdir == fSeekDir && tclass && !tclass->InheritsFrom(TFile::Class())
                               && strcmp(classname,"TBasket")) {
         key = new TKey(this);
         key->ReadKeyBuffer(bufread);
         if (!strcmp(key->GetName(),"StreamerInfo")) {
            fSeekInfo = seekkey;
            SafeDelete(fInfoCache);
            fNbytesInfo = nbytes;
         } else {
            AppendKey(key);
            nrecov++;
            SetBit(kRecovered);
            Info("Recover", "%s, recovered key %s:%s at address %lld",GetName(),key->GetClassName(),key->GetName(),idcur);
         }
      }
      delete [] classname;
      idcur += nbytes;
   }
   if (fWritable) {
      Long64_t max_file_size = Long64_t(kStartBigFile);
      if (max_file_size < fEND) max_file_size = fEND+1000000000;
      TFree *last = (TFree*)fFree->Last();
      if (last) {
         last->AddFree(fFree,fEND,max_file_size);
      } else {
         new TFree(fFree,fEND,max_file_size);
      }
      if (nrecov) Write();
   }
   return nrecov;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Reopen a file with a different access mode.
///
/// For example, it is possible to change from READ to
/// UPDATE or from NEW, CREATE, RECREATE, UPDATE to READ. Thus the
/// mode argument can be either "READ" or "UPDATE". The method returns
/// 0 in case the mode was successfully modified, 1 in case the mode
/// did not change (was already as requested or wrong input arguments)
/// and -1 in case of failure, in which case the file cannot be used
/// anymore. The current directory (gFile) is changed to this file.
 
Int_t TFile::ReOpen(Option_t *mode)
{
   cd();
 
   TString opt = mode;
   opt.ToUpper();
 
   if (opt != "READ" && opt != "UPDATE") {
      Error("ReOpen", "mode must be either READ or UPDATE, not %s", opt.Data());
      return 1;
   }
 
   if (opt == fOption || (opt == "UPDATE" && fOption == "CREATE"))
      return 1;
 
   if (opt == "READ") {
      // switch to READ mode
 
      // flush data still in the pipeline and close the file
      if (IsOpen() && IsWritable()) {
         WriteStreamerInfo();
 
         // save directory key list and header
         Save();
 
         TFree *f1 = (TFree*)fFree->First();
         if (f1) {
            WriteFree();       // write free segments linked list
            WriteHeader();     // now write file header
         }
 
         FlushWriteCache();
 
         // delete free segments from free list
         fFree->Delete();
         SafeDelete(fFree);
 
         SysClose(fD);
         fD = -1;
 
         SetWritable(kFALSE);
      }
 
      // open in READ mode
      fOption = opt;    // set fOption before SysOpen() for TNetFile
#ifndef WIN32
      fD = SysOpen(fRealName, O_RDONLY, 0644);
#else
      fD = SysOpen(fRealName, O_RDONLY | O_BINARY, S_IREAD | S_IWRITE);
#endif
      if (fD == -1) {
         SysError("ReOpen", "file %s can not be opened in read mode", GetName());
         return -1;
      }
      SetWritable(kFALSE);
 
   } else {
      // switch to UPDATE mode
 
      // close readonly file
      if (IsOpen()) {
         SysClose(fD);
         fD = -1;
      }
 
      // open in UPDATE mode
      fOption = opt;    // set fOption before SysOpen() for TNetFile
#ifndef WIN32
      fD = SysOpen(fRealName, O_RDWR | O_CREAT, 0644);
#else
      fD = SysOpen(fRealName, O_RDWR | O_CREAT | O_BINARY, S_IREAD | S_IWRITE);
#endif
      if (fD == -1) {
         SysError("ReOpen", "file %s can not be opened in update mode", GetName());
         return -1;
      }
      SetWritable(kTRUE);
 
      fFree = new TList;
      if (fSeekFree > fBEGIN)
         ReadFree();
      else
         Warning("ReOpen","file %s probably not closed, cannot read free segments", GetName());
   }
 
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set position from where to start reading.
 
void TFile::SetOffset(Long64_t offset, ERelativeTo pos)
{
   switch (pos) {
      case kBeg:
         fOffset = offset + fArchiveOffset;
         break;
      case kCur:
         fOffset += offset;
         break;
      case kEnd:
         // this option is not used currently in the ROOT code
         if (fArchiveOffset)
            Error("SetOffset", "seeking from end in archive is not (yet) supported");
         fOffset = fEND + offset;  // is fEND really EOF or logical EOF?
         break;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Seek to a specific position in the file. Pos it either kBeg, kCur or kEnd.
 
void TFile::Seek(Long64_t offset, ERelativeTo pos)
{
   int whence = 0;
   switch (pos) {
      case kBeg:
         whence = SEEK_SET;
         offset += fArchiveOffset;
         break;
      case kCur:
         whence = SEEK_CUR;
         break;
      case kEnd:
         whence = SEEK_END;
         // this option is not used currently in the ROOT code
         if (fArchiveOffset)
            Error("Seek", "seeking from end in archive is not (yet) supported");
         break;
   }
   Long64_t retpos;
   if ((retpos = SysSeek(fD, offset, whence)) < 0)  // NOLINT: silence clang-tidy warnings
      SysError("Seek", "cannot seek to position %lld in file %s, retpos=%lld",
               offset, GetName(), retpos);
 
   // used by TFileCacheRead::ReadBuffer()
   fOffset = retpos;
}
 
////////////////////////////////////////////////////////////////////////////////
/// See comments for function SetCompressionSettings
///
 
void TFile::SetCompressionAlgorithm(Int_t algorithm)
{
   if (algorithm < 0 || algorithm >= ROOT::RCompressionSetting::EAlgorithm::kUndefined) algorithm = 0;
   if (fCompress < 0) {
      fCompress = 100 * algorithm + ROOT::RCompressionSetting::ELevel::kUseMin;
   } else {
      int level = fCompress % 100;
      fCompress = 100 * algorithm + level;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// See comments for function SetCompressionSettings
 
void TFile::SetCompressionLevel(Int_t level)
{
   if (level < 0) level = 0;
   if (level > 99) level = 99;
   if (fCompress < 0) {
      // if the algorithm is not defined yet use 0 as a default
      fCompress = level;
   } else {
      int algorithm = fCompress / 100;
      if (algorithm >= ROOT::RCompressionSetting::EAlgorithm::kUndefined) algorithm = 0;
      fCompress = 100 * algorithm + level;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Used to specify the compression level and algorithm.
///
/// See the TFile constructor for the details.
 
void TFile::SetCompressionSettings(Int_t settings)
{
   fCompress = settings;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set a pointer to the read cache.
///
/// <b>This relinquishes ownership</b> of the previous cache, so if you do not
/// already have a pointer to the previous cache (and there was a previous
/// cache), you ought to retrieve (and delete it if needed) using:
///
///     TFileCacheRead *older = myfile->GetCacheRead();
///
/// The action specifies how to behave when detaching a cache from the
/// the TFile.  If set to (default) kDisconnect, the contents of the cache
/// will be flushed when it is removed from the file, and it will disconnect
/// the cache object from the file.  In almost all cases, this is what you want.
/// If you want to disconnect the cache temporarily from this tree and re-attach
/// later to the same fil, you can set action to kDoNotDisconnect.  This will allow
/// things like prefetching to continue in the background while it is no longer the
/// default cache for the TTree.  Except for a few expert use cases, kDisconnect is
/// likely the correct setting.
///
/// WARNING: if action=kDoNotDisconnect, you MUST delete the cache before TFile.
///
 
void TFile::SetCacheRead(TFileCacheRead *cache, TObject* tree, ECacheAction action)
{
   if (tree) {
      if (cache) fCacheReadMap->Add(tree, cache);
      else {
         // The only addition to fCacheReadMap is via an interface that takes
         // a TFileCacheRead* so the C-cast is safe.
         TFileCacheRead* tpf = (TFileCacheRead *)fCacheReadMap->GetValue(tree);
         fCacheReadMap->Remove(tree);
         if (tpf && (tpf->GetFile() == this) && (action != kDoNotDisconnect)) tpf->SetFile(0, action);
      }
   }
   if (cache) cache->SetFile(this, action);
   else if (!tree && fCacheRead && (action != kDoNotDisconnect)) fCacheRead->SetFile(0, action);
   // For backward compatibility the last Cache set is the default cache.
   fCacheRead = cache;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set a pointer to the write cache.
///
/// If file is null the existing write cache is deleted.
 
void TFile::SetCacheWrite(TFileCacheWrite *cache)
{
   if (!cache && fCacheWrite) delete fCacheWrite;
   fCacheWrite = cache;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the size in bytes of the file header.
 
Int_t TFile::Sizeof() const
{
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Stream a TFile object.
 
void TFile::Streamer(TBuffer &b)
{
   if (b.IsReading()) {
      b.ReadVersion();  //Version_t v = b.ReadVersion();
   } else {
      b.WriteVersion(TFile::IsA());
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Increment statistics for buffer sizes of objects in this file.
 
void TFile::SumBuffer(Int_t bufsize)
{
   fWritten++;
   fSumBuffer  += double(bufsize);
   fSum2Buffer += double(bufsize) * double(bufsize); // avoid reaching MAXINT for temporary
}
 
////////////////////////////////////////////////////////////////////////////////
/// Write memory objects to this file.
///
/// Loop on all objects in memory (including subdirectories).
/// A new key is created in the KEYS linked list for each object.
/// The list of keys is then saved on the file (via WriteKeys)
/// as a single data record.
/// For values of opt see TObject::Write().
/// The directory header info is rewritten on the directory header record.
/// The linked list of FREE segments is written.
/// The file header is written (bytes 1->fBEGIN).
 
Int_t TFile::Write(const char *, Int_t opt, Int_t bufsize)
{
   if (!IsWritable()) {
      if (!TestBit(kWriteError)) {
         // Do not print the warning if we already had a SysError.
         Warning("Write", "file %s not opened in write mode", GetName());
      }
      return 0;
   }
 
   if (gDebug) {
      if (!GetTitle() || strlen(GetTitle()) == 0)
         Info("Write", "writing name = %s", GetName());
      else
         Info("Write", "writing name = %s title = %s", GetName(), GetTitle());
   }
 
   fMustFlush = kFALSE;
   Int_t nbytes = TDirectoryFile::Write(0, opt, bufsize); // Write directory tree
   WriteStreamerInfo();
   WriteFree();                       // Write free segments linked list
   WriteHeader();                     // Now write file header
   fMustFlush = kTRUE;
 
   return nbytes;
}
 
////////////////////////////////////////////////////////////////////////////////
/// One can not save a const TDirectory object.
 
Int_t TFile::Write(const char *n, Int_t opt, Int_t bufsize) const
{
   Error("Write const","A const TFile object should not be saved. We try to proceed anyway.");
   return const_cast<TFile*>(this)->Write(n, opt, bufsize);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Write a buffer to the file. This is the basic low level write operation.
/// Returns kTRUE in case of failure.
 
Bool_t TFile::WriteBuffer(const char *buf, Int_t len)
{
   if (IsOpen() && fWritable) {
 
      Int_t st;
      if ((st = WriteBufferViaCache(buf, len))) {
         if (st == 2)
            return kTRUE;
         return kFALSE;
      }
 
      ssize_t siz;
      gSystem->IgnoreInterrupt();
      while ((siz = SysWrite(fD, buf, len)) < 0 && GetErrno() == EINTR)  // NOLINT: silence clang-tidy warnings
         ResetErrno();                                                   // NOLINT: silence clang-tidy warnings
      gSystem->IgnoreInterrupt(kFALSE);
      if (siz < 0) {
         // Write the system error only once for this file
         SetBit(kWriteError); SetWritable(kFALSE);
         SysError("WriteBuffer", "error writing to file %s (%ld)", GetName(), (Long_t)siz);
         return kTRUE;
      }
      if (siz != len) {
         SetBit(kWriteError);
         Error("WriteBuffer", "error writing all requested bytes to file %s, wrote %ld of %d",
               GetName(), (Long_t)siz, len);
         return kTRUE;
      }
      fBytesWrite  += siz;
      fgBytesWrite += siz;
 
      if (gMonitoringWriter)
         gMonitoringWriter->SendFileWriteProgress(this);
 
      return kFALSE;
   }
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Write buffer via cache. Returns 0 if cache is not active, 1 in case
/// write via cache was successful, 2 in case write via cache failed.
 
Int_t TFile::WriteBufferViaCache(const char *buf, Int_t len)
{
   if (!fCacheWrite) return 0;
 
   Int_t st;
   Long64_t off = GetRelOffset();
   if ((st = fCacheWrite->WriteBuffer(buf, off, len)) < 0) {
      SetBit(kWriteError);
      Error("WriteBuffer", "error writing to cache");
      return 2;
   }
   if (st > 0) {
      // fOffset might have been changed via TFileCacheWrite::WriteBuffer(), reset it
      Seek(off + len);
      return 1;
   }
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Write FREE linked list on the file.
/// The linked list of FREE segments (fFree) is written as a single data
/// record.
 
void TFile::WriteFree()
{
   //*-* Delete old record if it exists
   if (fSeekFree != 0) {
      MakeFree(fSeekFree, fSeekFree + fNbytesFree -1);
   }
 
   Bool_t largeFile = (fEND > TFile::kStartBigFile);
 
   auto createKey = [this]() {
      Int_t nbytes = 0;
      TFree *afree;
      TIter next (fFree);
      while ((afree = (TFree*) next())) {
         nbytes += afree->Sizeof();
      }
      if (!nbytes) return (TKey*)nullptr;
 
      TKey *key = new TKey(fName,fTitle,IsA(),nbytes,this);
 
      if (key->GetSeekKey() == 0) {
         delete key;
         return (TKey*)nullptr;
      }
      return key;
   };
 
   TKey *key = createKey();
   if (!key) return;
 
   if (!largeFile && (fEND > TFile::kStartBigFile)) {
      // The free block list is large enough to bring the file to larger
      // than 2Gb, the references/offsets are now 64bits in the output
      // so we need to redo the calculation since the list of free block
      // information will not fit in the original size.
      key->Delete();
      delete key;
 
      key = createKey();
      if (!key) return;
   }
 
   Int_t nbytes = key->GetObjlen();
   char *buffer = key->GetBuffer();
   char *start = buffer;
 
   TIter next (fFree);
   TFree *afree;
   while ((afree = (TFree*) next())) {
      // We could 'waste' time here and double check that
      //   (buffer+afree->Sizeof() < (start+nbytes)
      afree->FillBuffer(buffer);
   }
   auto actualBytes = buffer-start;
   if ( actualBytes != nbytes ) {
      if (actualBytes < nbytes) {
         // Most likely one of the 'free' segment was used to store this
         // TKey, so we had one less TFree to store than we planned.
         memset(buffer,0,nbytes-actualBytes);
      } else {
         Error("WriteFree","The free block list TKey wrote more data than expected (%d vs %ld). Most likely there has been an out-of-bound write.",nbytes,(long int)actualBytes);
      }
   }
   fNbytesFree = key->GetNbytes();
   fSeekFree   = key->GetSeekKey();
   key->WriteFile();
   delete key;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Write File Header.
 
void TFile::WriteHeader()
{
   SafeDelete(fInfoCache);
   TFree *lastfree = (TFree*)fFree->Last();
   if (lastfree) fEND  = lastfree->GetFirst();
   const char *root = "root";
   char *psave  = new char[fBEGIN];
   char *buffer = psave;
   Int_t nfree  = fFree->GetSize();
   memcpy(buffer, root, 4); buffer += 4;
   Int_t version = fVersion;
   if (version <1000000 && fEND > kStartBigFile) {version += 1000000; fUnits = 8;}
   tobuf(buffer, version);
   tobuf(buffer, (Int_t)fBEGIN);
   if (version < 1000000) {
      tobuf(buffer, (Int_t)fEND);
      tobuf(buffer, (Int_t)fSeekFree);
      tobuf(buffer, fNbytesFree);
      tobuf(buffer, nfree);
      tobuf(buffer, fNbytesName);
      tobuf(buffer, fUnits);
      tobuf(buffer, fCompress);
      tobuf(buffer, (Int_t)fSeekInfo);
      tobuf(buffer, fNbytesInfo);
   } else {
      tobuf(buffer, fEND);
      tobuf(buffer, fSeekFree);
      tobuf(buffer, fNbytesFree);
      tobuf(buffer, nfree);
      tobuf(buffer, fNbytesName);
      tobuf(buffer, fUnits);
      tobuf(buffer, fCompress);
      tobuf(buffer, fSeekInfo);
      tobuf(buffer, fNbytesInfo);
   }
   if (TestBit(kReproducible))
      TUUID("00000000-0000-0000-0000-000000000000").FillBuffer(buffer);
   else
      fUUID.FillBuffer(buffer);
   Int_t nbytes  = buffer - psave;
   Seek(0);                                    // NOLINT: silence clang-tidy warnings
   WriteBuffer(psave, nbytes);                 // NOLINT: silence clang-tidy warnings
   Flush(); // NOLINT: silence clang-tidy warnings, Intentionally not conditional on fMustFlush, this is the 'obligatory' flush.
   delete [] psave;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Generate source code necessary to access the objects stored in the file.
///
/// Generate code in directory dirname for all classes specified in
/// argument classes If classes = "*" (default and currently the
/// only supported value), the function generates an include file
/// for each class in the StreamerInfo list for which a TClass
/// object does not exist.
///
/// The code generated includes:
///   - <em>dirnameProjectHeaders.h</em>, which contains one `#include` statement per generated header file
///   - <em>dirnameProjectSource.cxx</em>,which contains all the constructors and destructors implementation.
/// and one header per class that is not nested inside another class.
/// The header file name is the fully qualified name of the class after all the special characters
/// "<>,:" are replaced by underscored.  For example for std::pair<edm::Vertex,int> the file name is
/// pair_edm__Vertex_int_.h
///
/// In the generated classes, map, multimap when the first template parameter is a class
/// are replaced by a vector of pair. set and multiset when the tempalte parameter
/// is a class are replaced by a vector. This is required since we do not have the
/// code needed to order and/or compare the object of the classes.
/// This is a quick explanation of the options available:
/// Option | Details
/// -------|--------
/// new (default) | A new directory dirname is created. If dirname already exist, an error message is printed and the function returns.
/// recreate      | If dirname does not exist, it is created (like in "new"). If dirname already exist, all existing files in dirname are deleted before creating the new files.
/// update        | New classes are added to the existing directory. Existing classes with the same name are replaced by the new definition. If the directory dirname doest not exist, same effect as "new".
/// genreflex     | Use genreflex rather than rootcint to generate the dictionary.
/// par           | Create a PAR file with the minimal set of code needed to read the content of the ROOT file. The name of the PAR file is basename(dirname), with extension '.par' enforced; the PAR file will be created at dirname(dirname).
///
/// If, in addition to one of the 3 above options, the option "+" is specified,
/// the function will generate:
///   - a script called MAKEP to build the shared lib
///   - a dirnameLinkDef.h file
///   - rootcint will be run to generate a dirnameProjectDict.cxx file
///   - dirnameProjectDict.cxx will be compiled with the current options in compiledata.h
///   - a shared lib dirname.so will be created.
/// If the option "++" is specified, the generated shared lib is dynamically
/// linked with the current executable module.
/// If the option "+" and "nocompile" are specified, the utility files are generated
/// as in the option "+" but they are not executed.
/// Example:
///  file.MakeProject("demo","*","recreate++");
///   - creates a new directory demo unless it already exist
///   - clear the previous directory content
///   - generate the xxx.h files for all classes xxx found in this file
///    and not yet known to the CINT dictionary.
///   - creates the build script MAKEP
///   - creates a LinkDef.h file
///   - runs rootcint generating demoProjectDict.cxx
///   - compiles demoProjectDict.cxx into demoProjectDict.o
///   - generates a shared lib demo.so
///   - dynamically links the shared lib demo.so to the executable
///  If only the option "+" had been specified, one can still link the
///  shared lib to the current executable module with:
///
///      gSystem->load("demo/demo.so");
///
/// The following feature is not yet enabled:
/// One can restrict the list of classes to be generated by using expressions like:
///
///     classes = "Ali*" generate code only for classes starting with Ali
///     classes = "myClass" generate code for class MyClass only.
///
 
void TFile::MakeProject(const char *dirname, const char * /*classes*/,
                        Option_t *option)
{
   TString opt = option;
   opt.ToLower();
 
   void *dir = gSystem->OpenDirectory(dirname);
   TString dirpath;
 
   if (opt.Contains("update")) {
      // check that directory exist, if not create it
      if (!dir) {
         gSystem->mkdir(dirname);
      }
 
   } else if (opt.Contains("recreate")) {
      // check that directory exist, if not create it
      if (!dir) {
         if (gSystem->mkdir(dirname) < 0) {
            Error("MakeProject","cannot create directory '%s'",dirname);
            return;
         }
      }
      // clear directory
      while (dir) {
         const char *afile = gSystem->GetDirEntry(dir);
         if (!afile) break;
         if (strcmp(afile,".") == 0) continue;
         if (strcmp(afile,"..") == 0) continue;
         dirpath.Form("%s/%s",dirname,afile);
         gSystem->Unlink(dirpath);
      }
 
   } else {
      // new is assumed
      // if directory already exist, print error message and return
      if (dir) {
         Error("MakeProject","cannot create directory %s, already existing",dirname);
         gSystem->FreeDirectory(dir);
         return;
      }
      if (gSystem->mkdir(dirname) < 0) {
         Error("MakeProject","cannot create directory '%s'",dirname);
         return;
      }
   }
   if (dir) {
      gSystem->FreeDirectory(dir);
   }
 
   Bool_t genreflex = opt.Contains("genreflex");
 
   // we are now ready to generate the classes
   // loop on all TStreamerInfo
   TList *filelist = (TList*)GetStreamerInfoCache();
   if (filelist) filelist = (TList*)filelist->Clone();
   if (!filelist) {
      Error("MakeProject","file %s has no StreamerInfo", GetName());
      return;
   }
 
   TString clean_dirname(dirname);
   if (clean_dirname[clean_dirname.Length()-1]=='/') {
      clean_dirname.Remove(clean_dirname.Length()-1);
   } else if (clean_dirname[clean_dirname.Length()-1]=='\\') {
      clean_dirname.Remove(clean_dirname.Length()-1);
      if (clean_dirname[clean_dirname.Length()-1]=='\\') {
         clean_dirname.Remove(clean_dirname.Length()-1);
      }
   }
   TString subdirname( gSystem->BaseName(clean_dirname) );
   if (subdirname == "") {
      Error("MakeProject","Directory name must not be empty.");
      return;
   }
 
   // Start the source file
   TString spath; spath.Form("%s/%sProjectSource.cxx",clean_dirname.Data(),subdirname.Data());
   FILE *sfp = fopen(spath.Data(),"w");
   if (!sfp) {
      Error("MakeProject","Unable to create the source file %s.",spath.Data());
      return;
   }
   fprintf(sfp, "namespace std {}\nusing namespace std;\n");
   fprintf(sfp, "#include \"%sProjectHeaders.h\"\n\n",subdirname.Data() );
   if (!genreflex) fprintf(sfp, "#include \"%sLinkDef.h\"\n\n",subdirname.Data() );
   fprintf(sfp, "#include \"%sProjectDict.cxx\"\n\n",subdirname.Data() );
   fprintf(sfp, "struct DeleteObjectFunctor {\n");
   fprintf(sfp, "   template <typename T>\n");
   fprintf(sfp, "   void operator()(const T *ptr) const {\n");
   fprintf(sfp, "      delete ptr;\n");
   fprintf(sfp, "   }\n");
   fprintf(sfp, "   template <typename T, typename Q>\n");
   fprintf(sfp, "   void operator()(const std::pair<T,Q> &) const {\n");
   fprintf(sfp, "      // Do nothing\n");
   fprintf(sfp, "   }\n");
   fprintf(sfp, "   template <typename T, typename Q>\n");
   fprintf(sfp, "   void operator()(const std::pair<T,Q*> &ptr) const {\n");
   fprintf(sfp, "      delete ptr.second;\n");
   fprintf(sfp, "   }\n");
   fprintf(sfp, "   template <typename T, typename Q>\n");
   fprintf(sfp, "   void operator()(const std::pair<T*,Q> &ptr) const {\n");
   fprintf(sfp, "      delete ptr.first;\n");
   fprintf(sfp, "   }\n");
   fprintf(sfp, "   template <typename T, typename Q>\n");
   fprintf(sfp, "   void operator()(const std::pair<T*,Q*> &ptr) const {\n");
   fprintf(sfp, "      delete ptr.first;\n");
   fprintf(sfp, "      delete ptr.second;\n");
   fprintf(sfp, "   }\n");
   fprintf(sfp, "};\n\n");
   fclose( sfp );
 
   // loop on all TStreamerInfo classes to check for empty classes
   // and enums listed either as data member or template parameters,
   // and filter out 'duplicates' classes/streamerInfos.
   TStreamerInfo *info;
   TIter flnext(filelist);
   TList extrainfos;
   TList *list = new TList();
   while ((info = (TStreamerInfo*)flnext())) {
      if (info->IsA() != TStreamerInfo::Class()) {
         continue;
      }
      if (strstr(info->GetName(),"@@")) {
         // Skip schema evolution support streamerInfo
         continue;
      }
      TClass *cl = TClass::GetClass(info->GetName());
      if (cl) {
         if (cl->HasInterpreterInfo()) continue; // skip known classes
      }
      // Find and use the proper rules for the TStreamerInfos.
      TMakeProject::GenerateMissingStreamerInfos( &extrainfos, info->GetName() );
      TIter enext( info->GetElements() );
      TStreamerElement *el;
      ROOT::Detail::TSchemaRuleSet::TMatches rules;
      if (cl && cl->GetSchemaRules()) {
         rules = cl->GetSchemaRules()->FindRules(cl->GetName(), info->GetClassVersion());
      }
      while( (el=(TStreamerElement*)enext()) ) {
         for(auto rule : rules) {
            if( rule->IsRenameRule() || rule->IsAliasRule() )
               continue;
            // Check whether this is an 'attribute' rule.
            if ( rule->HasTarget( el->GetName()) && rule->GetAttributes()[0] != 0 ) {
               TString attr( rule->GetAttributes() );
               attr.ToLower();
               if (attr.Contains("owner")) {
                  if (attr.Contains("notowner")) {
                     el->SetBit(TStreamerElement::kDoNotDelete);
                  } else {
                     el->ResetBit(TStreamerElement::kDoNotDelete);
                  }
               }
            }
         }
         TMakeProject::GenerateMissingStreamerInfos(&extrainfos, el);
      }
      TVirtualStreamerInfo *alternate = (TVirtualStreamerInfo*)list->FindObject(info->GetName());
      if (alternate) {
         if ((info->GetClass() && info->GetClassVersion() == info->GetClass()->GetClassVersion())
             || (info->GetClassVersion() > alternate->GetClassVersion()) ) {
            list->AddAfter(alternate, info);
            list->Remove(alternate);
         } // otherwise ignore this info as not being the official one.
      } else {
         list->Add(info);
      }
   }
   // Now transfer the new StreamerInfo onto the main list and
   // to the owning list.
   TIter nextextra(&extrainfos);
   while ((info = (TStreamerInfo*)nextextra())) {
      list->Add(info);
      filelist->Add(info);
   }
 
   // loop on all TStreamerInfo classes
   TIter next(list);
   Int_t ngener = 0;
   while ((info = (TStreamerInfo*)next())) {
      if (info->IsA() != TStreamerInfo::Class()) {
         continue;
      }
      if (info->GetClassVersion()==-4) continue; // Skip outer level namespace
      TIter subnext(list);
      TStreamerInfo *subinfo;
      TList subClasses;
      Int_t len = strlen(info->GetName());
      while ((subinfo = (TStreamerInfo*)subnext())) {
         if (subinfo->IsA() != TStreamerInfo::Class()) {
            continue;
         }
         if (strncmp(info->GetName(),subinfo->GetName(),len)==0) {
            // The 'sub' StreamerInfo start with the main StreamerInfo name,
            // it subinfo is likely to be a nested class.
            const Int_t sublen = strlen(subinfo->GetName());
            if ( (sublen > len) && subinfo->GetName()[len+1]==':'
               && !subClasses.FindObject(subinfo->GetName()) /* We need to insure uniqueness */)
            {
               subClasses.Add(subinfo);
            }
         }
      }
      ngener += info->GenerateHeaderFile(clean_dirname.Data(),&subClasses,&extrainfos);
      subClasses.Clear("nodelete");
   }
   extrainfos.Clear("nodelete"); // We are done with this list.
 
   TString path;
   path.Form("%s/%sProjectHeaders.h",clean_dirname.Data(),subdirname.Data());
   FILE *allfp = fopen(path,"a");
   if (!allfp) {
      Error("MakeProject","Cannot open output file:%s\n",path.Data());
   } else {
      fprintf(allfp,"#include \"%sProjectInstances.h\"\n", subdirname.Data());
      fclose(allfp);
   }
 
   printf("MakeProject has generated %d classes in %s\n",ngener,clean_dirname.Data());
 
   // generate the shared lib
   if (!opt.Contains("+")) {
      delete list;
      filelist->Delete();
      delete filelist;
      return;
   }
 
   // Makefiles files
   FILE *fpMAKE = nullptr;
   // Create the MAKEP file by looping on all *.h files
   // delete MAKEP if it already exists
#ifdef WIN32
   path.Form("%s/makep.cmd",clean_dirname.Data());
#else
   path.Form("%s/MAKEP",clean_dirname.Data());
#endif
#ifdef R__WINGCC
   fpMAKE = fopen(path,"wb");
#else
   fpMAKE = fopen(path,"w");
#endif
   if (!fpMAKE) {
      Error("MakeProject", "cannot open file %s", path.Data());
      delete list;
      filelist->Delete();
      delete filelist;
      return;
   }
 
   // Add rootcint/genreflex statement generating ProjectDict.cxx
   FILE *ifp = nullptr;
   path.Form("%s/%sProjectInstances.h",clean_dirname.Data(),subdirname.Data());
#ifdef R__WINGCC
   ifp = fopen(path,"wb");
#else
   ifp = fopen(path,"w");
#endif
   if (!ifp) {
      Error("MakeProject", "cannot open path file %s", path.Data());
      delete list;
      filelist->Delete();
      delete filelist;
      fclose(fpMAKE);
      return;
   }
 
   if (genreflex) {
      fprintf(fpMAKE,"genreflex %sProjectHeaders.h -o %sProjectDict.cxx --comments --iocomments %s ",subdirname.Data(),subdirname.Data(),gSystem->GetIncludePath());
      path.Form("%s/%sSelection.xml",clean_dirname.Data(),subdirname.Data());
   } else {
      fprintf(fpMAKE,"rootcint -v1 -f %sProjectDict.cxx %s ", subdirname.Data(), gSystem->GetIncludePath());
      path.Form("%s/%sLinkDef.h",clean_dirname.Data(),subdirname.Data());
   }
 
   // Create the LinkDef.h or xml selection file by looping on all *.h files
   // replace any existing file.
#ifdef R__WINGCC
   FILE *fp = fopen(path,"wb");
#else
   FILE *fp = fopen(path,"w");
#endif
   if (!fp) {
      Error("MakeProject", "cannot open path file %s", path.Data());
      delete list;
      filelist->Delete();
      delete filelist;
      fclose(fpMAKE);
      fclose(ifp);
      return;
   }
   if (genreflex) {
      fprintf(fp,"<lcgdict>\n");
      fprintf(fp,"\n");
   } else {
      fprintf(fp,"#ifdef __CINT__\n");
      fprintf(fp,"\n");
   }
 
   TString tmp;
   TString instances;
   TString selections;
   next.Reset();
   while ((info = (TStreamerInfo*)next())) {
      if (info->IsA() != TStreamerInfo::Class()) {
         continue;
      }
      if (strncmp(info->GetName(), "auto_ptr<", std::char_traits<char>::length("auto_ptr<")) == 0) {
         continue;
      }
      TClass *cl = TClass::GetClass(info->GetName());
      if (cl) {
         if (cl->HasInterpreterInfo()) continue; // skip known classes
         if (cl->GetSchemaRules()) {
            auto rules = cl->GetSchemaRules()->FindRules(cl->GetName(), info->GetClassVersion());
            TString strrule;
            for(auto rule : rules) {
               strrule.Clear();
               if (genreflex) {
                  rule->AsString(strrule,"x");
                  strrule.Append("\n");
                  if ( selections.Index(strrule) == kNPOS ) {
                     selections.Append(strrule);
                  }
               } else {
                  rule->AsString(strrule);
                  if (strncmp(strrule.Data(),"type=",5)==0) {
                     strrule.Remove(0,5);
                  }
                  fprintf(fp,"#pragma %s;\n",strrule.Data());
               }
            }
         }
 
      }
      if ((info->GetClass() && info->GetClass()->GetCollectionType()) || TClassEdit::IsSTLCont(info->GetName())) {
         std::vector<std::string> inside;
         int nestedLoc;
         TClassEdit::GetSplit( info->GetName(), inside, nestedLoc, TClassEdit::kLong64 );
         Int_t stlkind =  TClassEdit::STLKind(inside[0]);
         TClass *key = TClass::GetClass(inside[1].c_str());
         if (key) {
            TString what;
            switch ( stlkind )  {
            case ROOT::kSTLmap:
            case ROOT::kSTLmultimap:
               if (TClass::GetClass(inside[1].c_str())) {
                  what = "std::pair<";
                  what += TMakeProject::UpdateAssociativeToVector( inside[1].c_str() );
                  what += ",";
                  what += TMakeProject::UpdateAssociativeToVector( inside[2].c_str() );
                  if (what[what.Length()-1]=='>') {
                     what += " >";
                  } else {
                     what += ">";
                  }
                  if (genreflex) {
                     tmp.Form("<class name=\"%s\" />\n",what.Data());
                     if ( selections.Index(tmp) == kNPOS ) {
                        selections.Append(tmp);
                     }
                     tmp.Form("template class %s;\n",what.Data());
                     if ( instances.Index(tmp) == kNPOS ) {
                        instances.Append(tmp);
                     }
                  } else {
                     what.ReplaceAll("std::","");
                     TClass *paircl = TClass::GetClass(what.Data());
                     if (!paircl || !paircl->HasInterpreterInfo()) {
                        fprintf(fp,"#pragma link C++ class %s+;\n",what.Data());
                     }
                  }
                  break;
               }
            default:
               if (TClassEdit::IsStdPair(key->GetName())) {
                  if (genreflex) {
                     tmp.Form("<class name=\"%s\" />\n",key->GetName());
                     if ( selections.Index(tmp) == kNPOS ) {
                        selections.Append(tmp);
                     }
                     tmp.Form("template class %s;\n",key->GetName());
                     if ( instances.Index(tmp) == kNPOS ) {
                        instances.Append(tmp);
                     }
                  } else {
                     what.ReplaceAll("std::","");
                     fprintf(fp,"#pragma link C++ class %s+;\n",key->GetName());
                  }
               }
               break;
            }
         }
         continue;
      }
      {
         TString what(TMakeProject::UpdateAssociativeToVector(info->GetName()).Data());
         if (genreflex) {
            tmp.Form("<class name=\"%s\" />\n",what.Data());
            if ( selections.Index(tmp) == kNPOS ) {
               selections.Append(tmp);
            }
            if (what[what.Length()-1] == '>') {
               tmp.Form("template class %s;\n",what.Data());
               if ( instances.Index(tmp) == kNPOS ) {
                  instances.Append(tmp);
               }
            }
         } else {
            what.ReplaceAll("std::","");
            fprintf(fp,"#pragma link C++ class %s+;\n",what.Data());
         }
      }
      if (genreflex) {
         // Also request the dictionary for the STL container used as members ...
         TIter eliter( info->GetElements() );
         TStreamerElement *element;
         while( (element = (TStreamerElement*)eliter() ) ) {
            if (element->GetClass() && !element->GetClass()->IsLoaded() && element->GetClass()->GetCollectionProxy()) {
               TString what( TMakeProject::UpdateAssociativeToVector(element->GetClass()->GetName()) );
               tmp.Form("<class name=\"%s\" />\n",what.Data());
               if ( selections.Index(tmp) == kNPOS ) {
                  selections.Append(tmp);
               }
               tmp.Form("template class %s;\n",what.Data());
               if ( instances.Index(tmp) == kNPOS ) {
                  instances.Append(tmp);
               }
            }
         }
      }
   }
   if (genreflex) {
      fprintf(ifp,"#ifndef PROJECT_INSTANCES_H\n");
      fprintf(ifp,"#define PROJECT_INSTANCES_H\n");
      fprintf(ifp,"%s",instances.Data());
      fprintf(ifp,"#endif\n");
      fprintf(fp,"%s",selections.Data());
      fprintf(fp,"</lcgdict>\n");
   } else {
      fprintf(fp,"#endif\n");
   }
   fclose(fp);
   fclose(ifp);
 
   // add compilation line
   TString sdirname(subdirname);
 
   TString cmd = gSystem->GetMakeSharedLib();
   TString sources = TString::Format("%sProjectSource.cxx ", sdirname.Data());
   cmd.ReplaceAll("$SourceFiles",sources.Data());
   TString object = TString::Format("%sProjectSource.", sdirname.Data());
   object.Append( gSystem->GetObjExt() );
   cmd.ReplaceAll("$ObjectFiles", object.Data());
   cmd.ReplaceAll("$IncludePath",TString(gSystem->GetIncludePath()) + " -I" + clean_dirname.Data());
   cmd.ReplaceAll("$SharedLib",sdirname+"."+gSystem->GetSoExt());
   cmd.ReplaceAll("$LinkedLibs",gSystem->GetLibraries("","SDL"));
   cmd.ReplaceAll("$LibName",sdirname);
   cmd.ReplaceAll("$BuildDir",".");
   TString sOpt;
   TString rootbuild = ROOTBUILD;
   if (rootbuild.Index("debug",0,TString::kIgnoreCase)==kNPOS) {
      sOpt = gSystem->GetFlagsOpt();
   } else {
      sOpt = gSystem->GetFlagsDebug();
   }
#if defined(_MSC_VER) && defined(_DEBUG)
   // if ROOT is build in debug mode, ACLiC must also build in debug mode
   // for compatibility reasons
   sOpt = gSystem->GetFlagsDebug();
#endif
   cmd.ReplaceAll("$Opt", sOpt);
 
   if (genreflex) {
      fprintf(fpMAKE,"-s %sSelection.xml \n",subdirname.Data());
   } else {
      fprintf(fpMAKE,"%sProjectHeaders.h ",subdirname.Data());
      fprintf(fpMAKE,"%sLinkDef.h \n",subdirname.Data());
   }
 
   fprintf(fpMAKE,"%s\n",cmd.Data());
 
   printf("%s/MAKEP file has been generated\n", clean_dirname.Data());
 
   fclose(fpMAKE);
 
 
   if (!opt.Contains("nocompilation")) {
      // now execute the generated script compiling and generating the shared lib
      path = gSystem->WorkingDirectory();
      gSystem->ChangeDirectory(clean_dirname.Data());
#ifndef WIN32
      gSystem->Exec("chmod +x MAKEP");
      int res = !gSystem->Exec("./MAKEP");
#else
      // not really needed for Windows but it would work both both Unix and NT
      chmod("makep.cmd",00700);
      int res = !gSystem->Exec("MAKEP");
#endif
      gSystem->ChangeDirectory(path);
      path.Form("%s/%s.%s",clean_dirname.Data(),subdirname.Data(),gSystem->GetSoExt());
      if (res) printf("Shared lib %s has been generated\n",path.Data());
 
      //dynamically link the generated shared lib
      if (opt.Contains("++")) {
         res = !gSystem->Load(path);
         if (res) printf("Shared lib %s has been dynamically linked\n",path.Data());
      }
   }
 
   delete list;
   filelist->Delete();
   delete filelist;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Read the list of StreamerInfo from this file.
///
/// The key with name holding the list of TStreamerInfo objects is read.
/// The corresponding TClass objects are updated.
/// Note that this function is not called if the static member fgReadInfo is false.
/// (see TFile::SetReadStreamerInfo)
 
void TFile::ReadStreamerInfo()
{
   auto listRetcode = GetStreamerInfoListImpl(/*lookupSICache*/ true);  // NOLINT: silence clang-tidy warnings
   TList *list = listRetcode.fList;
   auto retcode = listRetcode.fReturnCode;
   if (!list) {
      if (retcode) MakeZombie();
      return;
   }
 
   list->SetOwner(kFALSE);
 
   if (gDebug > 0) Info("ReadStreamerInfo", "called for file %s",GetName());
 
   TStreamerInfo *info;
 
   Int_t version = fVersion;
   if (version > 1000000) version -= 1000000;
   if (version < 53419 || (59900 < version && version < 59907)) {
      // We need to update the fCheckSum field of the TStreamerBase.
 
      // loop on all TStreamerInfo classes
      TObjLink *lnk = list->FirstLink();
      while (lnk) {
         info = (TStreamerInfo*)lnk->GetObject();
         if (!info || info->IsA() != TStreamerInfo::Class()) {
            lnk = lnk->Next();
            continue;
         }
         TIter next(info->GetElements());
         TStreamerElement *element;
         while ((element = (TStreamerElement*) next())) {
            TStreamerBase *base = dynamic_cast<TStreamerBase*>(element);
            if (!base) continue;
            if (base->GetBaseCheckSum() != 0) continue;
            TStreamerInfo *baseinfo = (TStreamerInfo*)list->FindObject(base->GetName());
            if (baseinfo) {
               base->SetBaseCheckSum(baseinfo->GetCheckSum());
            }
         }
         lnk = lnk->Next();
      }
   }
 
   std::vector<Int_t> si_uids;
   // loop on all TStreamerInfo classes
   for (int mode=0;mode<2; ++mode) {
      // In order for the collection proxy to be initialized properly, we need
      // to setup the TStreamerInfo for non-stl class before the stl classes.
      TObjLink *lnk = list->FirstLink();
      while (lnk) {
         info = (TStreamerInfo*)lnk->GetObject();
         if (!info) {
            lnk = lnk->Next();
            continue;
         }
         if (info->IsA() != TStreamerInfo::Class()) {
            if (mode==1) {
               TObject *obj = (TObject*)info;
               if (strcmp(obj->GetName(),"listOfRules")==0) {
#if 0
                  // Completely ignore the rules for now.
                  TList *listOfRules = (TList*)obj;
                  TObjLink *rulelnk = listOfRules->FirstLink();
                  while (rulelnk) {
                     TObjString *rule = (TObjString*)rulelnk->GetObject();
                     TClass::AddRule( rule->String().Data() );
                     rulelnk = rulelnk->Next();
                  }
#endif
               } else {
                  Warning("ReadStreamerInfo","%s has a %s in the list of TStreamerInfo.", GetName(), info->IsA()->GetName());
               }
               info->SetBit(kCanDelete);
            }
            lnk = lnk->Next();
            continue;
         }
         // This is a quick way (instead of parsing the name) to see if this is
         // the description of an STL container.
         if (info->GetElements()==0) {
            Warning("ReadStreamerInfo","The StreamerInfo for %s does not have a list of elements.",info->GetName());
            lnk = lnk->Next();
            continue;
         }
         TObject *element = info->GetElements()->UncheckedAt(0);
         Bool_t isstl = element && strcmp("This",element->GetName())==0;
 
         if ( (!isstl && mode ==0) || (isstl && mode ==1) ) {
               // Skip the STL container the first time around
               // Skip the regular classes the second time around;
            info->BuildCheck(this);
            Int_t uid = info->GetNumber();
            Int_t asize = fClassIndex->GetSize();
            if (uid >= asize && uid <100000) fClassIndex->Set(2*asize);
            if (uid >= 0 && uid < fClassIndex->GetSize()) {
               si_uids.push_back(uid);
               fClassIndex->fArray[uid] = 1;
            }
            else if (!isstl && !info->GetClass()->IsSyntheticPair()) {
               printf("ReadStreamerInfo, class:%s, illegal uid=%d\n",info->GetName(),uid);
            }
            if (gDebug > 0) printf(" -class: %s version: %d info read at slot %d\n",info->GetName(), info->GetClassVersion(),uid);
         }
         lnk = lnk->Next();
      }
   }
   fClassIndex->fArray[0] = 0;
   list->Clear();  //this will delete all TStreamerInfo objects with kCanDelete bit set
   delete list;
 
   // We are done processing the record, let future calls and other threads that it
   // has been done.
   fgTsSIHashes.Insert(listRetcode.fHash, std::move(si_uids));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Specify if the streamerinfos must be read at file opening.
///
/// If fgReadInfo is true (default) TFile::ReadStreamerInfo is called
///  when opening the file.
/// It may be interesting to set fgReadInfo to false to speedup the file
/// opening time or in case libraries containing classes referenced
/// by the file have not yet been loaded.
/// if fgReadInfo is false, one can still read the StreamerInfo with
///    myfile.ReadStreamerInfo();
 
void TFile::SetReadStreamerInfo(Bool_t readinfo)
{
   fgReadInfo = readinfo;
}
 
////////////////////////////////////////////////////////////////////////////////
/// If the streamerinfos are to be read at file opening.
///
/// See TFile::SetReadStreamerInfo for more documentation.
 
Bool_t TFile::GetReadStreamerInfo()
{
   return fgReadInfo;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Show the StreamerInfo of all classes written to this file.
 
void TFile::ShowStreamerInfo()
{
   TList *list = GetStreamerInfoList();
   if (!list) return;
 
   list->ls();
   delete list;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Check if the ProcessID pidd is already in the file,
/// if not, add it and return the index  number in the local file list.
 
UShort_t TFile::WriteProcessID(TProcessID *pidd)
{
   TProcessID *pid = pidd;
   if (!pid) pid = TProcessID::GetPID();
   TObjArray *pids = GetListOfProcessIDs();
   Int_t npids = GetNProcessIDs();
   for (Int_t i=0;i<npids;i++) {
      if (pids->At(i) == pid) return (UShort_t)i;
   }
 
   this->SetBit(TFile::kHasReferences);
   pids->AddAtAndExpand(pid,npids);
   pid->IncrementCount();
   char name[32];
   snprintf(name,32,"ProcessID%d",npids);
   this->WriteTObject(pid,name);
   this->IncrementProcessIDs();
   if (gDebug > 0) {
      Info("WriteProcessID", "name=%s, file=%s", name, GetName());
   }
   return (UShort_t)npids;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Write the list of TStreamerInfo as a single object in this file
/// The class Streamer description for all classes written to this file
/// is saved. See class TStreamerInfo.
 
void TFile::WriteStreamerInfo()
{
   //if (!gFile) return;
   if (!fWritable) return;
   if (!fClassIndex) return;
   if (fIsPcmFile) return; // No schema evolution for ROOT PCM files.
   if (fClassIndex->fArray[0] == 0
       && fSeekInfo != 0) {
      // No need to update the index if no new classes added to the file
      // but write once an empty StreamerInfo list to mark that there is no need
      // for StreamerInfos in this file.
      return;
   }
   if (gDebug > 0) Info("WriteStreamerInfo", "called for file %s",GetName());
 
   SafeDelete(fInfoCache);
 
   // build a temporary list with the marked files
   TIter next(gROOT->GetListOfStreamerInfo());
   TStreamerInfo *info;
   TList list;
   TList listOfRules;
   listOfRules.SetOwner(kTRUE);
   listOfRules.SetName("listOfRules");
   std::set<TClass*> classSet;
 
   while ((info = (TStreamerInfo*)next())) {
      Int_t uid = info->GetNumber();
      if (fClassIndex->fArray[uid]) {
         list.Add(info);
         if (gDebug > 0) printf(" -class: %s info number %d saved\n",info->GetName(),uid);
 
         // Add the IO customization rules to the list to be saved for the underlying
         // class but make sure to add them only once.
         TClass *clinfo = info->GetClass();
         if (clinfo && clinfo->GetSchemaRules()) {
            if ( classSet.find( clinfo ) == classSet.end() ) {
               if (gDebug > 0) printf(" -class: %s stored the I/O customization rules\n",info->GetName());
 
               TObjArrayIter it( clinfo->GetSchemaRules()->GetRules() );
               ROOT::TSchemaRule *rule;
               while( (rule = (ROOT::TSchemaRule*)it.Next()) ) {
                  TObjString *obj = new TObjString();
                  rule->AsString(obj->String());
                  listOfRules.Add(obj);
               }
               classSet.insert(clinfo);
            }
         }
      }
   }
 
   // Write the StreamerInfo list even if it is empty.
   fClassIndex->fArray[0] = 2; //to prevent adding classes in TStreamerInfo::TagFile
 
   if (listOfRules.GetEntries()) {
      // Only add the list of rules if we have something to say.
      list.Add(&listOfRules);
   }
 
   //free previous StreamerInfo record
   if (fSeekInfo) MakeFree(fSeekInfo,fSeekInfo+fNbytesInfo-1);
   //Create new key
   TKey key(&list,"StreamerInfo",GetBestBuffer(), this);
   fKeys->Remove(&key);
   fSeekInfo   = key.GetSeekKey();
   fNbytesInfo = key.GetNbytes();
   SumBuffer(key.GetObjlen());
   key.WriteFile(0);
 
   fClassIndex->fArray[0] = 0;
 
   list.RemoveLast(); // remove the listOfRules.
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a file for reading through the file cache.
///
/// The file will be downloaded to the cache and opened from there.
/// If the download fails, it will be opened remotely.
/// The file will be downloaded to the directory specified by SetCacheFileDir().
 
TFile *TFile::OpenFromCache(const char *name, Option_t *, const char *ftitle,
                   Int_t compress, Int_t netopt)
{
   TFile *f = nullptr;
 
   if (fgCacheFileDir == "") {
      ::Warning("TFile::OpenFromCache",
                "you want to read through a cache, but you have no valid cache "
                "directory set - reading remotely");
      ::Info("TFile::OpenFromCache", "set cache directory using TFile::SetCacheFileDir()");
   } else {
      TUrl fileurl(name);
 
      if ((!strcmp(fileurl.GetProtocol(), "file"))) {
         // it makes no sense to read local files through a file cache
         if (!fgCacheFileForce)
            ::Warning("TFile::OpenFromCache",
                      "you want to read through a cache, but you are reading "
                      "local files - CACHEREAD disabled");
      } else {
         // this is a remote file and worthwhile to be put into the local cache
         // now create cachepath to put it
         TString cachefilepath;
         TString cachefilepathbasedir;
         cachefilepath = fgCacheFileDir;
         cachefilepath += fileurl.GetFile();
         cachefilepathbasedir = gSystem->GetDirName(cachefilepath);
         if ((gSystem->mkdir(cachefilepathbasedir, kTRUE) < 0) &&
               (gSystem->AccessPathName(cachefilepathbasedir, kFileExists))) {
            ::Warning("TFile::OpenFromCache","you want to read through a cache, but I "
                      "cannot create the directory %s - CACHEREAD disabled",
                      cachefilepathbasedir.Data());
         } else {
            // check if this should be a zip file
            if (strlen(fileurl.GetAnchor())) {
               // remove the anchor and change the target name
               cachefilepath += "__";
               cachefilepath += fileurl.GetAnchor();
               fileurl.SetAnchor("");
            }
            if (strstr(name,"zip=")) {
               // filter out this option and change the target cache name
               TString urloptions = fileurl.GetOptions();
               TString newoptions;
               TObjArray *objOptions = urloptions.Tokenize("&");
               Int_t optioncount = 0;
               TString zipname;
               for (Int_t n = 0; n < objOptions->GetEntries(); n++) {
                  TString loption = ((TObjString*)objOptions->At(n))->GetName();
                  TObjArray *objTags = loption.Tokenize("=");
                  if (objTags->GetEntries() == 2) {
                     TString key   = ((TObjString*)objTags->At(0))->GetName();
                     TString value = ((TObjString*)objTags->At(1))->GetName();
                     if (key.CompareTo("zip", TString::kIgnoreCase)) {
                        if (optioncount!=0) {
                           newoptions += "&";
                        }
                        newoptions += key;
                        newoptions += "=";
                        newoptions += value;
                        ++optioncount;
                     } else {
                        zipname = value;
                     }
                  }
                  delete objTags;
               }
               delete objOptions;
               fileurl.SetOptions(newoptions.Data());
               cachefilepath += "__";
               cachefilepath += zipname;
               fileurl.SetAnchor("");
            }
 
            Bool_t need2copy = kFALSE;
 
            // check if file is in the cache
            Long_t id;
            Long64_t size;
            Long_t flags;
            Long_t modtime;
            if (!gSystem->GetPathInfo(cachefilepath, &id, &size, &flags, &modtime)) {
               // file is in the cache
               if (!fgCacheFileDisconnected) {
                  char cacheblock[256];
                  char remotblock[256];
                  // check the remote file for it's size and compare some magic bytes
                  TString cfurl;
                  cfurl = cachefilepath;
                  cfurl += "?filetype=raw";
                  TUrl rurl(name);
                  TString ropt = rurl.GetOptions();
                  ropt += "&filetype=raw";
                  rurl.SetOptions(ropt);
 
                  Bool_t forcedcache = fgCacheFileForce;
                  fgCacheFileForce = kFALSE;
 
                  TFile *cachefile = TFile::Open(cfurl, "READ");
                  TFile *remotfile = TFile::Open(rurl.GetUrl(), "READ");
 
                  fgCacheFileForce = forcedcache;
 
                  if (!cachefile) {
                     need2copy = kTRUE;
                     ::Error("TFile::OpenFromCache",
                             "cannot open the cache file to check cache consistency");
                     return nullptr;
                  }
 
                  if (!remotfile) {
                     ::Error("TFile::OpenFromCache",
                             "cannot open the remote file to check cache consistency");
                     return nullptr;
                  }
 
                  cachefile->Seek(0);
                  remotfile->Seek(0);
 
                  if ((!cachefile->ReadBuffer(cacheblock,256)) &&
                      (!remotfile->ReadBuffer(remotblock,256))) {
                     if (memcmp(cacheblock, remotblock, 256)) {
                        ::Warning("TFile::OpenFromCache", "the header of the cache file "
                                  "differs from the remote file - forcing an update");
                        need2copy = kTRUE;
                     }
                  } else {
                     ::Warning("TFile::OpenFromCache", "the header of the cache and/or "
                               "remote file are not readable - forcing an update");
                     need2copy = kTRUE;
                  }
 
                  delete remotfile;
                  delete cachefile;
               }
            } else {
               need2copy = kTRUE;
            }
 
            // try to fetch the file (disable now the forced caching)
            Bool_t forcedcache = fgCacheFileForce;
            fgCacheFileForce = kFALSE;
            if (need2copy) {
               const auto cachefilepathtmp = cachefilepath + std::to_string(gSystem->GetPid()) + ".tmp";
               if (!TFile::Cp(name, cachefilepathtmp)) {
                  ::Warning("TFile::OpenFromCache",
                            "you want to read through a cache, but I "
                            "cannot make a cache copy of %s - CACHEREAD disabled",
                            cachefilepathbasedir.Data());
                  fgCacheFileForce = forcedcache;
                  return nullptr;
               }
               if (gSystem->AccessPathName(cachefilepath)) // then file _does not_ exist (weird convention)
                  gSystem->Rename(cachefilepathtmp, cachefilepath);
               else // another process or thread already wrote a file with the same name while we were copying it
                  gSystem->Unlink(cachefilepathtmp);
            }
            fgCacheFileForce = forcedcache;
            ::Info("TFile::OpenFromCache", "using local cache copy of %s [%s]", name, cachefilepath.Data());
            // finally we have the file and can open it locally
            fileurl.SetProtocol("file");
            fileurl.SetFile(cachefilepath);
 
            TString tagfile;
            tagfile = cachefilepath;
            tagfile += ".ROOT.cachefile";
            // we symlink this file as a ROOT cached file
            gSystem->Symlink(gSystem->BaseName(cachefilepath), tagfile);
            return TFile::Open(fileurl.GetUrl(), "READ", ftitle, compress, netopt);
         }
      }
   }
 
   // Failed
   return f;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create / open a file
///
/// The type of the file can be either a
/// TFile, TNetFile, TWebFile or any TFile derived class for which an
/// plugin library handler has been registered with the plugin manager
/// (for the plugin manager see the TPluginManager class). The returned
/// type of TFile depends on the file name specified by 'url'.
/// If 'url' is a '|'-separated list of file URLs, the 'URLs' are tried
/// sequentially in the specified order until a successful open.
/// If the file starts with "root:", "roots:" or "rootk:" a TNetFile object
/// will be returned, with "http:" a TWebFile, with "file:" a local TFile,
/// etc. (see the list of TFile plugin handlers in $ROOTSYS/etc/system.rootrc
/// for regular expressions that will be checked) and as last a local file will
/// be tried.
/// Before opening a file via TNetFile a check is made to see if the URL
/// specifies a local file. If that is the case the file will be opened
/// via a normal TFile. To force the opening of a local file via a
/// TNetFile use either TNetFile directly or specify as host "localhost".
/// The netopt argument is only used by TNetFile. For the meaning of the
/// options and other arguments see the constructors of the individual
/// file classes. In case of error, it returns a nullptr.
///
/// For TFile implementations supporting asynchronous file open, see
/// TFile::AsyncOpen(...), it is possible to request a timeout with the
/// option <b>`TIMEOUT=<secs>`</b>: the timeout must be specified in seconds and
/// it will be internally checked with granularity of one millisec.
/// For remote files there is the option: <b>CACHEREAD</b> opens an existing
/// file for reading through the file cache. The file will be downloaded to
/// the cache and opened from there. If the download fails, it will be opened remotely.
/// The file will be downloaded to the directory specified by SetCacheFileDir().
///
/// *The caller is responsible for deleting the pointer.*
/// In READ mode, a nullptr is returned if the file does not exist or cannot be opened.
/// In CREATE mode, a nullptr is returned if the file already exists or cannot be created.
/// In RECREATE mode, a nullptr is returned if the file can not be created.
/// In UPDATE mode, a nullptr is returned if the file cannot be created or opened.
 
TFile *TFile::Open(const char *url, Option_t *options, const char *ftitle,
                   Int_t compress, Int_t netopt)
{
   TPluginHandler *h;
   TFile *f = nullptr;
   EFileType type = kFile;
 
   // Check input
   if (!url || strlen(url) <= 0) {
      ::Error("TFile::Open", "no url specified");
      return f;
   }
 
   TString expandedUrl(url);
   gSystem->ExpandPathName(expandedUrl);
 
#ifdef R__UNIX
   // If URL is a file on an EOS FUSE mount, attempt redirection to XRootD protocol.
   if (gEnv->GetValue("TFile.CrossProtocolRedirects", 1) == 1) {
      TUrl fileurl(expandedUrl, /* default is file */ kTRUE);
      if (strcmp(fileurl.GetProtocol(), "file") == 0) {
         ssize_t len = getxattr(fileurl.GetFile(), "eos.url.xroot", nullptr, 0);
         if (len > 0) {
            std::string xurl(len, 0);
            std::string fileNameFromUrl{fileurl.GetFile()};
            if (getxattr(fileNameFromUrl.c_str(), "eos.url.xroot", &xurl[0], len) == len) {
               // Sometimes the `getxattr` call may return an invalid URL due
               // to the POSIX attribute not being yet completely filled by EOS.
               if (auto baseName = fileNameFromUrl.substr(fileNameFromUrl.find_last_of("/") + 1);
                   std::equal(baseName.crbegin(), baseName.crend(), xurl.crbegin())) {
                  if ((f = TFile::Open(xurl.c_str(), options, ftitle, compress, netopt))) {
                     if (!f->IsZombie()) {
                        return f;
                     } else {
                        delete f;
                        f = nullptr;
                     }
                  }
               }
            }
         }
      }
   }
#endif
 
   // If a timeout has been specified extract the value and try to apply it (it requires
   // support for asynchronous open, though; the following is completely transparent if
   // such support if not available for the required protocol)
   TString opts(options);
   opts.ToUpper();
   Int_t ito = opts.Index("TIMEOUT=");
   if (ito != kNPOS) {
      TString sto = opts(ito + std::char_traits<char>::length("TIMEOUT="), opts.Length());
      while (!(sto.IsDigit()) && !(sto.IsNull())) { sto.Remove(sto.Length()-1,1); }
      if (!(sto.IsNull())) {
         // Timeout in millisecs
         Int_t toms = sto.Atoi() * 1000;
         if (gDebug > 0) ::Info("TFile::Open", "timeout of %d millisec requested", toms);
         // Remove from the options field
         sto.Insert(0, "TIMEOUT=");
         opts.ReplaceAll(sto, "");
         // Asynchronous open
         TFileOpenHandle *fh = TFile::AsyncOpen(expandedUrl, opts, ftitle, compress, netopt);
         // Check the result in steps of 1 millisec
         TFile::EAsyncOpenStatus aos = TFile::kAOSNotAsync;
         aos = TFile::GetAsyncOpenStatus(fh);
         Int_t xtms = toms;
         while (aos == TFile::kAOSInProgress && xtms > 0) {
            gSystem->Sleep(1);
            xtms -= 1;
            aos = TFile::GetAsyncOpenStatus(fh);
         }
         if (aos == TFile::kAOSNotAsync || aos == TFile::kAOSSuccess) {
            // Do open the file now
            f = TFile::Open(fh);
            if (gDebug > 0) {
               if (aos == TFile::kAOSSuccess)
                  ::Info("TFile::Open", "waited %d millisec for asynchronous open", toms - xtms);
               else
                  ::Info("TFile::Open", "timeout option not supported (requires asynchronous"
                                        " open support)");
            }
         } else {
            if (xtms <= 0)
               ::Error("TFile::Open", "timeout expired while opening '%s'", expandedUrl.Data());
            // Cleanup the request
            SafeDelete(fh);
         }
         // Done
         return f;
      } else {
         ::Warning("TFile::Open", "incomplete 'TIMEOUT=' option specification - ignored");
         opts.ReplaceAll("TIMEOUT=", "");
      }
   }
 
   // We will use this from now on
   const char *option = opts;
 
   // Many URLs? Redirect output and print errors in case of global failure
   TString namelist(expandedUrl);
   Ssiz_t ip = namelist.Index("|");
   Bool_t rediroutput = (ip != kNPOS &&
                         ip != namelist.Length()-1 && gDebug <= 0) ? kTRUE : kFALSE;
   RedirectHandle_t rh;
   if (rediroutput) {
      TString outf = ".TFileOpen_";
      FILE *fout = gSystem->TempFileName(outf);
      if (fout) {
         fclose(fout);
         gSystem->RedirectOutput(outf, "w", &rh);
      }
   }
 
   // Try sequentially all names in 'names'
   TString name, n;
   Ssiz_t from = 0;
   while (namelist.Tokenize(n, from, "|") && !f) {
 
      // check if we read through a file cache
      if (!strcasecmp(option, "CACHEREAD") ||
         ((!strcasecmp(option,"READ") || !option[0]) && fgCacheFileForce)) {
         // Try opening the file from the cache
         if ((f = TFile::OpenFromCache(n, option, ftitle, compress, netopt)))
            return f;
      }
 
      IncrementFileCounter();
 
      // change names to be recognized by the plugin manager
      // e.g. /protocol/path/to/file.root -> protocol:/path/to/file.root
      TUrl urlname(n, kTRUE);
      name = urlname.GetUrl();
      // Check first if a pending async open request matches this one
      if (fgAsyncOpenRequests && (fgAsyncOpenRequests->GetSize() > 0)) {
         TIter nxr(fgAsyncOpenRequests);
         TFileOpenHandle *fh = nullptr;
         while ((fh = (TFileOpenHandle *)nxr()))
            if (fh->Matches(name))
               return TFile::Open(fh);
      }
 
      TString urlOptions(urlname.GetOptions());
      if (urlOptions.BeginsWith("pmerge") || urlOptions.Contains("&pmerge") || urlOptions.Contains(" pmerge")) {
         type = kMerge;
 
         // Pass the full name including the url options:
         f = (TFile*) gROOT->ProcessLineFast(TString::Format("new TParallelMergingFile(\"%s\",\"%s\",\"%s\",%d)",n.Data(),option,ftitle,compress));
 
      } else {
         // Resolve the file type; this also adjusts names
         TString lfname = gEnv->GetValue("Path.Localroot", "");
         type = GetType(name, option, &lfname);
 
         if (type == kLocal) {
 
            // Local files
            if (lfname.IsNull()) {
               urlname.SetHost("");
               urlname.SetProtocol("file");
               lfname = urlname.GetUrl();
            }
            f = new TFile(lfname.Data(), option, ftitle, compress);
 
         } else if (type == kNet) {
 
            // Network files
            if ((h = gROOT->GetPluginManager()->FindHandler("TFile", name))) {
               if (h->LoadPlugin() == -1)
                  return nullptr;
               f = (TFile*) h->ExecPlugin(5, name.Data(), option, ftitle, compress, netopt);
            }
 
         } else if (type == kWeb) {
 
            // Web files
            if ((h = gROOT->GetPluginManager()->FindHandler("TFile", name))) {
               if (h->LoadPlugin() == -1)
                  return nullptr;
               f = (TFile*) h->ExecPlugin(2, name.Data(), option);
            }
 
         } else if (type == kFile) {
 
            // 'file:' protocol
            if ((h = gROOT->GetPluginManager()->FindHandler("TFile", name)) &&
                h->LoadPlugin() == 0) {
               name.ReplaceAll("file:", "");
               f = (TFile*) h->ExecPlugin(4, name.Data(), option, ftitle, compress);
            } else
               f = new TFile(name.Data(), option, ftitle, compress);
 
         } else {
 
            // no recognized specification: try the plugin manager
            if ((h = gROOT->GetPluginManager()->FindHandler("TFile", name.Data()))) {
               if (h->LoadPlugin() == -1)
                  return nullptr;
               TClass *cl = TClass::GetClass(h->GetClass());
               if (cl && cl->InheritsFrom("TNetFile"))
                  f = (TFile*) h->ExecPlugin(5, name.Data(), option, ftitle, compress, netopt);
               else
                  f = (TFile*) h->ExecPlugin(4, name.Data(), option, ftitle, compress);
            } else {
               // Just try to open it locally but via TFile::Open, so that we pick-up the correct
               // plug-in in the case file name contains information about a special backend (e.g.)
               if (strcmp(name, urlname.GetFileAndOptions()) != 0)
                  f = TFile::Open(urlname.GetFileAndOptions(), option, ftitle, compress);
            }
         }
      }
 
      if (f && f->IsZombie()) {
         TString newUrl = f->GetNewUrl();
         delete f;
         if( newUrl.Length() && (newUrl != name) && gEnv->GetValue("TFile.CrossProtocolRedirects", 1) )
            f = TFile::Open( newUrl, option, ftitle, compress );
         else
            f = nullptr;
      }
   }
 
   if (rediroutput) {
      // Restore output to stdout
      gSystem->RedirectOutput(0, "", &rh);
      // If we failed print error messages
      if (!f)
         gSystem->ShowOutput(&rh);
      // Remove the file
      gSystem->Unlink(rh.fFile);
   }
 
   // if the file is writable, non local, and not opened in raw mode
   // we create a default write cache of 512 KBytes
   if (type != kLocal && type != kFile &&
       f && f->IsWritable() && !f->IsRaw()) {
      new TFileCacheWrite(f, 1);
   }
 
   return f;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Submit an asynchronous open request.
 
/// See TFile::Open(const char *, ...) for an
/// explanation of the arguments. A handler is returned which is to be passed
/// to TFile::Open(TFileOpenHandle *) to get the real TFile instance once
/// the file is open.
/// This call never blocks and it is provided to allow parallel submission
/// of file opening operations expected to take a long time.
/// TFile::Open(TFileOpenHandle *) may block if the file is not yet ready.
/// The sequence
///
///     TFile::Open(TFile::AsyncOpen(const char *, ...))
///
/// is equivalent to
///
///     TFile::Open(const char *, ...)
///
/// To be effective, the underlying TFile implementation must be able to
/// support asynchronous open functionality. Currently, only TNetXNGFile
/// supports it. If the functionality is not implemented, this call acts
/// transparently by returning an handle with the arguments for the
/// standard synchronous open run by TFile::Open(TFileOpenHandle *).
/// The retuned handle will be adopted by TFile after opening completion
/// in TFile::Open(TFileOpenHandle *); if opening is not finalized the
/// handle must be deleted by the caller.
 
TFileOpenHandle *TFile::AsyncOpen(const char *url, Option_t *option,
                                  const char *ftitle, Int_t compress,
                                  Int_t netopt)
{
   TFileOpenHandle *fh = nullptr;
   TFile *f = nullptr;
   Bool_t notfound = kTRUE;
 
   // Check input
   if (!url || strlen(url) <= 0) {
      ::Error("TFile::AsyncOpen", "no url specified");
      return fh;
   }
 
   // Many URLs? Redirect output and print errors in case of global failure
   TString namelist(url);
   gSystem->ExpandPathName(namelist);
   Ssiz_t ip = namelist.Index("|");
   Bool_t rediroutput = (ip != kNPOS &&
                         ip != namelist.Length()-1 && gDebug <= 0) ? kTRUE : kFALSE;
   RedirectHandle_t rh;
   if (rediroutput) {
      TString outf = ".TFileAsyncOpen_";
      FILE *fout = gSystem->TempFileName(outf);
      if (fout) {
         fclose(fout);
         gSystem->RedirectOutput(outf, "w", &rh);
      }
   }
 
   // Try sequentially all names in 'names'
   TString name, n;
   Ssiz_t from = 0;
   while (namelist.Tokenize(n, from, "|") && !f) {
 
      // change names to be recognized by the plugin manager
      // e.g. /protocol/path/to/file.root -> protocol:/path/to/file.root
      TUrl urlname(n, kTRUE);
      name = urlname.GetUrl();
 
      // Resolve the file type; this also adjusts names
      EFileType type = GetType(name, option);
 
      TPluginHandler *h = nullptr;
 
      // Here we send the asynchronous request if the functionality is implemented
      if (type == kNet) {
         // Network files
         if ((h = gROOT->GetPluginManager()->FindHandler("TFile", name)) &&
            !strcmp(h->GetClass(),"TNetXNGFile")
            && h->LoadPlugin() == 0) {
            f = (TFile*) h->ExecPlugin(6, name.Data(), option, ftitle, compress, netopt, kTRUE);
            notfound = kFALSE;
         }
      }
   }
 
   if (rediroutput) {
      // Restore output to stdout
      gSystem->RedirectOutput(0, "", &rh);
      // If we failed print error messages
      if (!notfound && !f)
         gSystem->ShowOutput(&rh);
      // Remove the file
      gSystem->Unlink(rh.fFile);
   }
 
   // Make sure that no error occurred
   if (notfound) {
      SafeDelete(f);
      // Save the arguments in the handler, so that a standard open can be
      // attempted later on
      fh = new TFileOpenHandle(name, option, ftitle, compress, netopt);
   } else if (f) {
      // Fill the opaque handler to be use to attach the file later on
      fh = new TFileOpenHandle(f);
   }
 
   // Record this request
   if (fh) {
      // Create the lst, if not done already
      if (!fgAsyncOpenRequests)
         fgAsyncOpenRequests = new TList;
      fgAsyncOpenRequests->Add(fh);
   }
 
   // We are done
   return fh;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Waits for the completion of an asynchronous open request.
///
/// Returns the pointer to the associated TFile, transferring ownership of the
/// handle to the TFile instance.
 
TFile *TFile::Open(TFileOpenHandle *fh)
{
   TFile *f = nullptr;
 
   // Note that the request may have failed
   if (fh && fgAsyncOpenRequests) {
      // Remove it from the pending list: we need to do it at this level to avoid
      // recursive calls in the standard TFile::Open
      fgAsyncOpenRequests->Remove(fh);
      // Was asynchronous open functionality implemented?
      if ((f = fh->GetFile()) && !(f->IsZombie())) {
         // Yes: wait for the completion of the open phase, if needed
         Bool_t cr = (!strcmp(f->GetOption(),"CREATE") ||
                      !strcmp(f->GetOption(),"RECREATE") ||
                      !strcmp(f->GetOption(),"NEW")) ? kTRUE : kFALSE;
         f->Init(cr);
      } else {
         // No: process a standard open
         f = TFile::Open(fh->GetName(), fh->GetOpt(), fh->GetTitle(),
                         fh->GetCompress(), fh->GetNetOpt());
      }
 
      // Adopt the handle instance in the TFile instance so that it gets
      // automatically cleaned up
      if (f) f->fAsyncHandle = fh;
   }
 
   // We are done
   return f;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Interface to system open. All arguments like in POSIX open().
 
Int_t TFile::SysOpen(const char *pathname, Int_t flags, UInt_t mode)
{
#if defined(R__WINGCC)
   // ALWAYS use binary mode - even cygwin text should be in unix format
   // although this is posix default it has to be set explicitly
   return ::open(pathname, flags | O_BINARY, mode);
#elif defined(R__SEEK64)
   return ::open64(pathname, flags, mode);
#else
   return ::open(pathname, flags, mode);
#endif
}
 
////////////////////////////////////////////////////////////////////////////////
/// Interface to system close. All arguments like in POSIX close().
 
Int_t TFile::SysClose(Int_t fd)
{
   if (fd < 0) return 0;
   return ::close(fd);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Interface to system read. All arguments like in POSIX read().
 
Int_t TFile::SysRead(Int_t fd, void *buf, Int_t len)
{
   return ::read(fd, buf, len);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Interface to system write. All arguments like in POSIX write().
 
Int_t TFile::SysWrite(Int_t fd, const void *buf, Int_t len)
{
   return ::write(fd, buf, len);
}
////////////////////////////////////////////////////////////////////////////////
/// Interface to system lseek.
///
/// All arguments like in POSIX lseek()
/// except that the offset and return value are of a type which are
/// able to handle 64 bit file systems.
 
Long64_t TFile::SysSeek(Int_t fd, Long64_t offset, Int_t whence)
{
#if defined (R__SEEK64)
   return ::lseek64(fd, offset, whence);
#elif defined(WIN32)
   return ::_lseeki64(fd, offset, whence);
#else
   return ::lseek(fd, offset, whence);
#endif
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return file stat information.
///
/// The interface and return value is
/// identical to TSystem::GetPathInfo(). The function returns 0 in
/// case of success and 1 if the file could not be stat'ed.
 
Int_t TFile::SysStat(Int_t, Long_t *id, Long64_t *size, Long_t *flags,
                     Long_t *modtime)
{
   return gSystem->GetPathInfo(fRealName, id, size, flags, modtime);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Interface to system fsync. All arguments like in POSIX fsync().
 
Int_t TFile::SysSync(Int_t fd)
{
   if (TestBit(kDevNull)) return 0;
 
#ifndef WIN32
   return ::fsync(fd);
#else
   return ::_commit(fd);
#endif
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the total number of bytes written so far to the file.
 
Long64_t TFile::GetBytesWritten() const
{
   return fCacheWrite ? fCacheWrite->GetBytesInCache() + fBytesWrite : fBytesWrite;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static function returning the total number of bytes read from all files.
 
Long64_t TFile::GetFileBytesRead()
{
   return fgBytesRead;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static function returning the total number of bytes written to all files.
/// Does not take into account what might still be in the write caches.
 
Long64_t TFile::GetFileBytesWritten()
{
   return fgBytesWrite;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static function returning the total number of read calls from all files.
 
Int_t TFile::GetFileReadCalls()
{
   return fgReadCalls;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Static function returning the readahead buffer size.
 
Int_t TFile::GetReadaheadSize()
{
   return fgReadaheadSize;
}
 
//______________________________________________________________________________
void TFile::SetReadaheadSize(Int_t bytes) { fgReadaheadSize = bytes; }
 
//______________________________________________________________________________
void TFile::SetFileBytesRead(Long64_t bytes) { fgBytesRead = bytes; }
 
//______________________________________________________________________________
void TFile::SetFileBytesWritten(Long64_t bytes) { fgBytesWrite = bytes; }
 
//______________________________________________________________________________
void TFile::SetFileReadCalls(Int_t readcalls) { fgReadCalls = readcalls; }
 
//______________________________________________________________________________
Long64_t TFile::GetFileCounter() { return fgFileCounter; }
 
//______________________________________________________________________________
void TFile::IncrementFileCounter() { fgFileCounter++; }
 
////////////////////////////////////////////////////////////////////////////////
/// Sets the directory where to locally stage/cache remote files.
/// If the directory is not writable by us return kFALSE.
 
Bool_t TFile::SetCacheFileDir(std::string_view cachedir, Bool_t operatedisconnected,
                              Bool_t forcecacheread )
{
   TString cached{cachedir};
   if (!cached.EndsWith("/"))
      cached += "/";
 
   if (gSystem->AccessPathName(cached, kFileExists)) {
      // try to create it
      gSystem->mkdir(cached, kTRUE);
      if (gSystem->AccessPathName(cached, kFileExists)) {
         ::Error("TFile::SetCacheFileDir", "no sufficient permissions on cache directory %s or cannot create it", TString(cachedir).Data());
         fgCacheFileDir = "";
         return kFALSE;
      }
      gSystem->Chmod(cached, 0700);
   }
   if (gSystem->AccessPathName(cached, kWritePermission))
      gSystem->Chmod(cached, 0700);
   fgCacheFileDir          = cached;
   fgCacheFileDisconnected = operatedisconnected;
   fgCacheFileForce        = forcecacheread;
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get the directory where to locally stage/cache remote files.
 
const char *TFile::GetCacheFileDir()
{
   return fgCacheFileDir;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Try to shrink the cache to the desired size.
///
/// With the clenupinterval you can specify the minimum amount of time after
/// the previous cleanup before the cleanup operation is repeated in
/// the cache directory
 
Bool_t TFile::ShrinkCacheFileDir(Long64_t shrinksize, Long_t cleanupinterval)
{
   if (fgCacheFileDir == "") {
      return kFALSE;
   }
 
   // check the last clean-up in the cache
   Long_t id;
   Long64_t size;
   Long_t flags;
   Long_t modtime;
 
   TString cachetagfile = fgCacheFileDir;
   cachetagfile += ".tag.ROOT.cache";
   if (!gSystem->GetPathInfo(cachetagfile, &id, &size, &flags, &modtime)) {
      // check the time passed since last cache cleanup
      Long_t lastcleanuptime = ((Long_t)time(0) - modtime);
      if (lastcleanuptime < cleanupinterval) {
         ::Info("TFile::ShrinkCacheFileDir", "clean-up is skipped - last cleanup %lu seconds ago - you requested %lu", lastcleanuptime, cleanupinterval);
         return kTRUE;
      }
   }
 
   // (re-)create the cache tag file
   cachetagfile += "?filetype=raw";
   TFile *tagfile = nullptr;
 
   if (!(tagfile = TFile::Open(cachetagfile, "RECREATE"))) {
      ::Error("TFile::ShrinkCacheFileDir", "cannot create the cache tag file %s", cachetagfile.Data());
      return kFALSE;
   }
 
   // the shortest garbage collector in the world - one long line of PERL - unlinks files only,
   // if there is a symbolic link with '.ROOT.cachefile' for safety ;-)
 
   TString cmd;
#if defined(R__WIN32)
   cmd = "echo <TFile::ShrinkCacheFileDir>: cleanup to be implemented";
#elif defined(R__MACOSX)
   cmd.Form("perl -e 'my $cachepath = \"%s\"; my $cachesize = %lld;my $findcommand=\"find $cachepath -type f -exec stat -f \\\"\\%%a::\\%%N::\\%%z\\\" \\{\\} \\\\\\;\";my $totalsize=0;open FIND, \"$findcommand | sort -k 1 |\";while (<FIND>) { my ($accesstime, $filename, $filesize) = split \"::\",$_; $totalsize += $filesize;if ($totalsize > $cachesize) {if ( ( -e \"${filename}.ROOT.cachefile\" ) || ( -e \"${filename}\" ) ) {unlink \"$filename.ROOT.cachefile\";unlink \"$filename\";}}}close FIND;' ", fgCacheFileDir.Data(),shrinksize);
#else
   cmd.Form("perl -e 'my $cachepath = \"%s\"; my $cachesize = %lld;my $findcommand=\"find $cachepath -type f -exec stat -c \\\"\\%%x::\\%%n::\\%%s\\\" \\{\\} \\\\\\;\";my $totalsize=0;open FIND, \"$findcommand | sort -k 1 |\";while (<FIND>) { my ($accesstime, $filename, $filesize) = split \"::\",$_; $totalsize += $filesize;if ($totalsize > $cachesize) {if ( ( -e \"${filename}.ROOT.cachefile\" ) || ( -e \"${filename}\" ) ) {unlink \"$filename.ROOT.cachefile\";unlink \"$filename\";}}}close FIND;' ", fgCacheFileDir.Data(),shrinksize);
#endif
 
   tagfile->WriteBuffer(cmd, 4096);
   delete tagfile;
 
   if ((gSystem->Exec(cmd)) != 0) {
      ::Error("TFile::ShrinkCacheFileDir", "error executing clean-up script");
      return kFALSE;
   }
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Sets open timeout time (in ms). Returns previous timeout value.
 
UInt_t TFile::SetOpenTimeout(UInt_t timeout)
{
   UInt_t to = fgOpenTimeout;
   fgOpenTimeout = timeout;
   return to;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns open timeout (in ms).
 
UInt_t TFile::GetOpenTimeout()
{
   return fgOpenTimeout;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Sets only staged flag. Returns previous value of flag.
/// When true we check before opening the file if it is staged, if not,
/// the open fails.
 
Bool_t TFile::SetOnlyStaged(Bool_t onlystaged)
{
   Bool_t f = fgOnlyStaged;
   fgOnlyStaged = onlystaged;
   return f;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns staged only flag.
 
Bool_t TFile::GetOnlyStaged()
{
   return fgOnlyStaged;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return kTRUE if 'url' matches the coordinates of this file.
///
/// The check is implementation dependent and may need to be overload
/// by each TFile implementation relying on this check.
/// The default implementation checks the file name only.
 
Bool_t TFile::Matches(const char *url)
{
   // Check the full URL, including port and FQDN.
   TUrl u(url);
 
   // Check
   if (!strcmp(u.GetFile(), fUrl.GetFile())) {
      // Check ports
      if (u.GetPort() == fUrl.GetPort()) {
         if (!strcmp(u.GetHostFQDN(), fUrl.GetHostFQDN())) {
            // Ok, coordinates match
            return kTRUE;
         }
      }
   }
 
   // Default is not matching
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return kTRUE if this async request matches the open request
/// specified by 'url'
 
Bool_t TFileOpenHandle::Matches(const char *url)
{
   if (fFile) {
      return fFile->Matches(url);
   } else if (fName.Length() > 0){
      // Deep check of URLs
      TUrl u(url);
      TUrl uref(fName);
      if (!strcmp(u.GetFile(), uref.GetFile())) {
         // Check ports
         if (u.GetPort() == uref.GetPort()) {
            // Check also the host name
            if (!strcmp(u.GetHostFQDN(), uref.GetHostFQDN())) {
               // Ok, coordinates match
               return kTRUE;
            }
         }
      }
   }
 
   // Default is not matching
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Resolve the file type as a function of the protocol field in 'name'
///
/// If defined, the string 'prefix' is added when testing the locality of
/// a 'name' with network-like structure (i.e. root://host//path); if the file
/// is local, on return 'prefix' will contain the actual local path of the file.
 
TFile::EFileType TFile::GetType(const char *name, Option_t *option, TString *prefix)
{
   EFileType type = kDefault;
 
   TPMERegexp re("^(root|xroot).*", "i");
   if (re.Match(name)) {
      //
      // Should be a network file ...
      type = kNet;
      // ... but make sure that is not local or that a remote-like connection
      // is forced. Treat it as local if:
      //    i)  the url points to the localhost, the file will be opened in
      //        readonly mode and the current user has read access;
      //    ii) the specified user is equal to the current user then open local
      //        TFile.
      Bool_t localFile = kFALSE;
      TUrl url(name);
      //
      // Check whether we should try to optimize for local files
      Bool_t forceRemote = gEnv->GetValue("Path.ForceRemote", 0);
      forceRemote = (forceRemote) ? kTRUE : gEnv->GetValue("TFile.ForceRemote", 0);
      TString opts = url.GetOptions();
      if (opts.Contains("remote=1"))
         forceRemote = kTRUE;
      else if (opts.Contains("remote=0"))
         forceRemote = kFALSE;
      if (!forceRemote) {
         // Generic locality test
         localFile = gSystem->IsPathLocal(name);
         if (localFile) {
            // Local path including the prefix
            const char *fname = url.GetFileAndOptions();
            TString lfname;
            if (fname[0] == '/') {
               if (prefix)
                  lfname.Form("%s%s", prefix->Data(), fname);
               else
                  lfname = fname;
            } else if (fname[0] == '~' || fname[0] == '$') {
               lfname = fname;
            } else {
               lfname.Form("%s/%s", gSystem->HomeDirectory(), fname);
            }
            // If option "READ" test existence and access
            TString opt = option;
            opt.ToUpper();
            Bool_t read = (opt.IsNull() ||
                          opt == "READ") ? kTRUE : kFALSE;
            if (read) {
               TString fn = TUrl(lfname).GetFile();
               if (!gSystem->ExpandPathName(fn)) {
                  if (gSystem->AccessPathName(fn, kReadPermission))
                     localFile = kFALSE;
               }
            }
            // Return full local path if requested (and if the case)
            if (localFile && prefix)
               *prefix = lfname;
         }
      }
      //
      // Adjust the type according to findings
      type = (localFile) ? kLocal : type;
   } else if (TPMERegexp("^(http[s]?|s3http[s]?|[a]?s3|gs|gshttp[s]?){1}:", "i").Match(name)) {
      //
      // Web file
      type = kWeb;
   } else if (!strncmp(name, "file:", 5)) {
      //
      // 'file' protocol
      type = kFile;
   }
   // We are done
   return type;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get status of the async open request related to 'name'.
 
TFile::EAsyncOpenStatus TFile::GetAsyncOpenStatus(const char* name)
{
   // Check the list of pending async open requests
   if (fgAsyncOpenRequests && (fgAsyncOpenRequests->GetSize() > 0)) {
      TIter nxr(fgAsyncOpenRequests);
      TFileOpenHandle *fh = nullptr;
      while ((fh = (TFileOpenHandle *)nxr()))
         if (fh->Matches(name))
            return TFile::GetAsyncOpenStatus(fh);
   }
 
   // Check also the list of files open
   R__LOCKGUARD(gROOTMutex);
   TSeqCollection *of = gROOT->GetListOfFiles();
   if (of && (of->GetSize() > 0)) {
      TIter nxf(of);
      TFile *f = nullptr;
      while ((f = (TFile *)nxf()))
         if (f->Matches(name))
            return f->GetAsyncOpenStatus();
   }
 
   // Default is synchronous mode
   return kAOSNotAsync;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get status of the async open request related to 'handle'.
 
TFile::EAsyncOpenStatus TFile::GetAsyncOpenStatus(TFileOpenHandle *handle)
{
   if (handle && handle->fFile) {
      if (!handle->fFile->IsZombie())
         return handle->fFile->GetAsyncOpenStatus();
      else
         return TFile::kAOSFailure;
   }
 
   // Default is synchronous mode
   return TFile::kAOSNotAsync;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get final URL for file being opened asynchronously.
/// Returns 0 is the information is not yet available.
 
const TUrl *TFile::GetEndpointUrl(const char* name)
{
   // Check the list of pending async open requests
   if (fgAsyncOpenRequests && (fgAsyncOpenRequests->GetSize() > 0)) {
      TIter nxr(fgAsyncOpenRequests);
      TFileOpenHandle *fh = nullptr;
      while ((fh = (TFileOpenHandle *)nxr()))
         if (fh->Matches(name))
            if (fh->fFile)
               return fh->fFile->GetEndpointUrl();
   }
 
   // Check also the list of files open
   R__LOCKGUARD(gROOTMutex);
   TSeqCollection *of = gROOT->GetListOfFiles();
   if (of && (of->GetSize() > 0)) {
      TIter nxf(of);
      TFile *f = nullptr;
      while ((f = (TFile *)nxf()))
         if (f->Matches(name))
            return f->GetEndpointUrl();
   }
 
   // Information not yet available
   return (const TUrl *)nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Print file copy progress.
 
void TFile::CpProgress(Long64_t bytesread, Long64_t size, TStopwatch &watch)
{
   fprintf(stderr, "[TFile::Cp] Total %.02f MB\t|", (Double_t)size/1048576);
 
   for (int l = 0; l < 20; l++) {
      if (size > 0) {
         if (l < 20*bytesread/size)
            fprintf(stderr, "=");
         else if (l == 20*bytesread/size)
            fprintf(stderr, ">");
         else if (l > 20*bytesread/size)
            fprintf(stderr, ".");
      } else
         fprintf(stderr, "=");
   }
   // Allow to update the GUI while uploading files
   gSystem->ProcessEvents();
   watch.Stop();
   Double_t lCopy_time = watch.RealTime();
   fprintf(stderr, "| %.02f %% [%.01f MB/s]\r",
           100.0*(size?(bytesread/((float)size)):1), (lCopy_time>0.)?bytesread/lCopy_time/1048576.:0.);
   watch.Continue();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Allows to copy this file to the dst URL. Returns kTRUE in case of success,
/// kFALSE otherwise.
 
Bool_t TFile::Cp(const char *dst, Bool_t progressbar, UInt_t bufsize)
{
   Bool_t rmdestiferror = kFALSE;
   TStopwatch watch;
   Bool_t success = kFALSE;
 
   TUrl dURL(dst, kTRUE);
 
   TString oopt = "RECREATE";
   TString ourl = dURL.GetUrl();
 
   // Files will be open in RAW mode
   TString raw = "filetype=raw";
 
   // Set optimization options for the destination file
   TString opt = dURL.GetOptions();
   if (opt != "") opt += "&";
   opt += raw;
 
   // AliEn files need to know where the source file is
   if (!strcmp(dURL.GetProtocol(), "alien"))
      opt += TString::Format("&source=%s", GetName());
 
   dURL.SetOptions(opt);
 
   char *copybuffer = nullptr;
 
   TFile *sfile = this;
   TFile *dfile = nullptr;
 
   // "RECREATE" does not work always well with XROOTD
   // namely when some pieces of the path are missing;
   // we force "NEW" in such a case
   if (TFile::GetType(ourl, "") == TFile::kNet) {
      if (gSystem->AccessPathName(ourl)) {
         oopt = "NEW";
         // Force creation of the missing parts of the path
         opt += "&mkpath=1";
         dURL.SetOptions(opt);
      }
   }
 
   // Open destination file
   if (!(dfile = TFile::Open(dURL.GetUrl(), oopt))) {
      ::Error("TFile::Cp", "cannot open destination file %s", dst);
      goto copyout;
   }
 
   // Probably we created a new file
   // We have to remove it in case of errors
   rmdestiferror = kTRUE;
 
   sfile->Seek(0);
   dfile->Seek(0);
 
   copybuffer = new char[bufsize];
   if (!copybuffer) {
      ::Error("TFile::Cp", "cannot allocate the copy buffer");
      goto copyout;
   }
 
   Bool_t   readop, writeop;
   Long64_t read, written, totalread, filesize, b00;
 
   totalread = 0;
   filesize = sfile->GetSize();
 
   watch.Start();
 
   b00 = sfile->GetBytesRead();
 
   do {
      if (progressbar) CpProgress(totalread, filesize,watch);
 
      Long64_t b1 = sfile->GetBytesRead() - b00;
 
      Long64_t readsize;
      if (filesize - b1 > (Long64_t)bufsize) {
         readsize = bufsize;
      } else {
         readsize = filesize - b1;
      }
 
      if (readsize == 0) break;
 
      Long64_t b0 = sfile->GetBytesRead();
      sfile->Seek(totalread,TFile::kBeg);
      readop = sfile->ReadBuffer(copybuffer, (Int_t)readsize);
      read   = sfile->GetBytesRead() - b0;
      if ((read <= 0) || readop) {
         ::Error("TFile::Cp", "cannot read from source file %s. readsize=%lld read=%lld readop=%d",
                              sfile->GetName(), readsize, read, readop);
         goto copyout;
      }
 
      Long64_t w0 = dfile->GetBytesWritten();
      writeop = dfile->WriteBuffer(copybuffer, (Int_t)read);
      written = dfile->GetBytesWritten() - w0;
      if ((written != read) || writeop) {
         ::Error("TFile::Cp", "cannot write %lld bytes to destination file %s", read, dst);
         goto copyout;
      }
      totalread += read;
   } while (read == (Long64_t)bufsize);
 
   if (progressbar) {
      CpProgress(totalread, filesize,watch);
      fprintf(stderr, "\n");
   }
 
   success = kTRUE;
 
copyout:
   if (dfile) dfile->Close();
 
   if (dfile) delete dfile;
   if (copybuffer) delete[] copybuffer;
 
   if (rmdestiferror && (success != kTRUE))
      gSystem->Unlink(dst);
 
   watch.Stop();
   watch.Reset();
 
   return success;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Allows to copy file from src to dst URL. Returns kTRUE in case of success,
/// kFALSE otherwise.
 
Bool_t TFile::Cp(const char *src, const char *dst, Bool_t progressbar,
                 UInt_t bufsize)
{
   TUrl sURL(src, kTRUE);
 
   TFile *sfile = nullptr;
 
   Bool_t success = kFALSE;
 
   // Open source file
   if (!(sfile = TFile::Open(sURL.GetUrl(), "READ"))) {
      ::Error("TFile::Cp", "cannot open source file %s", src);
   } else {
      success = sfile->Cp(dst, progressbar, bufsize);
   }
 
   if (sfile) {
      sfile->Close();
      delete sfile;
   }
 
   return success;
}
 
//______________________________________________________________________________
//The next statement is not active anymore on Linux.
//Using posix_fadvise introduces a performance penalty (10 %) on optimized files
//and in addition it destroys the information of TTreePerfStats
#if defined(R__neverLINUX) && !defined(R__WINGCC)
Bool_t TFile::ReadBufferAsync(Long64_t offset, Int_t len)
{
   // Read specified byte range asynchronously. Actually we tell the kernel
   // which blocks we are going to read so it can start loading these blocks
   // in the buffer cache.
 
   // Shortcut to avoid having to implement dummy ReadBufferAsync() in all
   // I/O plugins. Override ReadBufferAsync() in plugins if async is supported.
   if (IsA() != TFile::Class())
      return kTRUE;
 
   int advice = POSIX_FADV_WILLNEED;
   if (len == 0) {
      // according POSIX spec if len is zero, all data following offset
      // is specified. Nevertheless ROOT uses zero to probe readahead
      // capabilities.
      advice = POSIX_FADV_NORMAL;
   }
   Double_t start = 0;
   if (gPerfStats) start = TTimeStamp();
#if defined(R__SEEK64)
   Int_t result = posix_fadvise64(fD, offset, len, advice);
#else
   Int_t result = posix_fadvise(fD, offset, len, advice);
#endif
   if (gPerfStats) {
      gPerfStats->FileReadEvent(this, len, start);
   }
   return (result != 0);
}
#else
Bool_t TFile::ReadBufferAsync(Long64_t, Int_t)
{
   // Not supported yet on non Linux systems.
 
   return kTRUE;
}
#endif
 
////////////////////////////////////////////////////////////////////////////////
/// Max number of bytes to prefetch.
///
/// By default this is 75% of the
/// read cache size. But specific TFile implementations may need to change it
 
Int_t TFile::GetBytesToPrefetch() const
{
   TFileCacheRead *cr = nullptr;
   if ((cr = GetCacheRead())) {
      Int_t bytes = cr->GetBufferSize() / 4 * 3;
      return ((bytes < 0) ? 0 : bytes);
   }
   return 0;
}