TUnixSystem.cxx

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// @(#)root/unix:$Id: 887c618d89c4ed436e4034fc133f468fecad651b $
// Author: Fons Rademakers   15/09/95
 
/*************************************************************************
 * 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.             *
 *************************************************************************/
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TUnixSystem                                                          //
//                                                                      //
// Class providing an interface to the UNIX Operating System.           //
//                                                                      //
//////////////////////////////////////////////////////////////////////////
 
#include "RConfigure.h"
#include <ROOT/RConfig.hxx>
#include <ROOT/FoundationUtils.hxx>
#include "TUnixSystem.h"
#include "TROOT.h"
#include "TError.h"
#include "TOrdCollection.h"
#include "TRegexp.h"
#include "TPRegexp.h"
#include "TException.h"
#include "TEnv.h"
#include "Getline.h"
#include "TInterpreter.h"
#include "TApplication.h"
#include "TObjString.h"
#include "TVirtualMutex.h"
#include "ThreadLocalStorage.h"
#include "TObjArray.h"
#include "snprintf.h"
#include "strlcpy.h"
#include <iostream>
#include <fstream>
#include <map>
#include <algorithm>
#include <atomic>
 
//#define G__OLDEXPAND
 
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#if defined(R__SUN) || defined(R__AIX) || \
    defined(R__LINUX) || defined(R__SOLARIS) || \
    defined(R__FBSD) || defined(R__OBSD) || \
    defined(R__MACOSX) || defined(R__HURD)
#define HAS_DIRENT
#endif
#ifdef HAS_DIRENT
#   include <dirent.h>
#else
#   include <sys/dir.h>
#endif
#if defined(ULTRIX) || defined(R__SUN)
#   include <sgtty.h>
#endif
#if defined(R__AIX) || defined(R__LINUX) || \
    defined(R__FBSD) || defined(R__OBSD) || \
    defined(R__LYNXOS) || defined(R__MACOSX) || defined(R__HURD)
#   include <sys/ioctl.h>
#endif
#if defined(R__AIX) || defined(R__SOLARIS)
#   include <sys/select.h>
#endif
#if defined(R__MACOSX)
#   include <mach-o/dyld.h>
#   include <sys/mount.h>
   extern "C" int statfs(const char *file, struct statfs *buffer);
#elif defined(R__LINUX) || defined(R__HURD)
#   include <sys/vfs.h>
#elif defined(R__FBSD) || defined(R__OBSD)
#   include <sys/param.h>
#   include <sys/mount.h>
# ifdef R__FBSD
#   include <sys/user.h>
#   include <sys/types.h>
#   include <sys/param.h>
#   include <sys/queue.h>
#   include <libprocstat.h>
#   include <libutil.h>
# endif
#else
#   include <sys/statfs.h>
#endif
 
#include <utime.h>
#include <syslog.h>
#include <sys/stat.h>
#include <setjmp.h>
#include <signal.h>
#include <sys/param.h>
#include <pwd.h>
#include <grp.h>
#include <errno.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <time.h>
#include <sys/time.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#if defined(R__AIX)
#   define _XOPEN_EXTENDED_SOURCE
#   include <arpa/inet.h>
#   undef _XOPEN_EXTENDED_SOURCE
#   if !defined(_AIX41) && !defined(_AIX43)
    // AIX 3.2 doesn't have it
#   define HASNOT_INETATON
#   endif
#else
#   include <arpa/inet.h>
#endif
#include <sys/un.h>
#include <netdb.h>
#include <fcntl.h>
#if defined(R__SOLARIS)
#   include <sys/systeminfo.h>
#   include <sys/filio.h>
#   include <sys/sockio.h>
#   define HASNOT_INETATON
#   ifndef INADDR_NONE
#      define INADDR_NONE (UInt_t)-1
#   endif
#endif
 
#if defined(R__SOLARIS)
#   define HAVE_UTMPX_H
#   define UTMP_NO_ADDR
#endif
 
#if defined(MAC_OS_X_VERSION_10_5)
#   define HAVE_UTMPX_H
#   define UTMP_NO_ADDR
#endif
 
#if defined(R__FBSD)
#   include <sys/param.h>
#   if __FreeBSD_version >= 900007
#      define HAVE_UTMPX_H
#   endif
#endif
 
#if defined(R__AIX) || defined(R__FBSD) || \
    defined(R__OBSD) || defined(R__LYNXOS) || \
    (defined(R__MACOSX) && !defined(MAC_OS_X_VERSION_10_5))
#   define UTMP_NO_ADDR
#endif
 
#if defined(R__LYNXOS)
extern "C" {
   extern int putenv(const char *);
   extern int inet_aton(const char *, struct in_addr *);
};
#endif
 
#if defined(R__ARC4_STDLIB)
// do nothing, stdlib.h already included
#elif defined(R__ARC4_BSDLIB)
#include <bsd/stdlib.h>
#elif defined(R__GETRANDOM_CLIB)
#include <sys/random.h>
#endif
 
#ifdef HAVE_UTMPX_H
#include <utmpx.h>
#define STRUCT_UTMP struct utmpx
#else
#include <utmp.h>
#define STRUCT_UTMP struct utmp
#endif
#if !defined(UTMP_FILE) && defined(_PATH_UTMP)      // 4.4BSD
#define UTMP_FILE _PATH_UTMP
#endif
#if defined(UTMPX_FILE)                             // Solaris, SysVr4
#undef  UTMP_FILE
#define UTMP_FILE UTMPX_FILE
#endif
#ifndef UTMP_FILE
#define UTMP_FILE "/etc/utmp"
#endif
 
// stack trace code
#if (defined(R__LINUX) || defined(R__HURD)) && !defined(R__WINGCC)
#   if __GLIBC__ == 2 && __GLIBC_MINOR__ >= 1
#      define HAVE_BACKTRACE_SYMBOLS_FD
#   endif
#   define HAVE_DLADDR
#endif
#if defined(R__MACOSX) || defined(R__FBSD)
#      define HAVE_BACKTRACE_SYMBOLS_FD
#      define HAVE_DLADDR
#endif
 
#ifdef HAVE_BACKTRACE_SYMBOLS_FD
#   include <execinfo.h>
#endif
#ifdef HAVE_DLADDR
#   ifndef __USE_GNU
#      define __USE_GNU
#   endif
#   include <dlfcn.h>
#endif
 
#ifdef HAVE_BACKTRACE_SYMBOLS_FD
   // The maximum stack trace depth for systems where we request the
   // stack depth separately (currently glibc-based systems).
   static const int kMAX_BACKTRACE_DEPTH = 128;
#endif
 
// FPE handling includes
#if (defined(R__LINUX) && !defined(R__WINGCC))
#include <fenv.h>
#include <sys/prctl.h>    // for prctl() function used in StackTrace()
#endif
 
#if defined(R__MACOSX) && defined(__SSE2__)
#include <xmmintrin.h>
#endif
 
#if defined(R__MACOSX) && !defined(__SSE2__) && !defined(__xlC__) && \
   !defined(__i386__) && !defined(__x86_64__) && !defined(__arm__) && \
   !defined(__arm64__)
#include <fenv.h>
#include <signal.h>
#include <ucontext.h>
#include <stdlib.h>
#include <stdio.h>
#include <mach/thread_status.h>
 
#define fegetenvd(x) asm volatile("mffs %0" : "=f" (x));
#define fesetenvd(x) asm volatile("mtfsf 255,%0" : : "f" (x));
 
enum {
  FE_ENABLE_INEXACT    = 0x00000008,
  FE_ENABLE_DIVBYZERO  = 0x00000010,
  FE_ENABLE_UNDERFLOW  = 0x00000020,
  FE_ENABLE_OVERFLOW   = 0x00000040,
  FE_ENABLE_INVALID    = 0x00000080,
  FE_ENABLE_ALL_EXCEPT = 0x000000F8
};
#endif
 
#if defined(R__MACOSX) && !defined(__SSE2__) && \
    (defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__arm64__))
#include <fenv.h>
#endif
// End FPE handling includes
 
namespace {
   // Depending on the platform the struct utmp (or utmpx) has either ut_name or ut_user
   // which are semantically equivalent. Instead of using preprocessor magic,
   // which is bothersome for cxx modules use SFINAE.
 
   template<typename T>
   struct ut_name {
      template<typename U = T, typename std::enable_if<std::is_member_pointer<decltype(&U::ut_name)>::value, int>::type = 0>
      static char getValue(U* ue, int) {
         return ue->ut_name[0];
      }
 
      template<typename U = T, typename std::enable_if<std::is_member_pointer<decltype(&U::ut_user)>::value, int>::type = 0>
      static char getValue(U* ue, long) {
         return ue->ut_user[0];
      }
   };
 
   static char get_ut_name(STRUCT_UTMP *ue) {
      // 0 is an integer literal forcing an overload pickup in case both ut_name and ut_user are present.
      return ut_name<STRUCT_UTMP>::getValue(ue, 0);
   }
}
 
struct TUtmpContent {
   STRUCT_UTMP *fUtmpContents;
   UInt_t       fEntries; // Number of entries in utmp file.
 
   TUtmpContent() : fUtmpContents(nullptr), fEntries(0) {}
   ~TUtmpContent() { free(fUtmpContents); }
 
   STRUCT_UTMP *SearchUtmpEntry(const char *tty)
   {
      // Look for utmp entry which is connected to terminal tty.
 
      STRUCT_UTMP *ue = fUtmpContents;
 
      UInt_t n = fEntries;
      while (n--) {
         if (get_ut_name(ue) && !strncmp(tty, ue->ut_line, sizeof(ue->ut_line)))
            return ue;
         ue++;
      }
      return nullptr;
   }
 
   int ReadUtmpFile()
   {
      // Read utmp file. Returns number of entries in utmp file.
 
      FILE  *utmp;
      struct stat file_stats;
      size_t n_read, size;
 
      fEntries = 0;
 
      R__LOCKGUARD2(gSystemMutex);
 
      utmp = fopen(UTMP_FILE, "r");
      if (!utmp)
         return 0;
 
      if (fstat(fileno(utmp), &file_stats) == -1) {
         fclose(utmp);
         return 0;
      }
      size = file_stats.st_size;
      if (size <= 0) {
         fclose(utmp);
         return 0;
      }
 
      fUtmpContents = (STRUCT_UTMP *) malloc(size);
      if (!fUtmpContents) {
         fclose(utmp);
         return 0;
      }
 
      n_read = fread(fUtmpContents, 1, size, utmp);
      if (!ferror(utmp)) {
         if (fclose(utmp) != EOF && n_read == size) {
            fEntries = size / sizeof(STRUCT_UTMP);
            return fEntries;
         }
      } else
         fclose(utmp);
 
      free(fUtmpContents);
      fUtmpContents = nullptr;
      return 0;
   }
 
};
 
const char *kServerPath     = "/tmp";
const char *kProtocolName   = "tcp";
 
//------------------- Unix TFdSet ----------------------------------------------
#ifndef HOWMANY
#   define HOWMANY(x, y)   (((x)+((y)-1))/(y))
#endif
 
const Int_t kNFDBITS = (sizeof(Long_t) * 8);  // 8 bits per byte
#ifdef FD_SETSIZE
const Int_t kFDSETSIZE = FD_SETSIZE;          // Linux = 1024 file descriptors
#else
const Int_t kFDSETSIZE = 256;                 // upto 256 file descriptors
#endif
 
 
class TFdSet {
private:
   ULong_t fds_bits[HOWMANY(kFDSETSIZE, kNFDBITS)];
public:
   TFdSet() { memset(fds_bits, 0, sizeof(fds_bits)); }
   TFdSet(const TFdSet &org) { memcpy(fds_bits, org.fds_bits, sizeof(org.fds_bits)); }
   TFdSet &operator=(const TFdSet &rhs) { if (this != &rhs) { memcpy(fds_bits, rhs.fds_bits, sizeof(rhs.fds_bits));} return *this; }
   void   Zero() { memset(fds_bits, 0, sizeof(fds_bits)); }
   void   Set(Int_t n)
   {
      if (n >= 0 && n < kFDSETSIZE) {
         fds_bits[n/kNFDBITS] |= (1UL << (n % kNFDBITS));
      } else {
         ::Fatal("TFdSet::Set","fd (%d) out of range [0..%d]", n, kFDSETSIZE-1);
      }
   }
   void   Clr(Int_t n)
   {
      if (n >= 0 && n < kFDSETSIZE) {
         fds_bits[n/kNFDBITS] &= ~(1UL << (n % kNFDBITS));
      } else {
         ::Fatal("TFdSet::Clr","fd (%d) out of range [0..%d]", n, kFDSETSIZE-1);
      }
   }
   Int_t  IsSet(Int_t n)
   {
      if (n >= 0 && n < kFDSETSIZE) {
         return (fds_bits[n/kNFDBITS] & (1UL << (n % kNFDBITS))) != 0;
      } else {
         ::Fatal("TFdSet::IsSet","fd (%d) out of range [0..%d]", n, kFDSETSIZE-1);
         return 0;
      }
   }
   ULong_t *GetBits() { return (ULong_t *)fds_bits; }
};
 
////////////////////////////////////////////////////////////////////////////////
/// Unix signal handler.
 
static void SigHandler(ESignals sig)
{
   if (gSystem)
      ((TUnixSystem*)gSystem)->DispatchSignals(sig);
}
 
////////////////////////////////////////////////////////////////////////////////
 
static const char *GetExePath()
{
   TTHREAD_TLS_DECL(TString,exepath);
   if (exepath == "") {
#if defined(R__MACOSX)
      exepath = _dyld_get_image_name(0);
#elif defined(R__LINUX) || defined(R__SOLARIS) || defined(R__FBSD)
      char buf[kMAXPATHLEN]="";  // exe path name
 
      // get the name from the link in /proc
#if defined(R__LINUX)
      int ret = readlink("/proc/self/exe", buf, kMAXPATHLEN);
#elif defined(R__SOLARIS)
      int ret = readlink("/proc/self/path/a.out", buf, kMAXPATHLEN);
#elif defined(R__FBSD)
      procstat* ps = procstat_open_sysctl();
      kinfo_proc* kp = kinfo_getproc(getpid());
 
      int ret{0};
      if (kp!=NULL) {
   procstat_getpathname(ps, kp, buf, sizeof(buf));
      }
      free(kp);
      procstat_close(ps);
      exepath = buf;
#endif
      if (ret > 0 && ret < kMAXPATHLEN) {
         buf[ret] = 0;
         exepath = buf;
      }
#else
      if (!gApplication)
         return exepath;
      TString p = gApplication->Argv(0);
      if (p.BeginsWith("/"))
         exepath = p;
      else if (p.Contains("/")) {
         exepath = gSystem->WorkingDirectory();
         exepath += "/";
         exepath += p;
      } else {
         char *exe = gSystem->Which(gSystem->Getenv("PATH"), p, kExecutePermission);
         if (exe) {
            exepath = exe;
            delete [] exe;
         }
      }
#endif
   }
   return exepath;
}
 
#if defined(HAVE_DLADDR) && !defined(R__MACOSX)
////////////////////////////////////////////////////////////////////////////////
 
static void SetRootSys()
{
#ifdef ROOTPREFIX
   if (gSystem->Getenv("ROOTIGNOREPREFIX")) {
#endif
   void *addr = (void *)SetRootSys;
   Dl_info info;
   if (dladdr(addr, &info) && info.dli_fname && info.dli_fname[0]) {
      char respath[kMAXPATHLEN];
      if (!realpath(info.dli_fname, respath)) {
         if (!gSystem->Getenv("ROOTSYS"))
            ::SysError("TUnixSystem::SetRootSys", "error getting realpath of libCore, please set ROOTSYS in the shell");
      } else {
         TString rs = gSystem->GetDirName(respath);
         gSystem->Setenv("ROOTSYS", gSystem->GetDirName(rs.Data()).Data());
      }
   }
#ifdef ROOTPREFIX
   }
#endif
}
#endif
 
#if defined(R__MACOSX)
static TString gLinkedDylibs;
 
////////////////////////////////////////////////////////////////////////////////
 
static void DylibAdded(const struct mach_header *mh, intptr_t /* vmaddr_slide */)
{
   static int i = 0;
   static Bool_t gotFirstSo = kFALSE;
   static TString linkedDylibs;
 
   // to copy the local linkedDylibs to the global gLinkedDylibs call this
   // function with mh==0
   if (!mh) {
      gLinkedDylibs = linkedDylibs;
      return;
   }
 
   TString lib = _dyld_get_image_name(i++);
 
   TRegexp sovers = "libCore\\.[0-9]+\\.*[0-9]*\\.*[0-9]*\\.so";
   TRegexp dyvers = "libCore\\.[0-9]+\\.*[0-9]*\\.*[0-9]*\\.dylib";
 
#ifdef ROOTPREFIX
   if (gSystem->Getenv("ROOTIGNOREPREFIX")) {
#endif
   if (lib.EndsWith("libCore.dylib") || lib.EndsWith("libCore.so") ||
       lib.Index(sovers) != kNPOS    || lib.Index(dyvers) != kNPOS) {
      char respath[kMAXPATHLEN];
      if (!realpath(lib, respath)) {
         if (!gSystem->Getenv("ROOTSYS"))
            ::SysError("TUnixSystem::DylibAdded", "error getting realpath of libCore, please set ROOTSYS in the shell");
      } else {
         TString rs = gSystem->GetDirName(respath);
         gSystem->Setenv("ROOTSYS", gSystem->GetDirName(rs.Data()).Data());
      }
   }
#ifdef ROOTPREFIX
   }
#endif
 
   // when libSystem.B.dylib is loaded we have finished loading all dylibs
   // explicitly linked against the executable. Additional dylibs
   // come when they are explicitly linked against loaded so's, currently
   // we are not interested in these
   if (lib.EndsWith("/libSystem.B.dylib")) {
      gotFirstSo = kTRUE;
      if (linkedDylibs.IsNull()) {
         // TSystem::GetLibraries() assumes that an empty GetLinkedLibraries()
         // means failure to extract the linked libraries. Signal "we did
         // manage, but it's empty" by returning a single space.
         linkedDylibs = ' ';
      }
   }
 
   // add all libs loaded before libSystem.B.dylib
   if (!gotFirstSo && (lib.EndsWith(".dylib") || lib.EndsWith(".so"))) {
      sovers = "\\.[0-9]+\\.*[0-9]*\\.so";
      Ssiz_t idx = lib.Index(sovers);
      if (idx != kNPOS) {
         lib.Remove(idx);
         lib += ".so";
      }
      dyvers = "\\.[0-9]+\\.*[0-9]*\\.dylib";
      idx = lib.Index(dyvers);
      if (idx != kNPOS) {
         lib.Remove(idx);
         lib += ".dylib";
      }
      if (!gSystem->AccessPathName(lib, kReadPermission)) {
         if (linkedDylibs.Length())
            linkedDylibs += " ";
         linkedDylibs += lib;
      }
   }
}
#endif
 
ClassImp(TUnixSystem);
 
////////////////////////////////////////////////////////////////////////////////
 
TUnixSystem::TUnixSystem() : TSystem("Unix", "Unix System")
{ }
 
////////////////////////////////////////////////////////////////////////////////
/// Reset to original state.
 
TUnixSystem::~TUnixSystem()
{
   UnixResetSignals();
 
   delete fReadmask;
   delete fWritemask;
   delete fReadready;
   delete fWriteready;
   delete fSignals;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Initialize Unix system interface.
 
Bool_t TUnixSystem::Init()
{
   if (TSystem::Init())
      return kTRUE;
 
   fReadmask   = new TFdSet;
   fWritemask  = new TFdSet;
   fReadready  = new TFdSet;
   fWriteready = new TFdSet;
   fSignals    = new TFdSet;
 
   //--- install default handlers
   UnixSignal(kSigChild,                 SigHandler);
   UnixSignal(kSigBus,                   SigHandler);
   UnixSignal(kSigSegmentationViolation, SigHandler);
   UnixSignal(kSigIllegalInstruction,    SigHandler);
   UnixSignal(kSigAbort,                 SigHandler);
   UnixSignal(kSigSystem,                SigHandler);
   UnixSignal(kSigAlarm,                 SigHandler);
   UnixSignal(kSigUrgent,                SigHandler);
   UnixSignal(kSigFloatingException,     SigHandler);
   UnixSignal(kSigWindowChanged,         SigHandler);
   UnixSignal(kSigUser2,                 SigHandler);
 
#if defined(R__MACOSX)
   // trap loading of all dylibs to register dylib name,
   // sets also ROOTSYS if built without ROOTPREFIX
   _dyld_register_func_for_add_image(DylibAdded);
#elif defined(HAVE_DLADDR)
   SetRootSys();
#endif
 
   // This is a fallback in case TROOT::GetRootSys() can't determine ROOTSYS
   gRootDir = ROOT::FoundationUtils::GetFallbackRootSys().c_str();
 
   return kFALSE;
}
 
//---- Misc --------------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Set the application name (from command line, argv[0]) and copy it in
/// gProgName. Copy the application pathname in gProgPath.
/// If name is 0 let the system set the actual executable name and path
/// (works on MacOS X and Linux).
 
void TUnixSystem::SetProgname(const char *name)
{
   if (gProgName)
      delete [] gProgName;
   if (gProgPath)
      delete [] gProgPath;
 
   if (!name || !*name) {
      name = GetExePath();
      gProgName = StrDup(BaseName(name));
      gProgPath = StrDup(DirName(name));
   } else {
      gProgName = StrDup(BaseName(name));
      char *w   = Which(Getenv("PATH"), gProgName);
      gProgPath = StrDup(DirName(w));
      delete [] w;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set DISPLAY environment variable based on utmp entry. Only for UNIX.
 
void TUnixSystem::SetDisplay()
{
   if (!Getenv("DISPLAY")) {
      char *tty = ::ttyname(0);  // device user is logged in on
      if (tty) {
         tty += 5;               // remove "/dev/"
 
         TUtmpContent utmp;
         utmp.ReadUtmpFile();
 
         STRUCT_UTMP *utmp_entry = utmp.SearchUtmpEntry(tty);
         if (utmp_entry) {
            if (utmp_entry->ut_host[0]) {
               TString disp;
               for (unsigned n = 0; (n < sizeof(utmp_entry->ut_host)) && utmp_entry->ut_host[n]; n++)
                  disp.Append(utmp_entry->ut_host[n]);
               if (disp.First(':') == kNPOS)
                  disp.Append(":0.0");
               Setenv("DISPLAY", disp.Data());
               Warning("SetDisplay", "DISPLAY not set, setting it to %s", disp.Data());
            }
#ifndef UTMP_NO_ADDR
            else if (utmp_entry->ut_addr) {
 
               struct sockaddr_in addr;
               addr.sin_family = AF_INET;
               addr.sin_port = 0;
               memcpy(&addr.sin_addr, &utmp_entry->ut_addr, sizeof(addr.sin_addr));
               memset(&addr.sin_zero[0], 0, sizeof(addr.sin_zero));
               struct sockaddr *sa = (struct sockaddr *) &addr;    // input
 
               char hbuf[NI_MAXHOST + 4];
               if (getnameinfo(sa, sizeof(struct sockaddr), hbuf, sizeof(hbuf), nullptr, 0, NI_NAMEREQD) == 0) {
                  assert( strlen(hbuf) < NI_MAXHOST );
                  strlcat(hbuf, ":0.0", sizeof(hbuf));
                  Setenv("DISPLAY", hbuf);
                  Warning("SetDisplay", "DISPLAY not set, setting it to %s",
                          hbuf);
               }
            }
#endif
         }
      }
#ifndef R__HAS_COCOA
      if (!gROOT->IsBatch() && !getenv("DISPLAY")) {
         Error("SetDisplay", "Can't figure out DISPLAY, set it manually\n"
            "In case you run a remote ssh session, restart your ssh session with:\n"
            "=========>  ssh -Y");
      }
#endif
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return system error string.
 
const char *TUnixSystem::GetError()
{
   Int_t err = GetErrno();
   if (err == 0 && GetLastErrorString() != "")
      return GetLastErrorString();
 
#if defined(R__SOLARIS) || defined (R__LINUX) || defined(R__AIX) || \
    defined(R__FBSD) || defined(R__OBSD) || defined(R__HURD)
   return strerror(err);
#else
   if (err < 0 || err >= sys_nerr)
      return Form("errno out of range %d", err);
   return sys_errlist[err];
#endif
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return cryptographic random number
/// Fill provided buffer with random values
/// Returns number of bytes written to buffer or -1 in case of error
 
Int_t TUnixSystem::GetCryptoRandom(void *buf, Int_t len)
{
#if defined(R__ARC4_STDLIB) || defined(R__ARC4_BSDLIB)
   arc4random_buf(buf, len);
   return len;
#elif defined(R__GETRANDOM_CLIB)
   return getrandom(buf, len, GRND_NONBLOCK);
#elif defined(R__USE_URANDOM)
   std::ifstream urandom{"/dev/urandom"};
   if (!urandom)
      return -1;
   urandom.read(reinterpret_cast<char *>(buf), len);
   return len;
#else
#error "Reliable cryptographic random function not defined"
   return -1;
#endif
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the system's host name.
 
const char *TUnixSystem::HostName()
{
   if (fHostname == "") {
      char hn[64];
#if defined(R__SOLARIS)
      sysinfo(SI_HOSTNAME, hn, sizeof(hn));
#else
      gethostname(hn, sizeof(hn));
#endif
      fHostname = hn;
   }
   return (const char *)fHostname;
}
 
//---- EventLoop ---------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Add a file handler to the list of system file handlers. Only adds
/// the handler if it is not already in the list of file handlers.
 
void TUnixSystem::AddFileHandler(TFileHandler *h)
{
   R__LOCKGUARD2(gSystemMutex);
 
   TSystem::AddFileHandler(h);
   if (h) {
      int fd = h->GetFd();
      if (h->HasReadInterest()) {
         fReadmask->Set(fd);
         fMaxrfd = TMath::Max(fMaxrfd, fd);
      }
      if (h->HasWriteInterest()) {
         fWritemask->Set(fd);
         fMaxwfd = TMath::Max(fMaxwfd, fd);
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Remove a file handler from the list of file handlers. Returns
/// the handler or 0 if the handler was not in the list of file handlers.
 
TFileHandler *TUnixSystem::RemoveFileHandler(TFileHandler *h)
{
   if (!h) return nullptr;
 
   R__LOCKGUARD2(gSystemMutex);
 
   TFileHandler *oh = TSystem::RemoveFileHandler(h);
   if (oh) {       // found
      TFileHandler *th;
      TIter next(fFileHandler);
      fMaxrfd = -1;
      fMaxwfd = -1;
      fReadmask->Zero();
      fWritemask->Zero();
      while ((th = (TFileHandler *) next())) {
         int fd = th->GetFd();
         if (th->HasReadInterest()) {
            fReadmask->Set(fd);
            fMaxrfd = TMath::Max(fMaxrfd, fd);
         }
         if (th->HasWriteInterest()) {
            fWritemask->Set(fd);
            fMaxwfd = TMath::Max(fMaxwfd, fd);
         }
      }
   }
   return oh;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Add a signal handler to list of system signal handlers. Only adds
/// the handler if it is not already in the list of signal handlers.
 
void TUnixSystem::AddSignalHandler(TSignalHandler *h)
{
   R__LOCKGUARD2(gSystemMutex);
 
   TSystem::AddSignalHandler(h);
   UnixSignal(h->GetSignal(), SigHandler);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Remove a signal handler from list of signal handlers. Returns
/// the handler or 0 if the handler was not in the list of signal handlers.
 
TSignalHandler *TUnixSystem::RemoveSignalHandler(TSignalHandler *h)
{
   if (!h) return nullptr;
 
   R__LOCKGUARD2(gSystemMutex);
 
   TSignalHandler *oh = TSystem::RemoveSignalHandler(h);
 
   Bool_t last = kTRUE;
   TSignalHandler *hs;
   TIter next(fSignalHandler);
 
   while ((hs = (TSignalHandler*) next())) {
      if (hs->GetSignal() == h->GetSignal())
         last = kFALSE;
   }
   if (last)
      ResetSignal(h->GetSignal(), kTRUE);
 
   return oh;
}
 
////////////////////////////////////////////////////////////////////////////////
/// If reset is true reset the signal handler for the specified signal
/// to the default handler, else restore previous behaviour.
 
void TUnixSystem::ResetSignal(ESignals sig, Bool_t reset)
{
   if (reset)
      UnixResetSignal(sig);
   else
      UnixSignal(sig, SigHandler);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Reset signals handlers to previous behaviour.
 
void TUnixSystem::ResetSignals()
{
   UnixResetSignals();
}
 
////////////////////////////////////////////////////////////////////////////////
/// If ignore is true ignore the specified signal, else restore previous
/// behaviour.
 
void TUnixSystem::IgnoreSignal(ESignals sig, Bool_t ignore)
{
   UnixIgnoreSignal(sig, ignore);
}
 
////////////////////////////////////////////////////////////////////////////////
/// When the argument is true the SIGALRM signal handler is set so that
/// interrupted syscalls will not be restarted by the kernel. This is
/// typically used in case one wants to put a timeout on an I/O operation.
/// By default interrupted syscalls will always be restarted (for all
/// signals). This can be controlled for each a-synchronous TTimer via
/// the method TTimer::SetInterruptSyscalls().
 
void TUnixSystem::SigAlarmInterruptsSyscalls(Bool_t set)
{
   UnixSigAlarmInterruptsSyscalls(set);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the bitmap of conditions that trigger a floating point exception.
 
Int_t TUnixSystem::GetFPEMask()
{
   Int_t mask = 0;
 
#if defined(R__LINUX) && !defined(__powerpc__)
#if defined(__GLIBC__) && (__GLIBC__>2 || __GLIBC__==2 && __GLIBC_MINOR__>=1)
 
#if __GLIBC_MINOR__>=3
 
   Int_t oldmask = fegetexcept();
 
#else
   fenv_t oldenv;
   fegetenv(&oldenv);
   fesetenv(&oldenv);
#if __ia64__
   Int_t oldmask = ~oldenv;
#else
   Int_t oldmask = ~oldenv.__control_word;
#endif
#endif
 
   if (oldmask & FE_INVALID  )   mask |= kInvalid;
   if (oldmask & FE_DIVBYZERO)   mask |= kDivByZero;
   if (oldmask & FE_OVERFLOW )   mask |= kOverflow;
   if (oldmask & FE_UNDERFLOW)   mask |= kUnderflow;
# ifdef FE_INEXACT
   if (oldmask & FE_INEXACT  )   mask |= kInexact;
# endif
#endif
#endif
 
#if defined(R__MACOSX) && defined(__SSE2__)
   // OS X uses the SSE unit for all FP math by default, not the x87 FP unit
   Int_t oldmask = ~_MM_GET_EXCEPTION_MASK();
 
   if (oldmask & _MM_MASK_INVALID  )   mask |= kInvalid;
   if (oldmask & _MM_MASK_DIV_ZERO )   mask |= kDivByZero;
   if (oldmask & _MM_MASK_OVERFLOW )   mask |= kOverflow;
   if (oldmask & _MM_MASK_UNDERFLOW)   mask |= kUnderflow;
   if (oldmask & _MM_MASK_INEXACT  )   mask |= kInexact;
#endif
 
#if defined(R__MACOSX) && !defined(__SSE2__) && \
    (defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__arm64__))
   fenv_t oldenv;
   fegetenv(&oldenv);
   fesetenv(&oldenv);
#if defined(__arm__)
   Int_t oldmask = ~oldenv.__fpscr;
#elif defined(__arm64__)
   Int_t oldmask = ~oldenv.__fpcr;
#else
   Int_t oldmask = ~oldenv.__control;
#endif
 
   if (oldmask & FE_INVALID  )   mask |= kInvalid;
   if (oldmask & FE_DIVBYZERO)   mask |= kDivByZero;
   if (oldmask & FE_OVERFLOW )   mask |= kOverflow;
   if (oldmask & FE_UNDERFLOW)   mask |= kUnderflow;
   if (oldmask & FE_INEXACT  )   mask |= kInexact;
#endif
 
#if defined(R__MACOSX) && !defined(__SSE2__) && !defined(__xlC__) && \
    !defined(__i386__) && !defined(__x86_64__) && !defined(__arm__) && \
    !defined(__arm64__)
   Long64_t oldmask;
   fegetenvd(oldmask);
 
   if (oldmask & FE_ENABLE_INVALID  )   mask |= kInvalid;
   if (oldmask & FE_ENABLE_DIVBYZERO)   mask |= kDivByZero;
   if (oldmask & FE_ENABLE_OVERFLOW )   mask |= kOverflow;
   if (oldmask & FE_ENABLE_UNDERFLOW)   mask |= kUnderflow;
   if (oldmask & FE_ENABLE_INEXACT  )   mask |= kInexact;
#endif
 
   return mask;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set which conditions trigger a floating point exception.
/// Return the previous set of conditions.
 
Int_t TUnixSystem::SetFPEMask(Int_t mask)
{
   if (mask) { }  // use mask to avoid warning
 
   Int_t old = GetFPEMask();
 
#if defined(R__LINUX) && !defined(__powerpc__)
#if defined(__GLIBC__) && (__GLIBC__>2 || __GLIBC__==2 && __GLIBC_MINOR__>=1)
   Int_t newm = 0;
   if (mask & kInvalid  )   newm |= FE_INVALID;
   if (mask & kDivByZero)   newm |= FE_DIVBYZERO;
   if (mask & kOverflow )   newm |= FE_OVERFLOW;
   if (mask & kUnderflow)   newm |= FE_UNDERFLOW;
# ifdef FE_INEXACT
   if (mask & kInexact  )   newm |= FE_INEXACT;
# endif
 
#if __GLIBC_MINOR__>=3
 
   // clear pending exceptions so feenableexcept does not trigger them
   feclearexcept(FE_ALL_EXCEPT);
   fedisableexcept(FE_ALL_EXCEPT);
   feenableexcept(newm);
 
#else
 
   fenv_t cur;
   fegetenv(&cur);
#if defined __ia64__
   cur &= ~newm;
#else
   cur.__control_word &= ~newm;
#endif
   fesetenv(&cur);
 
#endif
#endif
#endif
 
#if defined(R__MACOSX) && defined(__SSE2__)
   // OS X uses the SSE unit for all FP math by default, not the x87 FP unit
   Int_t newm = 0;
   if (mask & kInvalid  )   newm |= _MM_MASK_INVALID;
   if (mask & kDivByZero)   newm |= _MM_MASK_DIV_ZERO;
   if (mask & kOverflow )   newm |= _MM_MASK_OVERFLOW;
   if (mask & kUnderflow)   newm |= _MM_MASK_UNDERFLOW;
   if (mask & kInexact  )   newm |= _MM_MASK_INEXACT;
 
   _MM_SET_EXCEPTION_MASK(_MM_GET_EXCEPTION_MASK() & ~newm);
#endif
 
#if defined(R__MACOSX) && !defined(__SSE2__) && \
    (defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__arm64__))
   Int_t newm = 0;
   if (mask & kInvalid  )   newm |= FE_INVALID;
   if (mask & kDivByZero)   newm |= FE_DIVBYZERO;
   if (mask & kOverflow )   newm |= FE_OVERFLOW;
   if (mask & kUnderflow)   newm |= FE_UNDERFLOW;
   if (mask & kInexact  )   newm |= FE_INEXACT;
 
   fenv_t cur;
   fegetenv(&cur);
#if defined(__arm__)
   cur.__fpscr &= ~newm;
#elif defined(__arm64__)
   cur.__fpcr &= ~newm;
#else
   cur.__control &= ~newm;
#endif
   fesetenv(&cur);
#endif
 
#if defined(R__MACOSX) && !defined(__SSE2__) && !defined(__xlC__) && \
    !defined(__i386__) && !defined(__x86_64__) && !defined(__arm__) && \
    !defined(__arm64__)
   Int_t newm = 0;
   if (mask & kInvalid  )   newm |= FE_ENABLE_INVALID;
   if (mask & kDivByZero)   newm |= FE_ENABLE_DIVBYZERO;
   if (mask & kOverflow )   newm |= FE_ENABLE_OVERFLOW;
   if (mask & kUnderflow)   newm |= FE_ENABLE_UNDERFLOW;
   if (mask & kInexact  )   newm |= FE_ENABLE_INEXACT;
 
   Long64_t curmask;
   fegetenvd(curmask);
   curmask = (curmask & ~FE_ENABLE_ALL_EXCEPT) | newm;
   fesetenvd(curmask);
#endif
 
   return old;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Dispatch a single event.
 
void TUnixSystem::DispatchOneEvent(Bool_t pendingOnly)
{
   Bool_t pollOnce = pendingOnly;
 
   while (1) {
      // first handle any X11 events
      if (gXDisplay && gXDisplay->Notify()) {
         if (fReadready->IsSet(gXDisplay->GetFd())) {
            fReadready->Clr(gXDisplay->GetFd());
            fNfd--;
         }
         if (!pendingOnly) return;
      }
 
      // check for file descriptors ready for reading/writing
      if (fNfd > 0 && fFileHandler && fFileHandler->GetSize() > 0)
         if (CheckDescriptors())
            if (!pendingOnly) return;
      fNfd = 0;
      fReadready->Zero();
      fWriteready->Zero();
 
      if (pendingOnly && !pollOnce)
         return;
 
      // check synchronous signals
      if (fSigcnt > 0 && fSignalHandler->GetSize() > 0)
         if (CheckSignals(kTRUE))
            if (!pendingOnly) return;
      fSigcnt = 0;
      fSignals->Zero();
 
      // check synchronous timers
      Long_t nextto;
      if (fTimers && fTimers->GetSize() > 0)
         if (DispatchTimers(kTRUE)) {
            // prevent timers from blocking file descriptor monitoring
            nextto = NextTimeOut(kTRUE);
            if (nextto > kItimerResolution || nextto == -1)
               return;
         }
 
      // if in pendingOnly mode poll once file descriptor activity
      nextto = NextTimeOut(kTRUE);
      if (pendingOnly) {
         if (fFileHandler && fFileHandler->GetSize() == 0)
            return;
         nextto = 0;
         pollOnce = kFALSE;
      }
 
      // nothing ready, so setup select call
      *fReadready  = *fReadmask;
      *fWriteready = *fWritemask;
 
      int mxfd = TMath::Max(fMaxrfd, fMaxwfd);
      mxfd++;
 
      // if nothing to select (socket or timer) return
      if (mxfd == 0 && nextto == -1)
         return;
 
      fNfd = UnixSelect(mxfd, fReadready, fWriteready, nextto);
      if (fNfd < 0 && fNfd != -2) {
         int fd, rc;
         TFdSet t;
         for (fd = 0; fd < mxfd; fd++) {
            t.Set(fd);
            if (fReadmask->IsSet(fd)) {
               rc = UnixSelect(fd+1, &t, nullptr, 0);
               if (rc < 0 && rc != -2) {
                  SysError("DispatchOneEvent", "select: read error on %d", fd);
                  fReadmask->Clr(fd);
               }
            }
            if (fWritemask->IsSet(fd)) {
               rc = UnixSelect(fd+1, nullptr, &t, 0);
               if (rc < 0 && rc != -2) {
                  SysError("DispatchOneEvent", "select: write error on %d", fd);
                  fWritemask->Clr(fd);
               }
            }
            t.Clr(fd);
         }
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Sleep milliSec milliseconds.
 
void TUnixSystem::Sleep(UInt_t milliSec)
{
   struct timeval tv;
 
   tv.tv_sec  = milliSec / 1000;
   tv.tv_usec = (milliSec % 1000) * 1000;
 
   select(0, nullptr, nullptr, nullptr, &tv);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Select on file descriptors. The timeout to is in millisec. Returns
/// the number of ready descriptors, or 0 in case of timeout, or < 0 in
/// case of an error, with -2 being EINTR and -3 EBADF. In case of EINTR
/// the errno has been reset and the method can be called again. Returns
/// -4 in case the list did not contain any file handlers or file handlers
/// with file descriptor >= 0.
 
Int_t TUnixSystem::Select(TList *act, Long_t to)
{
   Int_t rc = -4;
 
   TFdSet rd, wr;
   Int_t mxfd = -1;
   TIter next(act);
   TFileHandler *h = nullptr;
   while ((h = (TFileHandler *) next())) {
      Int_t fd = h->GetFd();
      if (fd > -1) {
         if (h->HasReadInterest()) {
            rd.Set(fd);
            mxfd = TMath::Max(mxfd, fd);
         }
         if (h->HasWriteInterest()) {
            wr.Set(fd);
            mxfd = TMath::Max(mxfd, fd);
         }
         h->ResetReadyMask();
      }
   }
   if (mxfd > -1)
      rc = UnixSelect(mxfd+1, &rd, &wr, to);
 
   // Set readiness bits
   if (rc > 0) {
      next.Reset();
      while ((h = (TFileHandler *) next())) {
         Int_t fd = h->GetFd();
         if (rd.IsSet(fd))
            h->SetReadReady();
         if (wr.IsSet(fd))
            h->SetWriteReady();
      }
   }
 
   return rc;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Select on the file descriptor related to file handler h.
/// The timeout to is in millisec. Returns the number of ready descriptors,
/// or 0 in case of timeout, or < 0 in case of an error, with -2 being EINTR
/// and -3 EBADF. In case of EINTR the errno has been reset and the method
/// can be called again. Returns -4 in case the file handler is 0 or does
/// not have a file descriptor >= 0.
 
Int_t TUnixSystem::Select(TFileHandler *h, Long_t to)
{
   Int_t rc = -4;
 
   TFdSet rd, wr;
   Int_t mxfd = -1;
   Int_t fd = -1;
   if (h) {
      fd = h->GetFd();
      if (fd > -1) {
         if (h->HasReadInterest())
            rd.Set(fd);
         if (h->HasWriteInterest())
            wr.Set(fd);
         h->ResetReadyMask();
         mxfd = fd;
         rc = UnixSelect(mxfd+1, &rd, &wr, to);
      }
   }
 
   // Fill output lists, if required
   if (rc > 0) {
      if (rd.IsSet(fd))
         h->SetReadReady();
      if (wr.IsSet(fd))
         h->SetWriteReady();
   }
 
   return rc;
}
 
//---- handling of system events -----------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Check if some signals were raised and call their Notify() member.
 
Bool_t TUnixSystem::CheckSignals(Bool_t sync)
{
   TSignalHandler *sh;
   Int_t sigdone = -1;
   {
      TOrdCollectionIter it((TOrdCollection*)fSignalHandler);
 
      while ((sh = (TSignalHandler*)it.Next())) {
         if (sync == sh->IsSync()) {
            ESignals sig = sh->GetSignal();
            if ((fSignals->IsSet(sig) && sigdone == -1) || sigdone == sig) {
               if (sigdone == -1) {
                  fSignals->Clr(sig);
                  sigdone = sig;
                  fSigcnt--;
               }
               if (sh->IsActive())
                  sh->Notify();
            }
         }
      }
   }
   if (sigdone != -1)
      return kTRUE;
 
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Check if children have finished.
 
void TUnixSystem::CheckChilds()
{
#if 0  //rdm
   int pid;
   while ((pid = UnixWaitchild()) > 0) {
      TIter next(zombieHandler);
      register UnixPtty *pty;
      while ((pty = (UnixPtty*) next()))
         if (pty->GetPid() == pid) {
            zombieHandler->RemovePtr(pty);
            pty->DiedNotify();
         }
   }
#endif
}
 
////////////////////////////////////////////////////////////////////////////////
/// Check if there is activity on some file descriptors and call their
/// Notify() member.
 
Bool_t TUnixSystem::CheckDescriptors()
{
   TFileHandler *fh;
   Int_t  fddone = -1;
   Bool_t read   = kFALSE;
   TOrdCollectionIter it((TOrdCollection*)fFileHandler);
   while ((fh = (TFileHandler*) it.Next())) {
      Int_t fd = fh->GetFd();
      if ((fd <= fMaxrfd && fReadready->IsSet(fd) && fddone == -1) ||
          (fddone == fd && read)) {
         if (fddone == -1) {
            fReadready->Clr(fd);
            fddone = fd;
            read = kTRUE;
            fNfd--;
         }
         if (fh->IsActive())
            fh->ReadNotify();
      }
      if ((fd <= fMaxwfd && fWriteready->IsSet(fd) && fddone == -1) ||
          (fddone == fd && !read)) {
         if (fddone == -1) {
            fWriteready->Clr(fd);
            fddone = fd;
            read = kFALSE;
            fNfd--;
         }
         if (fh->IsActive())
            fh->WriteNotify();
      }
   }
   if (fddone != -1)
      return kTRUE;
 
   return kFALSE;
}
 
//---- Directories -------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Make a Unix file system directory. Returns 0 in case of success and
/// -1 if the directory could not be created.
 
int TUnixSystem::MakeDirectory(const char *name)
{
   TSystem *helper = FindHelper(name);
   if (helper)
      return helper->MakeDirectory(name);
 
   return UnixMakedir(name);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a Unix file system directory. Returns 0 if directory does not exist.
 
void *TUnixSystem::OpenDirectory(const char *name)
{
   TSystem *helper = FindHelper(name);
   if (helper)
      return helper->OpenDirectory(name);
 
   return UnixOpendir(name);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Close a Unix file system directory.
 
void TUnixSystem::FreeDirectory(void *dirp)
{
   TSystem *helper = FindHelper(nullptr, dirp);
   if (helper) {
      helper->FreeDirectory(dirp);
      return;
   }
 
   if (dirp)
      ::closedir((DIR*)dirp);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get next Unix file system directory entry. Returns 0 if no more entries.
 
const char *TUnixSystem::GetDirEntry(void *dirp)
{
   TSystem *helper = FindHelper(nullptr, dirp);
   if (helper)
      return helper->GetDirEntry(dirp);
 
   if (dirp)
      return UnixGetdirentry(dirp);
 
   return nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Change directory. Returns kTRUE in case of success, kFALSE otherwise.
 
Bool_t TUnixSystem::ChangeDirectory(const char *path)
{
   Bool_t ret = (Bool_t) (::chdir(path) == 0);
   if (fWdpath != "")
      fWdpath = "";   // invalidate path cache
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return working directory.
 
const char *TUnixSystem::WorkingDirectory()
{
   // don't use cache as user can call chdir() directly somewhere else
   //if (fWdpath != "")
   //   return fWdpath.Data();
 
   R__LOCKGUARD2(gSystemMutex);
 
   static char cwd[kMAXPATHLEN];
   FillWithCwd(cwd);
   fWdpath = cwd;
 
   return fWdpath.Data();
}
 
//////////////////////////////////////////////////////////////////////////////
/// Return working directory.
 
std::string TUnixSystem::GetWorkingDirectory() const
{
   char cwd[kMAXPATHLEN];
   FillWithCwd(cwd);
   return std::string(cwd);
}
 
//////////////////////////////////////////////////////////////////////////////
/// Fill buffer with current working directory.
 
void TUnixSystem::FillWithCwd(char *cwd) const
{
   if (::getcwd(cwd, kMAXPATHLEN) == nullptr) {
      Error("WorkingDirectory", "getcwd() failed");
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the user's home directory.
 
const char *TUnixSystem::HomeDirectory(const char *userName)
{
   return UnixHomedirectory(userName);
}
 
//////////////////////////////////////////////////////////////////////////////
/// Return the user's home directory.
 
std::string TUnixSystem::GetHomeDirectory(const char *userName) const
{
   char path[kMAXPATHLEN], mydir[kMAXPATHLEN] = { '\0' };
   auto res = UnixHomedirectory(userName, path, mydir);
   if (res) return std::string(res);
   else return std::string();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return a user configured or systemwide directory to create
/// temporary files in.
 
const char *TUnixSystem::TempDirectory() const
{
   const char *dir = gSystem->Getenv("TMPDIR");
   if (!dir || gSystem->AccessPathName(dir, kWritePermission))
      dir = "/tmp";
 
   return dir;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a secure temporary file by appending a unique
/// 6 letter string to base. The file will be created in
/// a standard (system) directory or in the directory
/// provided in dir. Optionally one can provide suffix
/// append to the final name - like extension ".txt" or ".html".
/// The full filename is returned in base
/// and a filepointer is returned for safely writing to the file
/// (this avoids certain security problems). Returns 0 in case
/// of error.
 
FILE *TUnixSystem::TempFileName(TString &base, const char *dir, const char *suffix)
{
   char *b = ConcatFileName(dir ? dir : TempDirectory(), base);
   base = b;
   base += "XXXXXX";
   const bool hasSuffix = suffix && *suffix;
   if (hasSuffix)
      base.Append(suffix);
   delete [] b;
 
   char *arg = StrDup(base);
   int fd = hasSuffix ? mkstemps(arg, strlen(suffix)) : mkstemp(arg);
   base = arg;
   delete [] arg;
 
   if (fd == -1) {
      SysError("TempFileName", "%s", base.Data());
      return nullptr;
   } else {
      FILE *fp = fdopen(fd, "w+");
      if (!fp)
         SysError("TempFileName", "converting filedescriptor (%d)", fd);
      return fp;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Concatenate a directory and a file name.
 
const char *TUnixSystem::PrependPathName(const char *dir, TString& name)
{
   if (name.IsNull() || name == ".") {
      if (dir) {
         name = dir;
         if (dir[strlen(dir) - 1] != '/')
            name += '/';
      } else name = "";
      return name.Data();
   }
 
   if (!dir || !dir[0])
      dir = "/";
   else if (dir[strlen(dir) - 1] != '/')
      name.Prepend('/');
   name.Prepend(dir);
 
   return name.Data();
}
 
//---- Paths & Files -----------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Returns FALSE if one can access a file using the specified access mode.
/// Mode is the same as for the Unix access(2) function.
/// Attention, bizarre convention of return value!!
 
Bool_t TUnixSystem::AccessPathName(const char *path, EAccessMode mode)
{
   TSystem *helper = FindHelper(path);
   if (helper)
      return helper->AccessPathName(path, mode);
 
   if (::access(StripOffProto(path, "file:"), mode) == 0)
      return kFALSE;
   GetLastErrorString() = GetError();
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Copy a file. If overwrite is true and file already exists the
/// file will be overwritten. Returns 0 when successful, -1 in case
/// of file open failure, -2 in case the file already exists and overwrite
/// was false and -3 in case of error during copy.
 
int TUnixSystem::CopyFile(const char *f, const char *t, Bool_t overwrite)
{
   if (!AccessPathName(t) && !overwrite)
      return -2;
 
   FILE *from = fopen(f, "r");
   if (!from)
      return -1;
 
   FILE *to   = fopen(t, "w");
   if (!to) {
      fclose(from);
      return -1;
   }
 
   const int bufsize = 1024;
   char buf[bufsize];
   int ret = 0;
   while (!ret && !feof(from)) {
      size_t numread    = fread (buf, sizeof(char), bufsize, from);
      size_t numwritten = fwrite(buf, sizeof(char), numread, to);
      if (numread != numwritten)
         ret = -3;
   }
 
   fclose(from);
   fclose(to);
 
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Rename a file. Returns 0 when successful, -1 in case of failure.
 
int TUnixSystem::Rename(const char *f, const char *t)
{
   int ret = ::rename(f, t);
   GetLastErrorString() = GetError();
   return ret;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns TRUE if the url in 'path' points to the local file system.
/// This is used to avoid going through the NIC card for local operations.
 
Bool_t TUnixSystem::IsPathLocal(const char *path)
{
   TSystem *helper = FindHelper(path);
   if (helper)
      return helper->IsPathLocal(path);
 
   return TSystem::IsPathLocal(path);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get info about a file. Info is returned in the form of a FileStat_t
/// structure (see TSystem.h).
/// The function returns 0 in case of success and 1 if the file could
/// not be stat'ed.
 
int TUnixSystem::GetPathInfo(const char *path, FileStat_t &buf)
{
   TSystem *helper = FindHelper(path);
   if (helper)
      return helper->GetPathInfo(path, buf);
 
   return UnixFilestat(path, buf);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get info about a file system: id, bsize, bfree, blocks.
/// Id      is file system type (machine dependend, see statfs())
/// Bsize   is block size of file system
/// Blocks  is total number of blocks in file system
/// Bfree   is number of free blocks in file system
/// The function returns 0 in case of success and 1 if the file system could
/// not be stat'ed.
 
int TUnixSystem::GetFsInfo(const char *path, Long_t *id, Long_t *bsize,
                           Long_t *blocks, Long_t *bfree)
{
   return UnixFSstat(path, id, bsize, blocks, bfree);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a link from file1 to file2. Returns 0 when successful,
/// -1 in case of failure.
 
int TUnixSystem::Link(const char *from, const char *to)
{
   return ::link(from, to);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create a symlink from file1 to file2. Returns 0 when successful,
/// -1 in case of failure.
 
int TUnixSystem::Symlink(const char *from, const char *to)
{
#if defined(R__AIX)
   return ::symlink((char*)from, (char*)to);
#else
   return ::symlink(from, to);
#endif
}
 
////////////////////////////////////////////////////////////////////////////////
/// Unlink, i.e. remove, a file or directory. Returns 0 when successful,
/// -1 in case of failure.
 
int TUnixSystem::Unlink(const char *name)
{
   TSystem *helper = FindHelper(name);
   if (helper)
      return helper->Unlink(name);
 
#if defined(R__SEEK64)
   struct stat64 finfo;
   if (lstat64(name, &finfo) < 0)
#else
   struct stat finfo;
   if (lstat(name, &finfo) < 0)
#endif
      return -1;
 
   if (S_ISDIR(finfo.st_mode))
      return ::rmdir(name);
   else
      return ::unlink(name);
}
 
//---- expand the metacharacters as in the shell -------------------------------
 
// expand the metacharacters as in the shell
 
const char
#ifdef G__OLDEXPAND
   kShellEscape     = '\\',
   *kShellStuff     = "(){}<>\"'",
#endif
   *kShellMeta      = "~*[]{}?$";
 
 
#ifndef G__OLDEXPAND
////////////////////////////////////////////////////////////////////////////////
/// Expand a pathname getting rid of special shell characters like ~.$, etc.
/// For Unix/Win32 compatibility use $(XXX) instead of $XXX when using
/// environment variables in a pathname. If compatibility is not an issue
/// you can use on Unix directly $XXX. Returns kFALSE in case of success
/// or kTRUE in case of error.
 
Bool_t TUnixSystem::ExpandPathName(TString &path)
{
   const char *p, *patbuf = (const char *)path;
 
   // skip leading blanks
   while (*patbuf == ' ')
      patbuf++;
 
   // any shell meta characters ?
   for (p = patbuf; *p; p++)
      if (strchr(kShellMeta, *p))
         goto expand;
 
   return kFALSE;
 
expand:
   // replace $(XXX) by $XXX
   path.ReplaceAll("$(","$");
   path.ReplaceAll(")","");
 
   return ExpandFileName(path);
}
#endif
 
#ifdef G__OLDEXPAND
////////////////////////////////////////////////////////////////////////////////
/// Expand a pathname getting rid of special shell characters like ~.$, etc.
/// For Unix/Win32 compatibility use $(XXX) instead of $XXX when using
/// environment variables in a pathname. If compatibility is not an issue
/// you can use on Unix directly $XXX. Returns kFALSE in case of success
/// or kTRUE in case of error.
 
Bool_t TUnixSystem::ExpandPathName(TString &patbuf0)
{
   const char *patbuf = (const char *)patbuf0;
   const char *hd, *p;
   //   char   cmd[kMAXPATHLEN],
   char stuffedPat[kMAXPATHLEN], name[70];
   char  *q;
   FILE  *pf;
   int    ch;
 
   // skip leading blanks
   while (*patbuf == ' ')
      patbuf++;
 
   // any shell meta characters ?
   for (p = patbuf; *p; p++)
      if (strchr(kShellMeta, *p))
         goto needshell;
 
   return kFALSE;
 
needshell:
   // replace $(XXX) by $XXX
   patbuf0.ReplaceAll("$(","$");
   patbuf0.ReplaceAll(")","");
 
   // escape shell quote characters
   EscChar(patbuf, stuffedPat, sizeof(stuffedPat), (char*)kShellStuff, kShellEscape);
 
   TString cmd("echo ");
 
   // emulate csh -> popen executes sh
   if (stuffedPat[0] == '~') {
      if (stuffedPat[1] != '\0' && stuffedPat[1] != '/') {
         // extract user name
         for (p = &stuffedPat[1], q = name; *p && *p !='/';)
            *q++ = *p++;
         *q = '\0';
         hd = UnixHomedirectory(name);
         if (!hd)
            cmd += stuffedPat;
         else {
            cmd += hd;
            cmd += p;
         }
      } else {
         hd = UnixHomedirectory(nullptr);
         if (!hd) {
            GetLastErrorString() = GetError();
            return kTRUE;
         }
         cmd += hd;
         cmd += &stuffedPat[1];
      }
   } else
      cmd += stuffedPat;
 
   if ((pf = ::popen(cmd.Data(), "r")) == 0) {
      GetLastErrorString() = GetError();
      return kTRUE;
   }
 
   // read first argument
   patbuf0 = "";
   int cnt = 0;
#if defined(R__AIX)
again:
#endif
   for (ch = fgetc(pf); ch != EOF && ch != ' ' && ch != '\n'; ch = fgetc(pf)) {
      patbuf0.Append(ch);
      cnt++;
   }
#if defined(R__AIX)
   // Work around bug timing problem due to delay in forking a large program
   if (cnt == 0 && ch == EOF) goto again;
#endif
 
   // skip rest of pipe
   while (ch != EOF) {
      ch = fgetc(pf);
      if (ch == ' ' || ch == '\t') {
         GetLastErrorString() = "expression ambigous";
         ::pclose(pf);
         return kTRUE;
      }
   }
 
   ::pclose(pf);
 
   return kFALSE;
}
#endif
 
////////////////////////////////////////////////////////////////////////////////
/// Expand a pathname getting rid of special shell characaters like ~.$, etc.
/// For Unix/Win32 compatibility use $(XXX) instead of $XXX when using
/// environment variables in a pathname. If compatibility is not an issue
/// you can use on Unix directly $XXX. The user must delete returned string.
/// Returns the expanded pathname or 0 in case of error.
/// The user must delete returned string (delete []).
 
char *TUnixSystem::ExpandPathName(const char *path)
{
   TString patbuf = path;
   if (ExpandPathName(patbuf))
      return nullptr;
   return StrDup(patbuf.Data());
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set the file permission bits. Returns -1 in case or error, 0 otherwise.
 
int TUnixSystem::Chmod(const char *file, UInt_t mode)
{
   return ::chmod(file, mode);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set the process file creation mode mask.
 
int TUnixSystem::Umask(Int_t mask)
{
   return ::umask(mask);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set a files modification and access times. If actime = 0 it will be
/// set to the modtime. Returns 0 on success and -1 in case of error.
 
int TUnixSystem::Utime(const char *file, Long_t modtime, Long_t actime)
{
   if (!actime)
      actime = modtime;
 
   struct utimbuf t;
   t.actime  = (time_t)actime;
   t.modtime = (time_t)modtime;
   return ::utime(file, &t);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Find location of file "wfil" in a search path.
/// The search path is specified as a : separated list of directories.
/// Return value is pointing to wfile for compatibility with
/// Which(const char*,const char*,EAccessMode) version.
 
const char *TUnixSystem::FindFile(const char *search, TString& wfil, EAccessMode mode)
{
   TString show;
   if (gEnv->GetValue("Root.ShowPath", 0))
      show.Form("Which: %s =", wfil.Data());
 
   gSystem->ExpandPathName(wfil);
 
   if (wfil[0] == '/') {
#if defined(R__SEEK64)
      struct stat64 finfo;
      if (access(wfil.Data(), mode) == 0 &&
          stat64(wfil.Data(), &finfo) == 0 && S_ISREG(finfo.st_mode)) {
#else
      struct stat finfo;
      if (access(wfil.Data(), mode) == 0 &&
          stat(wfil.Data(), &finfo) == 0 && S_ISREG(finfo.st_mode)) {
#endif
         if (show != "")
            Printf("%s %s", show.Data(), wfil.Data());
         return wfil.Data();
      }
      if (show != "")
         Printf("%s <not found>", show.Data());
      wfil = "";
      return nullptr;
   }
 
   if (!search)
      search = ".";
 
   TString apwd(gSystem->WorkingDirectory());
   apwd += "/";
   for (const char* ptr = search; *ptr;) {
      TString name;
      if (*ptr != '/' && *ptr !='$' && *ptr != '~')
         name = apwd;
      const char* posEndOfPart = strchr(ptr, ':');
      if (posEndOfPart) {
         name.Append(ptr, posEndOfPart - ptr);
         ptr = posEndOfPart + 1; // skip ':'
      } else {
         name.Append(ptr);
         ptr += strlen(ptr);
      }
 
      if (!name.EndsWith("/"))
         name += '/';
      name += wfil;
 
      gSystem->ExpandPathName(name);
#if defined(R__SEEK64)
      struct stat64 finfo;
      if (access(name.Data(), mode) == 0 &&
          stat64(name.Data(), &finfo) == 0 && S_ISREG(finfo.st_mode)) {
#else
      struct stat finfo;
      if (access(name.Data(), mode) == 0 &&
          stat(name.Data(), &finfo) == 0 && S_ISREG(finfo.st_mode)) {
#endif
         if (show != "")
            Printf("%s %s", show.Data(), name.Data());
         wfil = name;
         return wfil.Data();
      }
   }
 
   if (show != "")
      Printf("%s <not found>", show.Data());
   wfil = "";
   return nullptr;
}
 
//---- Users & Groups ----------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the user's id. If user = 0, returns current user's id.
 
Int_t TUnixSystem::GetUid(const char *user)
{
   if (!user || !user[0])
      return getuid();
   else {
      struct passwd *apwd = getpwnam(user);
      if (apwd)
         return apwd->pw_uid;
   }
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the effective user id. The effective id corresponds to the
/// set id bit on the file being executed.
 
Int_t TUnixSystem::GetEffectiveUid()
{
   return geteuid();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the group's id. If group = 0, returns current user's group.
 
Int_t TUnixSystem::GetGid(const char *group)
{
   if (!group || !group[0])
      return getgid();
   else {
      struct group *grp = getgrnam(group);
      if (grp)
         return grp->gr_gid;
   }
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the effective group id. The effective group id corresponds
/// to the set id bit on the file being executed.
 
Int_t TUnixSystem::GetEffectiveGid()
{
   return getegid();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns all user info in the UserGroup_t structure. The returned
/// structure must be deleted by the user. In case of error 0 is returned.
 
UserGroup_t *TUnixSystem::GetUserInfo(Int_t uid)
{
   typedef std::map<Int_t /*uid*/, UserGroup_t> UserInfoCache_t;
   static UserInfoCache_t gUserInfo;
 
   UserInfoCache_t::const_iterator iUserInfo = gUserInfo.find(uid);
   if (iUserInfo != gUserInfo.end())
      return new UserGroup_t(iUserInfo->second);
 
   struct passwd *apwd = getpwuid(uid);
   if (apwd) {
      UserGroup_t *ug = new UserGroup_t;
      ug->fUid      = apwd->pw_uid;
      ug->fGid      = apwd->pw_gid;
      ug->fUser     = apwd->pw_name;
      ug->fPasswd   = apwd->pw_passwd;
      ug->fRealName = apwd->pw_gecos;
      ug->fShell    = apwd->pw_shell;
      UserGroup_t *gr = GetGroupInfo(apwd->pw_gid);
      if (gr) ug->fGroup = gr->fGroup;
      delete gr;
 
      gUserInfo[uid] = *ug;
      return ug;
   }
   return nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns all user info in the UserGroup_t structure. If user = 0, returns
/// current user's id info. The returned structure must be deleted by the
/// user. In case of error 0 is returned.
 
UserGroup_t *TUnixSystem::GetUserInfo(const char *user)
{
   return GetUserInfo(GetUid(user));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns all group info in the UserGroup_t structure. The only active
/// fields in the UserGroup_t structure for this call are:
///    fGid and fGroup
/// The returned structure must be deleted by the user. In case of
/// error 0 is returned.
 
UserGroup_t *TUnixSystem::GetGroupInfo(Int_t gid)
{
   struct group *grp = getgrgid(gid);
   if (grp) {
      UserGroup_t *gr = new UserGroup_t;
      gr->fUid   = 0;
      gr->fGid   = grp->gr_gid;
      gr->fGroup = grp->gr_name;
      return gr;
   }
   return nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns all group info in the UserGroup_t structure. The only active
/// fields in the UserGroup_t structure for this call are:
///    fGid and fGroup
/// If group = 0, returns current user's group. The returned structure
/// must be deleted by the user. In case of error 0 is returned.
 
UserGroup_t *TUnixSystem::GetGroupInfo(const char *group)
{
   return GetGroupInfo(GetGid(group));
}
 
//---- environment manipulation ------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Set environment variable.
 
void TUnixSystem::Setenv(const char *name, const char *value)
{
   ::setenv(name, value, 1);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get environment variable.
 
const char *TUnixSystem::Getenv(const char *name)
{
   return ::getenv(name);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Unset environment variable.
 
void TUnixSystem::Unsetenv(const char *name)
{
   ::unsetenv(name);
}
 
//---- Processes ---------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Execute a command.
 
int TUnixSystem::Exec(const char *shellcmd)
{
   return ::system(shellcmd);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a pipe.
 
FILE *TUnixSystem::OpenPipe(const char *command, const char *mode)
{
   return ::popen(command, mode);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Close the pipe.
 
int TUnixSystem::ClosePipe(FILE *pipe)
{
   return ::pclose(pipe);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get process id.
 
int TUnixSystem::GetPid()
{
   return ::getpid();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Exit the application.
 
void TUnixSystem::Exit(int code, Bool_t mode)
{
   // Insures that the files and sockets are closed before any library is unloaded
   // and before emptying CINT.
   TROOT::ShutDown();
 
   if (mode)
      ::exit(code);
   else
      ::_exit(code);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Abort the application.
 
void TUnixSystem::Abort(int)
{
   IgnoreSignal(kSigAbort);
   ::abort();
}
 
 
#ifdef R__MACOSX
/// Use CoreSymbolication to retrieve the stacktrace.
#include <mach/mach.h>
extern "C" {
  // Adapted from https://github.com/mountainstorm/CoreSymbolication
  // Under the hood the framework basically just calls through to a set of C++ libraries
  typedef struct {
    void* csCppData;
    void* csCppObj;
  } CSTypeRef;
  typedef CSTypeRef CSSymbolicatorRef;
  typedef CSTypeRef CSSourceInfoRef;
  typedef CSTypeRef CSSymbolOwnerRef;
  typedef CSTypeRef CSSymbolRef;
 
  CSSymbolicatorRef CSSymbolicatorCreateWithPid(pid_t pid);
  CSSymbolRef CSSymbolicatorGetSymbolWithAddressAtTime(CSSymbolicatorRef cs, vm_address_t addr, uint64_t time);
  CSSourceInfoRef CSSymbolicatorGetSourceInfoWithAddressAtTime(CSSymbolicatorRef cs, vm_address_t addr, uint64_t time);
  const char* CSSymbolGetName(CSSymbolRef sym);
  CSSymbolOwnerRef CSSymbolGetSymbolOwner(CSSymbolRef sym);
  const char* CSSymbolOwnerGetPath(CSSymbolOwnerRef symbol);
  const char* CSSourceInfoGetPath(CSSourceInfoRef info);
  int CSSourceInfoGetLineNumber(CSSourceInfoRef info);
}
 
bool CSTypeRefIdValid(CSTypeRef ref) {
   return ref.csCppData || ref.csCppObj;
}
 
void macosx_backtrace() {
void* addrlist[kMAX_BACKTRACE_DEPTH];
  // retrieve current stack addresses
  int numstacks = backtrace( addrlist, sizeof( addrlist ) / sizeof( void* ));
 
  CSSymbolicatorRef symbolicator = CSSymbolicatorCreateWithPid(getpid());
 
  // skip TUnixSystem::Backtrace(), macosx_backtrace()
  static const int skipFrames = 2;
  for (int i = skipFrames; i < numstacks; ++i) {
    // No debug info, try to get at least the symbol name.
    CSSymbolRef sym = CSSymbolicatorGetSymbolWithAddressAtTime(symbolicator,
                                                               (vm_address_t)addrlist[i],
                                                               0x80000000u);
    CSSymbolOwnerRef symOwner = CSSymbolGetSymbolOwner(sym);
 
    if (const char* libPath = CSSymbolOwnerGetPath(symOwner)) {
      printf("[%s]", libPath);
    } else {
      printf("[<unknown binary>]");
    }
 
    if (const char* symname = CSSymbolGetName(sym)) {
      printf(" %s", symname);
    }
 
    CSSourceInfoRef sourceInfo
      = CSSymbolicatorGetSourceInfoWithAddressAtTime(symbolicator,
                                                     (vm_address_t)addrlist[i],
                                                     0x80000000u /*"now"*/);
    if (const char* sourcePath = CSSourceInfoGetPath(sourceInfo)) {
      printf(" %s:%d", sourcePath, (int)CSSourceInfoGetLineNumber(sourceInfo));
    } else {
      printf(" (no debug info)");
    }
    printf("\n");
  }
}
#endif // R__MACOSX
 
////////////////////////////////////////////////////////////////////////////////
/// Print a stack trace.
 
void TUnixSystem::StackTrace()
{
   if (!gEnv->GetValue("Root.Stacktrace", 1))
      return;
 
#ifndef R__MACOSX
   TString gdbscript = gEnv->GetValue("Root.StacktraceScript", "");
   gdbscript = gdbscript.Strip();
   if (gdbscript != "") {
      if (AccessPathName(gdbscript, kReadPermission)) {
         fprintf(stderr, "Root.StacktraceScript %s does not exist\n", gdbscript.Data());
         gdbscript = "";
      }
   }
   if (gdbscript == "") {
      gdbscript = "gdb-backtrace.sh";
      gSystem->PrependPathName(TROOT::GetEtcDir(), gdbscript);
      if (AccessPathName(gdbscript, kReadPermission)) {
         fprintf(stderr, "Error in <TUnixSystem::StackTrace> script %s is missing\n", gdbscript.Data());
         return;
      }
   }
   gdbscript += " ";
 
   TString gdbmess = gEnv->GetValue("Root.StacktraceMessage", "");
   gdbmess = gdbmess.Strip();
 
   std::cout.flush();
   fflush(stdout);
 
   std::cerr.flush();
   fflush(stderr);
 
   int fd = STDERR_FILENO;
 
   const char *message = " Generating stack trace...\n";
 
   if (fd && message) { }  // remove unused warning (remove later)
 
   if (gApplication && !strcmp(gApplication->GetName(), "TRint"))
      Getlinem(kCleanUp, nullptr);
 
#if defined(USE_GDB_STACK_TRACE)
   char *gdb = Which(Getenv("PATH"), "gdb", kExecutePermission);
   if (!gdb) {
      fprintf(stderr, "gdb not found, need it for stack trace\n");
      return;
   }
 
   // write custom message file
   TString gdbmessf = "gdb-message";
   if (gdbmess != "") {
      FILE *f = TempFileName(gdbmessf);
      fprintf(f, "%s\n", gdbmess.Data());
      fclose(f);
   }
 
   // use gdb to get stack trace
   gdbscript += GetExePath();
   gdbscript += " ";
   gdbscript += GetPid();
   if (gdbmess != "") {
      gdbscript += " ";
      gdbscript += gdbmessf;
   }
   gdbscript += " 1>&2";
   Exec(gdbscript);
   delete [] gdb;
   return;
 
#elif defined(R__AIX)
   TString script = "procstack ";
   script += GetPid();
   Exec(script);
   return;
#elif defined(R__SOLARIS)
   char *cppfilt = Which(Getenv("PATH"), "c++filt", kExecutePermission);
   TString script = "pstack ";
   script += GetPid();
   if (cppfilt) {
      script += " | ";
      script += cppfilt;
      delete [] cppfilt;
   }
   Exec(script);
   return;
#elif defined(HAVE_BACKTRACE_SYMBOLS_FD) && defined(HAVE_DLADDR)  // linux + MacOS X >= 10.5
   // we could have used backtrace_symbols_fd, except its output
   // format is pretty bad, so recode that here :-(
 
   // take care of demangling
   Bool_t demangle = kTRUE;
 
   // check for c++filt
   const char *cppfilt = "c++filt";
   const char *cppfiltarg = "";
#ifdef R__B64
   const char *format1 = " 0x%016lx in %.200s %s 0x%lx from %.200s\n";
#ifdef R__MACOSX
   const char *format2 = " 0x%016lx in %.200s\n";
#else
   const char *format2 = " 0x%016lx in %.200s at %.200s from %.200s\n";
#endif
   const char *format3 = " 0x%016lx in %.200s from %.200s\n";
   const char *format4 = " 0x%016lx in <unknown function>\n";
#else
   const char *format1 = " 0x%08lx in %.200s %s 0x%lx from %.200s\n";
#ifdef R__MACOSX
   const char *format2 = " 0x%08lx in %.200s\n";
#else
   const char *format2 = " 0x%08lx in %.200s at %.200s from %.200s\n";
#endif
   const char *format3 = " 0x%08lx in %.200s from %.200s\n";
   const char *format4 = " 0x%08lx in <unknown function>\n";
#endif
 
   char *filter = Which(Getenv("PATH"), cppfilt, kExecutePermission);
   if (!filter)
      demangle = kFALSE;
 
#if (__GNUC__ >= 3)
   // try finding supported format option for g++ v3
   if (filter) {
      FILE *p = OpenPipe(TString::Format("%s --help 2>&1", filter), "r");
      TString help;
      while (help.Gets(p)) {
         if (help.Index("gnu-v3") != kNPOS) {
            cppfiltarg = "--format=gnu-v3";
            break;
         } else if (help.Index("gnu-new-abi") != kNPOS) {
            cppfiltarg = "--format=gnu-new-abi";
            break;
         }
      }
      ClosePipe(p);
   }
#endif
   // gdb-backtrace.sh uses gdb to produce a backtrace. See if it is available.
   // If it is, use it. If not proceed as before.
#if (defined(R__LINUX) && !defined(R__WINGCC))
   // Declare the process that will be generating the stacktrace
   // For more see: http://askubuntu.com/questions/41629/after-upgrade-gdb-wont-attach-to-process
#ifdef PR_SET_PTRACER
   prctl(PR_SET_PTRACER, getpid(), 0, 0, 0);
#endif
#endif
   char *gdb = Which(Getenv("PATH"), "gdb", kExecutePermission);
   if (gdb) {
      // write custom message file
      TString gdbmessf = "gdb-message";
      if (gdbmess != "") {
         FILE *f = TempFileName(gdbmessf);
         fprintf(f, "%s\n", gdbmess.Data());
         fclose(f);
      }
 
      // use gdb to get stack trace
#ifdef R__MACOSX
      gdbscript += GetExePath();
      gdbscript += " ";
#endif
      gdbscript += GetPid();
      if (gdbmess != "") {
         gdbscript += " ";
         gdbscript += gdbmessf;
      }
      gdbscript += " 1>&2";
      Exec(gdbscript);
      delete [] gdb;
   } else {
      // addr2line uses debug info to convert addresses into file names
      // and line numbers
#ifdef R__MACOSX
      char *addr2line = Which(Getenv("PATH"), "atos", kExecutePermission);
#else
      char *addr2line = Which(Getenv("PATH"), "addr2line", kExecutePermission);
#endif
      if (addr2line) {
         // might take some time so tell what we are doing...
         if (write(fd, message, strlen(message)) < 0)
            Warning("StackTrace", "problems writing line numbers (errno: %d)", TSystem::GetErrno());
      }
 
      // open tmp file for demangled stack trace
      TString tmpf1 = "gdb-backtrace";
      std::ofstream file1;
      if (demangle) {
         FILE *f = TempFileName(tmpf1);
         if (f) fclose(f);
         file1.open(tmpf1);
         if (!file1) {
            Error("StackTrace", "could not open file %s", tmpf1.Data());
            Unlink(tmpf1);
            demangle = kFALSE;
         }
      }
 
#ifdef R__MACOSX
      if (addr2line)
         demangle = kFALSE;  // atos always demangles
#endif
 
      char buffer[4096];
      void *trace[kMAX_BACKTRACE_DEPTH];
      int  depth = backtrace(trace, kMAX_BACKTRACE_DEPTH);
      for (int n = 5; n < depth; n++) {
         ULong_t addr = (ULong_t) trace[n];
         Dl_info info;
 
         if (dladdr(trace[n], &info) && info.dli_fname && info.dli_fname[0]) {
            const char *libname = info.dli_fname;
            const char *symname = (info.dli_sname && info.dli_sname[0]) ?
                                   info.dli_sname : "<unknown>";
            ULong_t libaddr = (ULong_t) info.dli_fbase;
            ULong_t symaddr = (ULong_t) info.dli_saddr;
            Bool_t  gte = (addr >= symaddr);
            ULong_t diff = (gte) ? addr - symaddr : symaddr - addr;
            if (addr2line && symaddr) {
               Bool_t nodebug = kTRUE;
#ifdef R__MACOSX
               if (libaddr) { }  // use libaddr
#if defined(MAC_OS_X_VERSION_10_10)
               snprintf(buffer, sizeof(buffer), "%s -p %d 0x%016lx", addr2line, GetPid(), addr);
#elif defined(MAC_OS_X_VERSION_10_9)
               // suppress deprecation warning with opti
               snprintf(buffer, sizeof(buffer), "%s -d -p %d 0x%016lx", addr2line, GetPid(), addr);
#else
               snprintf(buffer, sizeof(buffer), "%s -p %d 0x%016lx", addr2line, GetPid(), addr);
#endif
#else
               ULong_t offset = (addr >= libaddr) ? addr - libaddr :
                                                    libaddr - addr;
               TString name   = TString(libname);
               Bool_t noPath  = kFALSE;
               Bool_t noShare = kTRUE;
               if (name[0] != '/') noPath = kTRUE;
               if (name.Contains(".so") || name.Contains(".sl")) noShare = kFALSE;
               if (noShare) offset = addr;
               if (noPath)  name = "`which " + name + "`";
               snprintf(buffer, sizeof(buffer), "%s -e %s 0x%016lx", addr2line, name.Data(), offset);
#endif
               if (FILE *pf = ::popen(buffer, "r")) {
                  char buf[2048];
                  if (fgets(buf, 2048, pf)) {
                     buf[strlen(buf)-1] = 0;  // remove trailing \n
                     if (strncmp(buf, "??", 2)) {
#ifdef R__MACOSX
                        snprintf(buffer, sizeof(buffer), format2, addr, buf);
#else
                        snprintf(buffer, sizeof(buffer), format2, addr, symname, buf, libname);
#endif
                        nodebug = kFALSE;
                     }
                  }
                  ::pclose(pf);
               }
               if (nodebug)
                  snprintf(buffer, sizeof(buffer), format1, addr, symname,
                           gte ? "+" : "-", diff, libname);
            } else {
               if (symaddr)
                  snprintf(buffer, sizeof(buffer), format1, addr, symname,
                           gte ? "+" : "-", diff, libname);
               else
                  snprintf(buffer, sizeof(buffer), format3, addr, symname, libname);
            }
         } else {
            snprintf(buffer, sizeof(buffer), format4, addr);
         }
 
         if (demangle)
            file1 << buffer;
         else
            if (write(fd, buffer, ::strlen(buffer)) < 0)
               Warning("StackTrace", "problems writing buffer (errno: %d)", TSystem::GetErrno());
      }
 
      if (demangle) {
         TString tmpf2 = "gdb-backtrace";
         FILE *f = TempFileName(tmpf2);
         if (f) fclose(f);
         file1.close();
         snprintf(buffer, sizeof(buffer), "%s %s < %s > %s", filter, cppfiltarg, tmpf1.Data(), tmpf2.Data());
         Exec(buffer);
         std::ifstream file2(tmpf2);
         TString line;
         while (file2) {
            line = "";
            line.ReadString(file2);
            if (write(fd, line.Data(), line.Length()) < 0)
               Warning("StackTrace", "problems writing line (errno: %d)", TSystem::GetErrno());
         }
         file2.close();
         Unlink(tmpf1);
         Unlink(tmpf2);
      }
 
      delete [] addr2line;
   }
   delete [] filter;
#elif defined(HAVE_EXCPT_H) && defined(HAVE_PDSC_H) && \
                               defined(HAVE_RLD_INTERFACE_H) // tru64
   // Tru64 stack walk.  Uses the exception handling library and the
   // run-time linker's core functions (loader(5)).  FIXME: Tru64
   // should have _RLD_DLADDR like IRIX below.  Verify and update.
 
   char         buffer [128];
   sigcontext   context;
   int          rc = 0;
 
   exc_capture_context (&context);
   while (!rc && context.sc_pc) {
      // FIXME: Elf32?
      pdsc_crd *func, *base, *crd
         = exc_remote_lookup_function_entry(0, 0, context.sc_pc, 0, &func, &base);
      Elf32_Addr addr = PDSC_CRD_BEGIN_ADDRESS(base, func);
      // const char *name = _rld_address_to_name(addr);
      const char *name = "<unknown function>";
      sprintf(buffer, " 0x%012lx %.200s + 0x%lx\n",
              context.sc_pc, name, context.sc_pc - addr);
      write(fd, buffer, ::strlen(buffer));
      rc = exc_virtual_unwind(0, &context);
   }
#endif
#else //R__MACOSX
  macosx_backtrace();
#endif //R__MACOSX
}
 
//---- System Logging ----------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Open connection to system log daemon. For the use of the options and
/// facility see the Unix openlog man page.
 
void TUnixSystem::Openlog(const char *name, Int_t options, ELogFacility facility)
{
   int fac = 0;
 
   switch (facility) {
      case kLogLocal0:
         fac = LOG_LOCAL0;
         break;
      case kLogLocal1:
         fac = LOG_LOCAL1;
         break;
      case kLogLocal2:
         fac = LOG_LOCAL2;
         break;
      case kLogLocal3:
         fac = LOG_LOCAL3;
         break;
      case kLogLocal4:
         fac = LOG_LOCAL4;
         break;
      case kLogLocal5:
         fac = LOG_LOCAL5;
         break;
      case kLogLocal6:
         fac = LOG_LOCAL6;
         break;
      case kLogLocal7:
         fac = LOG_LOCAL7;
         break;
   }
 
   ::openlog(name, options, fac);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Send mess to syslog daemon. Level is the logging level and mess the
/// message that will be written on the log.
 
void TUnixSystem::Syslog(ELogLevel level, const char *mess)
{
   // ELogLevel matches exactly the Unix values.
   ::syslog(level, "%s", mess);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Close connection to system log daemon.
 
void TUnixSystem::Closelog()
{
   ::closelog();
}
 
//---- Standard output redirection ---------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Redirect standard output (stdout, stderr) to the specified file.
/// If the file argument is 0 the output is set again to stderr, stdout.
/// The second argument specifies whether the output should be added to the
/// file ("a", default) or the file be truncated before ("w").
/// This function saves internally the current state into a static structure.
/// The call can be made reentrant by specifying the opaque structure pointed
/// by 'h', which is filled with the relevant information. The handle 'h'
/// obtained on the first call must then be used in any subsequent call,
/// included ShowOutput, to display the redirected output.
/// Returns 0 on success, -1 in case of error.
 
Int_t TUnixSystem::RedirectOutput(const char *file, const char *mode,
                                  RedirectHandle_t *h)
{
   // Instance to be used if the caller does not passes 'h'
   static RedirectHandle_t loch;
 
   Int_t rc = 0;
 
   // Which handle to use ?
   RedirectHandle_t *xh = (h) ? h : &loch;
 
   if (file) {
      // Save the paths
      Bool_t outdone = kFALSE;
      if (xh->fStdOutTty.IsNull()) {
         const char *tty = ttyname(STDOUT_FILENO);
         if (tty) {
            xh->fStdOutTty = tty;
         } else {
            if ((xh->fStdOutDup = dup(STDOUT_FILENO)) < 0) {
               SysError("RedirectOutput", "could not 'dup' stdout (errno: %d)", TSystem::GetErrno());
               return -1;
            }
            outdone = kTRUE;
         }
      }
      if (xh->fStdErrTty.IsNull()) {
         const char *tty = ttyname(STDERR_FILENO);
         if (tty) {
            xh->fStdErrTty = tty;
         } else {
            if ((xh->fStdErrDup = dup(STDERR_FILENO)) < 0) {
               SysError("RedirectOutput", "could not 'dup' stderr (errno: %d)", TSystem::GetErrno());
               if (outdone && dup2(xh->fStdOutDup, STDOUT_FILENO) < 0) {
                  Warning("RedirectOutput", "could not restore stdout (back to original redirected"
                          " file) (errno: %d)", TSystem::GetErrno());
               }
               return -1;
            }
         }
      }
 
      // Make sure mode makes sense; default "a"
      const char *m = (mode[0] == 'a' || mode[0] == 'w') ? mode : "a";
 
      // Current file size
      xh->fReadOffSet = 0;
      if (m[0] == 'a') {
         // If the file exists, save the current size
         FileStat_t st;
         if (!gSystem->GetPathInfo(file, st))
            xh->fReadOffSet = (st.fSize > 0) ? st.fSize : xh->fReadOffSet;
      }
      xh->fFile = file;
 
      // Redirect stdout & stderr
      if (freopen(file, m, stdout) == nullptr) {
         SysError("RedirectOutput", "could not freopen stdout (errno: %d)", TSystem::GetErrno());
         return -1;
      }
      if (freopen(file, m, stderr) == nullptr) {
         SysError("RedirectOutput", "could not freopen stderr (errno: %d)", TSystem::GetErrno());
         if (freopen(xh->fStdOutTty.Data(), "a", stdout) == nullptr)
            SysError("RedirectOutput", "could not restore stdout (errno: %d)", TSystem::GetErrno());
         return -1;
      }
   } else {
      // Restore stdout & stderr
      fflush(stdout);
      if (!(xh->fStdOutTty.IsNull())) {
         if (freopen(xh->fStdOutTty.Data(), "a", stdout) == nullptr) {
            SysError("RedirectOutput", "could not restore stdout (errno: %d)", TSystem::GetErrno());
            rc = -1;
         }
         xh->fStdOutTty = "";
      } else {
         if (close(STDOUT_FILENO) != 0) {
            SysError("RedirectOutput",
                     "problems closing STDOUT_FILENO (%d) before 'dup2' (errno: %d)",
                     STDOUT_FILENO, TSystem::GetErrno());
            rc = -1;
         }
         if (dup2(xh->fStdOutDup, STDOUT_FILENO) < 0) {
            SysError("RedirectOutput", "could not restore stdout (back to original redirected"
                     " file) (errno: %d)", TSystem::GetErrno());
            rc = -1;
         }
         if (close(xh->fStdOutDup) != 0) {
            SysError("RedirectOutput",
                     "problems closing temporary 'out' descriptor %d (errno: %d)",
                     TSystem::GetErrno(), xh->fStdOutDup);
            rc = -1;
         }
      }
      fflush(stderr);
      if (!(xh->fStdErrTty.IsNull())) {
         if (freopen(xh->fStdErrTty.Data(), "a", stderr) == nullptr) {
            SysError("RedirectOutput", "could not restore stderr (errno: %d)", TSystem::GetErrno());
            rc = -1;
         }
         xh->fStdErrTty = "";
      } else {
         if (close(STDERR_FILENO) != 0) {
            SysError("RedirectOutput",
                     "problems closing STDERR_FILENO (%d) before 'dup2' (errno: %d)",
                     STDERR_FILENO, TSystem::GetErrno());
            rc = -1;
         }
         if (dup2(xh->fStdErrDup, STDERR_FILENO) < 0) {
            SysError("RedirectOutput", "could not restore stderr (back to original redirected"
                     " file) (errno: %d)", TSystem::GetErrno());
            rc = -1;
         }
         if (close(xh->fStdErrDup) != 0) {
            SysError("RedirectOutput",
                     "problems closing temporary 'err' descriptor %d (errno: %d)",
                     TSystem::GetErrno(), xh->fStdErrDup);
            rc = -1;
         }
      }
      // Reset the static instance, if using that
      if (xh == &loch)
         xh->Reset();
   }
   return rc;
}
 
//---- dynamic loading and linking ---------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
///dynamic linking of module
 
Func_t TUnixSystem::DynFindSymbol(const char * /*module*/, const char *entry)
{
   return TSystem::DynFindSymbol("*", entry);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Load a shared library. Returns 0 on successful loading, 1 in
/// case lib was already loaded and -1 in case lib does not exist
/// or in case of error.
 
int TUnixSystem::Load(const char *module, const char *entry, Bool_t system)
{
   return TSystem::Load(module, entry, system);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Unload a shared library.
 
void TUnixSystem::Unload(const char *module)
{
   if (module) { TSystem::Unload(module); }
}
 
////////////////////////////////////////////////////////////////////////////////
/// List symbols in a shared library.
 
void TUnixSystem::ListSymbols(const char * /*module*/, const char * /*regexp*/)
{
   Error("ListSymbols", "not yet implemented");
}
 
////////////////////////////////////////////////////////////////////////////////
/// List all loaded shared libraries.
 
void TUnixSystem::ListLibraries(const char *regexp)
{
   TSystem::ListLibraries(regexp);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get list of shared libraries loaded at the start of the executable.
/// Returns 0 in case list cannot be obtained or in case of error.
 
const char *TUnixSystem::GetLinkedLibraries()
{
   static TString linkedLibs;
   static Bool_t once = kFALSE;
 
   R__LOCKGUARD2(gSystemMutex);
 
   if (!linkedLibs.IsNull())
      return linkedLibs;
 
   if (once)
      return nullptr;
 
#if !defined(R__MACOSX)
   const char *exe = GetExePath();
   if (!exe || !*exe)
      return nullptr;
#endif
 
#if defined(R__MACOSX)
   DylibAdded(0, 0);
   linkedLibs = gLinkedDylibs;
#if 0
   FILE *p = OpenPipe(TString::Format("otool -L %s", exe), "r");
   TString otool;
   while (otool.Gets(p)) {
      TString delim(" \t");
      TObjArray *tok = otool.Tokenize(delim);
      TString dylib = ((TObjString*)tok->At(0))->String();
      if (dylib.EndsWith(".dylib") && !dylib.Contains("/libSystem.B.dylib")) {
         if (!linkedLibs.IsNull())
            linkedLibs += " ";
         linkedLibs += dylib;
      }
      delete tok;
   }
   if (p) {
      ClosePipe(p);
   }
#endif
#elif defined(R__LINUX) || defined(R__SOLARIS) || defined(R__AIX)
#if defined(R__WINGCC )
   const char *cLDD="cygcheck";
   const char *cSOEXT=".dll";
   size_t lenexe = strlen(exe);
   if (strcmp(exe + lenexe - 4, ".exe")
       && strcmp(exe + lenexe - 4, ".dll")) {
      // it's not a dll and exe doesn't end on ".exe";
      // need to add it for cygcheck to find it:
      char* longerexe = new char[lenexe + 5];
      strlcpy(longerexe, exe,lenexe+5);
      strlcat(longerexe, ".exe",lenexe+5);
      exe = longerexe;  // memory leak
      #error "unsupported platform, fix memory leak to use it"
   }
   TRegexp sovers = "\\.so\\.[0-9]+";
#else
   const char *cLDD="ldd";
#if defined(R__AIX)
   const char *cSOEXT=".a";
   TRegexp sovers = "\\.a\\.[0-9]+";
#else
   const char *cSOEXT=".so";
   TRegexp sovers = "\\.so\\.[0-9]+";
#endif
#endif
   FILE *p = OpenPipe(TString::Format("%s '%s'", cLDD, exe), "r");
   if (p) {
      TString ldd;
      while (ldd.Gets(p)) {
         TString delim(" \t");
         TObjArray *tok = ldd.Tokenize(delim);
 
         // expected format:
         //    libCore.so => /home/rdm/root/lib/libCore.so (0x40017000)
         TObjString *solibName = (TObjString*)tok->At(2);
         if (!solibName) {
            // case where there is only one name of the list:
            //    /usr/platform/SUNW,UltraAX-i2/lib/libc_psr.so.1
            solibName = (TObjString*)tok->At(0);
         }
         if (solibName) {
            TString solib = solibName->String();
            Ssiz_t idx = solib.Index(sovers);
            if (solib.EndsWith(cSOEXT) || idx != kNPOS) {
               if (idx != kNPOS)
                  solib.Remove(idx+3);
               if (!AccessPathName(solib, kReadPermission)) {
                  if (!linkedLibs.IsNull())
                     linkedLibs += " ";
                  linkedLibs += solib;
               }
            }
         }
         delete tok;
      }
      ClosePipe(p);
   }
#endif
 
   once = kTRUE;
 
   if (linkedLibs.IsNull())
      return nullptr;
 
   return linkedLibs;
}
 
//---- Time & Date -------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Get current time in milliseconds since 0:00 Jan 1 1995.
 
TTime TUnixSystem::Now()
{
   return UnixNow();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Handle and dispatch timers. If mode = kTRUE dispatch synchronous
/// timers else a-synchronous timers.
 
Bool_t TUnixSystem::DispatchTimers(Bool_t mode)
{
   if (!fTimers) return kFALSE;
 
   fInsideNotify = kTRUE;
 
   TListIter it(fTimers);
   TTimer *t;
   Bool_t  timedout = kFALSE;
 
   while ((t = (TTimer *) it.Next())) {
      // NB: the timer resolution is added in TTimer::CheckTimer()
      Long64_t now = UnixNow();
      if (mode && t->IsSync()) {
         if (t->CheckTimer(now))
            timedout = kTRUE;
      } else if (!mode && t->IsAsync()) {
         if (t->CheckTimer(now)) {
            UnixSetitimer(NextTimeOut(kFALSE));
            timedout = kTRUE;
         }
      }
   }
   fInsideNotify = kFALSE;
   return timedout;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Add timer to list of system timers.
 
void TUnixSystem::AddTimer(TTimer *ti)
{
   TSystem::AddTimer(ti);
   ResetTimer(ti);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Remove timer from list of system timers.
 
TTimer *TUnixSystem::RemoveTimer(TTimer *ti)
{
   if (!ti) return nullptr;
 
   R__LOCKGUARD2(gSystemMutex);
 
   TTimer *t = TSystem::RemoveTimer(ti);
   if (ti->IsAsync())
      UnixSetitimer(NextTimeOut(kFALSE));
   return t;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Reset a-sync timer.
 
void TUnixSystem::ResetTimer(TTimer *ti)
{
   if (!fInsideNotify && ti && ti->IsAsync())
      UnixSetitimer(NextTimeOut(kFALSE));
}
 
//---- RPC ---------------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Get Internet Protocol (IP) address of host. Returns an TInetAddress
/// object. To see if the hostname lookup was successfull call
/// TInetAddress::IsValid().
 
TInetAddress TUnixSystem::GetHostByName(const char *hostname)
{
   TInetAddress ia;
   struct addrinfo hints;
   struct addrinfo *result, *rp;
   memset(&hints, 0, sizeof(struct addrinfo));
   hints.ai_family = AF_INET;       // only IPv4
   hints.ai_socktype = 0;           // any socket type
   hints.ai_protocol = 0;           // any protocol
   hints.ai_flags = AI_CANONNAME;   // get canonical name
#ifdef R__MACOSX
   // Anything ending on ".local" causes a 5 second delay in getaddrinfo().
   // See e.g. https://apple.stackexchange.com/questions/175320/why-is-my-hostname-resolution-taking-so-long
   // Only reasonable solution: remove the "domain" part if it's ".local".
   size_t lenHostname = strlen(hostname);
   std::string hostnameWithoutLocal{hostname};
   if (lenHostname > 6 && !strcmp(hostname + lenHostname - 6, ".local")) {
      hostnameWithoutLocal.erase(lenHostname - 6);
      hostname = hostnameWithoutLocal.c_str();
   }
#endif
 
   // obsolete gethostbyname() replaced by getaddrinfo()
   int rc = getaddrinfo(hostname, nullptr, &hints, &result);
   if (rc != 0) {
      if (rc == EAI_NONAME) {
         if (gDebug > 0) Error("GetHostByName", "unknown host '%s'", hostname);
         ia.fHostname = "UnNamedHost";
      } else {
         Error("GetHostByName", "getaddrinfo failed for '%s': %s", hostname, gai_strerror(rc));
         ia.fHostname = "UnknownHost";
      }
      return ia;
   }
 
   std::string hostcanon(result->ai_canonname ? result->ai_canonname : hostname);
   ia.fHostname = hostcanon.data();
   ia.fFamily = result->ai_family;
   ia.fAddresses[0] = ntohl(((struct sockaddr_in *)(result->ai_addr))->sin_addr.s_addr);
   // with getaddrinfo() no way to get list of aliases for a hostname
   if (hostcanon.compare(hostname) != 0) ia.AddAlias(hostname);
 
   // check on numeric hostname
   char tmp[sizeof(struct in_addr)];
   if (inet_pton(AF_INET, hostcanon.data(), tmp) == 1) {
      char hbuf[NI_MAXHOST];
      if (getnameinfo(result->ai_addr, result->ai_addrlen, hbuf, sizeof(hbuf), nullptr, 0, 0) == 0)
         ia.fHostname = hbuf;
   }
 
   // check other addresses (if exist)
   rp = result->ai_next;
   for (; rp != nullptr; rp = rp->ai_next) {
      UInt_t arp = ntohl(((struct sockaddr_in *)(rp->ai_addr))->sin_addr.s_addr);
      if ( !(std::find(ia.fAddresses.begin(), ia.fAddresses.end(), arp) != ia.fAddresses.end()) )
         ia.AddAddress(arp);
   }
 
   freeaddrinfo(result);
   return ia;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get Internet Protocol (IP) address of host and port #.
 
TInetAddress TUnixSystem::GetSockName(int sock)
{
   struct sockaddr addr;
   socklen_t len = sizeof(addr);
 
   TInetAddress ia;
   if (getsockname(sock, &addr, &len) == -1) {
      SysError("GetSockName", "getsockname failed");
      return ia;
   }
 
   if (addr.sa_family != AF_INET) return ia; // only IPv4
   ia.fFamily = addr.sa_family;
   struct sockaddr_in *addrin = (struct sockaddr_in *)&addr;
   ia.fPort = ntohs(addrin->sin_port);
   ia.fAddresses[0] = ntohl(addrin->sin_addr.s_addr);
 
   char hbuf[NI_MAXHOST];
   if (getnameinfo(&addr, sizeof(struct sockaddr), hbuf, sizeof(hbuf), nullptr, 0, 0) != 0) {
      Error("GetSockName", "getnameinfo failed");
      ia.fHostname = "????";
   } else
      ia.fHostname = hbuf;
 
   return ia;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get Internet Protocol (IP) address of remote host and port #.
 
TInetAddress TUnixSystem::GetPeerName(int sock)
{
   struct sockaddr addr;
   socklen_t len = sizeof(addr);
 
   TInetAddress ia;
   if (getpeername(sock, &addr, &len) == -1) {
      SysError("GetPeerName", "getpeername failed");
      return ia;
   }
 
   if (addr.sa_family != AF_INET) return ia; // only IPv4
   ia.fFamily = addr.sa_family;
   struct sockaddr_in *addrin = (struct sockaddr_in *)&addr;
   ia.fPort = ntohs(addrin->sin_port);
   ia.fAddresses[0] = ntohl(addrin->sin_addr.s_addr);
 
   char hbuf[NI_MAXHOST];
   if (getnameinfo(&addr, sizeof(struct sockaddr), hbuf, sizeof(hbuf), nullptr, 0, 0) != 0) {
      Error("GetPeerName", "getnameinfo failed");
      ia.fHostname = "????";
   } else
      ia.fHostname = hbuf;
 
   return ia;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get port # of internet service.
 
int TUnixSystem::GetServiceByName(const char *servicename)
{
   struct servent *sp;
 
   if ((sp = getservbyname(servicename, kProtocolName)) == nullptr) {
      Error("GetServiceByName", "no service \"%s\" with protocol \"%s\"\n",
              servicename, kProtocolName);
      return -1;
   }
   return ntohs(sp->s_port);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get name of internet service.
 
char *TUnixSystem::GetServiceByPort(int port)
{
   struct servent *sp;
 
   if ((sp = getservbyport(htons(port), kProtocolName)) == nullptr) {
      //::Error("GetServiceByPort", "no service \"%d\" with protocol \"%s\"",
      //        port, kProtocolName);
      return Form("%d", port);
   }
   return sp->s_name;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Connect to service servicename on server servername.
 
int TUnixSystem::ConnectService(const char *servername, int port,
                                int tcpwindowsize, const char *protocol)
{
   if (!strcmp(servername, "unix")) {
      return UnixUnixConnect(port);
   } else if (!gSystem->AccessPathName(servername) || servername[0] == '/') {
      return UnixUnixConnect(servername);
   }
 
   if (!strcmp(protocol, "udp")){
      return UnixUdpConnect(servername, port);
   }
 
   return UnixTcpConnect(servername, port, tcpwindowsize);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a connection to a service on a server. Returns -1 in case
/// connection cannot be opened.
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// Is called via the TSocket constructor.
 
int TUnixSystem::OpenConnection(const char *server, int port, int tcpwindowsize, const char *protocol)
{
   return ConnectService(server, port, tcpwindowsize, protocol);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Announce TCP/IP service.
/// Open a socket, bind to it and start listening for TCP/IP connections
/// on the port. If reuse is true reuse the address, backlog specifies
/// how many sockets can be waiting to be accepted.
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// Returns socket fd or -1 if socket() failed, -2 if bind() failed
/// or -3 if listen() failed.
 
int TUnixSystem::AnnounceTcpService(int port, Bool_t reuse, int backlog,
                                    int tcpwindowsize, ESocketBindOption socketBindOption)
{
   return UnixTcpService(port, reuse, backlog, tcpwindowsize, socketBindOption);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Announce UDP service.
 
int TUnixSystem::AnnounceUdpService(int port, int backlog, ESocketBindOption socketBindOption)
{
   return UnixUdpService(port, backlog, socketBindOption);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Announce unix domain service on path "kServerPath/<port>"
 
int TUnixSystem::AnnounceUnixService(int port, int backlog)
{
   return UnixUnixService(port, backlog);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Announce unix domain service on path 'sockpath'
 
int TUnixSystem::AnnounceUnixService(const char *sockpath, int backlog)
{
   return UnixUnixService(sockpath, backlog);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Accept a connection. In case of an error return -1. In case
/// non-blocking I/O is enabled and no connections are available
/// return -2.
 
int TUnixSystem::AcceptConnection(int sock)
{
   int soc = -1;
 
   while ((soc = ::accept(sock, nullptr, nullptr)) == -1 && GetErrno() == EINTR)
      ResetErrno();
 
   if (soc == -1) {
      if (GetErrno() == EWOULDBLOCK)
         return -2;
      else {
         SysError("AcceptConnection", "accept");
         return -1;
      }
   }
 
   return soc;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Close socket.
 
void TUnixSystem::CloseConnection(int sock, Bool_t force)
{
   if (sock < 0) return;
 
#if !defined(R__AIX) || defined(_AIX41) || defined(_AIX43)
   if (force)
      ::shutdown(sock, 2);   // will also close connection of parent
#endif
 
   while (::close(sock) == -1 && GetErrno() == EINTR)
      ResetErrno();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Receive a buffer headed by a length indicator. Length is the size of
/// the buffer. Returns the number of bytes received in buf or -1 in
/// case of error.
 
int TUnixSystem::RecvBuf(int sock, void *buf, int length)
{
   Int_t header;
 
   if (UnixRecv(sock, &header, sizeof(header), 0) > 0) {
      int count = ntohl(header);
 
      if (count > length) {
         Error("RecvBuf", "record header exceeds buffer size");
         return -1;
      } else if (count > 0) {
         if (UnixRecv(sock, buf, count, 0) < 0) {
            Error("RecvBuf", "cannot receive buffer");
            return -1;
         }
      }
      return count;
   }
   return -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Send a buffer headed by a length indicator. Returns length of sent buffer
/// or -1 in case of error.
 
int TUnixSystem::SendBuf(int sock, const void *buf, int length)
{
   Int_t header = htonl(length);
 
   if (UnixSend(sock, &header, sizeof(header), 0) < 0) {
      Error("SendBuf", "cannot send header");
      return -1;
   }
   if (length > 0) {
      if (UnixSend(sock, buf, length, 0) < 0) {
         Error("SendBuf", "cannot send buffer");
         return -1;
      }
   }
   return length;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Receive exactly length bytes into buffer. Use opt to receive out-of-band
/// data or to have a peek at what is in the buffer (see TSocket). Buffer
/// must be able to store at least length bytes. Returns the number of
/// bytes received (can be 0 if other side of connection was closed) or -1
/// in case of error, -2 in case of MSG_OOB and errno == EWOULDBLOCK, -3
/// in case of MSG_OOB and errno == EINVAL and -4 in case of kNoBlock and
/// errno == EWOULDBLOCK. Returns -5 if pipe broken or reset by peer
/// (EPIPE || ECONNRESET).
 
int TUnixSystem::RecvRaw(int sock, void *buf, int length, int opt)
{
   int flag;
 
   switch (opt) {
   case kDefault:
      flag = 0;
      break;
   case kOob:
      flag = MSG_OOB;
      break;
   case kPeek:
      flag = MSG_PEEK;
      break;
   case kDontBlock:
      flag = -1;
      break;
   default:
      flag = 0;
      break;
   }
 
   int n;
   if ((n = UnixRecv(sock, buf, length, flag)) <= 0) {
      if (n == -1 && GetErrno() != EINTR)
         Error("RecvRaw", "cannot receive buffer");
      return n;
   }
   return n;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Send exactly length bytes from buffer. Use opt to send out-of-band
/// data (see TSocket). Returns the number of bytes sent or -1 in case of
/// error. Returns -4 in case of kNoBlock and errno == EWOULDBLOCK.
/// Returns -5 if pipe broken or reset by peer (EPIPE || ECONNRESET).
 
int TUnixSystem::SendRaw(int sock, const void *buf, int length, int opt)
{
   int flag;
 
   switch (opt) {
   case kDefault:
      flag = 0;
      break;
   case kOob:
      flag = MSG_OOB;
      break;
   case kDontBlock:
      flag = -1;
      break;
   case kPeek:            // receive only option (see RecvRaw)
   default:
      flag = 0;
      break;
   }
 
   int n;
   if ((n = UnixSend(sock, buf, length, flag)) <= 0) {
      if (n == -1 && GetErrno() != EINTR)
         Error("SendRaw", "cannot send buffer");
      return n;
   }
   return n;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set socket option.
 
int TUnixSystem::SetSockOpt(int sock, int opt, int val)
{
   if (sock < 0) return -1;
 
   switch (opt) {
   case kSendBuffer:
      if (setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char*)&val, sizeof(val)) == -1) {
         SysError("SetSockOpt", "setsockopt(SO_SNDBUF)");
         return -1;
      }
      break;
   case kRecvBuffer:
      if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char*)&val, sizeof(val)) == -1) {
         SysError("SetSockOpt", "setsockopt(SO_RCVBUF)");
         return -1;
      }
      break;
   case kOobInline:
      if (setsockopt(sock, SOL_SOCKET, SO_OOBINLINE, (char*)&val, sizeof(val)) == -1) {
         SysError("SetSockOpt", "setsockopt(SO_OOBINLINE)");
         return -1;
      }
      break;
   case kKeepAlive:
      if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (char*)&val, sizeof(val)) == -1) {
         SysError("SetSockOpt", "setsockopt(SO_KEEPALIVE)");
         return -1;
      }
      break;
   case kReuseAddr:
      if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char*)&val, sizeof(val)) == -1) {
         SysError("SetSockOpt", "setsockopt(SO_REUSEADDR)");
         return -1;
      }
      break;
   case kNoDelay:
      if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char*)&val, sizeof(val)) == -1) {
         SysError("SetSockOpt", "setsockopt(TCP_NODELAY)");
         return -1;
      }
      break;
   case kNoBlock:
      if (ioctl(sock, FIONBIO, (char*)&val) == -1) {
         SysError("SetSockOpt", "ioctl(FIONBIO)");
         return -1;
      }
      break;
   case kProcessGroup:
#ifndef R__WINGCC
      if (ioctl(sock, SIOCSPGRP, (char*)&val) == -1) {
         SysError("SetSockOpt", "ioctl(SIOCSPGRP)");
         return -1;
      }
#else
      Error("SetSockOpt", "ioctl(SIOCGPGRP) not supported on cygwin/gcc");
      return -1;
#endif
      break;
   case kAtMark:       // read-only option (see GetSockOpt)
   case kBytesToRead:  // read-only option
   default:
      Error("SetSockOpt", "illegal option (%d)", opt);
      return -1;
   }
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get socket option.
 
int TUnixSystem::GetSockOpt(int sock, int opt, int *val)
{
   if (sock < 0) return -1;
 
   socklen_t optlen = sizeof(*val);
 
   switch (opt) {
   case kSendBuffer:
      if (getsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char*)val, &optlen) == -1) {
         SysError("GetSockOpt", "getsockopt(SO_SNDBUF)");
         return -1;
      }
      break;
   case kRecvBuffer:
      if (getsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char*)val, &optlen) == -1) {
         SysError("GetSockOpt", "getsockopt(SO_RCVBUF)");
         return -1;
      }
      break;
   case kOobInline:
      if (getsockopt(sock, SOL_SOCKET, SO_OOBINLINE, (char*)val, &optlen) == -1) {
         SysError("GetSockOpt", "getsockopt(SO_OOBINLINE)");
         return -1;
      }
      break;
   case kKeepAlive:
      if (getsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (char*)val, &optlen) == -1) {
         SysError("GetSockOpt", "getsockopt(SO_KEEPALIVE)");
         return -1;
      }
      break;
   case kReuseAddr:
      if (getsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (char*)val, &optlen) == -1) {
         SysError("GetSockOpt", "getsockopt(SO_REUSEADDR)");
         return -1;
      }
      break;
   case kNoDelay:
      if (getsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char*)val, &optlen) == -1) {
         SysError("GetSockOpt", "getsockopt(TCP_NODELAY)");
         return -1;
      }
      break;
   case kNoBlock:
      int flg;
      if ((flg = fcntl(sock, F_GETFL, 0)) == -1) {
         SysError("GetSockOpt", "fcntl(F_GETFL)");
         return -1;
      }
      *val = flg & O_NDELAY;
      break;
   case kProcessGroup:
#if !defined(R__LYNXOS) && !defined(R__WINGCC)
      if (ioctl(sock, SIOCGPGRP, (char*)val) == -1) {
         SysError("GetSockOpt", "ioctl(SIOCGPGRP)");
         return -1;
      }
#else
      Error("GetSockOpt", "ioctl(SIOCGPGRP) not supported on LynxOS and cygwin/gcc");
      return -1;
#endif
      break;
   case kAtMark:
#if !defined(R__LYNXOS)
      if (ioctl(sock, SIOCATMARK, (char*)val) == -1) {
         SysError("GetSockOpt", "ioctl(SIOCATMARK)");
         return -1;
      }
#else
      Error("GetSockOpt", "ioctl(SIOCATMARK) not supported on LynxOS");
      return -1;
#endif
      break;
   case kBytesToRead:
#if !defined(R__LYNXOS)
      if (ioctl(sock, FIONREAD, (char*)val) == -1) {
         SysError("GetSockOpt", "ioctl(FIONREAD)");
         return -1;
      }
#else
      Error("GetSockOpt", "ioctl(FIONREAD) not supported on LynxOS");
      return -1;
#endif
      break;
   default:
      Error("GetSockOpt", "illegal option (%d)", opt);
      *val = 0;
      return -1;
   }
   return 0;
}
 
//////////////////////////////////////////////////////////////////////////
//                                                                      //
// Static Protected Unix Interface functions.                           //
//                                                                      //
//////////////////////////////////////////////////////////////////////////
 
//---- signals -----------------------------------------------------------------
 
static struct Signalmap_t {
   int               fCode;
   SigHandler_t      fHandler;
   struct sigaction *fOldHandler;
   const char       *fSigName;
} gSignalMap[kMAXSIGNALS] = {       // the order of the signals should be identical
   { SIGBUS,   nullptr, nullptr, "bus error" }, // to the one in TSysEvtHandler.h
   { SIGSEGV,  nullptr, nullptr, "segmentation violation" },
   { SIGSYS,   nullptr, nullptr, "bad argument to system call" },
   { SIGPIPE,  nullptr, nullptr, "write on a pipe with no one to read it" },
   { SIGILL,   nullptr, nullptr, "illegal instruction" },
   { SIGABRT,  nullptr, nullptr, "abort" },
   { SIGQUIT,  nullptr, nullptr, "quit" },
   { SIGINT,   nullptr, nullptr, "interrupt" },
   { SIGWINCH, nullptr, nullptr, "window size change" },
   { SIGALRM,  nullptr, nullptr, "alarm clock" },
   { SIGCHLD,  nullptr, nullptr, "death of a child" },
   { SIGURG,   nullptr, nullptr, "urgent data arrived on an I/O channel" },
   { SIGFPE,   nullptr, nullptr, "floating point exception" },
   { SIGTERM,  nullptr, nullptr, "termination signal" },
   { SIGUSR1,  nullptr, nullptr, "user-defined signal 1" },
   { SIGUSR2,  nullptr, nullptr, "user-defined signal 2" }
};
 
 
////////////////////////////////////////////////////////////////////////////////
/// Call the signal handler associated with the signal.
 
static void sighandler(int sig)
{
   for (int i= 0; i < kMAXSIGNALS; i++) {
      if (gSignalMap[i].fCode == sig) {
         (*gSignalMap[i].fHandler)((ESignals)i);
         return;
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Handle and dispatch signals.
 
void TUnixSystem::DispatchSignals(ESignals sig)
{
   switch (sig) {
   case kSigAlarm:
      DispatchTimers(kFALSE);
      break;
   case kSigChild:
      CheckChilds();
      break;
   case kSigBus:
   case kSigSegmentationViolation:
   case kSigIllegalInstruction:
   case kSigAbort:
   case kSigFloatingException:
      if (gExceptionHandler)
         gExceptionHandler->HandleException(sig);
      else {
         if (sig == kSigAbort)
            return;
         Break("TUnixSystem::DispatchSignals", "%s", UnixSigname(sig));
         StackTrace();
         if (gApplication)
            //sig is ESignal, should it be mapped to the correct signal number?
            gApplication->HandleException(sig);
         else
            //map to the real signal code + set the
            //high order bit to indicate a signal (?)
            Exit(gSignalMap[sig].fCode + 0x80);
      }
      break;
   case kSigSystem:
   case kSigPipe:
      Break("TUnixSystem::DispatchSignals", "%s", UnixSigname(sig));
      break;
   case kSigWindowChanged:
      Gl_windowchanged();
      break;
   case kSigUser2:
      Break("TUnixSystem::DispatchSignals", "%s: printing stacktrace", UnixSigname(sig));
      StackTrace();
      // Intentional fall-through; pass the signal to handlers (or terminate):
   default:
      fSignals->Set(sig);
      fSigcnt++;
      break;
   }
 
   // check a-synchronous signals
   if (fSigcnt > 0 && fSignalHandler->GetSize() > 0)
      CheckSignals(kFALSE);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set a signal handler for a signal.
 
void TUnixSystem::UnixSignal(ESignals sig, SigHandler_t handler)
{
   if (gEnv && !gEnv->GetValue("Root.ErrorHandlers", 1))
      return;
 
   if (gSignalMap[sig].fHandler != handler) {
      struct sigaction sigact;
 
      gSignalMap[sig].fHandler    = handler;
      gSignalMap[sig].fOldHandler = new struct sigaction();
 
#if defined(R__SUN)
      sigact.sa_handler = (void (*)())sighandler;
#elif defined(R__SOLARIS)
      sigact.sa_handler = sighandler;
#elif defined(R__LYNXOS)
#  if (__GNUG__>=3)
      sigact.sa_handler = sighandler;
#  else
      sigact.sa_handler = (void (*)(...))sighandler;
#  endif
#else
      sigact.sa_handler = sighandler;
#endif
      sigemptyset(&sigact.sa_mask);
      sigact.sa_flags = 0;
#if defined(SA_RESTART)
      sigact.sa_flags |= SA_RESTART;
#endif
      if (sigaction(gSignalMap[sig].fCode, &sigact,
                    gSignalMap[sig].fOldHandler) < 0)
         ::SysError("TUnixSystem::UnixSignal", "sigaction");
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// If ignore is true ignore the specified signal, else restore previous
/// behaviour.
 
void TUnixSystem::UnixIgnoreSignal(ESignals sig, Bool_t ignore)
{
   TTHREAD_TLS(Bool_t) ignoreSig[kMAXSIGNALS] = { kFALSE };
   TTHREAD_TLS_ARRAY(struct sigaction,kMAXSIGNALS,oldsigact);
 
   if (ignore != ignoreSig[sig]) {
      ignoreSig[sig] = ignore;
      if (ignore) {
         struct sigaction sigact;
#if defined(R__SUN)
         sigact.sa_handler = (void (*)())SIG_IGN;
#elif defined(R__SOLARIS)
         sigact.sa_handler = (void (*)(int))SIG_IGN;
#else
         sigact.sa_handler = SIG_IGN;
#endif
         sigemptyset(&sigact.sa_mask);
         sigact.sa_flags = 0;
         if (sigaction(gSignalMap[sig].fCode, &sigact, &oldsigact[sig]) < 0)
            ::SysError("TUnixSystem::UnixIgnoreSignal", "sigaction");
      } else {
         if (sigaction(gSignalMap[sig].fCode, &oldsigact[sig], nullptr) < 0)
            ::SysError("TUnixSystem::UnixIgnoreSignal", "sigaction");
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// When the argument is true the SIGALRM signal handler is set so that
/// interrupted syscalls will not be restarted by the kernel. This is
/// typically used in case one wants to put a timeout on an I/O operation.
/// By default interrupted syscalls will always be restarted (for all
/// signals). This can be controlled for each a-synchronous TTimer via
/// the method TTimer::SetInterruptSyscalls().
 
void TUnixSystem::UnixSigAlarmInterruptsSyscalls(Bool_t set)
{
   if (gSignalMap[kSigAlarm].fHandler) {
      struct sigaction sigact;
#if defined(R__SUN)
      sigact.sa_handler = (void (*)())sighandler;
#elif defined(R__SOLARIS)
      sigact.sa_handler = sighandler;
#elif defined(R__LYNXOS)
#  if (__GNUG__>=3)
      sigact.sa_handler = sighandler;
#  else
      sigact.sa_handler = (void (*)(...))sighandler;
#  endif
#else
      sigact.sa_handler = sighandler;
#endif
      sigemptyset(&sigact.sa_mask);
      sigact.sa_flags = 0;
      if (set) {
#if defined(SA_INTERRUPT)       // SunOS
         sigact.sa_flags |= SA_INTERRUPT;
#endif
      } else {
#if defined(SA_RESTART)
         sigact.sa_flags |= SA_RESTART;
#endif
      }
      if (sigaction(gSignalMap[kSigAlarm].fCode, &sigact, nullptr) < 0)
         ::SysError("TUnixSystem::UnixSigAlarmInterruptsSyscalls", "sigaction");
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the signal name associated with a signal.
 
const char *TUnixSystem::UnixSigname(ESignals sig)
{
   return gSignalMap[sig].fSigName;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Restore old signal handler for specified signal.
 
void TUnixSystem::UnixResetSignal(ESignals sig)
{
   if (gSignalMap[sig].fOldHandler) {
      // restore old signal handler
      if (sigaction(gSignalMap[sig].fCode, gSignalMap[sig].fOldHandler, nullptr) < 0)
         ::SysError("TUnixSystem::UnixSignal", "sigaction");
      delete gSignalMap[sig].fOldHandler;
      gSignalMap[sig].fOldHandler = nullptr;
      gSignalMap[sig].fHandler    = nullptr;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Restore old signal handlers.
 
void TUnixSystem::UnixResetSignals()
{
   for (int sig = 0; sig < kMAXSIGNALS; sig++)
      UnixResetSignal((ESignals)sig);
}
 
//---- time --------------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Get current time in milliseconds since 0:00 Jan 1 1995.
 
Long64_t TUnixSystem::UnixNow()
{
   static std::atomic<time_t> jan95{0};
   if (!jan95) {
      struct tm tp;
      tp.tm_year  = 95;
      tp.tm_mon   = 0;
      tp.tm_mday  = 1;
      tp.tm_hour  = 0;
      tp.tm_min   = 0;
      tp.tm_sec   = 0;
      tp.tm_isdst = -1;
 
      jan95 = mktime(&tp);
      if ((int)jan95 == -1) {
         ::SysError("TUnixSystem::UnixNow", "error converting 950001 0:00 to time_t");
         return 0;
      }
   }
 
   struct timeval t;
   gettimeofday(&t, nullptr);
   return Long64_t(t.tv_sec-(Long_t)jan95)*1000 + t.tv_usec/1000;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set interval timer to time-out in ms milliseconds.
 
int TUnixSystem::UnixSetitimer(Long_t ms)
{
   struct itimerval itv;
   itv.it_value.tv_sec     = 0;
   itv.it_value.tv_usec    = 0;
   itv.it_interval.tv_sec  = 0;
   itv.it_interval.tv_usec = 0;
   if (ms > 0) {
      itv.it_value.tv_sec  = time_t(ms / 1000);
      itv.it_value.tv_usec = time_t((ms % 1000) * 1000);
   }
   int st = setitimer(ITIMER_REAL, &itv, nullptr);
   if (st == -1)
      ::SysError("TUnixSystem::UnixSetitimer", "setitimer");
   return st;
}
 
//---- file descriptors --------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Wait for events on the file descriptors specified in the readready and
/// writeready masks or for timeout (in milliseconds) to occur. Returns
/// the number of ready descriptors, or 0 in case of timeout, or < 0 in
/// case of an error, with -2 being EINTR and -3 EBADF. In case of EINTR
/// the errno has been reset and the method can be called again.
 
int TUnixSystem::UnixSelect(Int_t nfds, TFdSet *readready, TFdSet *writeready,
                            Long_t timeout)
{
   int retcode;
 
   fd_set *rd = (readready)  ? (fd_set*)readready->GetBits()  : nullptr;
   fd_set *wr = (writeready) ? (fd_set*)writeready->GetBits() : nullptr;
 
   if (timeout >= 0) {
      struct timeval tv;
      tv.tv_sec  = Int_t(timeout / 1000);
      tv.tv_usec = (timeout % 1000) * 1000;
      retcode = select(nfds, rd, wr, nullptr, &tv);
   } else {
      retcode = select(nfds, rd, wr, nullptr, nullptr);
   }
   if (retcode == -1) {
      if (GetErrno() == EINTR) {
         ResetErrno();  // errno is not self reseting
         return -2;
      }
      if (GetErrno() == EBADF)
         return -3;
      return -1;
   }
 
   return retcode;
}
 
//---- directories -------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the user's home directory.
 
const char *TUnixSystem::UnixHomedirectory(const char *name)
{
   static char path[kMAXPATHLEN], mydir[kMAXPATHLEN] = { '\0' };
   return UnixHomedirectory(name, path, mydir);
}
 
////////////////////////////////////////////////////////////////////////////
/// Returns the user's home directory.
 
const char *TUnixSystem::UnixHomedirectory(const char *name, char *path, char *mydir)
{
   struct passwd *pw;
   if (name) {
      pw = getpwnam(name);
      if (pw) {
         strncpy(path, pw->pw_dir, kMAXPATHLEN-1);
         path[kMAXPATHLEN-1] = '\0';
         return path;
      }
   } else {
      if (mydir[0])
         return mydir;
      pw = getpwuid(getuid());
      if (gSystem->Getenv("HOME")) {
         strncpy(mydir, gSystem->Getenv("HOME"), kMAXPATHLEN-1);
         mydir[kMAXPATHLEN-1] = '\0';
         return mydir;
      } else if (pw && pw->pw_dir) {
         strncpy(mydir, pw->pw_dir, kMAXPATHLEN-1);
         mydir[kMAXPATHLEN-1] = '\0';
         return mydir;
      }
   }
   return nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Make a Unix file system directory. Returns 0 in case of success and
/// -1 if the directory could not be created (either already exists or
/// illegal path name).
 
int TUnixSystem::UnixMakedir(const char *dir)
{
   return ::mkdir(StripOffProto(dir, "file:"), 0755);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a directory.
 
void *TUnixSystem::UnixOpendir(const char *dir)
{
   struct stat finfo;
 
   const char *edir = StripOffProto(dir, "file:");
 
   if (stat(edir, &finfo) < 0)
      return nullptr;
 
   if (!S_ISDIR(finfo.st_mode))
      return nullptr;
 
   return (void*) opendir(edir);
}
 
#if defined(_POSIX_SOURCE)
// Posix does not require that the d_ino field be present, and some
// systems do not provide it.
#   define REAL_DIR_ENTRY(dp) 1
#else
#   define REAL_DIR_ENTRY(dp) (dp->d_ino != 0)
#endif
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the next directory entry.
 
const char *TUnixSystem::UnixGetdirentry(void *dirp1)
{
   DIR *dirp = (DIR*)dirp1;
#ifdef HAS_DIRENT
   struct dirent *dp;
#else
   struct direct *dp;
#endif
 
   if (dirp) {
      for (;;) {
         dp = readdir(dirp);
         if (!dp)
            return nullptr;
         if (REAL_DIR_ENTRY(dp))
            return dp->d_name;
      }
   }
   return nullptr;
}
 
//---- files -------------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Get info about a file. Info is returned in the form of a FileStat_t
/// structure (see TSystem.h).
/// The function returns 0 in case of success and 1 if the file could
/// not be stat'ed.
 
int TUnixSystem::UnixFilestat(const char *fpath, FileStat_t &buf)
{
   const char *path = StripOffProto(fpath, "file:");
   buf.fIsLink = kFALSE;
 
#if defined(R__SEEK64)
   struct stat64 sbuf;
   if (path && lstat64(path, &sbuf) == 0) {
#else
   struct stat sbuf;
   if (path && lstat(path, &sbuf) == 0) {
#endif
      buf.fIsLink = S_ISLNK(sbuf.st_mode);
      if (buf.fIsLink) {
#if defined(R__SEEK64)
         if (stat64(path, &sbuf) == -1) {
#else
         if (stat(path, &sbuf) == -1) {
#endif
            return 1;
         }
      }
      buf.fDev   = sbuf.st_dev;
      buf.fIno   = sbuf.st_ino;
      buf.fMode  = sbuf.st_mode;
      buf.fUid   = sbuf.st_uid;
      buf.fGid   = sbuf.st_gid;
      buf.fSize  = sbuf.st_size;
      buf.fMtime = sbuf.st_mtime;
 
      return 0;
   }
   return 1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get info about a file system: id, bsize, bfree, blocks.
/// Id      is file system type (machine dependend, see statfs())
/// Bsize   is block size of file system
/// Blocks  is total number of blocks in file system
/// Bfree   is number of free blocks in file system
/// The function returns 0 in case of success and 1 if the file system could
/// not be stat'ed.
 
int TUnixSystem::UnixFSstat(const char *path, Long_t *id, Long_t *bsize,
                            Long_t *blocks, Long_t *bfree)
{
   struct statfs statfsbuf;
#if (defined(R__SOLARIS) && !defined(R__LINUX))
   if (statfs(path, &statfsbuf, sizeof(struct statfs), 0) == 0) {
      *id = statfsbuf.f_fstyp;
      *bsize = statfsbuf.f_bsize;
      *blocks = statfsbuf.f_blocks;
      *bfree = statfsbuf.f_bfree;
#else
   if (statfs((char*)path, &statfsbuf) == 0) {
#ifdef R__OBSD
      // Convert BSD filesystem names to Linux filesystem type numbers
      // where possible.  Linux statfs uses a value of -1 to indicate
      // an unsupported field.
 
      if (!strcmp(statfsbuf.f_fstypename, MOUNT_FFS) ||
          !strcmp(statfsbuf.f_fstypename, MOUNT_MFS))
         *id = 0x11954;
      else if (!strcmp(statfsbuf.f_fstypename, MOUNT_NFS))
         *id = 0x6969;
      else if (!strcmp(statfsbuf.f_fstypename, MOUNT_MSDOS))
         *id = 0x4d44;
      else if (!strcmp(statfsbuf.f_fstypename, MOUNT_EXT2FS))
         *id = 0xef53;
      else if (!strcmp(statfsbuf.f_fstypename, MOUNT_CD9660))
         *id = 0x9660;
      else if (!strcmp(statfsbuf.f_fstypename, MOUNT_NCPFS))
         *id = 0x6969;
      else
         *id = -1;
#else
      *id = statfsbuf.f_type;
#endif
      *bsize = statfsbuf.f_bsize;
      *blocks = statfsbuf.f_blocks;
      *bfree = statfsbuf.f_bavail;
#endif
      return 0;
   }
   return 1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Wait till child is finished.
 
int TUnixSystem::UnixWaitchild()
{
   int status;
   return (int) waitpid(0, &status, WNOHANG);
}
 
//---- RPC -------------------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Open a TCP/IP connection to server and connect to a service (i.e. port).
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// Is called via the TSocket constructor. Returns -1 in case of error.
 
int TUnixSystem::UnixTcpConnect(const char *hostname, int port,
                                int tcpwindowsize)
{
   short  sport;
   struct servent *sp;
 
   if ((sp = getservbyport(htons(port), kProtocolName)))
      sport = sp->s_port;
   else
      sport = htons(port);
 
   TInetAddress addr = gSystem->GetHostByName(hostname);
   if (!addr.IsValid()) return -1;
   UInt_t adr = htonl(addr.GetAddress());
 
   struct sockaddr_in server;
   memset(&server, 0, sizeof(server));
   memcpy(&server.sin_addr, &adr, sizeof(adr));
   server.sin_family = addr.GetFamily();
   server.sin_port   = sport;
 
   // Create socket
   int sock;
   if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
      ::SysError("TUnixSystem::UnixTcpConnect", "socket (%s:%d)",
                 hostname, port);
      return -1;
   }
 
   if (tcpwindowsize > 0) {
      gSystem->SetSockOpt(sock, kRecvBuffer, tcpwindowsize);
      gSystem->SetSockOpt(sock, kSendBuffer, tcpwindowsize);
   }
 
   while (connect(sock, (struct sockaddr*) &server, sizeof(server)) == -1) {
      if (GetErrno() == EINTR)
         ResetErrno();
      else {
         ::SysError("TUnixSystem::UnixTcpConnect", "connect (%s:%d)",
                    hostname, port);
         close(sock);
         return -1;
      }
   }
   return sock;
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Creates a UDP socket connection
/// Is called via the TSocket constructor. Returns -1 in case of error.
 
int TUnixSystem::UnixUdpConnect(const char *hostname, int port)
{
   short  sport;
   struct servent *sp;
 
   if ((sp = getservbyport(htons(port), kProtocolName)))
      sport = sp->s_port;
   else
      sport = htons(port);
 
   TInetAddress addr = gSystem->GetHostByName(hostname);
   if (!addr.IsValid()) return -1;
   UInt_t adr = htonl(addr.GetAddress());
 
   struct sockaddr_in server;
   memset(&server, 0, sizeof(server));
   memcpy(&server.sin_addr, &adr, sizeof(adr));
   server.sin_family = addr.GetFamily();
   server.sin_port   = sport;
 
   // Create socket
   int sock;
   if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
      ::SysError("TUnixSystem::UnixUdpConnect", "socket (%s:%d)",
                 hostname, port);
      return -1;
   }
 
   while (connect(sock, (struct sockaddr*) &server, sizeof(server)) == -1) {
      if (GetErrno() == EINTR)
         ResetErrno();
      else {
         ::SysError("TUnixSystem::UnixUdpConnect", "connect (%s:%d)",
                    hostname, port);
         close(sock);
         return -1;
      }
   }
   return sock;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Connect to a Unix domain socket.
 
int TUnixSystem::UnixUnixConnect(int port)
{
   return UnixUnixConnect(TString::Format("%s/%d", kServerPath, port));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Connect to a Unix domain socket. Returns -1 in case of error.
 
int TUnixSystem::UnixUnixConnect(const char *sockpath)
{
   if (!sockpath || strlen(sockpath) <= 0) {
      ::SysError("TUnixSystem::UnixUnixConnect", "socket path undefined");
      return -1;
   }
 
   int sock;
   struct sockaddr_un unserver;
   unserver.sun_family = AF_UNIX;
 
   if (strlen(sockpath) > sizeof(unserver.sun_path)-1) {
      ::Error("TUnixSystem::UnixUnixConnect", "socket path %s, longer than max allowed length (%u)",
              sockpath, (UInt_t)sizeof(unserver.sun_path)-1);
      return -1;
   }
   strlcpy(unserver.sun_path, sockpath, sizeof(unserver.sun_path));
 
   // Open socket
   if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
      ::SysError("TUnixSystem::UnixUnixConnect", "socket");
      return -1;
   }
 
   while (connect(sock, (struct sockaddr*) &unserver, strlen(unserver.sun_path)+2) == -1) {
      if (GetErrno() == EINTR)
         ResetErrno();
      else {
         ::SysError("TUnixSystem::UnixUnixConnect", "connect");
         close(sock);
         return -1;
      }
   }
   return sock;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a socket, bind to it and start listening for TCP/IP connections
/// on the port. If reuse is true reuse the address, backlog specifies
/// how many sockets can be waiting to be accepted. If port is 0 a port
/// scan will be done to find a free port. This option is mutual exlusive
/// with the reuse option.
/// Use tcpwindowsize to specify the size of the receive buffer, it has
/// to be specified here to make sure the window scale option is set (for
/// tcpwindowsize > 65KB and for platforms supporting window scaling).
/// The socketBindOption parameter allows to specify how the socket will be 
/// bound. See the documentation of ESocketBindOption for the details.
/// Returns socket fd or -1 if socket() failed, -2 if bind() failed
/// or -3 if listen() failed.
 
int TUnixSystem::UnixTcpService(int port, Bool_t reuse, int backlog,
                                int tcpwindowsize, ESocketBindOption socketBindOption)
{
   const short kSOCKET_MINPORT = 5000, kSOCKET_MAXPORT = 15000;
   short  sport, tryport = kSOCKET_MINPORT;
   struct servent *sp;
 
   if (port == 0 && reuse) {
      ::Error("TUnixSystem::UnixTcpService", "cannot do a port scan while reuse is true");
      return -1;
   }
 
   if ((sp = getservbyport(htons(port), kProtocolName)))
      sport = sp->s_port;
   else
      sport = htons(port);
 
   // Create tcp socket
   int sock;
   if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
      ::SysError("TUnixSystem::UnixTcpService", "socket");
      return -1;
   }
 
   if (reuse)
      gSystem->SetSockOpt(sock, kReuseAddr, 1);
 
   if (tcpwindowsize > 0) {
      gSystem->SetSockOpt(sock, kRecvBuffer, tcpwindowsize);
      gSystem->SetSockOpt(sock, kSendBuffer, tcpwindowsize);
   }
 
   struct sockaddr_in inserver;
   memset(&inserver, 0, sizeof(inserver));
   inserver.sin_family = AF_INET;
   inserver.sin_addr.s_addr = socketBindOption == ESocketBindOption::kInaddrAny ? htonl(INADDR_ANY) : htonl(INADDR_LOOPBACK);
   inserver.sin_port = sport;
 
   // Bind socket
   if (port > 0) {
      if (::bind(sock, (struct sockaddr*) &inserver, sizeof(inserver))) {
         ::SysError("TUnixSystem::UnixTcpService", "bind");
         close(sock);
         return -2;
      }
   } else {
      int bret;
      do {
         inserver.sin_port = htons(tryport);
         bret = ::bind(sock, (struct sockaddr*) &inserver, sizeof(inserver));
         tryport++;
      } while (bret < 0 && GetErrno() == EADDRINUSE && tryport < kSOCKET_MAXPORT);
      if (bret < 0) {
         ::SysError("TUnixSystem::UnixTcpService", "bind (port scan)");
         close(sock);
         return -2;
      }
   }
 
   // Start accepting connections
   if (::listen(sock, backlog)) {
      ::SysError("TUnixSystem::UnixTcpService", "listen");
      close(sock);
      return -3;
   }
 
   return sock;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a socket, bind to it and start listening for UDP connections
/// on the port. If reuse is true reuse the address, backlog specifies
/// how many sockets can be waiting to be accepted. If port is 0 a port
/// scan will be done to find a free port. This option is mutual exlusive
/// with the reuse option.
/// The socketBindOption parameter allows to specify how the socket will be 
/// bound. See the documentation of ESocketBindOption for the details.
 
int TUnixSystem::UnixUdpService(int port, int backlog, ESocketBindOption socketBindOption)
{
   const short kSOCKET_MINPORT = 5000, kSOCKET_MAXPORT = 15000;
   short  sport, tryport = kSOCKET_MINPORT;
   struct servent *sp;
 
   if ((sp = getservbyport(htons(port), kProtocolName)))
      sport = sp->s_port;
   else
      sport = htons(port);
 
   // Create udp socket
   int sock;
   if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
      ::SysError("TUnixSystem::UnixUdpService", "socket");
      return -1;
   }
 
   struct sockaddr_in inserver;
   memset(&inserver, 0, sizeof(inserver));
   inserver.sin_family = AF_INET;
   inserver.sin_addr.s_addr = socketBindOption == ESocketBindOption::kInaddrAny ? htonl(INADDR_ANY) : htonl(INADDR_LOOPBACK);
   inserver.sin_port = sport;
 
   // Bind socket
   if (port > 0) {
      if (::bind(sock, (struct sockaddr*) &inserver, sizeof(inserver))) {
         ::SysError("TUnixSystem::UnixUdpService", "bind");
         close(sock);
         return -2;
      }
   } else {
      int bret;
      do {
         inserver.sin_port = htons(tryport);
         bret = ::bind(sock, (struct sockaddr*) &inserver, sizeof(inserver));
         tryport++;
      } while (bret < 0 && GetErrno() == EADDRINUSE && tryport < kSOCKET_MAXPORT);
      if (bret < 0) {
         ::SysError("TUnixSystem::UnixUdpService", "bind (port scan)");
         close(sock);
         return -2;
      }
   }
 
   // Start accepting connections
   if (::listen(sock, backlog)) {
      ::SysError("TUnixSystem::UnixUdpService", "listen");
      close(sock);
      return -3;
   }
 
   return sock;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a socket, bind to it and start listening for Unix domain connections
/// to it. Returns socket fd or -1.
 
int TUnixSystem::UnixUnixService(int port, int backlog)
{
   int oldumask;
 
   // Assure that socket directory exists
   oldumask = umask(0);
   int res = ::mkdir(kServerPath, 0777);
   umask(oldumask);
 
   if (res == -1)
      return -1;
 
   // Socket path
   TString sockpath;
   sockpath.Form("%s/%d", kServerPath, port);
 
   // Remove old socket
   unlink(sockpath.Data());
 
   return UnixUnixService(sockpath, backlog);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Open a socket on path 'sockpath', bind to it and start listening for Unix
/// domain connections to it. Returns socket fd or -1.
 
int TUnixSystem::UnixUnixService(const char *sockpath, int backlog)
{
   if (!sockpath || strlen(sockpath) <= 0) {
      ::SysError("TUnixSystem::UnixUnixService", "socket path undefined");
      return -1;
   }
 
   struct sockaddr_un unserver;
   int sock;
 
   // Prepare structure
   memset(&unserver, 0, sizeof(unserver));
   unserver.sun_family = AF_UNIX;
 
   if (strlen(sockpath) > sizeof(unserver.sun_path)-1) {
      ::Error("TUnixSystem::UnixUnixService", "socket path %s, longer than max allowed length (%u)",
              sockpath, (UInt_t)sizeof(unserver.sun_path)-1);
      return -1;
   }
   strlcpy(unserver.sun_path, sockpath, sizeof(unserver.sun_path));
 
   // Create socket
   if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
      ::SysError("TUnixSystem::UnixUnixService", "socket");
      return -1;
   }
 
   if (::bind(sock, (struct sockaddr*) &unserver, strlen(unserver.sun_path)+2)) {
      ::SysError("TUnixSystem::UnixUnixService", "bind");
      close(sock);
      return -1;
   }
 
   // Start accepting connections
   if (::listen(sock, backlog)) {
      ::SysError("TUnixSystem::UnixUnixService", "listen");
      close(sock);
      return -1;
   }
 
   return sock;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Receive exactly length bytes into buffer. Returns number of bytes
/// received. Returns -1 in case of error, -2 in case of MSG_OOB
/// and errno == EWOULDBLOCK, -3 in case of MSG_OOB and errno == EINVAL
/// and -4 in case of kNoBlock and errno == EWOULDBLOCK.
/// Returns -5 if pipe broken or reset by peer (EPIPE || ECONNRESET).
 
int TUnixSystem::UnixRecv(int sock, void *buffer, int length, int flag)
{
   ResetErrno();
 
   if (sock < 0) return -1;
 
   int once = 0;
   if (flag == -1) {
      flag = 0;
      once = 1;
   }
   if (flag == MSG_PEEK)
      once = 1;
 
   int n, nrecv = 0;
   char *buf = (char *)buffer;
 
   for (n = 0; n < length; n += nrecv) {
      if ((nrecv = recv(sock, buf+n, length-n, flag)) <= 0) {
         if (nrecv == 0)
            break;        // EOF
         if (flag == MSG_OOB) {
            if (GetErrno() == EWOULDBLOCK)
               return -2;
            else if (GetErrno() == EINVAL)
               return -3;
         }
         if (GetErrno() == EWOULDBLOCK)
            return -4;
         else {
            if (GetErrno() != EINTR)
               ::SysError("TUnixSystem::UnixRecv", "recv");
            if (GetErrno() == EPIPE || GetErrno() == ECONNRESET)
               return -5;
            else
               return -1;
         }
      }
      if (once)
         return nrecv;
   }
   return n;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Send exactly length bytes from buffer. Returns -1 in case of error,
/// otherwise number of sent bytes. Returns -4 in case of kNoBlock and
/// errno == EWOULDBLOCK. Returns -5 if pipe broken or reset by peer
/// (EPIPE || ECONNRESET).
 
int TUnixSystem::UnixSend(int sock, const void *buffer, int length, int flag)
{
   if (sock < 0) return -1;
 
   int once = 0;
   if (flag == -1) {
      flag = 0;
      once = 1;
   }
 
   int n, nsent = 0;
   const char *buf = (const char *)buffer;
 
   for (n = 0; n < length; n += nsent) {
      if ((nsent = send(sock, buf+n, length-n, flag)) <= 0) {
         if (nsent == 0)
            break;
         if (GetErrno() == EWOULDBLOCK)
            return -4;
         else {
            if (GetErrno() != EINTR)
               ::SysError("TUnixSystem::UnixSend", "send");
            if (GetErrno() == EPIPE || GetErrno() == ECONNRESET)
               return -5;
            else
               return -1;
         }
      }
      if (once)
         return nsent;
   }
   return n;
}
 
//---- Dynamic Loading ---------------------------------------------------------
 
////////////////////////////////////////////////////////////////////////////////
/// Get shared library search path. Static utility function.
 
static const char *DynamicPath(const char *newpath = nullptr, Bool_t reset = kFALSE)
{
   static TString dynpath_full;
   static std::atomic<bool> initialized(kFALSE);
   static std::atomic<bool> seenCling(kFALSE);
 
   // If we have not seen Cling but the result has been initialized and gCling
   // is still nullptr, the result won't change.
   if (newpath == nullptr && !reset && (seenCling || (initialized && gCling == nullptr)))
      return dynpath_full;
 
   R__LOCKGUARD2(gSystemMutex);
 
   if (newpath) {
      dynpath_full = newpath;
      // Don't erase the user given path at the next call.
      initialized = kTRUE;
      // We do not (otherwise) record whether the path was set automatically or
      // whether it was set explicitly by the user. If the user set the path
      // explicitly, we should never automatically over-ride the value; if
      // seenCling stayed false, it would tell this routine that at the next
      // call it should update the value (to insert the Cling provided parts)
      // back to the default.
      seenCling = kTRUE;
      return dynpath_full;
   }
 
   // Another thread might have updated this. Even-though this is executed at the
   // start of the process, we might get there if the user is explicitly
   // 'resetting' the value.
   if (!reset && (seenCling || (initialized && gCling == nullptr)))
      return dynpath_full;
 
   if (!initialized) {
      // force one time initialization of gROOT before we start
      // (otherwise it might be done as a side effect of gEnv->GetValue and
      // TROOT's initialization will call this routine).
      gROOT;
   }
 
   static TString dynpath_envpart;
   static TString dynpath_syspart;
 
   if (reset || !initialized) {
 
      dynpath_envpart = gSystem->Getenv("ROOT_LIBRARY_PATH");
      TString rdynpath = gEnv->GetValue("Root.DynamicPath", nullptr);
      rdynpath.ReplaceAll(": ", ":");  // in case DynamicPath was extended
      if (rdynpath.IsNull()) {
         rdynpath = ".:"; rdynpath += TROOT::GetLibDir();
      }
      TString ldpath;
   #if defined (R__AIX)
      ldpath = gSystem->Getenv("LIBPATH");
   #elif defined(R__MACOSX)
      ldpath = gSystem->Getenv("DYLD_LIBRARY_PATH");
      if (!ldpath.IsNull())
         ldpath += ":";
      ldpath += gSystem->Getenv("LD_LIBRARY_PATH");
      if (!ldpath.IsNull())
         ldpath += ":";
      ldpath += gSystem->Getenv("DYLD_FALLBACK_LIBRARY_PATH");
   #else
      ldpath = gSystem->Getenv("LD_LIBRARY_PATH");
   #endif
      if (!ldpath.IsNull()) {
         if (!dynpath_envpart.IsNull())
            dynpath_envpart += ":";
         dynpath_envpart += ldpath;
      }
      if (!rdynpath.IsNull()) {
         if (!dynpath_envpart.IsNull())
            dynpath_envpart += ":";
         dynpath_envpart += rdynpath;
      }
      if (!dynpath_envpart.Contains(TROOT::GetLibDir())) {
         dynpath_envpart += ":"; dynpath_envpart += TROOT::GetLibDir();
      }
 
   #if defined(R__WINGCC) || defined(R__MACOSX)
      // if (!dynpath.EndsWith(":")) dynpath += ":";
      dynpath_syspart = "/usr/local/lib:/usr/X11R6/lib:/usr/lib:/lib:";
      dynpath_syspart += "/lib/x86_64-linux-gnu:/usr/local/lib64:/usr/lib64:/lib64:";
   #else
      // trick to get the system search path
      std::string cmd("LD_DEBUG=libs LD_PRELOAD=DOESNOTEXIST ls 2>&1");
      FILE *pf = popen(cmd.c_str (), "r");
      std::string result = "";
      char buffer[128];
      while (!feof(pf)) {
         if (fgets(buffer, 128, pf) != nullptr)
            result += buffer;
      }
      pclose(pf);
      std::size_t from = result.find("search path=", result.find("(LD_LIBRARY_PATH)"));
      std::size_t to = result.find("(system search path)");
      if (from != std::string::npos && to != std::string::npos) {
         from += 12;
         std::string sys_path = result.substr(from, to-from);
         sys_path.erase(std::remove_if(sys_path.begin(), sys_path.end(), isspace), sys_path.end());
         dynpath_syspart = sys_path.c_str();
      }
      dynpath_envpart.ReplaceAll("::", ":");
      dynpath_syspart.ReplaceAll("::", ":");
   #endif
   }
 
   if (!initialized || (!seenCling && gCling)) {
      dynpath_full = dynpath_envpart;
      if (!dynpath_full.EndsWith(":")) dynpath_full += ":";
      if (gCling) {
         dynpath_full += gCling->GetSTLIncludePath();
         if (!dynpath_full.EndsWith(":")) dynpath_full += ":";
 
         seenCling = kTRUE;
      }
      dynpath_full += dynpath_syspart;
      initialized = kTRUE;
 
      if (gDebug > 0) std::cout << "dynpath = " << dynpath_full.Data() << std::endl;
   }
 
   return dynpath_full;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Add a new directory to the dynamic path.
 
void TUnixSystem::AddDynamicPath(const char *path)
{
   if (path) {
      TString oldpath = DynamicPath(nullptr, kFALSE);
      oldpath.Append(":");
      oldpath.Append(path);
      DynamicPath(oldpath);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return the dynamic path (used to find shared libraries).
 
const char *TUnixSystem::GetDynamicPath()
{
   return DynamicPath(nullptr, kFALSE);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set the dynamic path to a new value.
/// If the value of 'path' is zero, the dynamic path is reset to its
/// default value.
 
void TUnixSystem::SetDynamicPath(const char *path)
{
   if (!path)
      DynamicPath(nullptr, kTRUE);
   else
      DynamicPath(path);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns the path of a shared library (searches for library in the
/// shared library search path). If no file name extension is provided
/// it first tries .so, .sl, .dl and then .a (for AIX).
 
const char *TUnixSystem::FindDynamicLibrary(TString& sLib, Bool_t quiet)
{
   char buf[PATH_MAX + 1];
   char *res = realpath(sLib.Data(), buf);
   if (res) sLib = buf;
   TString searchFor = sLib;
   if (gSystem->FindFile(GetDynamicPath(), sLib, kReadPermission)) {
      return sLib;
   }
   sLib = searchFor;
   const char* lib = sLib.Data();
   int len = sLib.Length();
   if (len > 3 && (!strcmp(lib+len-3, ".so")    ||
                   !strcmp(lib+len-3, ".dl")    ||
                   !strcmp(lib+len-4, ".dll")   ||
                   !strcmp(lib+len-4, ".DLL")   ||
                   !strcmp(lib+len-6, ".dylib") ||
                   !strcmp(lib+len-3, ".sl")    ||
                   !strcmp(lib+len-2, ".a"))) {
      if (gSystem->FindFile(GetDynamicPath(), sLib, kReadPermission)) {
         return sLib;
      }
      if (!quiet)
         Error("FindDynamicLibrary",
               "%s does not exist in %s", searchFor.Data(), GetDynamicPath());
      return nullptr;
   }
   static const char* exts[] = {
      ".so", ".dll", ".dylib", ".sl", ".dl", ".a", nullptr };
   const char** ext = exts;
   while (*ext) {
      TString fname(sLib);
      fname += *ext;
      ++ext;
      if (gSystem->FindFile(GetDynamicPath(), fname, kReadPermission)) {
         sLib.Swap(fname);
         return sLib;
      }
   }
 
   if (!quiet)
      Error("FindDynamicLibrary",
            "%s[.so | .dll | .dylib | .sl | .dl | .a] does not exist in %s",
            searchFor.Data(), GetDynamicPath());
 
   return nullptr;
}
 
//---- System, CPU and Memory info ---------------------------------------------
 
#if defined(R__FBSD)
///////////////////////////////////////////////////////////////////////////////
//// Get system info for FreeBSD
 
static void GetFreeBSDSysInfo(SysInfo_t *sysinfo)
{
   // it probably would be better to get this information from syscalls
   // this is possibly less error prone
   FILE *p = gSystem->OpenPipe("sysctl -n kern.ostype hw.model hw.ncpu "
                               "hw.realmem dev.cpu.0.freq", "r");
   TString s;
   s.Gets(p);
   sysinfo->fOS = s;
   s.Gets(p);
   sysinfo->fCpuType = s;
   s.Gets(p);
   sysinfo->fCpus = s.Atoi();
   s.Gets(p);
   Long64_t t = s.Atoll();
   sysinfo->fPhysRam = Int_t(t / 1024 / 1024);
   s.Gets(p);
   t = s.Atoll();
   sysinfo->fCpuSpeed = Int_t(t);
   gSystem->ClosePipe(p);
}
 
static void GetFreeBSDCpuInfo(CpuInfo_t*, Int_t)
{
   Error("ListSymbols", "not yet implemented");
}
#endif
 
#if defined(R__MACOSX)
#include <sys/resource.h>
#include <mach/mach.h>
#include <mach/mach_error.h>
 
////////////////////////////////////////////////////////////////////////////////
/// Get system info for Mac OS X.
 
static void GetDarwinSysInfo(SysInfo_t *sysinfo)
{
   FILE *p = gSystem->OpenPipe("sysctl -n kern.ostype hw.model hw.ncpu hw.cpufrequency "
                               "hw.busfrequency hw.l2cachesize hw.memsize", "r");
   TString s;
   s.Gets(p);
   sysinfo->fOS = s;
   s.Gets(p);
   sysinfo->fModel = s;
   s.Gets(p);
   sysinfo->fCpus = s.Atoi();
   s.Gets(p);
   Long64_t t = s.Atoll();
   sysinfo->fCpuSpeed = Int_t(t / 1000000);
   s.Gets(p);
   t = s.Atoll();
   sysinfo->fBusSpeed = Int_t(t / 1000000);
   s.Gets(p);
   sysinfo->fL2Cache = s.Atoi() / 1024;
   s.Gets(p);
   t = s.Atoll();
   sysinfo->fPhysRam = Int_t(t / 1024 / 1024);
   gSystem->ClosePipe(p);
   p = gSystem->OpenPipe("hostinfo", "r");
   while (s.Gets(p)) {
      if (s.BeginsWith("Processor type: ")) {
         TPRegexp("Processor type: ([^ ]+).*").Substitute(s, "$1");
         sysinfo->fCpuType = s;
      }
   }
   gSystem->ClosePipe(p);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get CPU load on Mac OS X.
 
static void ReadDarwinCpu(long *ticks)
{
   mach_msg_type_number_t count;
   kern_return_t kr;
   host_cpu_load_info_data_t cpu;
 
   ticks[0] = ticks[1] = ticks[2] = ticks[3] = 0;
 
   count = HOST_CPU_LOAD_INFO_COUNT;
   kr = host_statistics(mach_host_self(), HOST_CPU_LOAD_INFO, (host_info_t)&cpu, &count);
   if (kr != KERN_SUCCESS) {
      ::Error("TUnixSystem::ReadDarwinCpu", "host_statistics: %s", mach_error_string(kr));
   } else {
      ticks[0] = cpu.cpu_ticks[CPU_STATE_USER];
      ticks[1] = cpu.cpu_ticks[CPU_STATE_SYSTEM];
      ticks[2] = cpu.cpu_ticks[CPU_STATE_IDLE];
      ticks[3] = cpu.cpu_ticks[CPU_STATE_NICE];
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get CPU stat for Mac OS X. Use sampleTime to set the interval over which
/// the CPU load will be measured, in ms (default 1000).
 
static void GetDarwinCpuInfo(CpuInfo_t *cpuinfo, Int_t sampleTime)
{
   Double_t avg[3];
   if (getloadavg(avg, sizeof(avg)) < 0) {
      ::Error("TUnixSystem::GetDarwinCpuInfo", "getloadavg failed");
   } else {
      cpuinfo->fLoad1m  = (Float_t)avg[0];
      cpuinfo->fLoad5m  = (Float_t)avg[1];
      cpuinfo->fLoad15m = (Float_t)avg[2];
   }
 
   Long_t cpu_ticks1[4], cpu_ticks2[4];
   ReadDarwinCpu(cpu_ticks1);
   gSystem->Sleep(sampleTime);
   ReadDarwinCpu(cpu_ticks2);
 
   Long_t userticks = (cpu_ticks2[0] + cpu_ticks2[3]) -
                      (cpu_ticks1[0] + cpu_ticks1[3]);
   Long_t systicks  = cpu_ticks2[1] - cpu_ticks1[1];
   Long_t idleticks = cpu_ticks2[2] - cpu_ticks1[2];
   if (userticks < 0) userticks = 0;
   if (systicks < 0)  systicks = 0;
   if (idleticks < 0) idleticks = 0;
   Long_t totalticks = userticks + systicks + idleticks;
   if (totalticks) {
      cpuinfo->fUser  = ((Float_t)(100 * userticks)) / ((Float_t)totalticks);
      cpuinfo->fSys   = ((Float_t)(100 * systicks))  / ((Float_t)totalticks);
      cpuinfo->fTotal = cpuinfo->fUser + cpuinfo->fSys;
      cpuinfo->fIdle  = ((Float_t)(100 * idleticks)) / ((Float_t)totalticks);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get VM stat for Mac OS X.
 
static void GetDarwinMemInfo(MemInfo_t *meminfo)
{
   static Int_t pshift = 0;
 
   mach_msg_type_number_t count = HOST_VM_INFO_COUNT;
   vm_statistics_data_t vm_info;
   kern_return_t kr = host_statistics(mach_host_self(), HOST_VM_INFO, (host_info_t)&vm_info, &count);
   if (kr != KERN_SUCCESS) {
      ::Error("TUnixSystem::GetDarwinMemInfo", "host_statistics: %s", mach_error_string(kr));
      return;
   }
   if (pshift == 0) {
      for (int psize = getpagesize(); psize > 1; psize >>= 1)
         pshift++;
   }
 
   // Figure out total swap. This adds up the size of the swapfiles */
   DIR *dirp = opendir("/private/var/vm");
   if (!dirp)
       return;
 
   Long64_t swap_total = 0;
   struct dirent *dp;
   while ((dp = readdir(dirp)) != 0) {
      struct stat sb;
      char fname [MAXNAMLEN];
      if (strncmp(dp->d_name, "swapfile", 8))
         continue;
      strlcpy(fname, "/private/var/vm/",MAXNAMLEN);
      strlcat (fname, dp->d_name,MAXNAMLEN);
      if (stat(fname, &sb) < 0)
         continue;
      swap_total += sb.st_size;
   }
   closedir(dirp);
 
   Long64_t used =  (Long64_t)(vm_info.active_count + vm_info.inactive_count + vm_info.wire_count) << pshift;
   Long64_t free =  (Long64_t)(vm_info.free_count) << pshift;
   Long64_t total = (Long64_t)(vm_info.active_count + vm_info.inactive_count + vm_info.free_count + vm_info.wire_count) << pshift;
   Long64_t avail = (Long64_t)(vm_info.inactive_count + vm_info.free_count) << pshift;
 
   // Swap is available at same time as mem, so grab values here.
   Long64_t swap_used = vm_info.pageouts << pshift;
 
   meminfo->fMemTotal  = (Int_t) (total >> 20);       // divide by 1024 * 1024
   meminfo->fMemUsed   = (Int_t) (used >> 20);
   meminfo->fMemFree   = (Int_t) (free >> 20);
   meminfo->fSwapTotal = (Int_t) (swap_total >> 20);
   meminfo->fSwapUsed  = (Int_t) (swap_used >> 20);
   meminfo->fSwapFree  = meminfo->fSwapTotal - meminfo->fSwapUsed;
   meminfo->fMemAvailable = (Int_t)(avail >> 20);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get process info for this process on Mac OS X.
/// Code largely taken from:
/// http://www.opensource.apple.com/source/top/top-15/libtop.c
/// The virtual memory usage is slightly over estimated as we don't
/// subtract shared regions, but the value makes more sense
/// than using `virtual_size`, which is useless on 64-bit machines.
 
static void GetDarwinProcInfo(ProcInfo_t *procinfo)
{
#ifdef _LP64
#define vm_region vm_region_64
#endif
 
// taken from <mach/shared_memory_server.h> which is obsoleted in 10.5
#define GLOBAL_SHARED_TEXT_SEGMENT      0x90000000U
#define GLOBAL_SHARED_DATA_SEGMENT      0xA0000000U
#define SHARED_TEXT_REGION_SIZE         0x10000000
#define SHARED_DATA_REGION_SIZE         0x10000000
 
   struct rusage ru;
   if (getrusage(RUSAGE_SELF, &ru) < 0) {
      ::SysError("TUnixSystem::GetDarwinProcInfo", "getrusage failed");
   } else {
      procinfo->fCpuUser = (Float_t)(ru.ru_utime.tv_sec) +
                           ((Float_t)(ru.ru_utime.tv_usec) / 1000000.);
      procinfo->fCpuSys  = (Float_t)(ru.ru_stime.tv_sec) +
                           ((Float_t)(ru.ru_stime.tv_usec) / 1000000.);
   }
 
   task_basic_info_data_t ti;
   mach_msg_type_number_t count;
   kern_return_t kr;
 
   task_t a_task = mach_task_self();
 
   count = TASK_BASIC_INFO_COUNT;
   kr = task_info(a_task, TASK_BASIC_INFO, (task_info_t)&ti, &count);
   if (kr != KERN_SUCCESS) {
      ::Error("TUnixSystem::GetDarwinProcInfo", "task_info: %s", mach_error_string(kr));
   } else {
      // resident size does not require any calculation. Virtual size
      // needs to be adjusted if traversing memory objects do not include the
      // globally shared text and data regions
      mach_port_t object_name;
      vm_address_t address;
      vm_region_top_info_data_t info;
      vm_size_t vprvt, rsize, size;
      rsize = ti.resident_size;
      vprvt = 0;
      for (address = 0; ; address += size) {
         // get memory region
         count = VM_REGION_TOP_INFO_COUNT;
         if (vm_region(a_task, &address, &size,
                       VM_REGION_TOP_INFO, (vm_region_info_t)&info, &count,
                       &object_name) != KERN_SUCCESS) {
            // no more memory regions.
            break;
         }
 
         if (address >= GLOBAL_SHARED_TEXT_SEGMENT &&
             address < (GLOBAL_SHARED_DATA_SEGMENT + SHARED_DATA_REGION_SIZE)) {
            // This region is private shared.
            // Check if this process has the globally shared
            // text and data regions mapped in. If so, adjust
            // virtual memory size and exit loop.
            if (info.share_mode == SM_EMPTY) {
               vm_region_basic_info_data_64_t b_info;
               count = VM_REGION_BASIC_INFO_COUNT_64;
               if (vm_region_64(a_task, &address,
                                &size, VM_REGION_BASIC_INFO,
                                (vm_region_info_t)&b_info, &count,
                                &object_name) != KERN_SUCCESS) {
                  break;
               }
            }
            // Short circuit the loop if this isn't a shared
            // private region, since that's the only region
            // type we care about within the current address range.
            if (info.share_mode != SM_PRIVATE) {
               continue;
            }
         }
         switch (info.share_mode) {
            case SM_COW: {
               if (info.ref_count == 1) {
                  vprvt += size;
               } else {
                  vprvt += info.private_pages_resident * getpagesize();
               }
               break;
            }
            case SM_PRIVATE: {
               vprvt += size;
               break;
            }
            default:
               break;
         }
      }
 
      procinfo->fMemResident = (Long_t)(rsize / 1024);
      procinfo->fMemVirtual  = (Long_t)(vprvt / 1024);
   }
}
#endif
 
#if defined(R__LINUX)
////////////////////////////////////////////////////////////////////////////////
/// Get system info for Linux. Only fBusSpeed is not set.
 
static void GetLinuxSysInfo(SysInfo_t *sysinfo)
{
   TString s;
   FILE *f = fopen("/proc/cpuinfo", "r");
   if (f) {
      while (s.Gets(f)) {
         if (s.BeginsWith("model name")) {
            TPRegexp("^.+: *(.*$)").Substitute(s, "$1");
            sysinfo->fModel = s;
         }
         if (s.BeginsWith("cpu MHz")) {
            TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
            sysinfo->fCpuSpeed = s.Atoi();
         }
         if (s.BeginsWith("cache size")) {
            TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
            sysinfo->fL2Cache = s.Atoi();
         }
         if (s.BeginsWith("processor")) {
            TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
            sysinfo->fCpus = s.Atoi();
            sysinfo->fCpus++;
         }
      }
      fclose(f);
   }
 
   f = fopen("/proc/meminfo", "r");
   if (f) {
      while (s.Gets(f)) {
         if (s.BeginsWith("MemTotal")) {
            TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
            sysinfo->fPhysRam = (s.Atoi() / 1024);
            break;
         }
      }
      fclose(f);
   }
 
   f = gSystem->OpenPipe("uname -s -p", "r");
   if (f) {
      s.Gets(f);
      Ssiz_t from = 0;
      s.Tokenize(sysinfo->fOS, from);
      s.Tokenize(sysinfo->fCpuType, from);
      gSystem->ClosePipe(f);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get CPU load on Linux.
 
static void ReadLinuxCpu(long *ticks)
{
   ticks[0] = ticks[1] = ticks[2] = ticks[3] = 0;
 
   TString s;
   FILE *f = fopen("/proc/stat", "r");
   if (!f) return;
   s.Gets(f);
   // user, user nice, sys, idle
   sscanf(s.Data(), "%*s %ld %ld %ld %ld", &ticks[0], &ticks[3], &ticks[1], &ticks[2]);
   fclose(f);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get CPU stat for Linux. Use sampleTime to set the interval over which
/// the CPU load will be measured, in ms (default 1000).
 
static void GetLinuxCpuInfo(CpuInfo_t *cpuinfo, Int_t sampleTime)
{
   Double_t avg[3] = { -1., -1., -1. };
#ifndef R__WINGCC
   if (getloadavg(avg, sizeof(avg)) < 0) {
      ::Error("TUnixSystem::GetLinuxCpuInfo", "getloadavg failed");
   } else
#endif
   {
      cpuinfo->fLoad1m  = (Float_t)avg[0];
      cpuinfo->fLoad5m  = (Float_t)avg[1];
      cpuinfo->fLoad15m = (Float_t)avg[2];
   }
 
   Long_t cpu_ticks1[4], cpu_ticks2[4];
   ReadLinuxCpu(cpu_ticks1);
   gSystem->Sleep(sampleTime);
   ReadLinuxCpu(cpu_ticks2);
 
   Long_t userticks = (cpu_ticks2[0] + cpu_ticks2[3]) -
                      (cpu_ticks1[0] + cpu_ticks1[3]);
   Long_t systicks  = cpu_ticks2[1] - cpu_ticks1[1];
   Long_t idleticks = cpu_ticks2[2] - cpu_ticks1[2];
   if (userticks < 0) userticks = 0;
   if (systicks < 0)  systicks = 0;
   if (idleticks < 0) idleticks = 0;
   Long_t totalticks = userticks + systicks + idleticks;
   if (totalticks) {
      cpuinfo->fUser  = ((Float_t)(100 * userticks)) / ((Float_t)totalticks);
      cpuinfo->fSys   = ((Float_t)(100 * systicks))  / ((Float_t)totalticks);
      cpuinfo->fTotal = cpuinfo->fUser + cpuinfo->fSys;
      cpuinfo->fIdle  = ((Float_t)(100 * idleticks)) / ((Float_t)totalticks);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get VM stat for Linux.
 
static void GetLinuxMemInfo(MemInfo_t *meminfo)
{
   TString s;
   FILE *f = fopen("/proc/meminfo", "r");
   if (!f) return;
   while (s.Gets(f)) {
      if (s.BeginsWith("MemTotal")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fMemTotal = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("MemFree")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fMemFree = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("MemAvailable")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fMemAvailable = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("Cached")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fMemCached = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("Buffers")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fMemBuffer = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("Shmem")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fMemShared = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("SwapTotal")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fSwapTotal = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("SwapFree")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fSwapFree = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("SwapCached")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fSwapCached = (s.Atoi() / 1024);
      }
      if (s.BeginsWith("SReclaimable")) {
         TPRegexp("^.+: *([^ ]+).*").Substitute(s, "$1");
         meminfo->fSReclaimable = (s.Atoi() / 1024);
      }
      
   }
   fclose(f);
 
   /*
    * Compute memory partition like procps(free), see https://gitlab.com/procps-ng/procps/-/blob/master/proc/sysinfo.c
    * 
    * fMemShared is a part of Cached (see https://lore.kernel.org/patchwork/patch/648763/), does not subtract twice from used
    */
   
   meminfo->fMemCached = meminfo->fMemCached + meminfo->fSReclaimable - meminfo->fMemShared;
   const Int_t usedDiff = meminfo->fMemFree + meminfo->fMemCached + meminfo->fSReclaimable + meminfo->fMemBuffer;
 
   meminfo->fMemUsed = (meminfo->fMemTotal >= usedDiff) ? meminfo->fMemTotal - usedDiff : meminfo->fMemTotal - meminfo->fMemFree;
   meminfo->fMemAvailable = meminfo->fMemAvailable != 0 ? std::min(meminfo->fMemAvailable, meminfo->fMemTotal) : meminfo->fMemFree;
 
   meminfo->fSwapUsed = meminfo->fSwapTotal - meminfo->fSwapFree - meminfo->fSwapCached;
 
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get process info for this process on Linux.
 
static void GetLinuxProcInfo(ProcInfo_t *procinfo)
{
   struct rusage ru;
   if (getrusage(RUSAGE_SELF, &ru) < 0) {
      ::SysError("TUnixSystem::GetLinuxProcInfo", "getrusage failed");
   } else {
      procinfo->fCpuUser = (Float_t)(ru.ru_utime.tv_sec) +
                           ((Float_t)(ru.ru_utime.tv_usec) / 1000000.);
      procinfo->fCpuSys  = (Float_t)(ru.ru_stime.tv_sec) +
                           ((Float_t)(ru.ru_stime.tv_usec) / 1000000.);
   }
 
   procinfo->fMemVirtual  = -1;
   procinfo->fMemResident = -1;
   TString s;
   FILE *f = fopen(TString::Format("/proc/%d/statm", gSystem->GetPid()), "r");
   if (f) {
      s.Gets(f);
      fclose(f);
      Long_t total, rss;
      sscanf(s.Data(), "%ld %ld", &total, &rss);
      procinfo->fMemVirtual  = total * (getpagesize() / 1024);
      procinfo->fMemResident = rss * (getpagesize() / 1024);
   }
}
#endif
 
////////////////////////////////////////////////////////////////////////////////
/// Returns static system info, like OS type, CPU type, number of CPUs
/// RAM size, etc into the SysInfo_t structure. Returns -1 in case of error,
/// 0 otherwise.
 
int TUnixSystem::GetSysInfo(SysInfo_t *info) const
{
   if (!info) return -1;
 
   static SysInfo_t sysinfo;
 
   if (!sysinfo.fCpus) {
#if defined(R__MACOSX)
      GetDarwinSysInfo(&sysinfo);
#elif defined(R__LINUX)
      GetLinuxSysInfo(&sysinfo);
#elif defined(R__FBSD)
      GetFreeBSDSysInfo(&sysinfo);
#endif
   }
 
   *info = sysinfo;
 
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns cpu load average and load info into the CpuInfo_t structure.
/// Returns -1 in case of error, 0 otherwise. Use sampleTime to set the
/// interval over which the CPU load will be measured, in ms (default 1000).
 
int TUnixSystem::GetCpuInfo(CpuInfo_t *info, Int_t sampleTime) const
{
   if (!info) return -1;
 
#if defined(R__MACOSX)
   GetDarwinCpuInfo(info, sampleTime);
#elif defined(R__LINUX)
   GetLinuxCpuInfo(info, sampleTime);
#elif defined(R__FBSD)
   GetFreeBSDCpuInfo(info, sampleTime);
#endif
 
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns ram and swap memory usage info into the MemInfo_t structure.
/// Returns -1 in case of error, 0 otherwise.
 
int TUnixSystem::GetMemInfo(MemInfo_t *info) const
{
   if (!info) return -1;
 
#if defined(R__MACOSX)
   GetDarwinMemInfo(info);
#elif defined(R__LINUX)
   GetLinuxMemInfo(info);
#endif
 
   return 0;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns cpu and memory used by this process into the ProcInfo_t structure.
/// Returns -1 in case of error, 0 otherwise.
 
int TUnixSystem::GetProcInfo(ProcInfo_t *info) const
{
   if (!info) return -1;
 
#if defined(R__MACOSX)
   GetDarwinProcInfo(info);
#elif defined(R__LINUX)
   GetLinuxProcInfo(info);
#endif
 
   return 0;
}