TRootSniffer.cxx

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// $Id$
// Author: Sergey Linev   22/12/2013
 
/*************************************************************************
 * Copyright (C) 1995-2013, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/
 
#include "TRootSniffer.h"
 
#include "TDirectoryFile.h"
#include "TKey.h"
#include "TList.h"
#include "TBufferJSON.h"
#include "TROOT.h"
#include "TInterpreter.h"
#include "TFolder.h"
#include "TClass.h"
#include "TRealData.h"
#include "TDataMember.h"
#include "TDataType.h"
#include "TObjString.h"
#include "TObjArray.h"
#include "TUrl.h"
#include "TVirtualMutex.h"
#include "TRootSnifferStore.h"
#include "THttpCallArg.h"
 
#include <cstdlib>
#include <memory>
#include <vector>
#include <cstring>
 
const char *item_prop_kind = "_kind";
const char *item_prop_more = "_more";
const char *item_prop_title = "_title";
const char *item_prop_hidden = "_hidden";
const char *item_prop_typename = "_typename";
const char *item_prop_arraydim = "_arraydim";
const char *item_prop_realname = "_realname"; // real object name
const char *item_prop_user = "_username";
const char *item_prop_autoload = "_autoload";
const char *item_prop_rootversion = "_root_version";
 
/** \class TRootSnifferScanRec
\ingroup http
 
Structure used to scan hierarchies of ROOT objects
 
Represents single level of hierarchy
*/
 
////////////////////////////////////////////////////////////////////////////////
/// constructor
 
TRootSnifferScanRec::TRootSnifferScanRec()
{
   fItemsNames.SetOwner(kTRUE);
}
 
////////////////////////////////////////////////////////////////////////////////
/// destructor
 
TRootSnifferScanRec::~TRootSnifferScanRec()
{
   CloseNode();
}
 
////////////////////////////////////////////////////////////////////////////////
/// record field for current element
 
void TRootSnifferScanRec::SetField(const char *name, const char *value, Bool_t with_quotes)
{
   if (CanSetFields())
      fStore->SetField(fLevel, name, value, with_quotes);
   fNumFields++;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Indicates that new child for current element will be started
 
void TRootSnifferScanRec::BeforeNextChild()
{
   if (CanSetFields())
      fStore->BeforeNextChild(fLevel, fNumChilds, fNumFields);
   fNumChilds++;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Constructs item name from object name
/// if special symbols like '/', '#', ':', '&', '?'  are used in object name
/// they will be replaced with '_'.
/// To avoid item name duplication, additional id number can be appended
 
void TRootSnifferScanRec::MakeItemName(const char *objname, TString &itemname)
{
   std::string nnn = objname;
 
   size_t pos;
 
   // replace all special symbols which can make problem to navigate in hierarchy
   while ((pos = nnn.find_first_of("- []<>#:&?/\'\"\\")) != std::string::npos)
      nnn.replace(pos, 1, "_");
 
   itemname = nnn.c_str();
   Int_t cnt = 0;
 
   while (fItemsNames.FindObject(itemname.Data())) {
      itemname.Form("%s_%d", nnn.c_str(), cnt++);
   }
 
   fItemsNames.Add(new TObjString(itemname.Data()));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Produce full name, including all parents
 
void TRootSnifferScanRec::BuildFullName(TString &buf, TRootSnifferScanRec *prnt)
{
   if (!prnt)
      prnt = fParent;
 
   if (prnt) {
      prnt->BuildFullName(buf);
 
      buf.Append("/");
      buf.Append(fItemName);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Creates new node with specified name
/// if special symbols like "[]&<>" are used, node name
/// will be replaced by default name like "extra_item_N" and
/// original node name will be recorded as "_original_name" field
/// Optionally, object name can be recorded as "_realname" field
 
void TRootSnifferScanRec::CreateNode(const char *_node_name)
{
   if (!CanSetFields())
      return;
 
   fNodeStarted = kTRUE;
 
   if (fParent)
      fParent->BeforeNextChild();
 
   if (fStore)
      fStore->CreateNode(fLevel, _node_name);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Close started node
 
void TRootSnifferScanRec::CloseNode()
{
   if (fStore && fNodeStarted) {
      fStore->CloseNode(fLevel, fNumChilds);
      fNodeStarted = kFALSE;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// set root class name as node kind
/// in addition, path to master item (streamer info) specified
/// Such master item required to correctly unstream data on JavaScript
 
void TRootSnifferScanRec::SetRootClass(TClass *cl)
{
   if (cl && CanSetFields())
      SetField(item_prop_kind, TString::Format("ROOT.%s", cl->GetName()));
}
 
////////////////////////////////////////////////////////////////////////////////
/// returns true if scanning is done
/// Can happen when searched element is found
 
Bool_t TRootSnifferScanRec::Done() const
{
   if (!fStore)
      return kFALSE;
 
   if ((fMask & kSearch) && fStore->GetResPtr())
      return kTRUE;
 
   if ((fMask & kCheckChilds) && fStore->GetResPtr() && (fStore->GetResNumChilds() >= 0))
      return kTRUE;
 
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Checks if result will be accepted.
/// Used to verify if sniffer should read object from the file
 
Bool_t TRootSnifferScanRec::IsReadyForResult() const
{
   if (Done())
      return kFALSE;
 
   // only when doing search, result will be propagated
   if ((fMask & (kSearch | kCheckChilds)) == 0)
      return kFALSE;
 
   // only when full search path is scanned
   if (fSearchPath)
      return kFALSE;
 
   if (!fStore)
      return kFALSE;
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// set results of scanning
/// when member should be specified, use SetFoundResult instead
 
Bool_t TRootSnifferScanRec::SetResult(void *obj, TClass *cl, TDataMember *member)
{
   if (!member)
      return SetFoundResult(obj, cl);
 
   fStore->Error("SetResult",
                 "When member specified, pointer on object (not member) should be provided; use SetFoundResult");
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// set results of scanning
/// when member specified, obj is pointer on object to which member belongs
 
Bool_t TRootSnifferScanRec::SetFoundResult(void *obj, TClass *cl, TDataMember *member)
{
   if (Done())
      return kTRUE;
 
   if (!IsReadyForResult())
      return kFALSE;
 
   fStore->SetResult(obj, cl, member, fNumChilds, fRestriction);
 
   return Done();
}
 
////////////////////////////////////////////////////////////////////////////////
/// returns current depth of scanned hierarchy
 
Int_t TRootSnifferScanRec::Depth() const
{
   Int_t cnt = 0;
   const TRootSnifferScanRec *rec = this;
   while (rec->fParent) {
      rec = rec->fParent;
      cnt++;
   }
 
   return cnt;
}
 
////////////////////////////////////////////////////////////////////////////////
/// returns true if current item can be expanded - means one could explore
/// objects members
 
Bool_t TRootSnifferScanRec::CanExpandItem()
{
   if (fMask & (kExpand | kSearch | kCheckChilds))
      return kTRUE;
 
   if (!fHasMore)
      return kFALSE;
 
   // if parent has expand mask, allow to expand item
   if (fParent && (fParent->fMask & kExpand))
      return kTRUE;
 
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// returns read-only flag for current item
/// Depends from default value and current restrictions
 
Bool_t TRootSnifferScanRec::IsReadOnly(Bool_t dflt)
{
   if (fRestriction == 0)
      return dflt;
 
   return fRestriction != 2;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method verifies if new level of hierarchy
/// should be started with provided object.
/// If required, all necessary nodes and fields will be created
/// Used when different collection kinds should be scanned
 
Bool_t TRootSnifferScanRec::GoInside(TRootSnifferScanRec &super, TObject *obj, const char *obj_name, TRootSniffer *sniffer)
{
   if (super.Done())
      return kFALSE;
 
   if (obj && !obj_name)
      obj_name = obj->GetName();
 
   // exclude zero names
   if (!obj_name || (*obj_name == 0))
      return kFALSE;
 
   const char *full_name = nullptr;
 
   // remove slashes from file names
   if (obj && obj->InheritsFrom(TDirectoryFile::Class())) {
      const char *slash = strrchr(obj_name, '/');
      if (slash) {
         full_name = obj_name;
         obj_name = slash + 1;
         if (*obj_name == 0)
            obj_name = "file";
      }
   }
 
   super.MakeItemName(obj_name, fItemName);
 
   if (sniffer && sniffer->HasRestriction(fItemName.Data())) {
      // check restriction more precisely
      TString fullname;
      BuildFullName(fullname, &super);
      fRestriction = sniffer->CheckRestriction(fullname.Data());
      if (fRestriction < 0)
         return kFALSE;
   }
 
   fParent = &super;
   fLevel = super.fLevel;
   fStore = super.fStore;
   fSearchPath = super.fSearchPath;
   fMask = super.fMask & kActions;
   if (fRestriction == 0)
      fRestriction = super.fRestriction; // get restriction from parent
   Bool_t topelement = kFALSE;
 
   if (fMask & kScan) {
      // if scanning only fields, ignore all childs
      if (super.ScanOnlyFields())
         return kFALSE;
      // only when doing scan, increment level, used for text formatting
      fLevel++;
   } else {
      if (!fSearchPath)
         return kFALSE;
 
      if (strncmp(fSearchPath, fItemName.Data(), fItemName.Length()) != 0)
         return kFALSE;
 
      const char *separ = fSearchPath + fItemName.Length();
 
      Bool_t isslash = kFALSE;
      while (*separ == '/') {
         separ++;
         isslash = kTRUE;
      }
 
      if (*separ == 0) {
         fSearchPath = nullptr;
         if (fMask & kExpand) {
            topelement = kTRUE;
            fMask = (fMask & kOnlyFields) | kScan;
            fHasMore = (fMask & kOnlyFields) == 0;
         }
      } else {
         if (!isslash)
            return kFALSE;
         fSearchPath = separ;
      }
   }
 
   CreateNode(fItemName.Data());
 
   if (obj_name && (fItemName != obj_name))
      SetField(item_prop_realname, obj_name);
 
   if (full_name)
      SetField("_fullname", full_name);
 
   if (topelement)
      SetField(item_prop_rootversion, TString::Format("%d", gROOT->GetVersionCode()), kFALSE);
 
   if (topelement && sniffer->GetAutoLoad())
      SetField(item_prop_autoload, sniffer->GetAutoLoad());
 
   return kTRUE;
}
 
 
/** \class TRootSniffer
\ingroup http
 
Sniffer of ROOT objects, data provider for THttpServer
 
Provides methods to scan different structures like folders,
directories, files and collections. Can locate objects (or its data member) per name.
Can be extended to application-specific classes.
 
Normally TRootSnifferFull class is used which able to access data from trees, canvases, histograms.
*/
 
 
////////////////////////////////////////////////////////////////////////////////
/// constructor
 
TRootSniffer::TRootSniffer(const char *name, const char *objpath)
   : TNamed(name, "sniffer of root objects"), fObjectsPath(objpath)
{
   fRestrictions.SetOwner(kTRUE);
}
 
////////////////////////////////////////////////////////////////////////////////
/// destructor
 
TRootSniffer::~TRootSniffer()
{
}
 
////////////////////////////////////////////////////////////////////////////////
/// set current http arguments, which then used in different process methods
/// For instance, if user authorized with some user name,
/// depending from restrictions some objects will be invisible
/// or user get full access to the element
/// Returns previous argument which was set before
 
THttpCallArg *TRootSniffer::SetCurrentCallArg(THttpCallArg *arg)
{
   auto res = fCurrentArg;
   fCurrentArg = arg;
   fCurrentRestrict = 0;
   fCurrentAllowedMethods = "";
   return res;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Restrict access to the specified location
///
/// Hides or provides read-only access to different parts of the hierarchy
/// Restriction done base on user-name specified with http requests
/// Options can be specified in URL style (separated with &)
/// Following parameters can be specified:
///
///     visible = [all|user(s)] - make item visible for all users or only specified user
///     hidden = [all|user(s)] - make item hidden from all users or only specified user
///     readonly = [all|user(s)] - make item read-only for all users or only specified user
///     allow = [all|user(s)] - make full access for all users or only specified user
///     allow_method = method(s)  - allow method(s) execution even when readonly flag specified for the object
///
/// Like make command seen by all but can be executed only by admin
///
///     sniff->Restrict("/CmdReset","allow=admin");
///
/// Or fully hide command from guest account
///
///     sniff->Restrict("/CmdRebin","hidden=guest");
 
void TRootSniffer::Restrict(const char *path, const char *options)
{
   const char *rslash = strrchr(path, '/');
   if (rslash)
      rslash++;
   if (!rslash || (*rslash == 0))
      rslash = path;
 
   fRestrictions.Add(new TNamed(rslash, TString::Format("%s%s%s", path, "%%%", options).Data()));
}
 
////////////////////////////////////////////////////////////////////////////////
/// When specified, _autoload attribute will be always add
/// to top element of h.json/h.hml requests
/// Used to instruct browser automatically load special code
 
void TRootSniffer::SetAutoLoad(const char *scripts)
{
   fAutoLoad = scripts ? scripts : "";
}
 
////////////////////////////////////////////////////////////////////////////////
/// return name of configured autoload scripts (or 0)
 
const char *TRootSniffer::GetAutoLoad() const
{
   return fAutoLoad.Length() > 0 ? fAutoLoad.Data() : nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Made fast check if item with specified name is in restriction list
/// If returns true, requires precise check with CheckRestriction() method
 
Bool_t TRootSniffer::HasRestriction(const char *item_name)
{
   if (!item_name || (*item_name == 0) || !fCurrentArg)
      return kFALSE;
 
   return fRestrictions.FindObject(item_name) != nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// return 2 when option match to current user name
/// return 1 when option==all
/// return 0 when option does not match user name
 
Int_t TRootSniffer::WithCurrentUserName(const char *option)
{
   const char *username = fCurrentArg ? fCurrentArg->GetUserName() : nullptr;
 
   if (!username || !option || (*option == 0))
      return 0;
 
   if (strcmp(option, "all") == 0)
      return 1;
 
   if (strcmp(username, option) == 0)
      return 2;
 
   if (strstr(option, username) == 0)
      return -1;
 
   TObjArray *arr = TString(option).Tokenize(",");
 
   Bool_t find = arr->FindObject(username) != nullptr;
 
   delete arr;
 
   return find ? 2 : -1;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Checked if restriction is applied to the item full_item_name
/// should have full path to the item. Returns:
///
/// * -1 - object invisible, cannot be accessed or listed
/// *  0 - no explicit restrictions, use default
/// *  1 - read-only access
/// *  2 - full access
 
Int_t TRootSniffer::CheckRestriction(const char *full_item_name)
{
   if (!full_item_name || (*full_item_name == 0))
      return 0;
 
   const char *item_name = strrchr(full_item_name, '/');
   if (item_name)
      item_name++;
   if (!item_name || (*item_name == 0))
      item_name = full_item_name;
 
   TString pattern1 = TString("*/") + item_name + "%%%";
   TString pattern2 = TString(full_item_name) + "%%%";
 
   const char *options = nullptr;
   TIter iter(&fRestrictions);
 
   while (auto obj = iter()) {
      const char *title = obj->GetTitle();
 
      if (strstr(title, pattern1.Data()) == title) {
         options = title + pattern1.Length();
         break;
      }
      if (strstr(title, pattern2.Data()) == title) {
         options = title + pattern2.Length();
         break;
      }
   }
 
   if (!options)
      return 0;
 
   TUrl url;
   url.SetOptions(options);
   url.ParseOptions();
 
   Int_t can_see =
      WithCurrentUserName(url.GetValueFromOptions("visible")) - WithCurrentUserName(url.GetValueFromOptions("hidden"));
 
   Int_t can_access =
      WithCurrentUserName(url.GetValueFromOptions("allow")) - WithCurrentUserName(url.GetValueFromOptions("readonly"));
 
   if (can_access > 0)
      return 2; // first of all, if access enabled, provide it
   if (can_see < 0)
      return -1; // if object to be hidden, do it
 
   const char *methods = url.GetValueFromOptions("allow_method");
   if (methods)
      fCurrentAllowedMethods = methods;
 
   if (can_access < 0)
      return 1; // read-only access
 
   return 0; // default behavior
}
 
////////////////////////////////////////////////////////////////////////////////
/// scan object data members
/// some members like enum or static members will be excluded
 
void TRootSniffer::ScanObjectMembers(TRootSnifferScanRec &rec, TClass *cl, char *ptr)
{
   if (!cl || !ptr || rec.Done())
      return;
 
   // ensure that real class data (including parents) exists
   if (!(cl->Property() & kIsAbstract))
      cl->BuildRealData();
 
   // scan only real data
   TIter iter(cl->GetListOfRealData());
   while (auto obj = iter()) {
      TRealData *rdata = dynamic_cast<TRealData *>(obj);
      if (!rdata || strchr(rdata->GetName(), '.'))
         continue;
 
      TDataMember *member = rdata->GetDataMember();
      // exclude enum or static variables
      if (!member || (member->Property() & (kIsStatic | kIsEnum | kIsUnion)))
         continue;
      char *member_ptr = ptr + rdata->GetThisOffset();
 
      if (member->IsaPointer())
         member_ptr = *((char **)member_ptr);
 
      TRootSnifferScanRec chld;
 
      if (chld.GoInside(rec, member, 0, this)) {
 
         TClass *mcl = (member->IsBasic() || member->IsSTLContainer()) ? nullptr : gROOT->GetClass(member->GetTypeName());
 
         Int_t coll_offset = mcl ? mcl->GetBaseClassOffset(TCollection::Class()) : -1;
         if (coll_offset >= 0) {
            chld.SetField(item_prop_more, "true", kFALSE);
            chld.fHasMore = kTRUE;
         }
 
         if (chld.SetFoundResult(ptr, cl, member))
            break;
 
         const char *title = member->GetTitle();
         if (title && *title)
            chld.SetField(item_prop_title, title);
 
         if (member->GetTypeName())
            chld.SetField(item_prop_typename, member->GetTypeName());
 
         if (member->GetArrayDim() > 0) {
            // store array dimensions in form [N1,N2,N3,...]
            TString dim("[");
            for (Int_t n = 0; n < member->GetArrayDim(); n++) {
               if (n > 0)
                  dim.Append(",");
               dim.Append(TString::Format("%d", member->GetMaxIndex(n)));
            }
            dim.Append("]");
            chld.SetField(item_prop_arraydim, dim, kFALSE);
         } else if (member->GetArrayIndex() != 0) {
            TRealData *idata = cl->GetRealData(member->GetArrayIndex());
            TDataMember *imember = idata ? idata->GetDataMember() : nullptr;
            if (imember && (strcmp(imember->GetTrueTypeName(), "int") == 0)) {
               Int_t arraylen = *((int *)(ptr + idata->GetThisOffset()));
               chld.SetField(item_prop_arraydim, TString::Format("[%d]", arraylen), kFALSE);
            }
         }
 
         chld.SetRootClass(mcl);
 
         if (chld.CanExpandItem()) {
            if (coll_offset >= 0) {
               // chld.SetField("#members", "true", kFALSE);
               ScanCollection(chld, (TCollection *)(member_ptr + coll_offset));
            }
         }
 
         if (chld.SetFoundResult(ptr, cl, member))
            break;
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Scans object properties
/// here such fields as _autoload or _icon properties depending on class or object name could be assigned
/// By default properties, coded in the Class title are scanned. Example:
///
///     ClassDef(UserClassName, 1) //  class comments *SNIFF*  _field1=value _field2="string value"
///
/// Here *SNIFF* mark is important. After it all expressions like field=value are parsed
/// One could use double quotes to code string values with spaces.
/// Fields separated from each other with spaces
 
void TRootSniffer::ScanObjectProperties(TRootSnifferScanRec &rec, TObject *obj)
{
   TClass *cl = obj ? obj->IsA() : nullptr;
 
   const char *pos = strstr(cl ? cl->GetTitle() : "", "*SNIFF*");
   if (!pos)
      return;
 
   pos += 7;
   while (*pos) {
      if (*pos == ' ') {
         pos++;
         continue;
      }
      // first locate identifier
      const char *pos0 = pos;
      while (*pos && (*pos != '='))
         pos++;
      if (*pos == 0)
         return;
      TString name(pos0, pos - pos0);
      pos++;
      Bool_t quotes = (*pos == '\"');
      if (quotes)
         pos++;
      pos0 = pos;
      // then value with or without quotes
      while (*pos && (*pos != (quotes ? '\"' : ' ')))
         pos++;
      TString value(pos0, pos - pos0);
      rec.SetField(name, value);
      if (quotes)
         pos++;
      pos++;
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Scans TKey properties
/// in special cases load objects from the file
 
void TRootSniffer::ScanKeyProperties(TRootSnifferScanRec &rec, TKey *key, TObject *&obj, TClass *&obj_class)
{
   if (strcmp(key->GetClassName(), "TDirectoryFile") == 0) {
      if (rec.fLevel == 0) {
         auto dir = key->ReadObject<TDirectory>();
         if (dir) {
            obj = dir;
            obj_class = dir->IsA();
         }
      } else {
         rec.SetField(item_prop_more, "true", kFALSE);
         rec.fHasMore = kTRUE;
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// scans object childs (if any)
/// here one scans collection, branches, trees and so on
 
void TRootSniffer::ScanObjectChilds(TRootSnifferScanRec &rec, TObject *obj)
{
   if (obj->InheritsFrom(TFolder::Class())) {
      ScanCollection(rec, ((TFolder *)obj)->GetListOfFolders());
   } else if (obj->InheritsFrom(TDirectory::Class())) {
      TDirectory *dir = (TDirectory *)obj;
      ScanCollection(rec, dir->GetList(), nullptr, dir->GetListOfKeys());
   } else if (rec.CanExpandItem()) {
      ScanObjectMembers(rec, obj->IsA(), (char *)obj);
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Scan collection content
 
void TRootSniffer::ScanCollection(TRootSnifferScanRec &rec, TCollection *lst, const char *foldername,
                                      TCollection *keys_lst)
{
   if ((!lst || (lst->GetSize() == 0)) && (!keys_lst || (keys_lst->GetSize() == 0)))
      return;
 
   TRootSnifferScanRec folderrec;
   if (foldername) {
      if (!folderrec.GoInside(rec, nullptr, foldername, this))
         return;
   }
 
   TRootSnifferScanRec &master = foldername ? folderrec : rec;
 
   if (lst) {
      TIter iter(lst);
      TObject *next = iter();
      Bool_t isany = kFALSE;
 
      while (next) {
         if (IsItemField(next)) {
            // special case - in the beginning one could have items for master folder
            if (!isany && (next->GetName() != nullptr) && ((*(next->GetName()) == '_') || master.ScanOnlyFields()))
               master.SetField(next->GetName(), next->GetTitle());
            next = iter();
            continue;
         }
 
         isany = kTRUE;
         TObject *obj = next;
 
         TRootSnifferScanRec chld;
         if (!chld.GoInside(master, obj, nullptr, this)) {
            next = iter();
            continue;
         }
 
         if (chld.SetResult(obj, obj->IsA()))
            return;
 
         Bool_t has_kind = kFALSE, has_title = kFALSE;
 
         ScanObjectProperties(chld, obj);
         // now properties, coded as TNamed objects, placed after object in the hierarchy
         while ((next = iter()) != nullptr) {
            if (!IsItemField(next))
               break;
            if ((next->GetName() != nullptr) && ((*(next->GetName()) == '_') || chld.ScanOnlyFields())) {
               // only fields starting with _ are stored
               chld.SetField(next->GetName(), next->GetTitle());
               if (strcmp(next->GetName(), item_prop_kind) == 0)
                  has_kind = kTRUE;
               if (strcmp(next->GetName(), item_prop_title) == 0)
                  has_title = kTRUE;
            }
         }
 
         if (!has_kind)
            chld.SetRootClass(obj->IsA());
         if (!has_title && obj->GetTitle())
            chld.SetField(item_prop_title, obj->GetTitle());
 
         ScanObjectChilds(chld, obj);
 
         if (chld.SetResult(obj, obj->IsA()))
            return;
      }
   }
 
   if (keys_lst) {
      TIter iter(keys_lst);
 
      while (auto kobj = iter()) {
         TKey *key = dynamic_cast<TKey *>(kobj);
         if (!key)
            continue;
         TObject *obj = lst ? lst->FindObject(key->GetName()) : nullptr;
 
         // even object with the name exists, it should also match with class name
         if (obj && (strcmp(obj->ClassName(), key->GetClassName()) != 0))
            obj = nullptr;
 
         // if object of that name and of that class already in the list, ignore appropriate key
         if (obj && (master.fMask & TRootSnifferScanRec::kScan))
            continue;
 
         Bool_t iskey = kFALSE;
         // if object not exists, provide key itself for the scan
         if (!obj) {
            obj = key;
            iskey = kTRUE;
         }
 
         TRootSnifferScanRec chld;
         TString fullname = TString::Format("%s;%d", key->GetName(), key->GetCycle());
 
         if (chld.GoInside(master, obj, fullname.Data(), this)) {
 
            if (!chld.IsReadOnly(fReadOnly) && iskey && chld.IsReadyForResult()) {
               TObject *keyobj = key->ReadObj();
               if (keyobj)
                  if (chld.SetResult(keyobj, keyobj->IsA()))
                     return;
            }
 
            if (chld.SetResult(obj, obj->IsA()))
               return;
 
            TClass *obj_class = obj->IsA();
 
            ScanObjectProperties(chld, obj);
 
            if (obj->GetTitle())
               chld.SetField(item_prop_title, obj->GetTitle());
 
            // special handling of TKey class - in non-readonly mode
            // sniffer allowed to fetch objects
            if (!chld.IsReadOnly(fReadOnly) && iskey)
               ScanKeyProperties(chld, key, obj, obj_class);
 
            rec.SetRootClass(obj_class);
 
            ScanObjectChilds(chld, obj);
 
            // here we should know how many childs are accumulated
            if (chld.SetResult(obj, obj_class))
               return;
         }
      }
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create own TFolder structures independent from gROOT
/// This allows to have many independent TRootSniffer instances
/// At the same time such sniffer lost access to all global lists and folders
 
void TRootSniffer::CreateOwnTopFolder()
{
   if (fTopFolder) return;
 
   SetScanGlobalDir(kFALSE);
 
   // this only works with c++14, use ROOT wrapper
   fTopFolder = std::make_unique<TFolder>("http","Dedicated instance");
 
   // not sure if we have to add that private folder to global list of cleanups
 
   // R__LOCKGUARD(gROOTMutex);
   // gROOT->GetListOfCleanups()->Add(fTopFolder.get());
 
}
 
////////////////////////////////////////////////////////////////////////////////
/// Returns top TFolder instance for the sniffer
 
TFolder *TRootSniffer::GetTopFolder(Bool_t force)
{
   if (fTopFolder) return fTopFolder.get();
 
   TFolder *topf = gROOT->GetRootFolder();
 
   if (!topf) {
      Error("RegisterObject", "Not found top ROOT folder!!!");
      return nullptr;
   }
 
   TFolder *httpfold = dynamic_cast<TFolder *>(topf->FindObject("http"));
   if (!httpfold) {
      if (!force)
         return nullptr;
      httpfold = topf->AddFolder("http", "ROOT http server");
      httpfold->SetBit(kCanDelete);
      // register top folder in list of cleanups
      R__LOCKGUARD(gROOTMutex);
      gROOT->GetListOfCleanups()->Add(httpfold);
   }
 
   return httpfold;
}
 
////////////////////////////////////////////////////////////////////////////////
/// scan complete ROOT objects hierarchy
/// For the moment it includes objects in gROOT directory
/// and list of canvases and files
/// Also all registered objects are included.
/// One could re-implement this method to provide alternative
/// scan methods or to extend some collection kinds
 
void TRootSniffer::ScanRoot(TRootSnifferScanRec &rec)
{
   rec.SetField(item_prop_kind, "ROOT.Session");
   if (fCurrentArg && fCurrentArg->GetUserName())
      rec.SetField(item_prop_user, fCurrentArg->GetUserName());
 
   // should be on the top while //root/http folder could have properties for itself
   TFolder *topf = GetTopFolder();
   if (topf) {
      rec.SetField(item_prop_title, topf->GetTitle());
      ScanCollection(rec, topf->GetListOfFolders());
   }
 
   if (HasStreamerInfo()) {
      TRootSnifferScanRec chld;
      if (chld.GoInside(rec, nullptr, "StreamerInfo", this)) {
         chld.SetField(item_prop_kind, "ROOT.TStreamerInfoList");
         chld.SetField(item_prop_title, "List of streamer infos for binary I/O");
         chld.SetField(item_prop_hidden, "true", kFALSE);
         chld.SetField("_module", "hierarchy");
         chld.SetField("_after_request", "markAsStreamerInfo");
      }
   }
 
   if (IsScanGlobalDir()) {
      ScanCollection(rec, gROOT->GetList());
 
      ScanCollection(rec, gROOT->GetListOfCanvases(), "Canvases");
 
      ScanCollection(rec, gROOT->GetListOfFiles(), "Files");
   }
}
 
////////////////////////////////////////////////////////////////////////////////
/// scan ROOT hierarchy with provided store object
 
void TRootSniffer::ScanHierarchy(const char *topname, const char *path, TRootSnifferStore *store,
                                     Bool_t only_fields)
{
   TRootSnifferScanRec rec;
   rec.fSearchPath = path;
   if (rec.fSearchPath) {
      while (*rec.fSearchPath == '/')
         rec.fSearchPath++;
      if (*rec.fSearchPath == 0)
         rec.fSearchPath = nullptr;
   }
 
   // if path non-empty, we should find item first and than start scanning
   rec.fMask = !rec.fSearchPath ? TRootSnifferScanRec::kScan : TRootSnifferScanRec::kExpand;
   if (only_fields)
      rec.fMask |= TRootSnifferScanRec::kOnlyFields;
 
   rec.fStore = store;
 
   rec.CreateNode(topname);
 
   if (!rec.fSearchPath)
      rec.SetField(item_prop_rootversion, TString::Format("%d", ROOT_VERSION_CODE), kFALSE);
 
   if (!rec.fSearchPath && GetAutoLoad())
      rec.SetField(item_prop_autoload, GetAutoLoad());
 
   ScanRoot(rec);
 
   rec.CloseNode();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Search element with specified path
/// Returns pointer on element
/// Optionally one could obtain element class, member description
/// and number of childs. When chld!=nullptr, not only element is searched,
/// but also number of childs are counted. When member!=0, any object
/// will be scanned for its data members (disregard of extra options)
 
void *TRootSniffer::FindInHierarchy(const char *path, TClass **cl, TDataMember **member, Int_t *chld)
{
   TRootSnifferStore store;
 
   TRootSnifferScanRec rec;
   rec.fSearchPath = path;
   rec.fMask = chld ? TRootSnifferScanRec::kCheckChilds : TRootSnifferScanRec::kSearch;
   if (*rec.fSearchPath == '/')
      rec.fSearchPath++;
   rec.fStore = &store;
 
   ScanRoot(rec);
 
   TDataMember *res_member = store.GetResMember();
   TClass *res_cl = store.GetResClass();
   void *res = store.GetResPtr();
 
   if (res_member && res_cl && !member) {
      res_cl = (res_member->IsBasic() || res_member->IsSTLContainer()) ? nullptr : gROOT->GetClass(res_member->GetTypeName());
      TRealData *rdata = res_cl ? res_cl->GetRealData(res_member->GetName()) : nullptr;
      if (rdata) {
         res = (char *)res + rdata->GetThisOffset();
         if (res_member->IsaPointer())
            res = *((char **)res);
      } else {
         res = nullptr; // should never happen
      }
   }
 
   if (cl)
      *cl = res_cl;
   if (member)
      *member = res_member;
   if (chld)
      *chld = store.GetResNumChilds();
 
   // remember current restriction
   fCurrentRestrict = store.GetResRestrict();
 
   return res;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Search element in hierarchy, derived from TObject
 
TObject *TRootSniffer::FindTObjectInHierarchy(const char *path)
{
   TClass *cl = nullptr;
 
   void *obj = FindInHierarchy(path, &cl);
 
   return cl && (cl->GetBaseClassOffset(TObject::Class()) == 0) ? (TObject *)obj : nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Get hash function for specified item
/// used to detect any changes in the specified object
 
ULong_t TRootSniffer::GetItemHash(const char *itemname)
{
   TObject *obj = FindTObjectInHierarchy(itemname);
 
   return !obj ? 0 : TString::Hash(obj, obj->IsA()->Size());
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method verifies if object can be drawn
 
Bool_t TRootSniffer::CanDrawItem(const char *path)
{
   TClass *obj_cl = nullptr;
   void *res = FindInHierarchy(path, &obj_cl);
   return (res != nullptr) && CanDrawClass(obj_cl);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method returns true when object has childs or
/// one could try to expand item
 
Bool_t TRootSniffer::CanExploreItem(const char *path)
{
   TClass *obj_cl = nullptr;
   Int_t obj_chld(-1);
   void *res = FindInHierarchy(path, &obj_cl, nullptr, &obj_chld);
   return res && (obj_chld > 0);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Produce JSON data for specified item
/// For object conversion TBufferJSON is used
 
Bool_t TRootSniffer::ProduceJson(const std::string &path, const std::string &options, std::string &res)
{
   if (path.empty())
      return kFALSE;
 
   const char *path_ = path.c_str();
   if (*path_ == '/')
      path_++;
 
   TUrl url;
   url.SetOptions(options.c_str());
   url.ParseOptions();
   Int_t compact = -1;
   if (url.GetValueFromOptions("compact"))
      compact = url.GetIntValueFromOptions("compact");
 
   TClass *obj_cl = nullptr;
   TDataMember *member = nullptr;
   void *obj_ptr = FindInHierarchy(path_, &obj_cl, &member);
   if (!obj_ptr || (!obj_cl && !member))
      return kFALSE;
 
   // TODO: implement direct storage into std::string
   TString buf = TBufferJSON::ConvertToJSON(obj_ptr, obj_cl, compact >= 0 ? compact : 0, member ? member->GetName() : nullptr);
   res = buf.Data();
 
   return !res.empty();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Execute command marked as _kind=='Command'
 
Bool_t TRootSniffer::ExecuteCmd(const std::string &path, const std::string &options, std::string &res)
{
   TFolder *parent = nullptr;
   TObject *obj = GetItem(path.c_str(), parent, kFALSE, kFALSE);
 
   const char *kind = GetItemField(parent, obj, item_prop_kind);
   if ((kind == 0) || (strcmp(kind, "Command") != 0)) {
      if (gDebug > 0)
         Info("ExecuteCmd", "Entry %s is not a command", path.c_str());
      res = "false";
      return kTRUE;
   }
 
   const char *cmethod = GetItemField(parent, obj, "method");
   if (!cmethod || (strlen(cmethod) == 0)) {
      if (gDebug > 0)
         Info("ExecuteCmd", "Entry %s do not defines method for execution", path.c_str());
      res = "false";
      return kTRUE;
   }
 
   // if read-only specified for the command, it is not allowed for execution
   if (fRestrictions.GetLast() >= 0) {
      FindInHierarchy(path.c_str()); // one need to call method to check access rights
      if (fCurrentRestrict == 1) {
         if (gDebug > 0)
            Info("ExecuteCmd", "Entry %s not allowed for specified user", path.c_str());
         res = "false";
         return kTRUE;
      }
   }
 
   TString method = cmethod;
 
   const char *cnumargs = GetItemField(parent, obj, "_numargs");
   Int_t numargs = cnumargs ? TString(cnumargs).Atoi() : 0;
   if (numargs > 0) {
      TUrl url;
      url.SetOptions(options.c_str());
      url.ParseOptions();
 
      for (Int_t n = 0; n < numargs; n++) {
         TString argname = TString::Format("arg%d", n + 1);
         const char *argvalue = url.GetValueFromOptions(argname);
         if (!argvalue) {
            if (gDebug > 0)
               Info("ExecuteCmd", "For command %s argument %s not specified in options %s", path.c_str(), argname.Data(),
                    options.c_str());
            res = "false";
            return kTRUE;
         }
 
         TString svalue = DecodeUrlOptionValue(argvalue, kTRUE);
         argname = TString("%") + argname + TString("%");
         method.ReplaceAll(argname, svalue);
      }
   }
 
   if (gDebug > 0)
      Info("ExecuteCmd", "Executing command %s method:%s", path.c_str(), method.Data());
 
   TObject *item_obj = nullptr;
   Ssiz_t separ = method.Index("/->");
 
   if (method.Index("this->") == 0) {
      // if command name started with this-> means method of sniffer will be executed
      item_obj = this;
      separ = 3;
   } else if (separ != kNPOS) {
      item_obj = FindTObjectInHierarchy(TString(method.Data(), separ).Data());
   }
 
   if (item_obj) {
      method = TString::Format("((%s*)%zu)->%s", item_obj->ClassName(), (size_t)item_obj, method.Data() + separ + 3);
      if (gDebug > 2)
         Info("ExecuteCmd", "Executing %s", method.Data());
   }
 
   Int_t err = 0;
   auto v = gROOT->ProcessLineSync(method.Data(), &err);
   if (err == TInterpreter::kProcessing) {
      gInterpreter->ProcessLine(".@");
      if (gDebug > 0)
         Info("ExecuteCmd", "Unbalanced braces in %s", method.Data());
      res = "false";
      return kTRUE;
   }
 
   res = std::to_string(v);
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Produce JSON/XML for specified item
///
/// Contrary to h.json request, only fields for specified item are stored
 
Bool_t TRootSniffer::ProduceItem(const std::string &path, const std::string &options, std::string &res, Bool_t asjson)
{
   TString buf; // TODO: implement direct storage into std::string
   if (asjson) {
      TRootSnifferStoreJson store(buf, options.find("compact") != std::string::npos);
      ScanHierarchy("top", path.c_str(), &store, kTRUE);
   } else {
      TRootSnifferStoreXml store(buf, options.find("compact") != std::string::npos);
      ScanHierarchy("top", path.c_str(), &store, kTRUE);
   }
   res = buf.Data();
   return !res.empty();
}
 
////////////////////////////////////////////////////////////////////////////////
/// Produce XML data for specified item
///
/// For object conversion TBufferXML is used
/// Method implemented only in TRootSnifferFull class
 
Bool_t TRootSniffer::ProduceXml(const std::string &/* path */, const std::string & /* options */, std::string & /* res */)
{
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method replaces all kind of special symbols, which could appear in URL options
 
TString TRootSniffer::DecodeUrlOptionValue(const char *value, Bool_t remove_quotes)
{
   if (!value || (strlen(value) == 0))
      return TString();
 
   TString res = value;
 
   res.ReplaceAll("%27", "\'");
   res.ReplaceAll("%22", "\"");
   res.ReplaceAll("%3E", ">");
   res.ReplaceAll("%3C", "<");
   res.ReplaceAll("%20", " ");
   res.ReplaceAll("%5B", "[");
   res.ReplaceAll("%5D", "]");
   res.ReplaceAll("%3D", "=");
 
   if (remove_quotes && (res.Length() > 1) && ((res[0] == '\'') || (res[0] == '\"')) &&
       (res[0] == res[res.Length() - 1])) {
      res.Remove(res.Length() - 1);
      res.Remove(0, 1);
   }
 
   return res;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Execute command for specified object
///
/// Options include method and extra list of parameters
/// sniffer should be not-readonly to allow execution of the commands
/// reskind defines kind of result 0 - debug, 1 - json, 2 - binary
///
/// Method implemented only in TRootSnifferFull class
 
Bool_t TRootSniffer::ProduceExe(const std::string & /*path*/, const std::string & /*options*/, Int_t /*reskind*/,
                                std::string & /*res*/)
{
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Process several requests, packing all results into binary or JSON buffer
///
/// Input parameters should be coded in the POST block and has
/// individual request relative to current path, separated with '\n' symbol like
/// item1/root.bin\n
/// item2/exe.bin?method=GetList\n
/// item3/exe.bin?method=GetTitle\n
/// Request requires 'number' URL option which contains number of requested items
///
/// In case of binary request output buffer looks like:
///
///     4bytes length + payload,
///     4bytes length + payload, ...
///
/// In case of JSON request output is array with results for each item
/// multi.json request do not support binary requests for the items
 
Bool_t TRootSniffer::ProduceMulti(const std::string &path, const std::string &options, std::string &str, Bool_t asjson)
{
   if (!fCurrentArg || (fCurrentArg->GetPostDataLength() <= 0) || !fCurrentArg->GetPostData())
      return kFALSE;
 
   const char *args = (const char *)fCurrentArg->GetPostData();
   const char *ends = args + fCurrentArg->GetPostDataLength();
 
   TUrl url;
   url.SetOptions(options.c_str());
 
   Int_t number = 0;
   if (url.GetValueFromOptions("number"))
      number = url.GetIntValueFromOptions("number");
 
   // binary buffers required only for binary requests, json output can be produced as is
   std::vector<std::string> mem;
 
   if (asjson)
      str = "[";
 
   for (Int_t n = 0; n < number; n++) {
      const char *next = args;
      while ((next < ends) && (*next != '\n'))
         next++;
      if (next == ends) {
         Error("ProduceMulti", "Not enough arguments in POST block");
         break;
      }
 
      std::string file1(args, next - args);
      args = next + 1;
 
      std::string path1, opt1;
 
      // extract options
      std::size_t pos = file1.find_first_of('?');
      if (pos != std::string::npos) {
         opt1 = file1.substr(pos + 1, file1.length() - pos);
         file1.resize(pos);
      }
 
      // extract extra path
      pos = file1.find_last_of('/');
      if (pos != std::string::npos) {
         path1 = file1.substr(0, pos);
         file1.erase(0, pos + 1);
      }
 
      if (!path.empty())
         path1 = path + "/" + path1;
 
      std::string res1;
 
      // produce next item request
      Produce(path1, file1, opt1, res1);
 
      if (asjson) {
         if (n > 0)
            str.append(", ");
         if (res1.empty())
            str.append("null");
         else
            str.append(res1);
      } else {
         mem.emplace_back(std::move(res1));
      }
   }
 
   if (asjson) {
      str.append("]");
   } else {
      Int_t length = 0;
      for (unsigned n = 0; n < mem.size(); n++)
         length += 4 + mem[n].length();
      str.resize(length);
      char *curr = (char *)str.data();
      for (unsigned n = 0; n < mem.size(); n++) {
         Long_t l = mem[n].length();
         *curr++ = (char)(l & 0xff);
         l = l >> 8;
         *curr++ = (char)(l & 0xff);
         l = l >> 8;
         *curr++ = (char)(l & 0xff);
         l = l >> 8;
         *curr++ = (char)(l & 0xff);
         if (!mem[n].empty())
            memcpy(curr, mem[n].data(), mem[n].length());
         curr += mem[n].length();
      }
   }
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Produce binary data for specified item
///
/// If "zipped" option specified in query, buffer will be compressed
///
/// Implemented only in TRootSnifferFull class
 
Bool_t TRootSniffer::ProduceBinary(const std::string & /*path*/, const std::string & /*query*/, std::string & /*res*/)
{
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Produce ROOT file for specified item
///
/// Implemented only in TRootSnifferFull class
 
Bool_t TRootSniffer::ProduceRootFile(const std::string & /*path*/, const std::string & /*query*/, std::string & /*res*/)
{
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method to produce image from specified object
///
/// Parameters:
///
///     kind - image kind TImage::kPng, TImage::kJpeg, TImage::kGif
///     path - path to object
///     options - extra options
///
/// By default, image 300x200 is produced
/// In options string one could provide following parameters:
///
///     w - image width
///     h - image height
///     opt - draw options
///
///  For instance:
///
///      http://localhost:8080/Files/hsimple.root/hpx/get.png?w=500&h=500&opt=lego1
///
///  Returns produced image in the res string
///
///  Method implemented only in TRootSnifferFull class
 
Bool_t TRootSniffer::ProduceImage(Int_t /*kind*/, const std::string & /*path*/, const std::string & /*options*/, std::string & /*res*/)
{
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Invokes TRootSniffer::ProduceIamge, converting kind into TImage::EImageFileTypes type
 
Bool_t TRootSniffer::CallProduceImage(const std::string &/*kind*/, const std::string &/*path*/, const std::string &/*options*/, std::string &/*res*/)
{
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Method produce different kind of data out of object
///
/// @param path specifies object or object member
/// @param file can be:
///
/// * "root.bin"  - binary data
/// * "root.png"  - png image
/// * "root.jpeg" - jpeg image
/// * "root.gif"  - gif image
/// * "root.xml"  - xml representation
/// * "root.json" - json representation
/// * "file.root" - ROOT file with stored object
/// * "exe.json"  - method execution with json reply
/// * "exe.bin"   - method execution with binary reply
/// * "exe.txt"   - method execution with debug output
/// * "cmd.json"  - execution of registered commands
///
/// @param options specific options
/// @param res returns result - binary or text.
 
Bool_t TRootSniffer::Produce(const std::string &path, const std::string &file, const std::string &options, std::string &res)
{
   if (file.empty())
      return kFALSE;
 
   if (file == "root.bin")
      return ProduceBinary(path, options, res);
 
   if (file == "root.png")
      return CallProduceImage("png", path, options, res);
 
   if (file == "root.jpeg")
      return CallProduceImage("jpeg", path, options, res);
 
   if (file == "root.gif")
      return CallProduceImage("gif", path, options, res);
 
   if (file == "exe.bin")
      return ProduceExe(path, options, 2, res);
 
   if (file == "root.xml")
      return ProduceXml(path, options, res);
 
   if (file == "root.json")
      return ProduceJson(path, options, res);
 
   if (file == "file.root")
      return ProduceRootFile(path, options, res);
 
   // used for debugging
   if (file == "exe.txt")
      return ProduceExe(path, options, 0, res);
 
   if (file == "exe.json")
      return ProduceExe(path, options, 1, res);
 
   if (file == "cmd.json")
      return ExecuteCmd(path, options, res);
 
   if (file == "item.json")
      return ProduceItem(path, options, res, kTRUE);
 
   if (file == "item.xml")
      return ProduceItem(path, options, res, kFALSE);
 
   if (file == "multi.bin")
      return ProduceMulti(path, options, res, kFALSE);
 
   if (file == "multi.json")
      return ProduceMulti(path, options, res, kTRUE);
 
   return kFALSE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return item from the subfolders structure
 
TObject *TRootSniffer::GetItem(const char *fullname, TFolder *&parent, Bool_t force, Bool_t within_objects)
{
   TFolder *httpfold = GetTopFolder(force);
   if (!httpfold) return nullptr;
 
   parent = httpfold;
   TObject *obj = httpfold;
 
   if (!fullname)
      return httpfold;
 
   // when full path started not with slash, "Objects" subfolder is appended
   TString path = fullname;
   if (within_objects && ((path.Length() == 0) || (path[0] != '/')))
      path = fObjectsPath + "/" + path;
 
   TString tok;
   Ssiz_t from = 0;
 
   while (path.Tokenize(tok, from, "/")) {
      if (tok.Length() == 0)
         continue;
 
      TFolder *fold = dynamic_cast<TFolder *>(obj);
      if (!fold)
         return nullptr;
 
      TIter iter(fold->GetListOfFolders());
      while ((obj = iter()) != nullptr) {
         if (IsItemField(obj))
            continue;
         if (tok.CompareTo(obj->GetName()) == 0)
            break;
      }
 
      if (!obj) {
         if (!force)
            return nullptr;
         obj = fold->AddFolder(tok, "sub-folder");
         obj->SetBit(kCanDelete);
      }
 
      parent = fold;
   }
 
   return obj;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Creates subfolder where objects can be registered
 
TFolder *TRootSniffer::GetSubFolder(const char *subfolder, Bool_t force)
{
   TFolder *parent = nullptr;
 
   return dynamic_cast<TFolder *>(GetItem(subfolder, parent, force));
}
 
////////////////////////////////////////////////////////////////////////////////
/// Register object in subfolder structure
///
/// @param obj pointer to TObject
/// @param subfolder can have many levels like:
///
///     TRootSniffer* sniff = new TRootSniffer("sniff");
///     sniff->RegisterObject("my/sub/subfolder", h1);
///
/// Such objects can be later found in "Objects" folder of sniffer like
///
///     auto h1 = sniff->FindTObjectInHierarchy("/Objects/my/sub/subfolder/h1");
///
/// If subfolder name starts with '/', object will be registered starting from top folder.
///
/// One could provide additional fields for registered objects
/// For instance, setting "_more" field to true let browser
/// explore objects members. For instance:
///
///     TEvent* ev = new TEvent("ev");
///     sniff->RegisterObject("Events", ev);
///     sniff->SetItemField("Events/ev", "_more", "true");
 
Bool_t TRootSniffer::RegisterObject(const char *subfolder, TObject *obj)
{
   TFolder *f = GetSubFolder(subfolder, kTRUE);
   if (!f)
      return kFALSE;
 
   // If object will be destroyed, it will be removed from the folders automatically
   obj->SetBit(kMustCleanup);
 
   f->Add(obj);
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Unregister (remove) object from folders structures
///
/// Folder itself will remain even when it will be empty
 
Bool_t TRootSniffer::UnregisterObject(TObject *obj)
{
   if (!obj)
      return kTRUE;
 
   TFolder *topf = GetTopFolder();
 
   if (!topf) {
      Error("UnregisterObject", "Not found top folder");
      return kFALSE;
   }
 
   // TODO - probably we should remove all set properties as well
   topf->RecursiveRemove(obj);
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Create item element
 
Bool_t TRootSniffer::CreateItem(const char *fullname, const char *title)
{
   TFolder *f = GetSubFolder(fullname, kTRUE);
   if (!f)
      return kFALSE;
 
   if (title)
      f->SetTitle(title);
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return true when object is TNamed with kItemField bit set
///
/// such objects used to keep field values for item
 
Bool_t TRootSniffer::IsItemField(TObject *obj) const
{
   return (obj != nullptr) && (obj->IsA() == TNamed::Class()) && obj->TestBit(kItemField);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set or get field for the child
///
/// each field coded as TNamed object, placed after chld in the parent hierarchy
 
Bool_t TRootSniffer::AccessField(TFolder *parent, TObject *chld, const char *name, const char *value, TNamed **only_get)
{
   if (!parent)
      return kFALSE;
 
   if (!chld) {
      Info("AccessField", "Should be special case for top folder, support later");
      return kFALSE;
   }
 
   TIter iter(parent->GetListOfFolders());
 
   Bool_t find = kFALSE, last_find = kFALSE;
   // this is special case of top folder - fields are on very top
   if (parent == chld)
      last_find = find = kTRUE;
 
   TNamed *curr = nullptr;
   while (auto obj = iter()) {
      if (IsItemField(obj)) {
         if (last_find && obj->GetName() && !strcmp(name, obj->GetName()))
            curr = (TNamed *)obj;
      } else {
         last_find = (obj == chld);
         if (last_find)
            find = kTRUE;
         if (find && !last_find)
            break; // no need to continue
      }
   }
 
   // object must be in childs list
   if (!find)
      return kFALSE;
 
   if (only_get) {
      *only_get = curr;
      return curr != nullptr;
   }
 
   if (curr) {
      if (value) {
         curr->SetTitle(value);
      } else {
         parent->Remove(curr);
         delete curr;
      }
      return kTRUE;
   }
 
   curr = new TNamed(name, value);
   curr->SetBit(kItemField);
 
   if (last_find) {
      // object is on last place, therefore just add property
      parent->Add(curr);
      return kTRUE;
   }
 
   // only here we do dynamic cast to the TList to use AddAfter
   TList *lst = dynamic_cast<TList *>(parent->GetListOfFolders());
   if (!lst) {
      Error("AccessField", "Fail cast to TList");
      return kFALSE;
   }
 
   if (parent == chld)
      lst->AddFirst(curr);
   else
      lst->AddAfter(chld, curr);
 
   return kTRUE;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Set field for specified item
 
Bool_t TRootSniffer::SetItemField(const char *fullname, const char *name, const char *value)
{
   if (!fullname || !name)
      return kFALSE;
 
   TFolder *parent = nullptr;
   TObject *obj = GetItem(fullname, parent);
 
   if (!parent || !obj)
      return kFALSE;
 
   if (strcmp(name, item_prop_title) == 0) {
      TNamed *n = dynamic_cast<TNamed *>(obj);
      if (n) {
         n->SetTitle(value);
         return kTRUE;
      }
   }
 
   return AccessField(parent, obj, name, value);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return field for specified item
 
const char *TRootSniffer::GetItemField(TFolder *parent, TObject *obj, const char *name)
{
   if (!parent || !obj || !name)
      return nullptr;
 
   TNamed *field = nullptr;
 
   if (!AccessField(parent, obj, name, nullptr, &field))
      return nullptr;
 
   return field ? field->GetTitle() : nullptr;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Return field for specified item
 
const char *TRootSniffer::GetItemField(const char *fullname, const char *name)
{
   if (!fullname)
      return nullptr;
 
   TFolder *parent = nullptr;
   TObject *obj = GetItem(fullname, parent);
 
   return GetItemField(parent, obj, name);
}
 
////////////////////////////////////////////////////////////////////////////////
/// Register command which can be executed from web interface
///
/// As method one typically specifies string, which is executed with
/// gROOT->ProcessLine() method. For instance:
///
///     serv->RegisterCommand("Invoke","InvokeFunction()");
///
/// Or one could specify any method of the object which is already registered
/// to the server. For instance:
///
///     serv->Register("/", hpx);
///     serv->RegisterCommand("/ResetHPX", "/hpx/->Reset()");
///
/// Here symbols '/->' separates item name from method to be executed
///
/// One could specify additional arguments in the command with
/// syntax like %arg1%, %arg2% and so on. For example:
///
///     serv->RegisterCommand("/ResetHPX", "/hpx/->SetTitle(\"%arg1%\")");
///     serv->RegisterCommand("/RebinHPXPY", "/hpxpy/->Rebin2D(%arg1%,%arg2%)");
///
/// Such parameter(s) will be requested when command clicked in the browser.
///
/// Once command is registered, one could specify icon which will appear in the browser:
///
///     serv->SetIcon("/ResetHPX", "rootsys/icons/ed_execute.png");
///
/// One also can set extra property '_fastcmd', that command appear as
/// tool button on the top of the browser tree:
///
///     serv->SetItemField("/ResetHPX", "_fastcmd", "true");
///
/// Or it is equivalent to specifying extra argument when register command:
///
///     serv->RegisterCommand("/ResetHPX", "/hpx/->Reset()", "button;rootsys/icons/ed_delete.png");
 
Bool_t TRootSniffer::RegisterCommand(const char *cmdname, const char *method, const char *icon)
{
   CreateItem(cmdname, TString::Format("command %s", method).Data());
   SetItemField(cmdname, "_kind", "Command");
   if (icon) {
      if (strncmp(icon, "button;", 7) == 0) {
         SetItemField(cmdname, "_fastcmd", "true");
         icon += 7;
      }
      if (*icon)
         SetItemField(cmdname, "_icon", icon);
   }
   SetItemField(cmdname, "method", method);
   Int_t numargs = 0;
   do {
      TString nextname = TString::Format("%sarg%d%s", "%", numargs + 1, "%");
      if (strstr(method, nextname.Data()) == nullptr)
         break;
      numargs++;
   } while (numargs < 100);
   if (numargs > 0)
      SetItemField(cmdname, "_numargs", TString::Format("%d", numargs));
 
   return kTRUE;
}