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 "TFolder.h"
#include "TClass.h"
#include "TRealData.h"
#include "TDataMember.h"
#include "TDataType.h"
#include "TObjString.h"
#include "TUrl.h"
#include "TImage.h"
#include "TVirtualMutex.h"
#include "TRootSnifferStore.h"
#include "THttpCallArg.h"
#include "ROOT/RMakeUnique.hxx"

#include <stdlib.h>
#include <vector>
#include <string.h>

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";

//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TRootSnifferScanRec                                                  //
//                                                                      //
// 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;
}

// ====================================================================

//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TRootSniffer                                                         //
//                                                                      //
// Sniffer of ROOT objects, data provider for THttpServer               //
// Provides methods to scan different structures like folders,          //
// directories, files, trees, collections                               //
// Can locate objects (or its data member) per name                     //
// Can be extended to application-specific classes                      //
//                                                                      //
//////////////////////////////////////////////////////////////////////////

ClassImp(TRootSniffer);

////////////////////////////////////////////////////////////////////////////////
/// 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

void TRootSniffer::SetCurrentCallArg(THttpCallArg *arg)
{
   fCurrentArg = arg;
   fCurrentRestrict = 0;
   fCurrentAllowedMethods = "";
}

////////////////////////////////////////////////////////////////////////////////
/// 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);
   TObject *obj;

   while ((obj = iter()) != nullptr) {
      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
   TObject *obj = nullptr;
   TIter iter(cl->GetListOfRealData());
   while ((obj = iter()) != nullptr) {
      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 && (strlen(title) != 0))
            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 != 0) {
      if (*pos == ' ') {
         pos++;
         continue;
      }
      // first locate identifier
      const char *pos0 = pos;
      while ((*pos != 0) && (*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 != 0) && (*pos != (quotes ? '\"' : ' ')))
         pos++;
      TString value(pos0, pos - pos0);
      rec.SetField(name, value);
      if (quotes)
         pos++;
      pos++;
   }
}

////////////////////////////////////////////////////////////////////////////////
/// scans key 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) {
         TDirectory *dir = dynamic_cast<TDirectory *>(key->ReadObj());
         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());
   }
   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);
      TObject *kobj = nullptr;

      while ((kobj = iter()) != nullptr) {
         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 reimplement 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("_after_request", "JSROOT.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!=0, 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*)%lu)->%s", item_obj->ClassName(), (long unsigned)item_obj, method.Data() + separ + 3);
      if (gDebug > 2)
         Info("ExecuteCmd", "Executing %s", method.Data());
   }

   Long_t v = gROOT->ProcessLineSync(method.Data());

   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;
}

////////////////////////////////////////////////////////////////////////////////
/// 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
///
///  Return is memory with produced image
///  Memory must be released by user with free(ptr) call
///
///  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;
}

////////////////////////////////////////////////////////////////////////////////
/// Method produce different kind of data out of object
/// Parameter 'path' specifies object or object member
/// Supported 'file' (case sensitive):
///   "root.bin"  - binary data
///   "root.png"  - png image
///   "root.jpeg" - jpeg image
///   "root.gif"  - gif image
///   "root.xml"  - xml representation
///   "root.json" - json representation
///   "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
/// Result returned in std::string - can be 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 ProduceImage(TImage::kPng, path, options, res);

   if (file == "root.jpeg")
      return ProduceImage(TImage::kJpeg, path, options, res);

   if (file == "root.gif")
      return ProduceImage(TImage::kGif, 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);

   // 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
/// subfolder parameter 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
///
/// 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());

   TObject *obj = nullptr;
   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 ((obj = iter()) != nullptr) {
      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, Form("command %s", method));
   SetItemField(cmdname, "_kind", "Command");
   if (icon) {
      if (strncmp(icon, "button;", 7) == 0) {
         SetItemField(cmdname, "_fastcmd", "true");
         icon += 7;
      }
      if (*icon != 0)
         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;
}