[ROOT] segmentation fault under root 3.01/06 and 3.02/06, but not under 3.00/06

From: Kay Ulbrich (ulbrich@iskp.uni-bonn.de)
Date: Thu Nov 08 2001 - 15:40:32 MET 

Hello,

in order to read histograms by their titles rather than by their names
I use a derived class TMyFile, base class: TFile, in which I have
defined a member-function (TList *histolist is initialized in the
constructor as histolist = GetListOfKeys()):

// >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
TH1 *TMyFile::get1dimHistoByTitle(TString Title) {

  TH1 *out = 0;
  bool foundit;
  TObject *objbuff;
  TH1 *h1dimbuff;
  TKey *listkey;
  TClass *clinfo;
  TString clname, htitle;
  TIter nextentry(histolist);

  while(listkey = (TKey *)nextentry()) {
    objbuff = Get(listkey->GetName());
    // -- here occasional segmentation fault -- <=== 
    clinfo = objbuff->IsA();
    h1dimbuff = (TH1 *)objbuff;
    htitle = TString(h1dimbuff -> GetTitle());
    clname = TString(clinfo -> GetName());
    if(foundit = htitle.Contains(Name) && clname.Contains("TH1")) break;
  } 
  if(foundit) {
    out = (TH1 *)objbuff;
    cout << "Found " << out->GetTitle() << endl;
  } else cout << "Could not find " << Name << endl;
  return out;
}
// <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Applying it to the same root-files with the same macros, it works
smoothly under root 3.00/06, but it crashes (obviously after the line
indicated in the source-code) in its second call under 3.01/06 and
3.02/06. I do not understand this behaviour, because in the case of
faulty code I would expect crashes in all versions.

The totally analogous member-function

// >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
TH2 *TMyFile::get2dimHistoByTitle(TString Title) {

  TH2 *out = 0;
  bool foundit;
  TObject *objbuff;
  TH1 *h1dimbuff;
  TKey *listkey;
  TClass *clinfo;
  TString clname, htitle;
  TIter nextentry(histolist);

  while(listkey = (TKey *)nextentry()) {
    objbuff = Get(listkey->GetName());
    clinfo = objbuff->IsA();
    h1dimbuff = (TH1 *)objbuff;
    htitle = TString(h1dimbuff -> GetTitle());
    clname = TString(clinfo -> GetName());
    if(foundit = htitle.Contains(Name) && clname.Contains("TH2")) break;
  } 
  if(foundit) {
    out = (TH2 *)objbuff;
    cout << "Found " << out->GetTitle() << endl;
  } else cout << "Could not find " << Name << endl;
  return out;
}
// <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

generates no segmentation-faults.
I have compiled all versons from source-code for the target
linuxsuse6.

Thanks for hints, Kay

-- 
Kay Ulbrich
Institut fuer Strahlen- und Kernphysik, Universitaet Bonn
Nussallee 14-16 / D-53115 Bonn / Deutschland
Tel.: 0228-73-1768 / E-Post: ulbrich@iskp.uni-bonn.de

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