Probleme with X access control and ROOT

From: Pascal Vincent (vincentp@in2p3.fr)
Date: Sat Mar 04 2000 - 13:48:12 MET 

 Hello,

I do not know if the following problem already appears in this mailing
list but please, help me.

I have a compiled ROOT program which run in background or in batch and
which does not need to access the X serveur of my PC. But when it run on
a remote host, I have a crash if the access to my display is denied?!?!? 

First let me introduce myself : I use 
 - ROOT version 2.23 
 
    and

 - Linux 2.2.10/RedHat 5.0  
 - My c++ compilator is egcs-1.1.2 release.
 - libc.so.6
 
        or

 - Linux 2.0.36/Slackware.
 - C++ compilator is gcc version 2.7.2.2
 - libc.so.5


As we can imagine I have a very big and beautiful program but, try this
simple example:

//-----------------------------
#include <iostream.h>
#include "TROOT.h"
#include "TFile.h"

extern void InitGui();
VoidFuncPtr_t initfuncs[] = { InitGui, 0 };

int main (int argc, char **argv) 
{
  cout<<"Just do it!"<<endl;

  // init ROOT system
  TROOT root("Hello","hello", initfuncs);

  // Create output file
  TFile *file  = new TFile("hello.txt","RECREATE","P'tit test entre amis",2);
  file->Close();
}
// ---------------- That's all

Then compile with
 
 g++ -O -Wall -fPIC -I/usr/local/root/include  -c test.C 

for gcc or

 g++ -O -fno-rtti -fno-exceptions -Wall -fPIC -I/usr/local/root/include
           -c test.C
 
for egcs and then link with :

 g++  test.o -L/usr/local/root/lib -lCore -lCint -lHist -lGX11
   -lGraf -lGraf3d -lGpad -lTree -lProof -lRint -lPostscript -lMatrix
  -lPhysics -lNew -lGpad -lGX11 -lX3d -lXpm   -L/usr/X11R6/lib -lXm -lXext
  -lXt -lX11 -lg++ -ldl -rdynamic -L/usr/lib -lm  -o hello

Run the program "hello" on remote host, accessed from your terminal by
telnet. 

      It Works! nice...

Then remove the remote host name from X control list : xhost -<remote>

Now run it again. It crash with the standard well known message :

Xlib: connection to "<local>:0.0" refused by server
Xlib: Client is not authorized to connect to Server
Error in <TGClient::TGClient>: can't open display "<local>:0", bombing...

Now, you can say : "Why do you deny the access to your remote machine?".

Event if I allow all machine over the world to access my display 
with "xhost +" command (I don't do that), unfortunatly I lock the screen
of my PC when I leave my office. So each night all batch job crash for the
same reason (I refuse to work day and night...). And anyway my program
don't need this authority.

Ok there is something wrong in the compilation. If I keep only the minimal
list of library needed for the load, for example :

g++ test.o -L/usr/local/root/lib -lCore -lCint -L/usr/X11R6/lib
    -lXm -lXext -lXt -lX11 -lg++ -ldl -rdynamic -L/usr/lib -lm -o hello

It works again ! I am the most happiest guy in the world!

But I can not control all libraries for each new line added in my code.
Could you say to me which library is responsible of this? It seems to me
that the beavior of some functionnality of ROOT is handled by different
libraries. If (as I think) the containt of the ROOT libraries is involved
in this behavior, that could makes ROOT unreliable.

What do you think about my probleme ? Maybe I am totally wrong. 

Thanks for your help,
Pascal.


for HESS Collaboration : http://www-hfm.mpi-hd.mpg.de/HESS/HESS.html
======================================================================
Pascal Vincent              LPNHE IN2P3-CNRS-Universite Paris VI & VII
4, Place Jussieu - BP 200 - Tour 33 Rdc, 75252 PARIS cedex 05 - France
Tel: 01 44 27 48 43    Fax: 01 44 27 46 38   e-mail: vincentp@in2p3.fr  
WWW: http://www-lpnhep.in2p3.fr/delphi/vincentp/     .................
======================================================================

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