Created attachment 338340 [details]
proposal patch

Description of problem:

Look at the following simple code:
----------------------------------------------------
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv){
  extern char **environ;
  int i = 0;

  while (environ[i]){
    if (environ[i] == strstr(environ[i], "DISPLAY"))
      fprintf (stderr, "argv[%i] is \"%s\"\n", i, environ[i]);
    i++;
  }
  return 0;
}
-----------------------------------------------------

When I
- login to GNOME session, launch xterm
- execute the code above on the xterm
the code above simply shows:
-----------------------------------------------------
argv[45] is "DISPLAY=:0.0"
-----------------------------------------------------
for example.

However when I
- login to GNOME session
- right click on GNOME panel, select "Add to panel"
- select "custom application launcher" and select
  the binary generated from the code above
- click the icon newly added on the panel
- watch ~/.xsession-errors
then the following appears:
-----------------------------------------------------
argv[34] is "DISPLAY=:0.0"
argv[45] is "DISPLAY=:0.0"
-----------------------------------------------------

This shows char **environ has two "DISPLAY" item??

Version-Release number of selected component (if applicable):
glib2-2.19.10-2.fc11
glib2-2.20.0-1.fc11

How reproducible:
100%

Steps to Reproduce:
1. See above
2.
3.
  
Actual results:
This causes that pcmanfm (which I maintain) cannot launch
any commands when pcmanfm is launched from GNOME menu
(sourceforge bug id 2313286)

Expected results:
"DISPLAY" item should appear only once

Additional info:
The attached patch seems to work.
Actually on static gboolean is_env (const char *a, const char *b)
in gio/gdesktopappinfo.c:
------------------------------------------------------
   828  static gboolean
   829  is_env (const char *a,
   830          const char *b)
   831  {
   832    while (*a == *b)
   833    {
   834      if (*a == 0 || *b == 0)
   835        return FALSE;
   836      
   837      if (*a == '=')
   838        return TRUE;
   839  
   840      a++;
   841      b++;
   842    }
   843  
   844    return FALSE;
   845  }
--------------------------------------------------------
suppose a="DISPLAY=:0.0" and b="DISPLAY"
I guess this should return TRUE but actually this returns
FALSE
- because after a,b both points to 'Y', at lines 840-841
  now *a='=' while *b=0, then while (*a == *b) at 832 fails.