elf/dl-environ.c

   1 /* Environment handling for dynamic loader.
   2    Copyright (C) 1995-1998, 2000, 2001, 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <string.h>
  21 #include <stdlib.h>
  22 #include <unistd.h>
  23 #include <ldsodefs.h>
  24
  25 /* Walk through the environment of the process and return all entries
  26    starting with `LD_'.  */
  27 char *
  28 internal_function
  29 _dl_next_ld_env_entry (char ***position)
  30 {
  31   char **current = *position;
  32   char *result = NULL;
  33
  34   while (*current != NULL)
  35     {
  36       if (__builtin_expect ((*current)[0] == 'L', 0)
  37           && (*current)[1] == 'D' && (*current)[2] == '_')
  38         {
  39           result = &(*current)[3];
  40
  41           /* Save current position for next visit.  */
  42           *position = ++current;
  43
  44           break;
  45         }
  46
  47       ++current;
  48     }
  49
  50   return result;
  51 }
  52
  53
  54 /* In ld.so __environ is not exported.  */
  55 extern char **__environ attribute_hidden;
  56
  57 int
  58 unsetenv (const char *name)
  59 {
  60   char **ep;
  61
  62   ep = __environ;
  63   while (*ep != NULL)
  64     {
  65       size_t cnt = 0;
  66
  67       while ((*ep)[cnt] == name[cnt] && name[cnt] != '\0')
  68         ++cnt;
  69
  70       if (name[cnt] == '\0' && (*ep)[cnt] == '=')
  71         {
  72           /* Found it.  Remove this pointer by moving later ones to
  73              the front.  */
  74           char **dp = ep;
  75
  76           do
  77             dp[0] = dp[1];
  78           while (*dp++);
  79           /* Continue the loop in case NAME appears again.  */
  80         }
  81       else
  82         ++ep;
  83     }
  84
  85   return 0;
  86 }