glibc/elf/dl-environ.c

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/* Environment handling for dynamic loader.
Copyright (C) 1995-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <ldsodefs.h>
/* Walk through the environment of the process and return all entries
starting with `LD_'. */
char *
internal_function
_dl_next_ld_env_entry (char ***position)
{
char **current = *position;
char *result = NULL;
while (*current != NULL)
{
if (__builtin_expect ((*current)[0] == 'L', 0)
&& (*current)[1] == 'D' && (*current)[2] == '_')
{
result = &(*current)[3];
/* Save current position for next visit. */
*position = ++current;
break;
}
++current;
}
return result;
}
/* In ld.so __environ is not exported. */
extern char **__environ attribute_hidden;
int
unsetenv (const char *name)
{
char **ep;
ep = __environ;
while (*ep != NULL)
{
size_t cnt = 0;
while ((*ep)[cnt] == name[cnt] && name[cnt] != '\0')
++cnt;
if (name[cnt] == '\0' && (*ep)[cnt] == '=')
{
/* Found it. Remove this pointer by moving later ones to
the front. */
char **dp = ep;
do
dp[0] = dp[1];
while (*dp++);
/* Continue the loop in case NAME appears again. */
}
else
++ep;
}
return 0;
}