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/* Copyright (C) 1992, 1995-2002, 2005-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
This file 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.
This file 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 this program. If not, see <https://www.gnu.org/licenses/>. */
/* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
optimizes away the name == NULL test below. */
#define _GL_ARG_NONNULL(params)
#include <config.h>
/* Specification. */
#include <stdlib.h>
#include <errno.h>
#if !_LIBC
# define __set_errno(ev) ((errno) = (ev))
#endif
#include <string.h>
#include <unistd.h>
#if !_LIBC
# define __environ environ
#endif
#if _LIBC
/* This lock protects against simultaneous modifications of 'environ'. */
# include <bits/libc-lock.h>
__libc_lock_define_initialized (static, envlock)
# define LOCK __libc_lock_lock (envlock)
# define UNLOCK __libc_lock_unlock (envlock)
#else
# define LOCK
# define UNLOCK
#endif
/* In the GNU C library we must keep the namespace clean. */
#ifdef _LIBC
# define unsetenv __unsetenv
#endif
#if _LIBC || !HAVE_UNSETENV
int
unsetenv (const char *name)
{
size_t len;
if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
{
__set_errno (EINVAL);
return -1;
}
len = strlen (name);
#if HAVE_DECL__PUTENV /* native Windows */
/* The Microsoft documentation
<https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/putenv-wputenv>
says:
"Don't change an environment entry directly: instead,
use _putenv or _wputenv to change it."
Note: Microsoft's _putenv updates not only the contents of _environ but
also the contents of _wenviron, so that both are in kept in sync.
The way to remove an environment variable is to pass to _putenv a string
of the form "NAME=". (NB: This is a different convention than with glibc
putenv, which expects a string of the form "NAME"!) */
{
int putenv_result;
char *name_ = malloc (len + 2);
if (name_ == NULL)
return -1;
memcpy (name_, name, len);
name_[len] = '=';
name_[len + 1] = 0;
putenv_result = _putenv (name_);
/* In this particular case it is OK to free() the argument passed to
_putenv. */
free (name_);
return putenv_result;
}
#else
LOCK;
char **ep = __environ;
while (*ep != NULL)
if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
{
/* Found it. Remove this pointer by moving later ones back. */
char **dp = ep;
do
dp[0] = dp[1];
while (*dp++);
/* Continue the loop in case NAME appears again. */
}
else
++ep;
UNLOCK;
return 0;
#endif
}
#ifdef _LIBC
# undef unsetenv
weak_alias (__unsetenv, unsetenv)
#endif
#else /* HAVE_UNSETENV */
# undef unsetenv
# if !HAVE_DECL_UNSETENV
# if VOID_UNSETENV
extern void unsetenv (const char *);
# else
extern int unsetenv (const char *);
# endif
# endif
/* Call the underlying unsetenv, in case there is hidden bookkeeping
that needs updating beyond just modifying environ. */
int
rpl_unsetenv (const char *name)
{
int result = 0;
if (!name || !*name || strchr (name, '='))
{
errno = EINVAL;
return -1;
}
while (getenv (name))
# if !VOID_UNSETENV
result =
# endif
unsetenv (name);
return result;
}
#endif /* HAVE_UNSETENV */
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