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setenv.c
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/* Copyright (C) 1992,1995-2001,2004 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/>.
* SPDX-License-Identifier: LGPL-2.1+
*/
#if HAVE_CONFIG_H
# include <config.h>
#endif
#ifndef HAVE_W32CE_SYSTEM
#define setenv _assuan_setenv
#define unsetenv _assuan_unsetenv
#define clearenv _assuan_clearenv
#define __builtin_expect(cond,val) (cond)
#include <errno.h>
#if !_LIBC
# if !defined errno && !defined HAVE_ERRNO_DECL
extern int errno;
# endif
# define __set_errno(ev) ((errno) = (ev))
#endif
#if _LIBC || HAVE_STDLIB_H
# include <stdlib.h>
#endif
#if _LIBC || HAVE_STRING_H
# include <string.h>
#endif
#if _LIBC || HAVE_UNISTD_H
# include <unistd.h>
#endif
#if !_LIBC
# define __environ environ
# ifndef HAVE_ENVIRON_DECL
extern char **environ;
# endif
#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 setenv __setenv
# define unsetenv __unsetenv
# define clearenv __clearenv
# define tfind __tfind
# define tsearch __tsearch
#endif
/* In the GNU C library implementation we try to be more clever and
allow arbitrarily many changes of the environment given that the used
values are from a small set. Outside glibc this will eat up all
memory after a while. */
#if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
&& defined __GNUC__)
# define USE_TSEARCH 1
# include <search.h>
/* This is a pointer to the root of the search tree with the known
values. */
static void *known_values;
# define KNOWN_VALUE(Str) \
({ \
void *value = tfind (Str, &known_values, (__compar_fn_t) strcmp); \
value != NULL ? *(char **) value : NULL; \
})
# define STORE_VALUE(Str) \
tsearch (Str, &known_values, (__compar_fn_t) strcmp)
#else
# undef USE_TSEARCH
# define KNOWN_VALUE(Str) NULL
# define STORE_VALUE(Str) do { } while (0)
#endif
/* If this variable is not a null pointer we allocated the current
environment. */
static char **last_environ;
/* This function is used by `setenv' and `putenv'. The difference between
the two functions is that for the former must create a new string which
is then placed in the environment, while the argument of `putenv'
must be used directly. This is all complicated by the fact that we try
to reuse values once generated for a `setenv' call since we can never
free the strings. */
static int
__add_to_environ (const char *name, const char *value, const char *combined,
int replace)
{
register char **ep;
register size_t size;
const size_t namelen = strlen (name);
const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
LOCK;
/* We have to get the pointer now that we have the lock and not earlier
since another thread might have created a new environment. */
ep = __environ;
size = 0;
if (ep != NULL)
{
for (; *ep != NULL; ++ep)
if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
break;
else
++size;
}
if (ep == NULL || __builtin_expect (*ep == NULL, 1))
{
char **new_environ;
/* We allocated this space; we can extend it. */
new_environ = (char **) realloc (last_environ,
(size + 2) * sizeof (char *));
if (new_environ == NULL)
{
UNLOCK;
return -1;
}
/* If the whole entry is given add it. */
if (combined != NULL)
/* We must not add the string to the search tree since it belongs
to the user. */
new_environ[size] = (char *) combined;
else
{
/* See whether the value is already known. */
#ifdef USE_TSEARCH
# ifdef __GNUC__
char new_value[namelen + 1 + vallen];
# else
char *new_value = (char *) alloca (namelen + 1 + vallen);
# endif
# ifdef _LIBC
__mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
value, vallen);
# else
memcpy (new_value, name, namelen);
new_value[namelen] = '=';
memcpy (&new_value[namelen + 1], value, vallen);
# endif
new_environ[size] = KNOWN_VALUE (new_value);
if (__builtin_expect (new_environ[size] == NULL, 1))
#endif
{
new_environ[size] = (char *) malloc (namelen + 1 + vallen);
if (__builtin_expect (new_environ[size] == NULL, 0))
{
__set_errno (ENOMEM);
UNLOCK;
return -1;
}
#ifdef USE_TSEARCH
memcpy (new_environ[size], new_value, namelen + 1 + vallen);
#else
memcpy (new_environ[size], name, namelen);
new_environ[size][namelen] = '=';
memcpy (&new_environ[size][namelen + 1], value, vallen);
#endif
/* And save the value now. We cannot do this when we remove
the string since then we cannot decide whether it is a
user string or not. */
STORE_VALUE (new_environ[size]);
}
}
if (__environ != last_environ)
memcpy ((char *) new_environ, (char *) __environ,
size * sizeof (char *));
new_environ[size + 1] = NULL;
last_environ = __environ = new_environ;
}
else if (replace)
{
char *np;
/* Use the user string if given. */
if (combined != NULL)
np = (char *) combined;
else
{
#ifdef USE_TSEARCH
# ifdef __GNUC__
char new_value[namelen + 1 + vallen];
# else
char *new_value = (char *) alloca (namelen + 1 + vallen);
# endif
# ifdef _LIBC
__mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
value, vallen);
# else
memcpy (new_value, name, namelen);
new_value[namelen] = '=';
memcpy (&new_value[namelen + 1], value, vallen);
# endif
np = KNOWN_VALUE (new_value);
if (__builtin_expect (np == NULL, 1))
#endif
{
np = malloc (namelen + 1 + vallen);
if (__builtin_expect (np == NULL, 0))
{
UNLOCK;
return -1;
}
#ifdef USE_TSEARCH
memcpy (np, new_value, namelen + 1 + vallen);
#else
memcpy (np, name, namelen);
np[namelen] = '=';
memcpy (&np[namelen + 1], value, vallen);
#endif
/* And remember the value. */
STORE_VALUE (np);
}
}
*ep = np;
}
UNLOCK;
return 0;
}
int
setenv (const char *name, const char *value, int replace)
{
if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
{
__set_errno (EINVAL);
return -1;
}
return __add_to_environ (name, value, NULL, replace);
}
int
unsetenv (const char *name)
{
size_t len;
char **ep;
if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
{
__set_errno (EINVAL);
return -1;
}
len = strlen (name);
LOCK;
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;
}
/* The `clearenv' was planned to be added to POSIX.1 but probably
never made it. Nevertheless the POSIX.9 standard (POSIX bindings
for Fortran 77) requires this function. */
int
clearenv (void)
{
LOCK;
if (__environ == last_environ && __environ != NULL)
{
/* We allocated this environment so we can free it. */
free (__environ);
last_environ = NULL;
}
/* Clear the environment pointer removes the whole environment. */
__environ = NULL;
UNLOCK;
return 0;
}
#ifdef _LIBC
libc_freeres_fn (free_mem)
{
/* Remove all traces. */
clearenv ();
/* Now remove the search tree. */
__tdestroy (known_values, free);
known_values = NULL;
}
# undef setenv
# undef unsetenv
# undef clearenv
weak_alias (__setenv, setenv)
weak_alias (__unsetenv, unsetenv)
weak_alias (__clearenv, clearenv)
#endif
#endif /*!HAVE_W32CE_SYSTEM*/

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