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glibc/stdlib/setenv.c
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/* Copyright (C) 1992,1995-2001,2004, 2008 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, write to the Free | |
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
02111-1307 USA. */ | |
#if HAVE_CONFIG_H | |
# include <config.h> | |
#endif | |
#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. */ | |
int | |
__add_to_environ (name, value, combined, replace) | |
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 (name, value, replace) | |
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 (name) | |
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; | |
if (ep != NULL) | |
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 () | |
{ | |
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 |