/* Copyright (C) 1992,1995-1999,2000-2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#include <sys/cdefs.h>
__RCSID("$NetBSD: setenv.c,v 1.2 2016/05/17 14:00:09 christos Exp $");
#if HAVE_CONFIG_H
# include <config.h>
#endif
#include <alloca.h>
#include <errno.h>
#ifndef __set_errno
# define __set_errno(ev) ((errno) = (ev))
#endif
#include <stdlib.h>
#include <string.h>
#if _LIBC || HAVE_UNISTD_H
# include <unistd.h>
#endif
#if !_LIBC
# include "allocsa.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 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>
typedef int (*compar_fn_t) (const void *, const void *);
/* 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 (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 || *ep == NULL)
{
char **new_environ;
#ifdef USE_TSEARCH
char *new_value;
#endif
/* We allocated this space; we can extend it. */
new_environ =
(char **) (last_environ == NULL
? malloc ((size + 2) * sizeof (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 _LIBC
new_value = (char *) alloca (namelen + 1 + vallen);
__mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
value, vallen);
# else
new_value = (char *) allocsa (namelen + 1 + vallen);
if (new_value == NULL)
{
__set_errno (ENOMEM);
UNLOCK;
return -1;
}
memcpy (new_value, name, namelen);
new_value[namelen] = '=';
memcpy (&new_value[namelen + 1], value, vallen);
# endif
new_environ[size] = KNOWN_VALUE (new_value);
if (new_environ[size] == NULL)
#endif
{
new_environ[size] = (char *) malloc (namelen + 1 + vallen);
if (new_environ[size] == NULL)
{
#if defined USE_TSEARCH && !defined _LIBC
freesa (new_value);
#endif
__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 defined USE_TSEARCH && !defined _LIBC
freesa (new_value);
#endif
}
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
char *new_value;
# ifdef _LIBC
new_value = alloca (namelen + 1 + vallen);
__mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
value, vallen);
# else
new_value = allocsa (namelen + 1 + vallen);
if (new_value == NULL)
{
__set_errno (ENOMEM);
UNLOCK;
return -1;
}
memcpy (new_value, name, namelen);
new_value[namelen] = '=';
memcpy (&new_value[namelen + 1], value, vallen);
# endif
np = KNOWN_VALUE (new_value);
if (np == NULL)
#endif
{
np = malloc (namelen + 1 + vallen);
if (np == NULL)
{
#if defined USE_TSEARCH && !defined _LIBC
freesa (new_value);
#endif
__set_errno (ENOMEM);
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);
}
#if defined USE_TSEARCH && !defined _LIBC
freesa (new_value);
#endif
}
*ep = np;
}
UNLOCK;
return 0;
}
int
setenv (const char *name, const char *value, int replace)
{
return __add_to_environ (name, value, NULL, replace);
}
/* 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
static void
free_mem (void)
{
/* Remove all traces. */
clearenv ();
/* Now remove the search tree. */
__tdestroy (known_values, free);
known_values = NULL;
}
text_set_element (__libc_subfreeres, free_mem);
# undef setenv
# undef clearenv
weak_alias (__setenv, setenv)
weak_alias (__clearenv, clearenv)
#endif