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/* Copyright (C) 1992,1995-1999,2000-2003 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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# define __set_errno(ev) ((errno) = (ev))
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#if _LIBC || HAVE_UNISTD_H
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# define __environ environ
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# ifndef HAVE_ENVIRON_DECL
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extern char **environ;
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/* This lock protects against simultaneous modifications of `environ'. */
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# include <bits/libc-lock.h>
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__libc_lock_define_initialized (static, envlock)
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# define LOCK __libc_lock_lock (envlock)
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# define UNLOCK __libc_lock_unlock (envlock)
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/* In the GNU C library we must keep the namespace clean. */
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# define setenv __setenv
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# define clearenv __clearenv
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# define tfind __tfind
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# define tsearch __tsearch
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/* In the GNU C library implementation we try to be more clever and
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allow arbitrarily many changes of the environment given that the used
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values are from a small set. Outside glibc this will eat up all
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memory after a while. */
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#if defined _LIBC || (defined HAVE_SEARCH_H && defined HAVE_TSEARCH \
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# define USE_TSEARCH 1
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typedef int (*compar_fn_t) (const void *, const void *);
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/* This is a pointer to the root of the search tree with the known
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static void *known_values;
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# define KNOWN_VALUE(Str) \
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void *value = tfind (Str, &known_values, (compar_fn_t) strcmp); \
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value != NULL ? *(char **) value : NULL; \
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# define STORE_VALUE(Str) \
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tsearch (Str, &known_values, (compar_fn_t) strcmp)
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# define KNOWN_VALUE(Str) NULL
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# define STORE_VALUE(Str) do { } while (0)
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/* If this variable is not a null pointer we allocated the current
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static char **last_environ;
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/* This function is used by `setenv' and `putenv'. The difference between
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the two functions is that for the former must create a new string which
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is then placed in the environment, while the argument of `putenv'
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must be used directly. This is all complicated by the fact that we try
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to reuse values once generated for a `setenv' call since we can never
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__add_to_environ (const char *name, const char *value, const char *combined,
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register size_t size;
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const size_t namelen = strlen (name);
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const size_t vallen = value != NULL ? strlen (value) + 1 : 0;
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/* We have to get the pointer now that we have the lock and not earlier
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since another thread might have created a new environment. */
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for (; *ep != NULL; ++ep)
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if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
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if (ep == NULL || *ep == NULL)
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/* We allocated this space; we can extend it. */
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(char **) (last_environ == NULL
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? malloc ((size + 2) * sizeof (char *))
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: realloc (last_environ, (size + 2) * sizeof (char *)));
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if (new_environ == NULL)
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/* If the whole entry is given add it. */
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if (combined != NULL)
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/* We must not add the string to the search tree since it belongs
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new_environ[size] = (char *) combined;
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/* See whether the value is already known. */
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new_value = (char *) alloca (namelen + 1 + vallen);
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__mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
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new_value = (char *) allocsa (namelen + 1 + vallen);
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if (new_value == NULL)
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__set_errno (ENOMEM);
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memcpy (new_value, name, namelen);
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new_value[namelen] = '=';
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memcpy (&new_value[namelen + 1], value, vallen);
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new_environ[size] = KNOWN_VALUE (new_value);
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if (new_environ[size] == NULL)
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new_environ[size] = (char *) malloc (namelen + 1 + vallen);
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if (new_environ[size] == NULL)
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#if defined USE_TSEARCH && !defined _LIBC
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__set_errno (ENOMEM);
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memcpy (new_environ[size], new_value, namelen + 1 + vallen);
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memcpy (new_environ[size], name, namelen);
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new_environ[size][namelen] = '=';
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memcpy (&new_environ[size][namelen + 1], value, vallen);
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/* And save the value now. We cannot do this when we remove
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the string since then we cannot decide whether it is a
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user string or not. */
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STORE_VALUE (new_environ[size]);
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#if defined USE_TSEARCH && !defined _LIBC
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if (__environ != last_environ)
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memcpy ((char *) new_environ, (char *) __environ,
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size * sizeof (char *));
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new_environ[size + 1] = NULL;
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last_environ = __environ = new_environ;
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/* Use the user string if given. */
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if (combined != NULL)
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np = (char *) combined;
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new_value = alloca (namelen + 1 + vallen);
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__mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
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new_value = allocsa (namelen + 1 + vallen);
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if (new_value == NULL)
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__set_errno (ENOMEM);
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memcpy (new_value, name, namelen);
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new_value[namelen] = '=';
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memcpy (&new_value[namelen + 1], value, vallen);
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np = KNOWN_VALUE (new_value);
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np = malloc (namelen + 1 + vallen);
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#if defined USE_TSEARCH && !defined _LIBC
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__set_errno (ENOMEM);
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memcpy (np, new_value, namelen + 1 + vallen);
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memcpy (np, name, namelen);
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memcpy (&np[namelen + 1], value, vallen);
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/* And remember the value. */
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#if defined USE_TSEARCH && !defined _LIBC
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setenv (const char *name, const char *value, int replace)
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return __add_to_environ (name, value, NULL, replace);
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/* The `clearenv' was planned to be added to POSIX.1 but probably
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never made it. Nevertheless the POSIX.9 standard (POSIX bindings
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for Fortran 77) requires this function. */
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if (__environ == last_environ && __environ != NULL)
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/* We allocated this environment so we can free it. */
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/* Clear the environment pointer removes the whole environment. */
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/* Remove all traces. */
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/* Now remove the search tree. */
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__tdestroy (known_values, free);
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text_set_element (__libc_subfreeres, free_mem);
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weak_alias (__setenv, setenv)
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weak_alias (__clearenv, clearenv)
added
removed
gl/setenv.c
