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-rw-r--r--sysdeps/generic/setenv.c353
1 files changed, 353 insertions, 0 deletions
diff --git a/sysdeps/generic/setenv.c b/sysdeps/generic/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, 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;
+ 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
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