setenv and unsetenv.

1 files changed, 298 insertions, 72 deletions

diff --git a/lib/setenv.c b/lib/setenv.c
index 3ed901b7cb..57e6dd9e6c 100644
--- a/lib/setenv.c
+++ b/lib/setenv.c
@@ -1,28 +1,63 @@
-/* Copyright (C) 1992, 1995, 2000 Free Software Foundation, Inc.
+/* Copyright (C) 1992,1995-1999,2000-2002 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
 
-NOTE: The canonical source of this file is maintained with the GNU C Library.
-Bugs can be reported to bug-glibc@prep.ai.mit.edu.
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
 
-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.
+   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
+   Library General Public License for more details.
 
-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 Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
 
-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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
-USA.  */
-
-#ifdef HAVE_CONFIG_H
+#if HAVE_CONFIG_H
 # include <config.h>
 #endif
 
+#ifdef __GNUC__
+# ifndef alloca
+#  define alloca __builtin_alloca
+# endif
+#else
+# ifdef _MSC_VER
+#  include <malloc.h>
+#  define alloca _alloca
+# else
+#  if HAVE_ALLOCA_H
+#   include <alloca.h>
+#  else
+#   ifdef _AIX
+ #pragma alloca
+#   else
+#    ifdef __hpux /* This section must match that of bison generated files. */
+#     ifdef __cplusplus
+extern "C" void *alloca (unsigned int);
+#     else /* not __cplusplus */
+void *alloca ();
+#     endif /* not __cplusplus */
+#    else /* not __hpux */
+#     ifndef alloca
+char *alloca ();
+#     endif
+#    endif /* __hpux */
+#   endif
+#  endif
+# endif
+#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>
@@ -34,96 +69,287 @@ USA.  */
 # include <unistd.h>
 #endif
 
-#ifndef	HAVE_GNU_LD
+/* For those losing systems which don't have 'alloca' we have to add
+   some additional code emulating it.  */
+#if _LIBC || HAVE_ALLOCA
+# define freea(p) /* nothing */
+#else
+# define alloca(n) malloc (n)
+# define freea(p) free (p)
+#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
-setenv (name, value, replace)
-     const char *name;
-     const char *value;
-     int replace;
+__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 = strlen (value) + 1;
+  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;
-  for (ep = __environ; *ep != NULL; ++ep)
-    if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
-      break;
-    else
-      ++size;
+  if (ep != NULL)
+    {
+      for (; *ep != NULL; ++ep)
+	if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
+	  break;
+	else
+	  ++size;
+    }
 
-  if (*ep == NULL)
+  if (ep == NULL || *ep == NULL)
     {
-      static char **last_environ;
       char **new_environ;
-      if (__environ == last_environ)
-	/* We allocated this space; we can extend it.  */
-	new_environ = (char **) realloc (last_environ,
-					 (size + 2) * sizeof (char *));
-      else
-	new_environ = (char **) malloc ((size + 2) * sizeof (char *));
+#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)
-	return -1;
-
-      new_environ[size] = malloc (namelen + 1 + vallen);
-      if (new_environ[size] == NULL)
 	{
-	  free ((char *) new_environ);
-	  errno = ENOMEM;
+	  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
+	  new_value = (char *) alloca (namelen + 1 + vallen);
+# 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 (new_environ[size] == NULL)
+#endif
+	    {
+	      new_environ[size] = (char *) malloc (namelen + 1 + vallen);
+	      if (new_environ[size] == NULL)
+		{
+#ifdef USE_TSEARCH
+		  freea (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]);
+	    }
+#ifdef USE_TSEARCH
+	  freea (new_value);
+#endif
+	}
+
       if (__environ != last_environ)
 	memcpy ((char *) new_environ, (char *) __environ,
 		size * sizeof (char *));
 
-      memcpy (new_environ[size], name, namelen);
-      new_environ[size][namelen] = '=';
-      memcpy (&new_environ[size][namelen + 1], value, vallen);
-
       new_environ[size + 1] = NULL;
 
       last_environ = __environ = new_environ;
     }
   else if (replace)
     {
-      size_t len = strlen (*ep);
-      if (len + 1 < namelen + 1 + vallen)
+      char *np;
+
+      /* Use the user string if given.  */
+      if (combined != NULL)
+	np = (char *) combined;
+      else
 	{
-	  /* The existing string is too short; malloc a new one.  */
-	  char *new = malloc (namelen + 1 + vallen);
-	  if (new == NULL)
-	    return -1;
-	  *ep = new;
+#ifdef USE_TSEARCH
+	  char *new_value = alloca (namelen + 1 + vallen);
+# 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 (np == NULL)
+#endif
+	    {
+	      np = malloc (namelen + 1 + vallen);
+	      if (np == NULL)
+		{
+#ifdef USE_TSEARCH
+		  freea (new_value);
+#endif
+		  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);
+	    }
+#ifdef USE_TSEARCH
+	  freea (new_value);
+#endif
 	}
-      memcpy (*ep, name, namelen);
-      (*ep)[namelen] = '=';
-      memcpy (&(*ep)[namelen + 1], value, vallen);
+
+      *ep = np;
     }
 
+  UNLOCK;
+
   return 0;
 }
 
-void
-unsetenv (name)
-     const char *name;
+int
+setenv (const char *name, const char *value, int replace)
 {
-  const size_t len = strlen (name);
-  char **ep;
-
-  for (ep = __environ; *ep; ++ep)
-    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.  */
-      }
+  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 ()
+{
+  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