sysdeps/generic/setenv.c

   1 /* Copyright (C) 1992, 1995, 1996, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #if HAVE_CONFIG_H
  20 # include <config.h>
  21 #endif
  22
  23 #include <errno.h>
  24 #if !_LIBC
  25 # if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  26 extern int errno;
  27 # endif
  28 # define __set_errno(ev) ((errno) = (ev))
  29 #endif
  30
  31 #if _LIBC || HAVE_STDLIB_H
  32 # include <stdlib.h>
  33 #endif
  34 #if _LIBC || HAVE_STRING_H
  35 # include <string.h>
  36 #endif
  37 #if _LIBC || HAVE_UNISTD_H
  38 # include <unistd.h>
  39 #endif
  40
  41 #if !_LIBC
  42 # define __environ      environ
  43 # ifndef HAVE_ENVIRON_DECL
  44 extern char **environ;
  45 # endif
  46 #endif
  47
  48 #if _LIBC
  49 /* This lock protects against simultaneous modifications of `environ'.  */
  50 # include <libc-lock.h>
  51 __libc_lock_define_initialized (static, envlock)
  52 # define LOCK   __libc_lock_lock (envlock)
  53 # define UNLOCK __libc_lock_unlock (envlock)
  54 #else
  55 # define LOCK
  56 # define UNLOCK
  57 #endif
  58
  59 /* In the GNU C library we must keep the namespace clean.  */
  60 #ifdef _LIBC
  61 # define clearenv __clearenv
  62 #endif
  63
  64
  65 /* If this variable is not a null pointer we allocated the current
  66    environment.  */
  67 static char **last_environ;
  68
  69
  70 int
  71 setenv (name, value, replace)
  72      const char *name;
  73      const char *value;
  74      int replace;
  75 {
  76   register char **ep;
  77   register size_t size;
  78   const size_t namelen = strlen (name);
  79   const size_t vallen = strlen (value) + 1;
  80
  81   LOCK;
  82
  83   size = 0;
  84   if (__environ != NULL)
  85     for (ep = __environ; *ep != NULL; ++ep)
  86       if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  87         break;
  88       else
  89         ++size;
  90
  91   if (__environ == NULL || *ep == NULL)
  92     {
  93       char **new_environ;
  94       if (__environ == last_environ && __environ != NULL)
  95         /* We allocated this space; we can extend it.  */
  96         new_environ = (char **) realloc (last_environ,
  97                                          (size + 2) * sizeof (char *));
  98       else
  99         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 100
 101       if (new_environ == NULL)
 102         {
 103           UNLOCK;
 104           return -1;
 105         }
 106
 107       new_environ[size] = malloc (namelen + 1 + vallen);
 108       if (new_environ[size] == NULL)
 109         {
 110           free ((char *) new_environ);
 111           __set_errno (ENOMEM);
 112           UNLOCK;
 113           return -1;
 114         }
 115
 116       if (__environ != last_environ)
 117         memcpy ((char *) new_environ, (char *) __environ,
 118                 size * sizeof (char *));
 119
 120       memcpy (new_environ[size], name, namelen);
 121       new_environ[size][namelen] = '=';
 122       memcpy (&new_environ[size][namelen + 1], value, vallen);
 123
 124       new_environ[size + 1] = NULL;
 125
 126       last_environ = __environ = new_environ;
 127     }
 128   else if (replace)
 129     {
 130       size_t len = strlen (*ep);
 131       if (len + 1 < namelen + 1 + vallen)
 132         {
 133           /* The existing string is too short; malloc a new one.  */
 134           char *new = malloc (namelen + 1 + vallen);
 135           if (new == NULL)
 136             {
 137               UNLOCK;
 138               return -1;
 139             }
 140           *ep = new;
 141           memcpy (*ep, name, namelen);
 142           (*ep)[namelen] = '=';
 143         }
 144       memcpy (&(*ep)[namelen + 1], value, vallen);
 145     }
 146
 147   UNLOCK;
 148
 149   return 0;
 150 }
 151
 152 void
 153 unsetenv (name)
 154      const char *name;
 155 {
 156   const size_t len = strlen (name);
 157   char **ep;
 158
 159   LOCK;
 160
 161   for (ep = __environ; *ep; ++ep)
 162     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 163       {
 164         /* Found it.  Remove this pointer by moving later ones back.  */
 165         char **dp = ep;
 166         do
 167           dp[0] = dp[1];
 168         while (*dp++);
 169         /* Continue the loop in case NAME appears again.  */
 170       }
 171
 172   UNLOCK;
 173 }
 174
 175 /* The `clearenv' was planned to be added to POSIX.1 but probably
 176    never made it.  Nevertheless the POSIX.9 standard (POSIX bindings
 177    for Fortran 77) requires this function.  */
 178 int
 179 clearenv ()
 180 {
 181   LOCK;
 182
 183   if (__environ == last_environ && __environ != NULL)
 184     {
 185       /* We allocated this environment so we can free it.  */
 186       free (__environ);
 187       last_environ = NULL;
 188     }
 189
 190   /* Clear the environment pointer removes the whole environment.  */
 191   __environ = NULL;
 192
 193   UNLOCK;
 194
 195   return 0;
 196 }
 197 #ifdef _LIBC
 198 # undef clearenv
 199 weak_alias (__clearenv, clearenv)
 200 #endif