libiberty/setenv.c

   1 /* Copyright (C) 1992, 1995, 1996, 1997 Free Software Foundation, Inc.
   2    This file based on setenv.c in 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 "ansidecl.h"
  24 #include <sys/types.h> /* For `size_t' */
  25 #include <stdio.h>     /* For `NULL' */
  26
  27 #include <errno.h>
  28 #if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  29 extern int errno;
  30 #endif
  31 #define __set_errno(ev) ((errno) = (ev))
  32
  33 #if HAVE_STDLIB_H
  34 # include <stdlib.h>
  35 #endif
  36 #if HAVE_STRING_H
  37 # include <string.h>
  38 #endif
  39 #if HAVE_UNISTD_H
  40 # include <unistd.h>
  41 #endif
  42
  43 #define __environ       environ
  44 #ifndef HAVE_ENVIRON_DECL
  45 extern char **environ;
  46 #endif
  47
  48 /* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
  49  * implementation MT-Unsafe. */
  50 #define LOCK
  51 #define UNLOCK
  52
  53 /* Below this point, it's verbatim code from the glibc-2.0 implementation */
  54
  55 /* If this variable is not a null pointer we allocated the current
  56    environment.  */
  57 static char **last_environ;
  58
  59
  60 int
  61 setenv (name, value, replace)
  62      const char *name;
  63      const char *value;
  64      int replace;
  65 {
  66   register char **ep = 0;
  67   register size_t size;
  68   const size_t namelen = strlen (name);
  69   const size_t vallen = strlen (value) + 1;
  70
  71   LOCK;
  72
  73   size = 0;
  74   if (__environ != NULL)
  75     {
  76       for (ep = __environ; *ep != NULL; ++ep)
  77         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  78           break;
  79         else
  80           ++size;
  81     }
  82
  83   if (__environ == NULL || *ep == NULL)
  84     {
  85       char **new_environ;
  86       if (__environ == last_environ && __environ != NULL)
  87         /* We allocated this space; we can extend it.  */
  88         new_environ = (char **) realloc (last_environ,
  89                                          (size + 2) * sizeof (char *));
  90       else
  91         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
  92
  93       if (new_environ == NULL)
  94         {
  95           UNLOCK;
  96           return -1;
  97         }
  98
  99       new_environ[size] = malloc (namelen + 1 + vallen);
 100       if (new_environ[size] == NULL)
 101         {
 102           free ((char *) new_environ);
 103           __set_errno (ENOMEM);
 104           UNLOCK;
 105           return -1;
 106         }
 107
 108       if (__environ != last_environ)
 109         memcpy ((char *) new_environ, (char *) __environ,
 110                 size * sizeof (char *));
 111
 112       memcpy (new_environ[size], name, namelen);
 113       new_environ[size][namelen] = '=';
 114       memcpy (&new_environ[size][namelen + 1], value, vallen);
 115
 116       new_environ[size + 1] = NULL;
 117
 118       last_environ = __environ = new_environ;
 119     }
 120   else if (replace)
 121     {
 122       size_t len = strlen (*ep);
 123       if (len + 1 < namelen + 1 + vallen)
 124         {
 125           /* The existing string is too short; malloc a new one.  */
 126           char *new = malloc (namelen + 1 + vallen);
 127           if (new == NULL)
 128             {
 129               UNLOCK;
 130               return -1;
 131             }
 132           *ep = new;
 133         }
 134       memcpy (*ep, name, namelen);
 135       (*ep)[namelen] = '=';
 136       memcpy (&(*ep)[namelen + 1], value, vallen);
 137     }
 138
 139   UNLOCK;
 140
 141   return 0;
 142 }
 143
 144 void
 145 unsetenv (name)
 146      const char *name;
 147 {
 148   const size_t len = strlen (name);
 149   char **ep;
 150
 151   LOCK;
 152
 153   for (ep = __environ; *ep; ++ep)
 154     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 155       {
 156         /* Found it.  Remove this pointer by moving later ones back.  */
 157         char **dp = ep;
 158         do
 159           dp[0] = dp[1];
 160         while (*dp++);
 161         /* Continue the loop in case NAME appears again.  */
 162       }
 163
 164   UNLOCK;
 165 }