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;
  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     for (ep = __environ; *ep != NULL; ++ep)
  76       if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  77         break;
  78       else
  79         ++size;
  80
  81   if (__environ == NULL || *ep == NULL)
  82     {
  83       char **new_environ;
  84       if (__environ == last_environ && __environ != NULL)
  85         /* We allocated this space; we can extend it.  */
  86         new_environ = (char **) realloc (last_environ,
  87                                          (size + 2) * sizeof (char *));
  88       else
  89         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
  90
  91       if (new_environ == NULL)
  92         {
  93           UNLOCK;
  94           return -1;
  95         }
  96
  97       new_environ[size] = malloc (namelen + 1 + vallen);
  98       if (new_environ[size] == NULL)
  99         {
 100           free ((char *) new_environ);
 101           __set_errno (ENOMEM);
 102           UNLOCK;
 103           return -1;
 104         }
 105
 106       if (__environ != last_environ)
 107         memcpy ((char *) new_environ, (char *) __environ,
 108                 size * sizeof (char *));
 109
 110       memcpy (new_environ[size], name, namelen);
 111       new_environ[size][namelen] = '=';
 112       memcpy (&new_environ[size][namelen + 1], value, vallen);
 113
 114       new_environ[size + 1] = NULL;
 115
 116       last_environ = __environ = new_environ;
 117     }
 118   else if (replace)
 119     {
 120       size_t len = strlen (*ep);
 121       if (len + 1 < namelen + 1 + vallen)
 122         {
 123           /* The existing string is too short; malloc a new one.  */
 124           char *new = malloc (namelen + 1 + vallen);
 125           if (new == NULL)
 126             {
 127               UNLOCK;
 128               return -1;
 129             }
 130           *ep = new;
 131         }
 132       memcpy (*ep, name, namelen);
 133       (*ep)[namelen] = '=';
 134       memcpy (&(*ep)[namelen + 1], value, vallen);
 135     }
 136
 137   UNLOCK;
 138
 139   return 0;
 140 }
 141
 142 void
 143 unsetenv (name)
 144      const char *name;
 145 {
 146   const size_t len = strlen (name);
 147   char **ep;
 148
 149   LOCK;
 150
 151   for (ep = __environ; *ep; ++ep)
 152     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 153       {
 154         /* Found it.  Remove this pointer by moving later ones back.  */
 155         char **dp = ep;
 156         do
 157           dp[0] = dp[1];
 158         while (*dp++);
 159         /* Continue the loop in case NAME appears again.  */
 160       }
 161
 162   UNLOCK;
 163 }