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