libiberty/setenv.c

   1 /* Copyright (C) 1992, 1995, 1996, 1997, 2002, 2011, 2015
   2    Free Software Foundation, Inc.
   3    This file based on setenv.c in the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  18    Boston, MA 02110-1301, USA.  */
  19
  20
  21 /*
  22
  23 @deftypefn Supplemental int setenv (const char *@var{name}, @
  24   const char *@var{value}, int @var{overwrite})
  25 @deftypefnx Supplemental void unsetenv (const char *@var{name})
  26
  27 @code{setenv} adds @var{name} to the environment with value
  28 @var{value}.  If the name was already present in the environment,
  29 the new value will be stored only if @var{overwrite} is nonzero.
  30 The companion @code{unsetenv} function removes @var{name} from the
  31 environment.  This implementation is not safe for multithreaded code.
  32
  33 @end deftypefn
  34
  35 */
  36
  37 #if HAVE_CONFIG_H
  38 # include <config.h>
  39 #endif
  40
  41 #define setenv libiberty_setenv
  42 #define unsetenv libiberty_unsetenv
  43
  44 #include "ansidecl.h"
  45 #include <sys/types.h> /* For `size_t' */
  46 #include <stdio.h>     /* For `NULL' */
  47
  48 #include <errno.h>
  49 #if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  50 extern int errno;
  51 #endif
  52 #define __set_errno(ev) ((errno) = (ev))
  53
  54 #if HAVE_STDLIB_H
  55 # include <stdlib.h>
  56 #endif
  57 #if HAVE_STRING_H
  58 # include <string.h>
  59 #endif
  60 #if HAVE_UNISTD_H
  61 # include <unistd.h>
  62 #endif
  63
  64 #define __environ       environ
  65 #include "environ.h"
  66
  67 #undef setenv
  68 #undef unsetenv
  69
  70 /* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
  71  * implementation MT-Unsafe. */
  72 #define LOCK
  73 #define UNLOCK
  74
  75 /* Below this point, it's verbatim code from the glibc-2.0 implementation */
  76
  77 /* If this variable is not a null pointer we allocated the current
  78    environment.  */
  79 static char **last_environ;
  80
  81
  82 int
  83 setenv (const char *name, const char *value, int replace)
  84 {
  85   register char **ep = 0;
  86   register size_t size;
  87   const size_t namelen = strlen (name);
  88   const size_t vallen = strlen (value) + 1;
  89
  90   LOCK;
  91
  92   size = 0;
  93   if (__environ != NULL)
  94     {
  95       for (ep = __environ; *ep != NULL; ++ep)
  96         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  97           break;
  98         else
  99           ++size;
 100     }
 101
 102   if (__environ == NULL || *ep == NULL)
 103     {
 104       char **new_environ;
 105       if (__environ == last_environ && __environ != NULL)
 106         /* We allocated this space; we can extend it.  */
 107         new_environ = (char **) realloc (last_environ,
 108                                          (size + 2) * sizeof (char *));
 109       else
 110         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 111
 112       if (new_environ == NULL)
 113         {
 114           UNLOCK;
 115           return -1;
 116         }
 117
 118       new_environ[size] = (char *) malloc (namelen + 1 + vallen);
 119       if (new_environ[size] == NULL)
 120         {
 121           free ((char *) new_environ);
 122           __set_errno (ENOMEM);
 123           UNLOCK;
 124           return -1;
 125         }
 126
 127       if (__environ != last_environ)
 128         memcpy ((char *) new_environ, (char *) __environ,
 129                 size * sizeof (char *));
 130
 131       memcpy (new_environ[size], name, namelen);
 132       new_environ[size][namelen] = '=';
 133       memcpy (&new_environ[size][namelen + 1], value, vallen);
 134
 135       new_environ[size + 1] = NULL;
 136
 137       last_environ = __environ = new_environ;
 138     }
 139   else if (replace)
 140     {
 141       size_t len = strlen (*ep);
 142       if (len + 1 < namelen + 1 + vallen)
 143         {
 144           /* The existing string is too short; malloc a new one.  */
 145           char *new_string = (char *) malloc (namelen + 1 + vallen);
 146           if (new_string == NULL)
 147             {
 148               UNLOCK;
 149               return -1;
 150             }
 151           *ep = new_string;
 152         }
 153       memcpy (*ep, name, namelen);
 154       (*ep)[namelen] = '=';
 155       memcpy (&(*ep)[namelen + 1], value, vallen);
 156     }
 157
 158   UNLOCK;
 159
 160   return 0;
 161 }
 162
 163 void
 164 unsetenv (const char *name)
 165 {
 166   const size_t len = strlen (name);
 167   char **ep;
 168
 169   LOCK;
 170
 171   for (ep = __environ; *ep; ++ep)
 172     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 173       {
 174         /* Found it.  Remove this pointer by moving later ones back.  */
 175         char **dp = ep;
 176         do
 177           dp[0] = dp[1];
 178         while (*dp++);
 179         /* Continue the loop in case NAME appears again.  */
 180       }
 181
 182   UNLOCK;
 183 }