libiberty/setenv.c

   1 /* Copyright (C) 1992-2023 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., 51 Franklin Street - Fifth Floor,
  17    Boston, MA 02110-1301, USA.  */
  18
  19
  20 /*
  21
  22 @deftypefn Supplemental int setenv (const char *@var{name}, @
  23   const char *@var{value}, int @var{overwrite})
  24 @deftypefnx Supplemental void unsetenv (const char *@var{name})
  25
  26 @code{setenv} adds @var{name} to the environment with value
  27 @var{value}.  If the name was already present in the environment,
  28 the new value will be stored only if @var{overwrite} is nonzero.
  29 The companion @code{unsetenv} function removes @var{name} from the
  30 environment.  This implementation is not safe for multithreaded code.
  31
  32 @end deftypefn
  33
  34 */
  35
  36 #if HAVE_CONFIG_H
  37 # include <config.h>
  38 #endif
  39
  40 #define setenv libiberty_setenv
  41 #define unsetenv libiberty_unsetenv
  42
  43 #include "ansidecl.h"
  44 #include <sys/types.h> /* For `size_t' */
  45 #include <stdio.h>     /* For `NULL' */
  46
  47 #include <errno.h>
  48 #if !defined(errno) && !defined(HAVE_ERRNO_DECL)
  49 extern int errno;
  50 #endif
  51 #define __set_errno(ev) ((errno) = (ev))
  52
  53 #if HAVE_STDLIB_H
  54 # include <stdlib.h>
  55 #endif
  56 #if HAVE_STRING_H
  57 # include <string.h>
  58 #endif
  59 #if HAVE_UNISTD_H
  60 # include <unistd.h>
  61 #endif
  62
  63 #define __environ       environ
  64 #include "environ.h"
  65
  66 #undef setenv
  67 #undef unsetenv
  68
  69 /* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
  70  * implementation MT-Unsafe. */
  71 #define LOCK
  72 #define UNLOCK
  73
  74 /* Below this point, it's verbatim code from the glibc-2.0 implementation */
  75
  76 /* If this variable is not a null pointer we allocated the current
  77    environment.  */
  78 static char **last_environ;
  79
  80
  81 int
  82 setenv (const char *name, const char *value, int replace)
  83 {
  84   register char **ep = 0;
  85   register size_t size;
  86   const size_t namelen = strlen (name);
  87   const size_t vallen = strlen (value) + 1;
  88
  89   LOCK;
  90
  91   size = 0;
  92   if (__environ != NULL)
  93     {
  94       for (ep = __environ; *ep != NULL; ++ep)
  95         if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  96           break;
  97         else
  98           ++size;
  99     }
 100
 101   if (__environ == NULL || *ep == NULL)
 102     {
 103       char **new_environ;
 104       if (__environ == last_environ && __environ != NULL)
 105         /* We allocated this space; we can extend it.  */
 106         new_environ = (char **) realloc (last_environ,
 107                                          (size + 2) * sizeof (char *));
 108       else
 109         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
 110
 111       if (new_environ == NULL)
 112         {
 113           UNLOCK;
 114           return -1;
 115         }
 116
 117       new_environ[size] = (char *) malloc (namelen + 1 + vallen);
 118       if (new_environ[size] == NULL)
 119         {
 120           free ((char *) new_environ);
 121           __set_errno (ENOMEM);
 122           UNLOCK;
 123           return -1;
 124         }
 125
 126       if (__environ != last_environ)
 127         memcpy ((char *) new_environ, (char *) __environ,
 128                 size * sizeof (char *));
 129
 130       memcpy (new_environ[size], name, namelen);
 131       new_environ[size][namelen] = '=';
 132       memcpy (&new_environ[size][namelen + 1], value, vallen);
 133
 134       new_environ[size + 1] = NULL;
 135
 136       last_environ = __environ = new_environ;
 137     }
 138   else if (replace)
 139     {
 140       size_t len = strlen (*ep);
 141       if (len + 1 < namelen + 1 + vallen)
 142         {
 143           /* The existing string is too short; malloc a new one.  */
 144           char *new_string = (char *) malloc (namelen + 1 + vallen);
 145           if (new_string == NULL)
 146             {
 147               UNLOCK;
 148               return -1;
 149             }
 150           *ep = new_string;
 151         }
 152       memcpy (*ep, name, namelen);
 153       (*ep)[namelen] = '=';
 154       memcpy (&(*ep)[namelen + 1], value, vallen);
 155     }
 156
 157   UNLOCK;
 158
 159   return 0;
 160 }
 161
 162 void
 163 unsetenv (const char *name)
 164 {
 165   const size_t len = strlen (name);
 166   char **ep;
 167
 168   LOCK;
 169
 170   for (ep = __environ; *ep; ++ep)
 171     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 172       {
 173         /* Found it.  Remove this pointer by moving later ones back.  */
 174         char **dp = ep;
 175         do
 176           dp[0] = dp[1];
 177         while (*dp++);
 178         /* Continue the loop in case NAME appears again.  */
 179       }
 180
 181   UNLOCK;
 182 }