sysdeps/generic/setenv.c

   1 /* Copyright (C) 1992, 1995 Free Software Foundation, Inc.
   2 This file is part of 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
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #ifdef HAVE_CONFIG_H
  20 #include <config.h>
  21 #endif
  22
  23 #include <errno.h>
  24
  25 #if _LIBC || HAVE_STDLIB_H
  26 #include <stdlib.h>
  27 #endif
  28 #if _LIBC || HAVE_STRING_H
  29 #include <string.h>
  30 #endif
  31 #if _LIBC || HAVE_UNISTD_H
  32 #include <unistd.h>
  33 #endif
  34
  35 #ifndef HAVE_GNU_LD
  36 #define __environ       environ
  37 #endif
  38
  39 int
  40 setenv (name, value, replace)
  41      const char *name;
  42      const char *value;
  43      int replace;
  44 {
  45   register char **ep;
  46   register size_t size;
  47   const size_t namelen = strlen (name);
  48   const size_t vallen = strlen (value) + 1;
  49
  50   size = 0;
  51   for (ep = __environ; *ep != NULL; ++ep)
  52     if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  53       break;
  54     else
  55       ++size;
  56
  57   if (*ep == NULL)
  58     {
  59       static char **last_environ;
  60       char **new_environ;
  61       if (__environ == last_environ)
  62         /* We allocated this space; we can extend it.  */
  63         new_environ = (char **) realloc (last_environ,
  64                                          (size + 2) * sizeof (char *));
  65       else
  66         new_environ = (char **) malloc ((size + 2) * sizeof (char *));
  67
  68       if (new_environ == NULL)
  69         return -1;
  70
  71       new_environ[size] = malloc (namelen + 1 + vallen);
  72       if (new_environ[size] == NULL)
  73         {
  74           free ((char *) new_environ);
  75           errno = ENOMEM;
  76           return -1;
  77         }
  78
  79       if (__environ != last_environ)
  80         memcpy ((char *) new_environ, (char *) __environ,
  81                 size * sizeof (char *));
  82
  83       memcpy (new_environ[size], name, namelen);
  84       new_environ[size][namelen] = '=';
  85       memcpy (&new_environ[size][namelen + 1], value, vallen);
  86
  87       new_environ[size + 1] = NULL;
  88
  89       last_environ = __environ = new_environ;
  90     }
  91   else if (replace)
  92     {
  93       size_t len = strlen (*ep);
  94       if (len + 1 < namelen + 1 + vallen)
  95         {
  96           /* The existing string is too short; malloc a new one.  */
  97           char *new = malloc (namelen + 1 + vallen);
  98           if (new == NULL)
  99             return -1;
 100           *ep = new;
 101         }
 102       memcpy (*ep, name, namelen);
 103       (*ep)[namelen] = '=';
 104       memcpy (&(*ep)[namelen + 1], value, vallen);
 105     }
 106
 107   return 0;
 108 }
 109
 110 void
 111 unsetenv (const char *name)
 112 {
 113   const size_t len = strlen (name);
 114   char **ep;
 115
 116   for (ep = __environ; *ep; ++ep)
 117     if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
 118       {
 119         /* Found it.  Remove this pointer by moving later ones back.  */
 120         char **dp = ep;
 121         do
 122           dp[0] = dp[1];
 123         while (*dp++);
 124         /* Continue the loop in case NAME appears again.  */
 125       }
 126 }