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 #include <ansidecl.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <errno.h>
  24
  25 #ifndef HAVE_GNU_LD
  26 #define __environ       environ
  27 #endif
  28
  29 int
  30 DEFUN(setenv, (name, value, replace),
  31       CONST char *name AND CONST char *value AND int replace)
  32 {
  33   register char **ep;
  34   register size_t size;
  35   CONST size_t namelen = strlen (name);
  36   CONST size_t vallen = strlen (value);
  37
  38   size = 0;
  39   for (ep = __environ; *ep != NULL; ++ep)
  40     if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  41       break;
  42     else
  43       ++size;
  44
  45   if (*ep == NULL)
  46     {
  47       static char **last_environ = NULL;
  48       char **new_environ = (char **) malloc((size + 2) * sizeof(char *));
  49       if (new_environ == NULL)
  50         return -1;
  51       (void) memcpy((PTR) new_environ, (PTR) __environ, size * sizeof(char *));
  52
  53       new_environ[size] = malloc (namelen + 1 + vallen + 1);
  54       if (new_environ[size] == NULL)
  55         {
  56           free (new_environ);
  57           errno = ENOMEM;
  58           return -1;
  59         }
  60       memcpy (new_environ[size], name, namelen);
  61       new_environ[size][namelen] = '=';
  62       memcpy (&new_environ[size][namelen + 1], value, vallen + 1);
  63
  64       new_environ[size + 1] = NULL;
  65
  66       if (last_environ != NULL)
  67         free ((PTR) last_environ);
  68       last_environ = new_environ;
  69       __environ = new_environ;
  70     }
  71   else if (replace)
  72     {
  73       size_t len = strlen (*ep);
  74       if (len < namelen + 1 + vallen)
  75         {
  76           char *new = malloc (namelen + 1 + vallen);
  77           if (new == NULL)
  78             return -1;
  79           *ep = new;
  80         }
  81       memcpy (*ep, name, namelen);
  82       (*ep)[namelen] = '=';
  83       memcpy (&(*ep)[namelen + 1], value, vallen + 1);
  84     }
  85
  86   return 0;
  87 }