compilers/linux86-0.16.17/libc/misc/setenv.c

   1 /* Copyright (C) 1992, 1995 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.  */
   3
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include <unistd.h>
   7 #include <errno.h>
   8
   9 extern char ** environ;
  10
  11 int
  12 setenv(name, value, replace)
  13 __const char *name;
  14 __const char *value;
  15 int replace;
  16 {
  17   register char **ep;
  18   register size_t size;
  19   __const size_t namelen = strlen (name);
  20   __const size_t vallen = strlen (value);
  21   int result = 0;
  22
  23   size = 0;
  24   for (ep = environ; *ep != NULL; ++ep)
  25     if (!memcmp (*ep, name, namelen) && (*ep)[namelen] == '=')
  26       break;
  27     else
  28       ++size;
  29
  30   if (*ep == NULL)
  31     {
  32       static char **last_environ = NULL;
  33       char **new_environ = (char **) malloc((size + 2) * sizeof(char *));
  34       if (new_environ == NULL)
  35         {
  36           result = -1;
  37           goto do_return;
  38         }
  39       (void) memcpy((void*) new_environ, (void*) environ, size * sizeof(char *));
  40
  41       new_environ[size] = malloc (namelen + 1 + vallen + 1);
  42       if (new_environ[size] == NULL)
  43         {
  44           free (new_environ);
  45           errno = ENOMEM;
  46           result = -1;
  47           goto do_return;
  48         }
  49       memcpy (new_environ[size], name, namelen);
  50       new_environ[size][namelen] = '=';
  51       memcpy (&new_environ[size][namelen + 1], value, vallen + 1);
  52
  53       new_environ[size + 1] = NULL;
  54
  55       if (last_environ != NULL)
  56         free ((void*) last_environ);
  57       last_environ = new_environ;
  58       environ = new_environ;
  59     }
  60   else if (replace)
  61     {
  62       size_t len = strlen (*ep);
  63       if (len < namelen + 1 + vallen)
  64         {
  65           char *new = malloc (namelen + 1 + vallen + 1);
  66           if (new == NULL)
  67             {
  68               result = -1;
  69               goto do_return;
  70             }
  71           *ep = new;
  72         }
  73       memcpy (*ep, name, namelen);
  74       (*ep)[namelen] = '=';
  75       memcpy (&(*ep)[namelen + 1], value, vallen + 1);
  76     }
  77
  78 do_return:
  79   return result;
  80 }
  81
  82 void
  83 unsetenv(name)
  84 __const char *name;
  85 {
  86   register char **ep;
  87   register char **dp;
  88   __const size_t namelen = strlen (name);
  89
  90   for (dp = ep = environ; *ep != NULL; ++ep)
  91     if (memcmp (*ep, name, namelen) || (*ep)[namelen] != '=')
  92       {
  93         *dp = *ep;
  94         ++dp;
  95       }
  96   *dp = NULL;
  97 }