putenv.c revision 75584 
1/* Copyright (C) 1991 Free Software Foundation, Inc.
2This file is part of the GNU C Library.
3
4The GNU C Library is free software; you can redistribute it and/or
5modify it under the terms of the GNU Library General Public License as
6published by the Free Software Foundation; either version 2 of the
7License, or (at your option) any later version.
8
9The GNU C Library is distributed in the hope that it will be useful,
10but WITHOUT ANY WARRANTY; without even the implied warranty of
11MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12Library General Public License for more details.
13
14You should have received a copy of the GNU Library General Public
15License along with the GNU C Library; see the file COPYING.LIB.  If
16not, write to the Free Software Foundation, Inc., 675 Mass Ave,
17Cambridge, MA 02139, USA.  */
18
19/* Hacked slightly by jjc@jclark.com for groff. */
20
21#include <string.h>
22
23#ifdef __STDC__
24#include <stddef.h>
25typedef void *PTR;
26typedef size_t SIZE_T;
27#else /* not __STDC__ */
28typedef char *PTR;
29typedef int SIZE_T;
30#endif /* not __STDC__ */
31
32#ifdef HAVE_STDLIB_H
33#include <stdlib.h>
34#else /* not HAVE_STDLIB_H */
35PTR malloc();
36#endif /* not HAVE_STDLIB_H */
37
38#ifndef NULL
39#define NULL 0
40#endif
41
42extern char **environ;
43
44/* Put STRING, which is of the form "NAME=VALUE", in the environment.  */
45
46int putenv(const char *string)
47{
48  char *name_end = strchr(string, '=');
49  SIZE_T size;
50  char **ep;
51
52  if (name_end == NULL)
53    {
54      /* Remove the variable from the environment.  */
55      size = strlen(string);
56      for (ep = environ; *ep != NULL; ++ep)
57	if (!strncmp(*ep, string, size) && (*ep)[size] == '=')
58	  {
59	    while (ep[1] != NULL)
60	      {
61		ep[0] = ep[1];
62		++ep;
63	      }
64	    *ep = NULL;
65	    return 0;
66	  }
67    }
68
69  size = 0;
70  for (ep = environ; *ep != NULL; ++ep)
71    if (!strncmp(*ep, string, name_end - string)
72	&& (*ep)[name_end - string] == '=')
73      break;
74    else
75      ++size;
76
77  if (*ep == NULL)
78    {
79      static char **last_environ = NULL;
80      char **new_environ = (char **) malloc((size + 2) * sizeof(char *));
81      if (new_environ == NULL)
82	return -1;
83      (void) memcpy((PTR) new_environ, (PTR) environ, size * sizeof(char *));
84      new_environ[size] = (char *) string;
85      new_environ[size + 1] = NULL;
86      if (last_environ != NULL)
87	free((PTR) last_environ);
88      last_environ = new_environ;
89      environ = new_environ;
90    }
91  else
92    *ep = (char *) string;
93
94  return 0;
95}
96