1/* Copyright (C) 1991, 1994, 1997-1998, 2000, 2003-2010 Free Software
2   Foundation, Inc.
3
4   NOTE: The canonical source of this file is maintained with the GNU C
5   Library.  Bugs can be reported to bug-glibc@prep.ai.mit.edu.
6
7   This program is free software: you can redistribute it and/or modify it
8   under the terms of the GNU General Public License as published by the
9   Free Software Foundation; either version 3 of the License, or any
10   later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
19
20#include <config.h>
21
22/* Specification.  */
23#include <stdlib.h>
24
25#include <stddef.h>
26
27/* Include errno.h *after* sys/types.h to work around header problems
28   on AIX 3.2.5.  */
29#include <errno.h>
30#ifndef __set_errno
31# define __set_errno(ev) ((errno) = (ev))
32#endif
33
34#include <string.h>
35#include <unistd.h>
36
37#if HAVE_GNU_LD
38# define environ __environ
39#else
40extern char **environ;
41#endif
42
43#if _LIBC
44/* This lock protects against simultaneous modifications of `environ'.  */
45# include <bits/libc-lock.h>
46__libc_lock_define_initialized (static, envlock)
47# define LOCK   __libc_lock_lock (envlock)
48# define UNLOCK __libc_lock_unlock (envlock)
49#else
50# define LOCK
51# define UNLOCK
52#endif
53
54static int
55_unsetenv (const char *name)
56{
57  size_t len;
58  char **ep;
59
60  if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
61    {
62      __set_errno (EINVAL);
63      return -1;
64    }
65
66  len = strlen (name);
67
68  LOCK;
69
70  ep = environ;
71  while (*ep != NULL)
72    if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
73      {
74        /* Found it.  Remove this pointer by moving later ones back.  */
75        char **dp = ep;
76
77        do
78          dp[0] = dp[1];
79        while (*dp++);
80        /* Continue the loop in case NAME appears again.  */
81      }
82    else
83      ++ep;
84
85  UNLOCK;
86
87  return 0;
88}
89
90
91/* Put STRING, which is of the form "NAME=VALUE", in the environment.
92   If STRING contains no `=', then remove STRING from the environment.  */
93int
94putenv (char *string)
95{
96  const char *const name_end = strchr (string, '=');
97  register size_t size;
98  register char **ep;
99
100  if (name_end == NULL)
101    {
102      /* Remove the variable from the environment.  */
103      return _unsetenv (string);
104    }
105
106  size = 0;
107  for (ep = environ; *ep != NULL; ++ep)
108    if (!strncmp (*ep, string, name_end - string) &&
109        (*ep)[name_end - string] == '=')
110      break;
111    else
112      ++size;
113
114  if (*ep == NULL)
115    {
116      static char **last_environ = NULL;
117      char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
118      if (new_environ == NULL)
119        return -1;
120      (void) memcpy ((void *) new_environ, (void *) environ,
121                     size * sizeof (char *));
122      new_environ[size] = (char *) string;
123      new_environ[size + 1] = NULL;
124      free (last_environ);
125      last_environ = new_environ;
126      environ = new_environ;
127    }
128  else
129    *ep = string;
130
131  return 0;
132}
133