1/* Copyright (C) 1992, 1995-2002, 2005-2012 Free Software Foundation, Inc.
2   This file is part of the GNU C Library.
3
4   This program is free software: you can redistribute it and/or modify
5   it under the terms of the GNU General Public License as published by
6   the Free Software Foundation; either version 3 of the License, or
7   (at your option) any later version.
8
9   This program 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
12   GNU General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
16
17#include <config.h>
18
19/* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
20   optimizes away the name == NULL test below.  */
21#define _GL_ARG_NONNULL(params)
22
23/* Specification.  */
24#include <stdlib.h>
25
26#include <errno.h>
27#if !_LIBC
28# define __set_errno(ev) ((errno) = (ev))
29#endif
30
31#include <string.h>
32#include <unistd.h>
33
34#if !_LIBC
35# define __environ      environ
36#endif
37
38#if _LIBC
39/* This lock protects against simultaneous modifications of 'environ'.  */
40# include <bits/libc-lock.h>
41__libc_lock_define_initialized (static, envlock)
42# define LOCK   __libc_lock_lock (envlock)
43# define UNLOCK __libc_lock_unlock (envlock)
44#else
45# define LOCK
46# define UNLOCK
47#endif
48
49/* In the GNU C library we must keep the namespace clean.  */
50#ifdef _LIBC
51# define unsetenv __unsetenv
52#endif
53
54#if _LIBC || !HAVE_UNSETENV
55
56int
57unsetenv (const char *name)
58{
59  size_t len;
60  char **ep;
61
62  if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
63    {
64      __set_errno (EINVAL);
65      return -1;
66    }
67
68  len = strlen (name);
69
70  LOCK;
71
72  ep = __environ;
73  while (*ep != NULL)
74    if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
75      {
76        /* Found it.  Remove this pointer by moving later ones back.  */
77        char **dp = ep;
78
79        do
80          dp[0] = dp[1];
81        while (*dp++);
82        /* Continue the loop in case NAME appears again.  */
83      }
84    else
85      ++ep;
86
87  UNLOCK;
88
89  return 0;
90}
91
92#ifdef _LIBC
93# undef unsetenv
94weak_alias (__unsetenv, unsetenv)
95#endif
96
97#else /* HAVE_UNSETENV */
98
99# undef unsetenv
100# if !HAVE_DECL_UNSETENV
101#  if VOID_UNSETENV
102extern void unsetenv (const char *);
103#  else
104extern int unsetenv (const char *);
105#  endif
106# endif
107
108/* Call the underlying unsetenv, in case there is hidden bookkeeping
109   that needs updating beyond just modifying environ.  */
110int
111rpl_unsetenv (const char *name)
112{
113  int result = 0;
114  if (!name || !*name || strchr (name, '='))
115    {
116      errno = EINVAL;
117      return -1;
118    }
119  while (getenv (name))
120# if !VOID_UNSETENV
121    result =
122# endif
123      unsetenv (name);
124  return result;
125}
126
127#endif /* HAVE_UNSETENV */
128