gsasl  1.10.0
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unsetenv.c
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1 /* Copyright (C) 1992, 1995-2002, 2005-2021 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 <https://www.gnu.org/licenses/>. */
16 
17 /* Don't use __attribute__ __nonnull__ in this compilation unit. Otherwise gcc
18  optimizes away the name == NULL test below. */
19 #define _GL_ARG_NONNULL(params)
20 
21 #include <config.h>
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 
56 int
57 unsetenv (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
94 weak_alias (__unsetenv, unsetenv)
95 #endif
96 
97 #else /* HAVE_UNSETENV */
98 
99 # undef unsetenv
100 # if !HAVE_DECL_UNSETENV
101 # if VOID_UNSETENV
102 extern void unsetenv (const char *);
103 # else
104 extern 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. */
110 int
111 rpl_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 */
#define NULL
Definition: stddef.in.h:72
#define LOCK
Definition: unsetenv.c:45
int unsetenv(const char *name)
Definition: unsetenv.c:57
#define __environ
Definition: unsetenv.c:35
#define UNLOCK
Definition: unsetenv.c:46
#define __set_errno(ev)
Definition: unsetenv.c:28
const char * name
Definition: error.c:43
#define weak_alias(name, aliasname)
Definition: libc-config.h:179