1 /* Copyright (C) 1992,1995-1999,2000-2002 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 2, or (at your option) 7 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 along 15 with this program; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 17 #include <sys/cdefs.h> 18 __RCSID("$NetBSD: unsetenv.c,v 1.2 2016/05/17 14:00:09 christos Exp $"); 19 20 21 #if HAVE_CONFIG_H 22 # include <config.h> 23 #endif 24 25 #include <errno.h> 26 #if !_LIBC 27 # if !defined errno && !defined HAVE_ERRNO_DECL 28 extern int errno; 29 # endif 30 # define __set_errno(ev) ((errno) = (ev)) 31 #endif 32 33 #include <stdlib.h> 34 #include <string.h> 35 #if _LIBC || HAVE_UNISTD_H 36 # include <unistd.h> 37 #endif 38 39 #if !_LIBC 40 # define __environ environ 41 # ifndef HAVE_ENVIRON_DECL 42 extern char **environ; 43 # endif 44 #endif 45 46 #if _LIBC 47 /* This lock protects against simultaneous modifications of `environ'. */ 48 # include <bits/libc-lock.h> 49 __libc_lock_define_initialized (static, envlock) 50 # define LOCK __libc_lock_lock (envlock) 51 # define UNLOCK __libc_lock_unlock (envlock) 52 #else 53 # define LOCK 54 # define UNLOCK 55 #endif 56 57 /* In the GNU C library we must keep the namespace clean. */ 58 #ifdef _LIBC 59 # define unsetenv __unsetenv 60 #endif 61 62 63 int 64 unsetenv (const char *name) 65 { 66 size_t len; 67 char **ep; 68 69 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL) 70 { 71 __set_errno (EINVAL); 72 return -1; 73 } 74 75 len = strlen (name); 76 77 LOCK; 78 79 ep = __environ; 80 while (*ep != NULL) 81 if (!strncmp (*ep, name, len) && (*ep)[len] == '=') 82 { 83 /* Found it. Remove this pointer by moving later ones back. */ 84 char **dp = ep; 85 86 do 87 dp[0] = dp[1]; 88 while (*dp++); 89 /* Continue the loop in case NAME appears again. */ 90 } 91 else 92 ++ep; 93 94 UNLOCK; 95 96 return 0; 97 } 98 99 #ifdef _LIBC 100 # undef unsetenv 101 weak_alias (__unsetenv, unsetenv) 102 #endif 103