1/* Copyright (C) 1992,1995-1999,2000-2002,2005-2006 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#include <errno.h> 20#if !_LIBC 21# define __set_errno(ev) ((errno) = (ev)) 22#endif 23 24#include <stdlib.h> 25#include <string.h> 26#include <unistd.h> 27 28#if !_LIBC 29# define __environ environ 30# ifndef HAVE_ENVIRON_DECL 31extern char **environ; 32# endif 33#endif 34 35#if _LIBC 36/* This lock protects against simultaneous modifications of `environ'. */ 37# include <bits/libc-lock.h> 38__libc_lock_define_initialized (static, envlock) 39# define LOCK __libc_lock_lock (envlock) 40# define UNLOCK __libc_lock_unlock (envlock) 41#else 42# define LOCK 43# define UNLOCK 44#endif 45 46/* In the GNU C library we must keep the namespace clean. */ 47#ifdef _LIBC 48# define unsetenv __unsetenv 49#endif 50 51 52int 53unsetenv (const char *name) 54{ 55 size_t len; 56 char **ep; 57 58 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL) 59 { 60 __set_errno (EINVAL); 61 return -1; 62 } 63 64 len = strlen (name); 65 66 LOCK; 67 68 ep = __environ; 69 while (*ep != NULL) 70 if (!strncmp (*ep, name, len) && (*ep)[len] == '=') 71 { 72 /* Found it. Remove this pointer by moving later ones back. */ 73 char **dp = ep; 74 75 do 76 dp[0] = dp[1]; 77 while (*dp++); 78 /* Continue the loop in case NAME appears again. */ 79 } 80 else 81 ++ep; 82 83 UNLOCK; 84 85 return 0; 86} 87 88#ifdef _LIBC 89# undef unsetenv 90weak_alias (__unsetenv, unsetenv) 91#endif 92