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 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Library General Public License as 6 published by the Free Software Foundation; either version 2 of the 7 License, or (at your option) any later version. 8 9 The GNU C Library 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 GNU 12 Library General Public License for more details. 13 14 You should have received a copy of the GNU Library General Public 15 License along with the GNU C Library; see the file COPYING.LIB. If not, 16 write to the Free Software Foundation, Inc., 51 Franklin Street, 17 Fifth Floor, Boston, MA 02110-1301, USA. */ 18 19#ifdef HAVE_CONFIG_H 20# include <config.h> 21#endif 22 23#include <errno.h> 24#if !_LIBC 25# define __set_errno(ev) ((errno) = (ev)) 26#endif 27 28#include <stdlib.h> 29#include <string.h> 30#include <unistd.h> 31 32#if !_LIBC 33# define __environ environ 34# ifndef HAVE_ENVIRON_DECL 35extern char **environ; 36# endif 37#endif 38 39#if _LIBC 40/* This lock protects against simultaneous modifications of `environ'. */ 41# include <bits/libc-lock.h> 42__libc_lock_define_initialized (static, envlock) 43# define LOCK __libc_lock_lock (envlock) 44# define UNLOCK __libc_lock_unlock (envlock) 45#else 46# define LOCK 47# define UNLOCK 48#endif 49 50/* In the GNU C library we must keep the namespace clean. */ 51#ifdef _LIBC 52# define unsetenv __unsetenv 53#endif 54 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