1/* Copyright (C) 1992,1995-1999,2000-2002 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., 59 Temple Place - Suite 330, 17 Boston, MA 02111-1307, USA. */ 18 19#if HAVE_CONFIG_H 20# include <config.h> 21#endif 22 23#include <errno.h> 24#if !_LIBC 25# if !defined errno && !defined HAVE_ERRNO_DECL 26extern int errno; 27# endif 28# define __set_errno(ev) ((errno) = (ev)) 29#endif 30 31#include <stdlib.h> 32#include <string.h> 33#if _LIBC || HAVE_UNISTD_H 34# include <unistd.h> 35#endif 36 37#if !_LIBC 38# define __environ environ 39# ifndef HAVE_ENVIRON_DECL 40extern char **environ; 41# endif 42#endif 43 44#if _LIBC 45/* This lock protects against simultaneous modifications of `environ'. */ 46# include <bits/libc-lock.h> 47__libc_lock_define_initialized (static, envlock) 48# define LOCK __libc_lock_lock (envlock) 49# define UNLOCK __libc_lock_unlock (envlock) 50#else 51# define LOCK 52# define UNLOCK 53#endif 54 55/* In the GNU C library we must keep the namespace clean. */ 56#ifdef _LIBC 57# define unsetenv __unsetenv 58#endif 59 60 61int 62unsetenv (const char *name) 63{ 64 size_t len; 65 char **ep; 66 67 if (name == NULL || *name == '\0' || strchr (name, '=') != NULL) 68 { 69 __set_errno (EINVAL); 70 return -1; 71 } 72 73 len = strlen (name); 74 75 LOCK; 76 77 ep = __environ; 78 while (*ep != NULL) 79 if (!strncmp (*ep, name, len) && (*ep)[len] == '=') 80 { 81 /* Found it. Remove this pointer by moving later ones back. */ 82 char **dp = ep; 83 84 do 85 dp[0] = dp[1]; 86 while (*dp++); 87 /* Continue the loop in case NAME appears again. */ 88 } 89 else 90 ++ep; 91 92 UNLOCK; 93 94 return 0; 95} 96 97#ifdef _LIBC 98# undef unsetenv 99weak_alias (__unsetenv, unsetenv) 100#endif 101