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