1 /* $NetBSD: unsetenv.c,v 1.10 2010/11/14 18:11:43 tron Exp $ */ 2 3 /* 4 * Copyright (c) 1987, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 #if 0 35 static char sccsid[] = "from: @(#)setenv.c 8.1 (Berkeley) 6/4/93"; 36 #else 37 __RCSID("$NetBSD: unsetenv.c,v 1.10 2010/11/14 18:11:43 tron Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include "namespace.h" 42 43 #include <assert.h> 44 #include <errno.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <bitstring.h> 48 49 #include "env.h" 50 #include "reentrant.h" 51 #include "local.h" 52 53 /* 54 * unsetenv(name) -- 55 * Delete environmental variable "name". 56 */ 57 int 58 unsetenv(const char *name) 59 { 60 size_t l_name; 61 ssize_t r_offset, w_offset; 62 63 _DIAGASSERT(name != NULL); 64 65 l_name = __envvarnamelen(name, false); 66 if (l_name == 0) { 67 errno = EINVAL; 68 return -1; 69 } 70 71 if (!__writelockenv()) 72 return -1; 73 74 /* Search for the given name in the environment. */ 75 r_offset = __getenvslot(name, l_name, false); 76 if (r_offset == -1) { 77 /* Not found. */ 78 (void)__unlockenv(); 79 return 0; 80 } 81 __freeenvvar(environ[r_offset]); 82 83 /* 84 * Remove all matches from the environment and free the associated 85 * memory if possible. 86 */ 87 w_offset = r_offset; 88 while (environ[++r_offset] != NULL) { 89 if (strncmp(environ[r_offset], name, l_name) != 0 || 90 environ[r_offset][l_name] != '=') { 91 /* Not a match, keep this entry. */ 92 environ[w_offset++] = environ[r_offset]; 93 } else { 94 /* We found another match. */ 95 __freeenvvar(environ[r_offset]); 96 } 97 } 98 99 /* Clear out remaining stale entries in the environment vector. */ 100 do { 101 environ[w_offset++] = NULL; 102 } while (w_offset < r_offset); 103 104 (void)__unlockenv(); 105 return 0; 106 } 107