1 /* $NetBSD: unsetenv.c,v 1.11 2015/01/20 18:31:25 christos 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 1.11 2015/01/20 18:31:25 christos 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 "local.h" 51 52 /* 53 * unsetenv(name) -- 54 * Delete environmental variable "name". 55 */ 56 int 57 unsetenv(const char *name) 58 { 59 size_t l_name; 60 ssize_t r_offset, w_offset; 61 62 _DIAGASSERT(name != NULL); 63 64 l_name = __envvarnamelen(name, false); 65 if (l_name == 0) { 66 errno = EINVAL; 67 return -1; 68 } 69 70 if (!__writelockenv()) 71 return -1; 72 73 /* Search for the given name in the environment. */ 74 r_offset = __getenvslot(name, l_name, false); 75 if (r_offset == -1) { 76 /* Not found. */ 77 (void)__unlockenv(); 78 return 0; 79 } 80 __freeenvvar(environ[r_offset]); 81 82 /* 83 * Remove all matches from the environment and free the associated 84 * memory if possible. 85 */ 86 w_offset = r_offset; 87 while (environ[++r_offset] != NULL) { 88 if (strncmp(environ[r_offset], name, l_name) != 0 || 89 environ[r_offset][l_name] != '=') { 90 /* Not a match, keep this entry. */ 91 environ[w_offset++] = environ[r_offset]; 92 } else { 93 /* We found another match. */ 94 __freeenvvar(environ[r_offset]); 95 } 96 } 97 98 /* Clear out remaining stale entries in the environment vector. */ 99 do { 100 environ[w_offset++] = NULL; 101 } while (w_offset < r_offset); 102 103 (void)__unlockenv(); 104 return 0; 105 } 106