1 /* $NetBSD: getenv.c,v 1.17 2003/08/07 16:43:39 agc 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[] = "@(#)getenv.c 8.1 (Berkeley) 6/4/93"; 36 #else 37 __RCSID("$NetBSD: getenv.c,v 1.17 2003/08/07 16:43:39 agc Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include <assert.h> 42 #include <errno.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include "local.h" 46 #include "reentrant.h" 47 48 #ifdef _REENTRANT 49 rwlock_t __environ_lock = RWLOCK_INITIALIZER; 50 #endif 51 extern char **environ; 52 53 /* 54 * getenv -- 55 * Returns ptr to value associated with name, if any, else NULL. 56 */ 57 char * 58 getenv(name) 59 const char *name; 60 { 61 int offset; 62 char *result; 63 64 _DIAGASSERT(name != NULL); 65 66 rwlock_rdlock(&__environ_lock); 67 result = __findenv(name, &offset); 68 rwlock_unlock(&__environ_lock); 69 return (result); 70 } 71 72 /* 73 * __findenv -- 74 * Returns pointer to value associated with name, if any, else NULL. 75 * Sets offset to be the offset of the name/value combination in the 76 * environmental array, for use by setenv(3) and unsetenv(3). 77 * Explicitly removes '=' in argument name. 78 * 79 * This routine *should* be a static; don't use it. 80 */ 81 char * 82 __findenv(name, offset) 83 const char *name; 84 int *offset; 85 { 86 size_t len; 87 const char *np; 88 char **p, *c; 89 90 if (name == NULL || environ == NULL) 91 return (NULL); 92 for (np = name; *np && *np != '='; ++np) 93 continue; 94 len = np - name; 95 for (p = environ; (c = *p) != NULL; ++p) 96 if (strncmp(c, name, len) == 0 && c[len] == '=') { 97 *offset = p - environ; 98 return (c + len + 1); 99 } 100 return (NULL); 101 } 102