1 /* $NetBSD: getenv.c,v 1.15 2000/12/19 21:17:37 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #if defined(LIBC_SCCS) && !defined(lint) 38 #if 0 39 static char sccsid[] = "@(#)getenv.c 8.1 (Berkeley) 6/4/93"; 40 #else 41 __RCSID("$NetBSD: getenv.c,v 1.15 2000/12/19 21:17:37 christos Exp $"); 42 #endif 43 #endif /* LIBC_SCCS and not lint */ 44 45 #include <assert.h> 46 #include <errno.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include "local.h" 50 #include "reentrant.h" 51 52 #ifdef _REENT 53 rwlock_t __environ_lock = RWLOCK_INITIALIZER; 54 #endif 55 extern char **environ; 56 57 /* 58 * getenv -- 59 * Returns ptr to value associated with name, if any, else NULL. 60 */ 61 char * 62 getenv(name) 63 const char *name; 64 { 65 int offset; 66 char *result; 67 68 _DIAGASSERT(name != NULL); 69 70 rwlock_rdlock(&__environ_lock); 71 result = __findenv(name, &offset); 72 rwlock_unlock(&__environ_lock); 73 return (result); 74 } 75 76 /* 77 * __findenv -- 78 * Returns pointer to value associated with name, if any, else NULL. 79 * Sets offset to be the offset of the name/value combination in the 80 * environmental array, for use by setenv(3) and unsetenv(3). 81 * Explicitly removes '=' in argument name. 82 * 83 * This routine *should* be a static; don't use it. 84 */ 85 char * 86 __findenv(name, offset) 87 const char *name; 88 int *offset; 89 { 90 size_t len; 91 const char *np; 92 char **p, *c; 93 94 if (name == NULL || environ == NULL) 95 return (NULL); 96 for (np = name; *np && *np != '='; ++np) 97 continue; 98 len = np - name; 99 for (p = environ; (c = *p) != NULL; ++p) 100 if (strncmp(c, name, len) == 0 && c[len] == '=') { 101 *offset = p - environ; 102 return (c + len + 1); 103 } 104 return (NULL); 105 } 106