1 /* $NetBSD: getenv.c,v 1.18 2005/09/25 20:08:01 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[] = "@(#)getenv.c 8.1 (Berkeley) 6/4/93"; 36 #else 37 __RCSID("$NetBSD: getenv.c,v 1.18 2005/09/25 20:08:01 christos Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include "namespace.h" 42 #include <assert.h> 43 #include <errno.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include "local.h" 47 #include "reentrant.h" 48 49 #ifdef _REENTRANT 50 rwlock_t __environ_lock = RWLOCK_INITIALIZER; 51 #endif 52 extern char **environ; 53 54 __weak_alias(getenv_r, _getenv_r) 55 56 /* 57 * getenv -- 58 * Returns ptr to value associated with name, if any, else NULL. 59 * XXX: we cannot use getenv_r to implement this, because getenv() 60 * cannot use a shared buffer, because if it did, subsequent calls 61 * to getenv would trash previous results. 62 */ 63 char * 64 getenv(const char *name) 65 { 66 int offset; 67 char *result; 68 69 _DIAGASSERT(name != NULL); 70 71 rwlock_rdlock(&__environ_lock); 72 result = __findenv(name, &offset); 73 rwlock_unlock(&__environ_lock); 74 return result; 75 } 76 77 int 78 getenv_r(const char *name, char *buf, size_t len) 79 { 80 int offset; 81 char *result; 82 int rv = -1; 83 84 _DIAGASSERT(name != NULL); 85 86 rwlock_rdlock(&__environ_lock); 87 result = __findenv(name, &offset); 88 if (result == NULL) { 89 errno = ENOENT; 90 goto out; 91 } 92 if (strlcpy(buf, result, len) >= len) { 93 errno = ERANGE; 94 goto out; 95 } 96 rv = 0; 97 out: 98 rwlock_unlock(&__environ_lock); 99 return rv; 100 } 101 102 /* 103 * __findenv -- 104 * Returns pointer to value associated with name, if any, else NULL. 105 * Sets offset to be the offset of the name/value combination in the 106 * environmental array, for use by setenv(3) and unsetenv(3). 107 * Explicitly removes '=' in argument name. 108 * 109 * This routine *should* be a static; don't use it. 110 */ 111 char * 112 __findenv(const char *name, int *offset) 113 { 114 size_t len; 115 const char *np; 116 char **p, *c; 117 118 if (name == NULL || environ == NULL) 119 return NULL; 120 for (np = name; *np && *np != '='; ++np) 121 continue; 122 len = np - name; 123 for (p = environ; (c = *p) != NULL; ++p) 124 if (strncmp(c, name, len) == 0 && c[len] == '=') { 125 *offset = p - environ; 126 return c + len + 1; 127 } 128 return NULL; 129 } 130