1 /* $NetBSD: getenv.c,v 1.20 2010/09/23 17:30:49 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 1.20 2010/09/23 17:30:49 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 <bitstring.h> 47 #include "reentrant.h" 48 #include "local.h" 49 50 #ifdef _REENTRANT 51 rwlock_t __environ_lock = RWLOCK_INITIALIZER; 52 #endif 53 bitstr_t *__environ_malloced; 54 static size_t environ_bitlen; 55 56 __weak_alias(getenv_r, _getenv_r) 57 58 /* 59 * getenv -- 60 * Returns ptr to value associated with name, if any, else NULL. 61 * XXX: we cannot use getenv_r to implement this, because getenv() 62 * cannot use a shared buffer, because if it did, subsequent calls 63 * to getenv would trash previous results. 64 */ 65 char * 66 getenv(const char *name) 67 { 68 int offset; 69 char *result; 70 71 _DIAGASSERT(name != NULL); 72 73 rwlock_rdlock(&__environ_lock); 74 result = __findenv(name, &offset); 75 rwlock_unlock(&__environ_lock); 76 return result; 77 } 78 79 int 80 getenv_r(const char *name, char *buf, size_t len) 81 { 82 int offset; 83 char *result; 84 int rv = -1; 85 86 _DIAGASSERT(name != NULL); 87 88 rwlock_rdlock(&__environ_lock); 89 result = __findenv(name, &offset); 90 if (result == NULL) { 91 errno = ENOENT; 92 goto out; 93 } 94 if (strlcpy(buf, result, len) >= len) { 95 errno = ERANGE; 96 goto out; 97 } 98 rv = 0; 99 out: 100 rwlock_unlock(&__environ_lock); 101 return rv; 102 } 103 104 int 105 __allocenv(int offset) 106 { 107 bitstr_t *s; 108 size_t nl; 109 110 if (offset == -1) { 111 char **ptr; 112 for (ptr = environ, offset = 0; *ptr; ptr++) 113 offset++; 114 } 115 nl = bitstr_size(offset + 2); 116 if (__environ_malloced == NULL) { 117 s = malloc(nl); 118 } else if (environ_bitlen < nl) 119 s = realloc(__environ_malloced, nl); 120 else 121 return 0; 122 123 if (s == NULL) 124 return -1; 125 126 (void)memset(&s[environ_bitlen], 0, nl - environ_bitlen); 127 environ_bitlen = nl; 128 __environ_malloced = s; 129 130 return 0; 131 } 132 133 /* 134 * __findenv -- 135 * Returns pointer to value associated with name, if any, else NULL. 136 * Sets offset to be the offset of the name/value combination in the 137 * environmental array, for use by setenv(3) and unsetenv(3). 138 * Explicitly removes '=' in argument name. 139 * 140 * This routine *should* be a static; don't use it. 141 */ 142 char * 143 __findenv(const char *name, int *offset) 144 { 145 size_t len; 146 const char *np; 147 char **p, *c; 148 149 if (name == NULL || environ == NULL) 150 return NULL; 151 for (np = name; *np && *np != '='; ++np) 152 continue; 153 len = np - name; 154 for (p = environ; (c = *p) != NULL; ++p) 155 if (strncmp(c, name, len) == 0 && c[len] == '=') { 156 *offset = p - environ; 157 return c + len + 1; 158 } 159 *offset = p - environ; 160 return NULL; 161 } 162