1 /* $NetBSD: getenv.c,v 1.22 2010/09/25 19:31:51 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 1.22 2010/09/25 19:31:51 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 "reentrant.h" 47 #include "local.h" 48 49 #ifdef _REENTRANT 50 rwlock_t __environ_lock = RWLOCK_INITIALIZER; 51 #endif 52 char **__environ_malloced; 53 static size_t environ_malloced_len; 54 55 __weak_alias(getenv_r, _getenv_r) 56 57 /* 58 * getenv -- 59 * Returns ptr to value associated with name, if any, else NULL. 60 * XXX: we cannot use getenv_r to implement this, because getenv() 61 * cannot use a shared buffer, because if it did, subsequent calls 62 * to getenv would trash previous results. 63 */ 64 char * 65 getenv(const char *name) 66 { 67 int offset; 68 char *result; 69 70 _DIAGASSERT(name != NULL); 71 72 rwlock_rdlock(&__environ_lock); 73 result = __findenv(name, &offset); 74 rwlock_unlock(&__environ_lock); 75 return result; 76 } 77 78 int 79 getenv_r(const char *name, char *buf, size_t len) 80 { 81 int offset; 82 char *result; 83 int rv = -1; 84 85 _DIAGASSERT(name != NULL); 86 87 rwlock_rdlock(&__environ_lock); 88 result = __findenv(name, &offset); 89 if (result == NULL) { 90 errno = ENOENT; 91 goto out; 92 } 93 if (strlcpy(buf, result, len) >= len) { 94 errno = ERANGE; 95 goto out; 96 } 97 rv = 0; 98 out: 99 rwlock_unlock(&__environ_lock); 100 return rv; 101 } 102 103 int 104 __allocenv(int offset) 105 { 106 char **p; 107 size_t nl; 108 109 if (offset == -1) { 110 char **ptr; 111 for (ptr = environ, offset = 0; *ptr != NULL; ptr++) 112 offset++; 113 } 114 115 nl = offset + 2; /* one for potentially new entry one for NULL */ 116 if (nl < environ_malloced_len) 117 return 0; 118 119 p = realloc(__environ_malloced, nl * sizeof(*p)); 120 if (p == NULL) 121 return -1; 122 123 (void)memset(&p[environ_malloced_len], 0, 124 (nl - environ_malloced_len) * sizeof(*p)); 125 environ_malloced_len = nl; 126 __environ_malloced = p; 127 128 return 0; 129 } 130 131 /* 132 * __findenv -- 133 * Returns pointer to value associated with name, if any, else NULL. 134 * Sets offset to be the offset of the name/value combination in the 135 * environmental array, for use by setenv(3) and unsetenv(3). 136 * Explicitly removes '=' in argument name. 137 * 138 * This routine *should* be a static; don't use it. 139 */ 140 char * 141 __findenv(const char *name, int *offset) 142 { 143 size_t len; 144 const char *np; 145 char **p, *c; 146 147 if (name == NULL || environ == NULL) 148 return NULL; 149 for (np = name; *np && *np != '='; ++np) 150 continue; 151 len = np - name; 152 for (p = environ; (c = *p) != NULL; ++p) 153 if (strncmp(c, name, len) == 0 && c[len] == '=') { 154 *offset = p - environ; 155 return c + len + 1; 156 } 157 *offset = p - environ; 158 return NULL; 159 } 160