getenv.c revision 1.26
1 /* $NetBSD: getenv.c,v 1.26 2010/10/24 17:53:27 tron 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 1.26 2010/10/24 17:53:27 tron 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 char **saveenv; 54 static size_t environ_malloced_len; 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 char **p; 108 size_t required_len, new_len; 109 110 if (offset == -1 || saveenv != environ) { 111 char **ptr; 112 for (ptr = environ, offset = 0; *ptr != NULL; ptr++) 113 offset++; 114 } 115 116 /* one for potentially new entry one for NULL */ 117 required_len = offset + 2; 118 119 if (required_len <= environ_malloced_len && saveenv == environ) 120 return 0; 121 122 /* Make sure we at least double the size of the arrays. */ 123 new_len = (environ_malloced_len >= 16) ? 124 (environ_malloced_len << 1) : 16; 125 while (new_len < required_len) 126 new_len = new_len << 1; 127 128 if (saveenv == environ) { /* just increase size */ 129 if ((p = realloc(saveenv, new_len * sizeof(*p))) == NULL) 130 return -1; 131 (void)memset(&p[environ_malloced_len], 0, 132 (new_len - environ_malloced_len) * sizeof(*p)); 133 saveenv = p; 134 } else { /* get new space */ 135 free(saveenv); 136 if ((saveenv = malloc(new_len * sizeof(*saveenv))) == NULL) 137 return -1; 138 (void)memcpy(saveenv, environ, 139 (required_len - 2) * sizeof(*saveenv)); 140 (void)memset(&saveenv[required_len - 2], 0, 141 (new_len - (required_len - 2)) * sizeof(*saveenv)); 142 } 143 environ = saveenv; 144 145 p = realloc(__environ_malloced, new_len * sizeof(*p)); 146 if (p == NULL) 147 return -1; 148 149 (void)memset(&p[environ_malloced_len], 0, 150 (new_len - environ_malloced_len) * sizeof(*p)); 151 environ_malloced_len = new_len; 152 __environ_malloced = p; 153 154 return 0; 155 } 156 157 /* 158 * __findenv -- 159 * Returns pointer to value associated with name, if any, else NULL. 160 * Sets offset to be the offset of the name/value combination in the 161 * environmental array, for use by setenv(3) and unsetenv(3). 162 * Explicitly removes '=' in argument name. 163 * 164 * This routine *should* be a static; don't use it. 165 */ 166 char * 167 __findenv(const char *name, int *offset) 168 { 169 size_t len; 170 const char *np; 171 char **p, *c; 172 173 if (name == NULL || environ == NULL) 174 return NULL; 175 for (np = name; *np && *np != '='; ++np) 176 continue; 177 len = np - name; 178 for (p = environ; (c = *p) != NULL; ++p) 179 if (strncmp(c, name, len) == 0 && c[len] == '=') { 180 *offset = (int)(p - environ); 181 return c + len + 1; 182 } 183 *offset = (int)(p - environ); 184 return NULL; 185 } 186
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