1 /* $NetBSD: getcwd.c,v 1.36 2005/01/30 22:37:32 enami Exp $ */ 2 3 /* 4 * Copyright (c) 1989, 1991, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Jan-Simon Pendry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)getcwd.c 8.5 (Berkeley) 2/7/95"; 39 #else 40 __RCSID("$NetBSD: getcwd.c,v 1.36 2005/01/30 22:37:32 enami Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/param.h> 46 #include <sys/stat.h> 47 48 #include <assert.h> 49 #include <errno.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 54 #include "extern.h" 55 56 #ifdef __weak_alias 57 __weak_alias(getcwd,_getcwd) 58 __weak_alias(realpath,_realpath) 59 #endif 60 61 /* 62 * char *realpath(const char *path, char resolved[MAXPATHLEN]); 63 * 64 * Find the real name of path, by removing all ".", ".." and symlink 65 * components. Returns (resolved) on success, or (NULL) on failure, 66 * in which case the path which caused trouble is left in (resolved). 67 */ 68 char * 69 realpath(const char *path, char *resolved) 70 { 71 struct stat sb; 72 int idx = 0, n, nlnk = 0, serrno = errno; 73 const char *q; 74 char *p, wbuf[2][MAXPATHLEN]; 75 size_t len; 76 77 _DIAGASSERT(path != NULL); 78 _DIAGASSERT(resolved != NULL); 79 80 /* 81 * Build real path one by one with paying an attention to ., 82 * .. and symbolic link. 83 */ 84 85 /* 86 * `p' is where we'll put a new component with prepending 87 * a delimiter. 88 */ 89 p = resolved; 90 91 if (*path == 0) { 92 *p = 0; 93 errno = ENOENT; 94 return (NULL); 95 } 96 97 /* If relative path, start from current working directory. */ 98 if (*path != '/') { 99 if (getcwd(resolved, MAXPATHLEN) == NULL) { 100 p[0] = '.'; 101 p[1] = 0; 102 return (NULL); 103 } 104 len = strlen(resolved); 105 if (len > 1) 106 p += len; 107 } 108 109 loop: 110 /* Skip any slash. */ 111 while (*path == '/') 112 path++; 113 114 if (*path == 0) { 115 if (p == resolved) 116 *p++ = '/'; 117 *p = 0; 118 return (resolved); 119 } 120 121 /* Find the end of this component. */ 122 q = path; 123 do 124 q++; 125 while (*q != '/' && *q != 0); 126 127 /* Test . or .. */ 128 if (path[0] == '.') { 129 if (q - path == 1) { 130 path = q; 131 goto loop; 132 } 133 if (path[1] == '.' && q - path == 2) { 134 /* Trim the last component. */ 135 if (p != resolved) 136 while (*--p != '/') 137 ; 138 path = q; 139 goto loop; 140 } 141 } 142 143 /* Append this component. */ 144 if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) { 145 errno = ENAMETOOLONG; 146 if (p == resolved) 147 *p++ = '/'; 148 *p = 0; 149 return (NULL); 150 } 151 p[0] = '/'; 152 memcpy(&p[1], path, 153 /* LINTED We know q > path. */ 154 q - path); 155 p[1 + q - path] = 0; 156 157 /* 158 * If this component is a symlink, toss it and prepend link 159 * target to unresolved path. 160 */ 161 if (lstat(resolved, &sb) == -1) { 162 /* Allow nonexistent component if this is the last one. */ 163 if (*q == 0 && errno == ENOENT) { 164 errno = serrno; 165 return (resolved); 166 } 167 return (NULL); 168 } 169 if (S_ISLNK(sb.st_mode)) { 170 if (nlnk++ >= MAXSYMLINKS) { 171 errno = ELOOP; 172 return (NULL); 173 } 174 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1); 175 if (n < 0) 176 return (NULL); 177 if (n == 0) { 178 errno = ENOENT; 179 return (NULL); 180 } 181 182 /* Append unresolved path to link target and switch to it. */ 183 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) { 184 errno = ENAMETOOLONG; 185 return (NULL); 186 } 187 memcpy(&wbuf[idx][n], q, len + 1); 188 path = wbuf[idx]; 189 idx ^= 1; 190 191 /* If absolute symlink, start from root. */ 192 if (*path == '/') 193 p = resolved; 194 goto loop; 195 } 196 197 /* Advance both resolved and unresolved path. */ 198 p += 1 + q - path; 199 path = q; 200 goto loop; 201 } 202 203 char * 204 getcwd(char *pt, size_t size) 205 { 206 char *npt; 207 208 /* 209 * If a buffer is specified, the size has to be non-zero. 210 */ 211 if (pt != NULL) { 212 if (size == 0) { 213 /* __getcwd(pt, 0) results ERANGE. */ 214 errno = EINVAL; 215 return (NULL); 216 } 217 if (__getcwd(pt, size) >= 0) 218 return (pt); 219 return (NULL); 220 } 221 222 /* 223 * If no buffer specified by the user, allocate one as necessary. 224 */ 225 size = 1024 >> 1; 226 do { 227 if ((npt = realloc(pt, size <<= 1)) == NULL) 228 break; 229 pt = npt; 230 if (__getcwd(pt, size) >= 0) 231 return (pt); 232 } while (size <= MAXPATHLEN * 4 && errno == ERANGE); 233 234 free(pt); 235 return (NULL); 236 } 237