1 /* $NetBSD: getcwd.c,v 1.46 2010/01/01 19:59:21 dholland 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 1.46 2010/01/01 19:59:21 dholland 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; 73 const char *q; 74 char *p, wbuf[2][MAXPATHLEN]; 75 size_t len; 76 77 _DIAGASSERT(resolved != NULL); 78 79 /* POSIX sez we must test for this */ 80 if (path == NULL) { 81 errno = EINVAL; 82 return NULL; 83 } 84 85 /* 86 * Build real path one by one with paying an attention to ., 87 * .. and symbolic link. 88 */ 89 90 /* 91 * `p' is where we'll put a new component with prepending 92 * a delimiter. 93 */ 94 p = resolved; 95 96 if (*path == 0) { 97 *p = 0; 98 errno = ENOENT; 99 return (NULL); 100 } 101 102 /* If relative path, start from current working directory. */ 103 if (*path != '/') { 104 /* check for resolved pointer to appease coverity */ 105 if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) { 106 p[0] = '.'; 107 p[1] = 0; 108 return (NULL); 109 } 110 len = strlen(resolved); 111 if (len > 1) 112 p += len; 113 } 114 115 loop: 116 /* Skip any slash. */ 117 while (*path == '/') 118 path++; 119 120 if (*path == 0) { 121 if (p == resolved) 122 *p++ = '/'; 123 *p = 0; 124 return (resolved); 125 } 126 127 /* Find the end of this component. */ 128 q = path; 129 do 130 q++; 131 while (*q != '/' && *q != 0); 132 133 /* Test . or .. */ 134 if (path[0] == '.') { 135 if (q - path == 1) { 136 path = q; 137 goto loop; 138 } 139 if (path[1] == '.' && q - path == 2) { 140 /* Trim the last component. */ 141 if (p != resolved) 142 while (*--p != '/') 143 ; 144 path = q; 145 goto loop; 146 } 147 } 148 149 /* Append this component. */ 150 if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) { 151 errno = ENAMETOOLONG; 152 if (p == resolved) 153 *p++ = '/'; 154 *p = 0; 155 return (NULL); 156 } 157 p[0] = '/'; 158 memcpy(&p[1], path, 159 /* LINTED We know q > path. */ 160 q - path); 161 p[1 + q - path] = 0; 162 163 /* 164 * If this component is a symlink, toss it and prepend link 165 * target to unresolved path. 166 */ 167 if (lstat(resolved, &sb) == -1) { 168 return (NULL); 169 } 170 if (S_ISLNK(sb.st_mode)) { 171 if (nlnk++ >= MAXSYMLINKS) { 172 errno = ELOOP; 173 return (NULL); 174 } 175 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1); 176 if (n < 0) 177 return (NULL); 178 if (n == 0) { 179 errno = ENOENT; 180 return (NULL); 181 } 182 183 /* Append unresolved path to link target and switch to it. */ 184 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) { 185 errno = ENAMETOOLONG; 186 return (NULL); 187 } 188 memcpy(&wbuf[idx][n], q, len + 1); 189 path = wbuf[idx]; 190 idx ^= 1; 191 192 /* If absolute symlink, start from root. */ 193 if (*path == '/') 194 p = resolved; 195 goto loop; 196 } 197 if (*q == '/' && !S_ISDIR(sb.st_mode)) { 198 errno = ENOTDIR; 199 return (NULL); 200 } 201 202 /* Advance both resolved and unresolved path. */ 203 p += 1 + q - path; 204 path = q; 205 goto loop; 206 } 207 208 209 #if defined(_FORTIFY_SOURCE) && !defined(__lint__) 210 #undef getcwd 211 #define getcwd _getcwd 212 #endif 213 214 char * 215 getcwd(char *pt, size_t size) 216 { 217 char *npt; 218 219 /* 220 * If a buffer is specified, the size has to be non-zero. 221 */ 222 if (pt != NULL) { 223 if (size == 0) { 224 /* __getcwd(pt, 0) results ERANGE. */ 225 errno = EINVAL; 226 return (NULL); 227 } 228 if (__getcwd(pt, size) >= 0) 229 return (pt); 230 return (NULL); 231 } 232 233 /* 234 * If no buffer specified by the user, allocate one as necessary. 235 */ 236 size = 1024 >> 1; 237 do { 238 if ((npt = realloc(pt, size <<= 1)) == NULL) 239 break; 240 pt = npt; 241 if (__getcwd(pt, size) >= 0) 242 return (pt); 243 } while (size <= MAXPATHLEN * 4 && errno == ERANGE); 244 245 free(pt); 246 return (NULL); 247 } 248