1 /* $NetBSD: getcwd.c,v 1.49 2011/02/16 20:20:25 tron 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 1.49 2011/02/16 20:20:25 tron 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,_sys_getcwd) 58 __weak_alias(_getcwd,_sys_getcwd) 59 __weak_alias(realpath,_realpath) 60 61 #if !defined(lint) 62 #undef getcwd 63 #define getcwd _sys_getcwd 64 #if !defined(_FORTIFY_SOURCE) 65 char *_sys_getcwd(char *, size_t); 66 #endif 67 68 #endif 69 #endif 70 71 /* 72 * char *realpath(const char *path, char resolved[MAXPATHLEN]); 73 * 74 * Find the real name of path, by removing all ".", ".." and symlink 75 * components. Returns (resolved) on success, or (NULL) on failure, 76 * in which case the path which caused trouble is left in (resolved). 77 */ 78 char * 79 realpath(const char *path, char *resolved) 80 { 81 struct stat sb; 82 int idx = 0, n, nlnk = 0; 83 const char *q; 84 char *p, wbuf[2][MAXPATHLEN]; 85 size_t len; 86 87 _DIAGASSERT(resolved != NULL); 88 89 /* POSIX sez we must test for this */ 90 if (path == NULL) { 91 errno = EINVAL; 92 return NULL; 93 } 94 95 /* 96 * Build real path one by one with paying an attention to ., 97 * .. and symbolic link. 98 */ 99 100 /* 101 * `p' is where we'll put a new component with prepending 102 * a delimiter. 103 */ 104 p = resolved; 105 106 if (*path == 0) { 107 *p = 0; 108 errno = ENOENT; 109 return (NULL); 110 } 111 112 /* If relative path, start from current working directory. */ 113 if (*path != '/') { 114 /* check for resolved pointer to appease coverity */ 115 if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) { 116 p[0] = '.'; 117 p[1] = 0; 118 return (NULL); 119 } 120 len = strlen(resolved); 121 if (len > 1) 122 p += len; 123 } 124 125 loop: 126 /* Skip any slash. */ 127 while (*path == '/') 128 path++; 129 130 if (*path == 0) { 131 if (p == resolved) 132 *p++ = '/'; 133 *p = 0; 134 return (resolved); 135 } 136 137 /* Find the end of this component. */ 138 q = path; 139 do 140 q++; 141 while (*q != '/' && *q != 0); 142 143 /* Test . or .. */ 144 if (path[0] == '.') { 145 if (q - path == 1) { 146 path = q; 147 goto loop; 148 } 149 if (path[1] == '.' && q - path == 2) { 150 /* Trim the last component. */ 151 if (p != resolved) 152 while (*--p != '/') 153 ; 154 path = q; 155 goto loop; 156 } 157 } 158 159 /* Append this component. */ 160 if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) { 161 errno = ENAMETOOLONG; 162 if (p == resolved) 163 *p++ = '/'; 164 *p = 0; 165 return (NULL); 166 } 167 p[0] = '/'; 168 memcpy(&p[1], path, 169 /* LINTED We know q > path. */ 170 q - path); 171 p[1 + q - path] = 0; 172 173 /* 174 * If this component is a symlink, toss it and prepend link 175 * target to unresolved path. 176 */ 177 if (lstat(resolved, &sb) == -1) { 178 return (NULL); 179 } 180 if (S_ISLNK(sb.st_mode)) { 181 if (nlnk++ >= MAXSYMLINKS) { 182 errno = ELOOP; 183 return (NULL); 184 } 185 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1); 186 if (n < 0) 187 return (NULL); 188 if (n == 0) { 189 errno = ENOENT; 190 return (NULL); 191 } 192 193 /* Append unresolved path to link target and switch to it. */ 194 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) { 195 errno = ENAMETOOLONG; 196 return (NULL); 197 } 198 memcpy(&wbuf[idx][n], q, len + 1); 199 path = wbuf[idx]; 200 idx ^= 1; 201 202 /* If absolute symlink, start from root. */ 203 if (*path == '/') 204 p = resolved; 205 goto loop; 206 } 207 if (*q == '/' && !S_ISDIR(sb.st_mode)) { 208 errno = ENOTDIR; 209 return (NULL); 210 } 211 212 /* Advance both resolved and unresolved path. */ 213 p += 1 + q - path; 214 path = q; 215 goto loop; 216 } 217 218 char * 219 getcwd(char *pt, size_t size) 220 { 221 char *npt; 222 223 /* 224 * If a buffer is specified, the size has to be non-zero. 225 */ 226 if (pt != NULL) { 227 if (size == 0) { 228 /* __getcwd(pt, 0) results ERANGE. */ 229 errno = EINVAL; 230 return (NULL); 231 } 232 if (__getcwd(pt, size) >= 0) 233 return (pt); 234 return (NULL); 235 } 236 237 /* 238 * If no buffer specified by the user, allocate one as necessary. 239 */ 240 size = 1024 >> 1; 241 do { 242 if ((npt = realloc(pt, size <<= 1)) == NULL) 243 break; 244 pt = npt; 245 if (__getcwd(pt, size) >= 0) 246 return (pt); 247 } while (size <= MAXPATHLEN * 4 && errno == ERANGE); 248 249 free(pt); 250 return (NULL); 251 } 252