1 /* $NetBSD: getcwd.c,v 1.47 2011/01/20 02:57:00 christos 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 1.47 2011/01/20 02:57:00 christos 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(_FORTIFY_SOURCE) && !defined(__lint__) 62 #undef getcwd 63 #define getcwd _sys_getcwd 64 #endif 65 66 #endif 67 68 /* 69 * char *realpath(const char *path, char resolved[MAXPATHLEN]); 70 * 71 * Find the real name of path, by removing all ".", ".." and symlink 72 * components. Returns (resolved) on success, or (NULL) on failure, 73 * in which case the path which caused trouble is left in (resolved). 74 */ 75 char * 76 realpath(const char *path, char *resolved) 77 { 78 struct stat sb; 79 int idx = 0, n, nlnk = 0; 80 const char *q; 81 char *p, wbuf[2][MAXPATHLEN]; 82 size_t len; 83 84 _DIAGASSERT(resolved != NULL); 85 86 /* POSIX sez we must test for this */ 87 if (path == NULL) { 88 errno = EINVAL; 89 return NULL; 90 } 91 92 /* 93 * Build real path one by one with paying an attention to ., 94 * .. and symbolic link. 95 */ 96 97 /* 98 * `p' is where we'll put a new component with prepending 99 * a delimiter. 100 */ 101 p = resolved; 102 103 if (*path == 0) { 104 *p = 0; 105 errno = ENOENT; 106 return (NULL); 107 } 108 109 /* If relative path, start from current working directory. */ 110 if (*path != '/') { 111 /* check for resolved pointer to appease coverity */ 112 if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) { 113 p[0] = '.'; 114 p[1] = 0; 115 return (NULL); 116 } 117 len = strlen(resolved); 118 if (len > 1) 119 p += len; 120 } 121 122 loop: 123 /* Skip any slash. */ 124 while (*path == '/') 125 path++; 126 127 if (*path == 0) { 128 if (p == resolved) 129 *p++ = '/'; 130 *p = 0; 131 return (resolved); 132 } 133 134 /* Find the end of this component. */ 135 q = path; 136 do 137 q++; 138 while (*q != '/' && *q != 0); 139 140 /* Test . or .. */ 141 if (path[0] == '.') { 142 if (q - path == 1) { 143 path = q; 144 goto loop; 145 } 146 if (path[1] == '.' && q - path == 2) { 147 /* Trim the last component. */ 148 if (p != resolved) 149 while (*--p != '/') 150 ; 151 path = q; 152 goto loop; 153 } 154 } 155 156 /* Append this component. */ 157 if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) { 158 errno = ENAMETOOLONG; 159 if (p == resolved) 160 *p++ = '/'; 161 *p = 0; 162 return (NULL); 163 } 164 p[0] = '/'; 165 memcpy(&p[1], path, 166 /* LINTED We know q > path. */ 167 q - path); 168 p[1 + q - path] = 0; 169 170 /* 171 * If this component is a symlink, toss it and prepend link 172 * target to unresolved path. 173 */ 174 if (lstat(resolved, &sb) == -1) { 175 return (NULL); 176 } 177 if (S_ISLNK(sb.st_mode)) { 178 if (nlnk++ >= MAXSYMLINKS) { 179 errno = ELOOP; 180 return (NULL); 181 } 182 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1); 183 if (n < 0) 184 return (NULL); 185 if (n == 0) { 186 errno = ENOENT; 187 return (NULL); 188 } 189 190 /* Append unresolved path to link target and switch to it. */ 191 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) { 192 errno = ENAMETOOLONG; 193 return (NULL); 194 } 195 memcpy(&wbuf[idx][n], q, len + 1); 196 path = wbuf[idx]; 197 idx ^= 1; 198 199 /* If absolute symlink, start from root. */ 200 if (*path == '/') 201 p = resolved; 202 goto loop; 203 } 204 if (*q == '/' && !S_ISDIR(sb.st_mode)) { 205 errno = ENOTDIR; 206 return (NULL); 207 } 208 209 /* Advance both resolved and unresolved path. */ 210 p += 1 + q - path; 211 path = q; 212 goto loop; 213 } 214 215 char * 216 getcwd(char *pt, size_t size) 217 { 218 char *npt; 219 220 /* 221 * If a buffer is specified, the size has to be non-zero. 222 */ 223 if (pt != NULL) { 224 if (size == 0) { 225 /* __getcwd(pt, 0) results ERANGE. */ 226 errno = EINVAL; 227 return (NULL); 228 } 229 if (__getcwd(pt, size) >= 0) 230 return (pt); 231 return (NULL); 232 } 233 234 /* 235 * If no buffer specified by the user, allocate one as necessary. 236 */ 237 size = 1024 >> 1; 238 do { 239 if ((npt = realloc(pt, size <<= 1)) == NULL) 240 break; 241 pt = npt; 242 if (__getcwd(pt, size) >= 0) 243 return (pt); 244 } while (size <= MAXPATHLEN * 4 && errno == ERANGE); 245 246 free(pt); 247 return (NULL); 248 } 249