1 /* $NetBSD: getcwd.c,v 1.51 2012/03/13 21:13:35 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 1.51 2012/03/13 21:13:35 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 #include <ssp/ssp.h> 54 55 #include "extern.h" 56 57 #ifdef __weak_alias 58 __weak_alias(getcwd,_getcwd) 59 __weak_alias(_sys_getcwd,_getcwd) 60 __weak_alias(realpath,_realpath) 61 #endif 62 63 /* 64 * char *realpath(const char *path, char resolved[MAXPATHLEN]); 65 * 66 * Find the real name of path, by removing all ".", ".." and symlink 67 * components. Returns (resolved) on success, or (NULL) on failure, 68 * in which case the path which caused trouble is left in (resolved). 69 */ 70 char * 71 realpath(const char *path, char *resolved) 72 { 73 struct stat sb; 74 int idx = 0, nlnk = 0; 75 const char *q; 76 char *p, wbuf[2][MAXPATHLEN]; 77 size_t len; 78 ssize_t n; 79 80 _DIAGASSERT(resolved != NULL); 81 82 /* POSIX sez we must test for this */ 83 if (path == NULL) { 84 errno = EINVAL; 85 return NULL; 86 } 87 88 /* 89 * Build real path one by one with paying an attention to ., 90 * .. and symbolic link. 91 */ 92 93 /* 94 * `p' is where we'll put a new component with prepending 95 * a delimiter. 96 */ 97 p = resolved; 98 99 if (*path == 0) { 100 *p = 0; 101 errno = ENOENT; 102 return (NULL); 103 } 104 105 /* If relative path, start from current working directory. */ 106 if (*path != '/') { 107 /* check for resolved pointer to appease coverity */ 108 if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) { 109 p[0] = '.'; 110 p[1] = 0; 111 return (NULL); 112 } 113 len = strlen(resolved); 114 if (len > 1) 115 p += len; 116 } 117 118 loop: 119 /* Skip any slash. */ 120 while (*path == '/') 121 path++; 122 123 if (*path == 0) { 124 if (p == resolved) 125 *p++ = '/'; 126 *p = 0; 127 return (resolved); 128 } 129 130 /* Find the end of this component. */ 131 q = path; 132 do 133 q++; 134 while (*q != '/' && *q != 0); 135 136 /* Test . or .. */ 137 if (path[0] == '.') { 138 if (q - path == 1) { 139 path = q; 140 goto loop; 141 } 142 if (path[1] == '.' && q - path == 2) { 143 /* Trim the last component. */ 144 if (p != resolved) 145 while (*--p != '/') 146 ; 147 path = q; 148 goto loop; 149 } 150 } 151 152 /* Append this component. */ 153 if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) { 154 errno = ENAMETOOLONG; 155 if (p == resolved) 156 *p++ = '/'; 157 *p = 0; 158 return (NULL); 159 } 160 p[0] = '/'; 161 memcpy(&p[1], path, 162 /* LINTED We know q > path. */ 163 q - path); 164 p[1 + q - path] = 0; 165 166 /* 167 * If this component is a symlink, toss it and prepend link 168 * target to unresolved path. 169 */ 170 if (lstat(resolved, &sb) == -1) { 171 return (NULL); 172 } 173 if (S_ISLNK(sb.st_mode)) { 174 if (nlnk++ >= MAXSYMLINKS) { 175 errno = ELOOP; 176 return (NULL); 177 } 178 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1); 179 if (n < 0) 180 return (NULL); 181 if (n == 0) { 182 errno = ENOENT; 183 return (NULL); 184 } 185 186 /* Append unresolved path to link target and switch to it. */ 187 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) { 188 errno = ENAMETOOLONG; 189 return (NULL); 190 } 191 memcpy(&wbuf[idx][n], q, len + 1); 192 path = wbuf[idx]; 193 idx ^= 1; 194 195 /* If absolute symlink, start from root. */ 196 if (*path == '/') 197 p = resolved; 198 goto loop; 199 } 200 if (*q == '/' && !S_ISDIR(sb.st_mode)) { 201 errno = ENOTDIR; 202 return (NULL); 203 } 204 205 /* Advance both resolved and unresolved path. */ 206 p += 1 + q - path; 207 path = q; 208 goto loop; 209 } 210 211 char * 212 __ssp_real(getcwd)(char *pt, size_t size) 213 { 214 char *npt; 215 216 /* 217 * If a buffer is specified, the size has to be non-zero. 218 */ 219 if (pt != NULL) { 220 if (size == 0) { 221 /* __getcwd(pt, 0) results ERANGE. */ 222 errno = EINVAL; 223 return (NULL); 224 } 225 if (__getcwd(pt, size) >= 0) 226 return (pt); 227 return (NULL); 228 } 229 230 /* 231 * If no buffer specified by the user, allocate one as necessary. 232 */ 233 size = 1024 >> 1; 234 do { 235 if ((npt = realloc(pt, size <<= 1)) == NULL) 236 break; 237 pt = npt; 238 if (__getcwd(pt, size) >= 0) 239 return (pt); 240 } while (size <= MAXPATHLEN * 4 && errno == ERANGE); 241 242 free(pt); 243 return (NULL); 244 } 245