1 /* $NetBSD: getcwd.c,v 1.50 2011/02/21 00:40:07 joerg 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 1.50 2011/02/21 00:40:07 joerg 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, n, nlnk = 0; 75 const char *q; 76 char *p, wbuf[2][MAXPATHLEN]; 77 size_t len; 78 79 _DIAGASSERT(resolved != NULL); 80 81 /* POSIX sez we must test for this */ 82 if (path == NULL) { 83 errno = EINVAL; 84 return NULL; 85 } 86 87 /* 88 * Build real path one by one with paying an attention to ., 89 * .. and symbolic link. 90 */ 91 92 /* 93 * `p' is where we'll put a new component with prepending 94 * a delimiter. 95 */ 96 p = resolved; 97 98 if (*path == 0) { 99 *p = 0; 100 errno = ENOENT; 101 return (NULL); 102 } 103 104 /* If relative path, start from current working directory. */ 105 if (*path != '/') { 106 /* check for resolved pointer to appease coverity */ 107 if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) { 108 p[0] = '.'; 109 p[1] = 0; 110 return (NULL); 111 } 112 len = strlen(resolved); 113 if (len > 1) 114 p += len; 115 } 116 117 loop: 118 /* Skip any slash. */ 119 while (*path == '/') 120 path++; 121 122 if (*path == 0) { 123 if (p == resolved) 124 *p++ = '/'; 125 *p = 0; 126 return (resolved); 127 } 128 129 /* Find the end of this component. */ 130 q = path; 131 do 132 q++; 133 while (*q != '/' && *q != 0); 134 135 /* Test . or .. */ 136 if (path[0] == '.') { 137 if (q - path == 1) { 138 path = q; 139 goto loop; 140 } 141 if (path[1] == '.' && q - path == 2) { 142 /* Trim the last component. */ 143 if (p != resolved) 144 while (*--p != '/') 145 ; 146 path = q; 147 goto loop; 148 } 149 } 150 151 /* Append this component. */ 152 if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) { 153 errno = ENAMETOOLONG; 154 if (p == resolved) 155 *p++ = '/'; 156 *p = 0; 157 return (NULL); 158 } 159 p[0] = '/'; 160 memcpy(&p[1], path, 161 /* LINTED We know q > path. */ 162 q - path); 163 p[1 + q - path] = 0; 164 165 /* 166 * If this component is a symlink, toss it and prepend link 167 * target to unresolved path. 168 */ 169 if (lstat(resolved, &sb) == -1) { 170 return (NULL); 171 } 172 if (S_ISLNK(sb.st_mode)) { 173 if (nlnk++ >= MAXSYMLINKS) { 174 errno = ELOOP; 175 return (NULL); 176 } 177 n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1); 178 if (n < 0) 179 return (NULL); 180 if (n == 0) { 181 errno = ENOENT; 182 return (NULL); 183 } 184 185 /* Append unresolved path to link target and switch to it. */ 186 if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) { 187 errno = ENAMETOOLONG; 188 return (NULL); 189 } 190 memcpy(&wbuf[idx][n], q, len + 1); 191 path = wbuf[idx]; 192 idx ^= 1; 193 194 /* If absolute symlink, start from root. */ 195 if (*path == '/') 196 p = resolved; 197 goto loop; 198 } 199 if (*q == '/' && !S_ISDIR(sb.st_mode)) { 200 errno = ENOTDIR; 201 return (NULL); 202 } 203 204 /* Advance both resolved and unresolved path. */ 205 p += 1 + q - path; 206 path = q; 207 goto loop; 208 } 209 210 char * 211 __ssp_real(getcwd)(char *pt, size_t size) 212 { 213 char *npt; 214 215 /* 216 * If a buffer is specified, the size has to be non-zero. 217 */ 218 if (pt != NULL) { 219 if (size == 0) { 220 /* __getcwd(pt, 0) results ERANGE. */ 221 errno = EINVAL; 222 return (NULL); 223 } 224 if (__getcwd(pt, size) >= 0) 225 return (pt); 226 return (NULL); 227 } 228 229 /* 230 * If no buffer specified by the user, allocate one as necessary. 231 */ 232 size = 1024 >> 1; 233 do { 234 if ((npt = realloc(pt, size <<= 1)) == NULL) 235 break; 236 pt = npt; 237 if (__getcwd(pt, size) >= 0) 238 return (pt); 239 } while (size <= MAXPATHLEN * 4 && errno == ERANGE); 240 241 free(pt); 242 return (NULL); 243 } 244