getcwd.c revision 1.31
1 /* $NetBSD: getcwd.c,v 1.31 2003/08/03 04:35:50 itojun 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. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the University of 21 * California, Berkeley and its contributors. 22 * 4. Neither the name of the University nor the names of its contributors 23 * may be used to endorse or promote products derived from this software 24 * without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36 * SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 #if 0 42 static char sccsid[] = "@(#)getcwd.c 8.5 (Berkeley) 2/7/95"; 43 #else 44 __RCSID("$NetBSD: getcwd.c,v 1.31 2003/08/03 04:35:50 itojun Exp $"); 45 #endif 46 #endif /* LIBC_SCCS and not lint */ 47 48 #include "namespace.h" 49 #include <sys/param.h> 50 #include <sys/stat.h> 51 52 #include <assert.h> 53 #include <dirent.h> 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <unistd.h> 60 61 #include "extern.h" 62 63 #ifdef __weak_alias 64 __weak_alias(getcwd,_getcwd) 65 __weak_alias(realpath,_realpath) 66 #endif 67 68 #define ISDOT(dp) \ 69 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 70 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 71 72 73 #if defined(__SVR4) || defined(__svr4__) 74 #define d_fileno d_ino 75 #endif 76 77 /* 78 * char *realpath(const char *path, char resolved_path[MAXPATHLEN]); 79 * 80 * Find the real name of path, by removing all ".", ".." and symlink 81 * components. Returns (resolved) on success, or (NULL) on failure, 82 * in which case the path which caused trouble is left in (resolved). 83 */ 84 char * 85 realpath(path, resolved) 86 const char *path; 87 char *resolved; 88 { 89 struct stat sb; 90 int fd, n, rootd, serrno, nlnk = 0; 91 char *p, *q, wbuf[MAXPATHLEN]; 92 93 _DIAGASSERT(path != NULL); 94 _DIAGASSERT(resolved != NULL); 95 96 /* Save the starting point. */ 97 if ((fd = open(".", O_RDONLY)) < 0) { 98 (void)strlcpy(resolved, ".", MAXPATHLEN); 99 return (NULL); 100 } 101 102 /* 103 * Find the dirname and basename from the path to be resolved. 104 * Change directory to the dirname component. 105 * lstat the basename part. 106 * if it is a symlink, read in the value and loop. 107 * if it is a directory, then change to that directory. 108 * get the current directory name and append the basename. 109 */ 110 if (strlcpy(resolved, path, MAXPATHLEN) >= MAXPATHLEN) { 111 errno = ENAMETOOLONG; 112 goto err1; 113 } 114 loop: 115 q = strrchr(resolved, '/'); 116 if (q != NULL) { 117 p = q + 1; 118 if (q == resolved) 119 q = "/"; 120 else { 121 do { 122 --q; 123 } while (q > resolved && *q == '/'); 124 q[1] = '\0'; 125 q = resolved; 126 } 127 if (chdir(q) < 0) 128 goto err1; 129 } else 130 p = resolved; 131 132 /* Deal with the last component. */ 133 if (lstat(p, &sb) == 0) { 134 if (S_ISLNK(sb.st_mode)) { 135 if (nlnk++ >= MAXSYMLINKS) { 136 errno = ELOOP; 137 goto err1; 138 } 139 n = readlink(p, resolved, MAXPATHLEN-1); 140 if (n < 0) 141 goto err1; 142 resolved[n] = '\0'; 143 goto loop; 144 } 145 if (S_ISDIR(sb.st_mode)) { 146 if (chdir(p) < 0) 147 goto err1; 148 p = ""; 149 } 150 } 151 152 /* 153 * Save the last component name and get the full pathname of 154 * the current directory. 155 */ 156 if (strlcpy(wbuf, p, sizeof(wbuf)) >= sizeof(wbuf)) { 157 errno = ENAMETOOLONG; 158 goto err1; 159 } 160 161 /* 162 * Call the inernal internal version of getcwd which 163 * does a physical search rather than using the $PWD short-cut 164 */ 165 if (getcwd(resolved, MAXPATHLEN) == 0) 166 goto err1; 167 168 /* 169 * Join the two strings together, ensuring that the right thing 170 * happens if the last component is empty, or the dirname is root. 171 */ 172 if (resolved[0] == '/' && resolved[1] == '\0') 173 rootd = 1; 174 else 175 rootd = 0; 176 177 if (*wbuf) { 178 if (strlen(resolved) + strlen(wbuf) + (rootd ? 0 : 1) + 1 > 179 MAXPATHLEN) { 180 errno = ENAMETOOLONG; 181 goto err1; 182 } 183 if (rootd == 0) 184 if (strlcat(resolved, "/", MAXPATHLEN) >= MAXPATHLEN) { 185 errno = ENAMETOOLONG; 186 goto err1; 187 } 188 if (strlcat(resolved, wbuf, MAXPATHLEN) >= MAXPATHLEN) { 189 errno = ENAMETOOLONG; 190 goto err1; 191 } 192 } 193 194 /* Go back to where we came from. */ 195 if (fchdir(fd) < 0) { 196 serrno = errno; 197 goto err2; 198 } 199 200 /* It's okay if the close fails, what's an fd more or less? */ 201 (void)close(fd); 202 return (resolved); 203 204 err1: serrno = errno; 205 (void)fchdir(fd); 206 err2: (void)close(fd); 207 errno = serrno; 208 return (NULL); 209 } 210 211 #ifdef OLD_GETCWD 212 213 char * 214 getcwd(pt, size) 215 char *pt; 216 size_t size; 217 { 218 struct dirent *dp; 219 DIR *dir; 220 dev_t dev; 221 ino_t ino; 222 int first; 223 char *bpt, *bup; 224 struct stat s; 225 dev_t root_dev; 226 ino_t root_ino; 227 size_t ptsize, upsize; 228 int save_errno; 229 char *ept, *eup, *up; 230 size_t dlen; 231 232 /* 233 * If no buffer specified by the user, allocate one as necessary. 234 * If a buffer is specified, the size has to be non-zero. The path 235 * is built from the end of the buffer backwards. 236 */ 237 if (pt) { 238 ptsize = 0; 239 if (!size) { 240 errno = EINVAL; 241 return (NULL); 242 } 243 ept = pt + size; 244 } else { 245 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 246 return (NULL); 247 ept = pt + ptsize; 248 } 249 bpt = ept - 1; 250 *bpt = '\0'; 251 252 /* 253 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 254 * Should always be enough (it's 340 levels). If it's not, allocate 255 * as necessary. Special case the first stat, it's ".", not "..". 256 */ 257 if ((up = malloc(upsize = 1024 - 4)) == NULL) 258 goto err; 259 eup = up + MAXPATHLEN; 260 bup = up; 261 up[0] = '.'; 262 up[1] = '\0'; 263 264 /* Save root values, so know when to stop. */ 265 if (stat("/", &s)) 266 goto err; 267 root_dev = s.st_dev; 268 root_ino = s.st_ino; 269 270 errno = 0; /* XXX readdir has no error return. */ 271 272 for (first = 1;; first = 0) { 273 /* Stat the current level. */ 274 if (lstat(up, &s)) 275 goto err; 276 277 /* Save current node values. */ 278 ino = s.st_ino; 279 dev = s.st_dev; 280 281 /* Check for reaching root. */ 282 if (root_dev == dev && root_ino == ino) { 283 *--bpt = '/'; 284 /* 285 * It's unclear that it's a requirement to copy the 286 * path to the beginning of the buffer, but it's always 287 * been that way and stuff would probably break. 288 */ 289 memmove(pt, bpt, (size_t)(ept - bpt)); 290 free(up); 291 return (pt); 292 } 293 294 /* 295 * Build pointer to the parent directory, allocating memory 296 * as necessary. Max length is 3 for "../", the largest 297 * possible component name, plus a trailing NULL. 298 */ 299 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 300 if ((up = realloc(up, upsize *= 2)) == NULL) 301 goto err; 302 bup = up; 303 eup = up + upsize; 304 } 305 *bup++ = '.'; 306 *bup++ = '.'; 307 *bup = '\0'; 308 309 /* Open and stat parent directory. */ 310 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 311 goto err; 312 313 /* Add trailing slash for next directory. */ 314 *bup++ = '/'; 315 316 /* 317 * If it's a mount point, have to stat each element because 318 * the inode number in the directory is for the entry in the 319 * parent directory, not the inode number of the mounted file. 320 */ 321 save_errno = 0; 322 if (s.st_dev == dev) { 323 for (;;) { 324 if (!(dp = readdir(dir))) 325 goto notfound; 326 if (dp->d_fileno == ino) { 327 #if defined(__SVR4) || defined(__svr4__) || defined(__linux__) 328 dlen = strlen(dp->d_name); 329 #else 330 dlen = dp->d_namlen; 331 #endif 332 break; 333 } 334 } 335 } else 336 for (;;) { 337 if (!(dp = readdir(dir))) 338 goto notfound; 339 if (ISDOT(dp)) 340 continue; 341 #if defined(__SVR4) || defined(__svr4__) || defined(__linux__) 342 dlen = strlen(dp->d_name); 343 #else 344 dlen = dp->d_namlen; 345 #endif 346 memmove(bup, dp->d_name, dlen + 1); 347 348 /* Save the first error for later. */ 349 if (lstat(up, &s)) { 350 if (!save_errno) 351 save_errno = errno; 352 errno = 0; 353 continue; 354 } 355 if (s.st_dev == dev && s.st_ino == ino) 356 break; 357 } 358 359 /* 360 * Check for length of the current name, preceding slash, 361 * leading slash. 362 */ 363 if (bpt - pt <= dlen + (first ? 1 : 2)) { 364 size_t len, off; 365 366 if (!ptsize) { 367 errno = ERANGE; 368 goto err; 369 } 370 off = bpt - pt; 371 len = ept - bpt; 372 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 373 goto err; 374 bpt = pt + off; 375 ept = pt + ptsize; 376 memmove(ept - len, bpt, len); 377 bpt = ept - len; 378 } 379 if (!first) 380 *--bpt = '/'; 381 bpt -= dlen; 382 memmove(bpt, dp->d_name, dlen); 383 (void)closedir(dir); 384 385 /* Truncate any file name. */ 386 *bup = '\0'; 387 } 388 389 notfound: 390 /* 391 * If readdir set errno, use it, not any saved error; otherwise, 392 * didn't find the current directory in its parent directory, set 393 * errno to ENOENT. 394 */ 395 if (!errno) 396 errno = save_errno ? save_errno : ENOENT; 397 /* FALLTHROUGH */ 398 err: 399 if (ptsize) 400 free(pt); 401 free(up); 402 return (NULL); 403 } 404 405 #else /* New getcwd */ 406 407 char * 408 getcwd(pt, size) 409 char *pt; 410 size_t size; 411 { 412 size_t ptsize, bufsize; 413 int len; 414 415 /* 416 * If no buffer specified by the user, allocate one as necessary. 417 * If a buffer is specified, the size has to be non-zero. The path 418 * is built from the end of the buffer backwards. 419 */ 420 if (pt) { 421 ptsize = 0; 422 if (!size) { 423 errno = EINVAL; 424 return (NULL); 425 } 426 bufsize = size; 427 } else { 428 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 429 return (NULL); 430 bufsize = ptsize; 431 } 432 for (;;) { 433 len = __getcwd(pt, bufsize); 434 if ((len < 0) && (size == 0) && (errno == ERANGE)) { 435 if (ptsize > (MAXPATHLEN*4)) 436 return NULL; 437 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 438 return NULL; 439 bufsize = ptsize; 440 continue; 441 } 442 break; 443 } 444 if (len < 0) 445 return NULL; 446 else 447 return pt; 448 } 449 450 #endif 451
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