getcwd.c revision 1.24.4.3
1 /* $NetBSD: getcwd.c,v 1.24.4.3 2004/05/12 04:20:34 jmc 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 1.24.4.3 2004/05/12 04:20:34 jmc 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)strcpy(resolved, "."); 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 (void)strncpy(resolved, path, MAXPATHLEN - 1); 111 resolved[MAXPATHLEN - 1] = '\0'; 112 loop: 113 q = strrchr(resolved, '/'); 114 if (q != NULL) { 115 p = q + 1; 116 if (q == resolved) 117 q = "/"; 118 else { 119 do { 120 --q; 121 } while (q > resolved && *q == '/'); 122 q[1] = '\0'; 123 q = resolved; 124 } 125 if (chdir(q) < 0) 126 goto err1; 127 } else 128 p = resolved; 129 130 /* Deal with the last component. */ 131 if (lstat(p, &sb) == 0) { 132 if (S_ISLNK(sb.st_mode)) { 133 if (nlnk++ >= MAXSYMLINKS) { 134 errno = ELOOP; 135 goto err1; 136 } 137 n = readlink(p, resolved, MAXPATHLEN-1); 138 if (n < 0) 139 goto err1; 140 resolved[n] = '\0'; 141 goto loop; 142 } 143 if (S_ISDIR(sb.st_mode)) { 144 if (chdir(p) < 0) 145 goto err1; 146 p = ""; 147 } 148 } 149 150 /* 151 * Save the last component name and get the full pathname of 152 * the current directory. 153 */ 154 (void)strlcpy(wbuf, p, sizeof(wbuf)); 155 156 /* 157 * Call the inernal internal version of getcwd which 158 * does a physical search rather than using the $PWD short-cut 159 */ 160 if (getcwd(resolved, MAXPATHLEN) == 0) 161 goto err1; 162 163 /* 164 * Join the two strings together, ensuring that the right thing 165 * happens if the last component is empty, or the dirname is root. 166 */ 167 if (resolved[0] == '/' && resolved[1] == '\0') 168 rootd = 1; 169 else 170 rootd = 0; 171 172 if (*wbuf) { 173 if (strlen(resolved) + strlen(wbuf) + (rootd ? 0 : 1) + 1 > 174 MAXPATHLEN) { 175 errno = ENAMETOOLONG; 176 goto err1; 177 } 178 if (rootd == 0) 179 (void)strcat(resolved, "/"); /* XXX: strcat is safe */ 180 (void)strcat(resolved, wbuf); /* XXX: strcat is safe */ 181 } 182 183 /* Go back to where we came from. */ 184 if (fchdir(fd) < 0) { 185 serrno = errno; 186 goto err2; 187 } 188 189 /* It's okay if the close fails, what's an fd more or less? */ 190 (void)close(fd); 191 return (resolved); 192 193 err1: serrno = errno; 194 (void)fchdir(fd); 195 err2: (void)close(fd); 196 errno = serrno; 197 return (NULL); 198 } 199 200 #ifdef OLD_GETCWD 201 202 char * 203 getcwd(pt, size) 204 char *pt; 205 size_t size; 206 { 207 struct dirent *dp; 208 DIR *dir; 209 dev_t dev; 210 ino_t ino; 211 int first; 212 char *bpt, *bup; 213 struct stat s; 214 dev_t root_dev; 215 ino_t root_ino; 216 size_t ptsize, upsize; 217 int save_errno; 218 char *ept, *eup, *up; 219 size_t dlen; 220 221 /* 222 * If no buffer specified by the user, allocate one as necessary. 223 * If a buffer is specified, the size has to be non-zero. The path 224 * is built from the end of the buffer backwards. 225 */ 226 if (pt) { 227 ptsize = 0; 228 if (!size) { 229 errno = EINVAL; 230 return (NULL); 231 } 232 ept = pt + size; 233 } else { 234 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 235 return (NULL); 236 ept = pt + ptsize; 237 } 238 bpt = ept - 1; 239 *bpt = '\0'; 240 241 /* 242 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 243 * Should always be enough (it's 340 levels). If it's not, allocate 244 * as necessary. Special case the first stat, it's ".", not "..". 245 */ 246 if ((up = malloc(upsize = 1024 - 4)) == NULL) 247 goto err; 248 eup = up + MAXPATHLEN; 249 bup = up; 250 up[0] = '.'; 251 up[1] = '\0'; 252 253 /* Save root values, so know when to stop. */ 254 if (stat("/", &s)) 255 goto err; 256 root_dev = s.st_dev; 257 root_ino = s.st_ino; 258 259 errno = 0; /* XXX readdir has no error return. */ 260 261 for (first = 1;; first = 0) { 262 /* Stat the current level. */ 263 if (lstat(up, &s)) 264 goto err; 265 266 /* Save current node values. */ 267 ino = s.st_ino; 268 dev = s.st_dev; 269 270 /* Check for reaching root. */ 271 if (root_dev == dev && root_ino == ino) { 272 *--bpt = '/'; 273 /* 274 * It's unclear that it's a requirement to copy the 275 * path to the beginning of the buffer, but it's always 276 * been that way and stuff would probably break. 277 */ 278 memmove(pt, bpt, (size_t)(ept - bpt)); 279 free(up); 280 return (pt); 281 } 282 283 /* 284 * Build pointer to the parent directory, allocating memory 285 * as necessary. Max length is 3 for "../", the largest 286 * possible component name, plus a trailing NULL. 287 */ 288 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 289 if ((up = realloc(up, upsize *= 2)) == NULL) 290 goto err; 291 bup = up; 292 eup = up + upsize; 293 } 294 *bup++ = '.'; 295 *bup++ = '.'; 296 *bup = '\0'; 297 298 /* Open and stat parent directory. */ 299 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 300 goto err; 301 302 /* Add trailing slash for next directory. */ 303 *bup++ = '/'; 304 305 /* 306 * If it's a mount point, have to stat each element because 307 * the inode number in the directory is for the entry in the 308 * parent directory, not the inode number of the mounted file. 309 */ 310 save_errno = 0; 311 if (s.st_dev == dev) { 312 for (;;) { 313 if (!(dp = readdir(dir))) 314 goto notfound; 315 if (dp->d_fileno == ino) { 316 #if defined(__SVR4) || defined(__svr4__) || defined(__linux__) 317 dlen = strlen(dp->d_name); 318 #else 319 dlen = dp->d_namlen; 320 #endif 321 break; 322 } 323 } 324 } else 325 for (;;) { 326 if (!(dp = readdir(dir))) 327 goto notfound; 328 if (ISDOT(dp)) 329 continue; 330 #if defined(__SVR4) || defined(__svr4__) || defined(__linux__) 331 dlen = strlen(dp->d_name); 332 #else 333 dlen = dp->d_namlen; 334 #endif 335 memmove(bup, dp->d_name, dlen + 1); 336 337 /* Save the first error for later. */ 338 if (lstat(up, &s)) { 339 if (!save_errno) 340 save_errno = errno; 341 errno = 0; 342 continue; 343 } 344 if (s.st_dev == dev && s.st_ino == ino) 345 break; 346 } 347 348 /* 349 * Check for length of the current name, preceding slash, 350 * leading slash. 351 */ 352 if (bpt - pt <= dlen + (first ? 1 : 2)) { 353 size_t len, off; 354 355 if (!ptsize) { 356 errno = ERANGE; 357 goto err; 358 } 359 off = bpt - pt; 360 len = ept - bpt; 361 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 362 goto err; 363 bpt = pt + off; 364 ept = pt + ptsize; 365 memmove(ept - len, bpt, len); 366 bpt = ept - len; 367 } 368 if (!first) 369 *--bpt = '/'; 370 bpt -= dlen; 371 memmove(bpt, dp->d_name, dlen); 372 (void)closedir(dir); 373 374 /* Truncate any file name. */ 375 *bup = '\0'; 376 } 377 378 notfound: 379 /* 380 * If readdir set errno, use it, not any saved error; otherwise, 381 * didn't find the current directory in its parent directory, set 382 * errno to ENOENT. 383 */ 384 if (!errno) 385 errno = save_errno ? save_errno : ENOENT; 386 /* FALLTHROUGH */ 387 err: 388 if (ptsize) 389 free(pt); 390 free(up); 391 return (NULL); 392 } 393 394 #else /* New getcwd */ 395 396 char * 397 getcwd(pt, size) 398 char *pt; 399 size_t size; 400 { 401 size_t ptsize, bufsize; 402 int len; 403 404 /* 405 * If no buffer specified by the user, allocate one as necessary. 406 * If a buffer is specified, the size has to be non-zero. The path 407 * is built from the end of the buffer backwards. 408 */ 409 if (pt) { 410 ptsize = 0; 411 if (!size) { 412 errno = EINVAL; 413 return (NULL); 414 } 415 bufsize = size; 416 } else { 417 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 418 return (NULL); 419 bufsize = ptsize; 420 } 421 for (;;) { 422 len = __getcwd(pt, bufsize); 423 if ((len < 0) && (size == 0) && (errno == ERANGE)) { 424 if (ptsize > (MAXPATHLEN*4)) 425 return NULL; 426 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 427 return NULL; 428 bufsize = ptsize; 429 continue; 430 } 431 break; 432 } 433 if (len < 0) 434 return NULL; 435 else 436 return pt; 437 } 438 439 #endif 440
Indexes created Tue Sep 30 20:09:53 GMT 2025