1 /* $NetBSD: getcwd.c,v 1.11 1998/02/26 02:49:21 perry 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 1.11 1998/02/26 02:49:21 perry 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 <dirent.h> 53 #include <errno.h> 54 #include <fcntl.h> 55 #include <stdio.h> 56 #include <stdlib.h> 57 #include <string.h> 58 #include <unistd.h> 59 60 #ifdef __weak_alias 61 __weak_alias(getcwd,_getcwd); 62 __weak_alias(realpath,_realpath); 63 #endif 64 65 static char *getcwd_physical __P((char *, size_t)); 66 67 #define ISDOT(dp) \ 68 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 69 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 70 71 char * 72 getcwd(pt, size) 73 char *pt; 74 size_t size; 75 { 76 char *pwd; 77 size_t pwdlen; 78 dev_t dev; 79 ino_t ino; 80 struct stat s; 81 82 /* Check $PWD -- if it's right, it's fast. */ 83 if ((pwd = getenv("PWD")) != NULL && pwd[0] == '/' && !stat(pwd, &s)) { 84 dev = s.st_dev; 85 ino = s.st_ino; 86 if (!stat(".", &s) && dev == s.st_dev && ino == s.st_ino) { 87 pwdlen = strlen(pwd); 88 if (size != 0) { 89 if (pwdlen + 1 > size) { 90 errno = ERANGE; 91 return (NULL); 92 } 93 } else if ((pt = malloc(pwdlen + 1)) == NULL) 94 return (NULL); 95 memmove(pt, pwd, pwdlen); 96 pt[pwdlen] = '\0'; 97 return (pt); 98 } 99 } 100 101 return (getcwd_physical(pt, size)); 102 } 103 104 /* 105 * char *realpath(const char *path, char resolved_path[MAXPATHLEN]); 106 * 107 * Find the real name of path, by removing all ".", ".." and symlink 108 * components. Returns (resolved) on success, or (NULL) on failure, 109 * in which case the path which caused trouble is left in (resolved). 110 */ 111 char * 112 realpath(path, resolved) 113 const char *path; 114 char *resolved; 115 { 116 struct stat sb; 117 int fd, n, rootd, serrno; 118 char *p, *q, wbuf[MAXPATHLEN]; 119 120 /* Save the starting point. */ 121 if ((fd = open(".", O_RDONLY)) < 0) { 122 (void)strcpy(resolved, "."); 123 return (NULL); 124 } 125 126 /* 127 * Find the dirname and basename from the path to be resolved. 128 * Change directory to the dirname component. 129 * lstat the basename part. 130 * if it is a symlink, read in the value and loop. 131 * if it is a directory, then change to that directory. 132 * get the current directory name and append the basename. 133 */ 134 (void)strncpy(resolved, path, MAXPATHLEN - 1); 135 resolved[MAXPATHLEN - 1] = '\0'; 136 loop: 137 q = strrchr(resolved, '/'); 138 if (q != NULL) { 139 p = q + 1; 140 if (q == resolved) 141 q = "/"; 142 else { 143 do { 144 --q; 145 } while (q > resolved && *q == '/'); 146 q[1] = '\0'; 147 q = resolved; 148 } 149 if (chdir(q) < 0) 150 goto err1; 151 } else 152 p = resolved; 153 154 /* Deal with the last component. */ 155 if (lstat(p, &sb) == 0) { 156 if (S_ISLNK(sb.st_mode)) { 157 n = readlink(p, resolved, MAXPATHLEN); 158 if (n < 0) 159 goto err1; 160 resolved[n] = '\0'; 161 goto loop; 162 } 163 if (S_ISDIR(sb.st_mode)) { 164 if (chdir(p) < 0) 165 goto err1; 166 p = ""; 167 } 168 } 169 170 /* 171 * Save the last component name and get the full pathname of 172 * the current directory. 173 */ 174 (void)strncpy(wbuf, p, (sizeof(wbuf) - 1)); 175 176 /* 177 * Call the inernal internal version of getcwd which 178 * does a physical search rather than using the $PWD short-cut 179 */ 180 if (getcwd_physical(resolved, MAXPATHLEN) == 0) 181 goto err1; 182 183 /* 184 * Join the two strings together, ensuring that the right thing 185 * happens if the last component is empty, or the dirname is root. 186 */ 187 if (resolved[0] == '/' && resolved[1] == '\0') 188 rootd = 1; 189 else 190 rootd = 0; 191 192 if (*wbuf) { 193 if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) { 194 errno = ENAMETOOLONG; 195 goto err1; 196 } 197 if (rootd == 0) 198 (void)strcat(resolved, "/"); /* XXX: strcat is safe */ 199 (void)strcat(resolved, wbuf); /* XXX: strcat is safe */ 200 } 201 202 /* Go back to where we came from. */ 203 if (fchdir(fd) < 0) { 204 serrno = errno; 205 goto err2; 206 } 207 208 /* It's okay if the close fails, what's an fd more or less? */ 209 (void)close(fd); 210 return (resolved); 211 212 err1: serrno = errno; 213 (void)fchdir(fd); 214 err2: (void)close(fd); 215 errno = serrno; 216 return (NULL); 217 } 218 219 static char * 220 getcwd_physical(pt, size) 221 char *pt; 222 size_t size; 223 { 224 struct dirent *dp; 225 DIR *dir; 226 dev_t dev; 227 ino_t ino; 228 int first; 229 char *bpt, *bup; 230 struct stat s; 231 dev_t root_dev; 232 ino_t root_ino; 233 size_t ptsize, upsize; 234 int save_errno; 235 char *ept, *eup, *up; 236 237 /* 238 * If no buffer specified by the user, allocate one as necessary. 239 * If a buffer is specified, the size has to be non-zero. The path 240 * is built from the end of the buffer backwards. 241 */ 242 if (pt) { 243 ptsize = 0; 244 if (!size) { 245 errno = EINVAL; 246 return (NULL); 247 } 248 ept = pt + size; 249 } else { 250 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 251 return (NULL); 252 ept = pt + ptsize; 253 } 254 bpt = ept - 1; 255 *bpt = '\0'; 256 257 /* 258 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 259 * Should always be enough (it's 340 levels). If it's not, allocate 260 * as necessary. Special case the first stat, it's ".", not "..". 261 */ 262 if ((up = malloc(upsize = 1024 - 4)) == NULL) 263 goto err; 264 eup = up + MAXPATHLEN; 265 bup = up; 266 up[0] = '.'; 267 up[1] = '\0'; 268 269 /* Save root values, so know when to stop. */ 270 if (stat("/", &s)) 271 goto err; 272 root_dev = s.st_dev; 273 root_ino = s.st_ino; 274 275 errno = 0; /* XXX readdir has no error return. */ 276 277 for (first = 1;; first = 0) { 278 /* Stat the current level. */ 279 if (lstat(up, &s)) 280 goto err; 281 282 /* Save current node values. */ 283 ino = s.st_ino; 284 dev = s.st_dev; 285 286 /* Check for reaching root. */ 287 if (root_dev == dev && root_ino == ino) { 288 *--bpt = '/'; 289 /* 290 * It's unclear that it's a requirement to copy the 291 * path to the beginning of the buffer, but it's always 292 * been that way and stuff would probably break. 293 */ 294 bcopy(bpt, pt, (size_t)(ept - bpt)); 295 free(up); 296 return (pt); 297 } 298 299 /* 300 * Build pointer to the parent directory, allocating memory 301 * as necessary. Max length is 3 for "../", the largest 302 * possible component name, plus a trailing NULL. 303 */ 304 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 305 if ((up = realloc(up, upsize *= 2)) == NULL) 306 goto err; 307 bup = up; 308 eup = up + upsize; 309 } 310 *bup++ = '.'; 311 *bup++ = '.'; 312 *bup = '\0'; 313 314 /* Open and stat parent directory. */ 315 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 316 goto err; 317 318 /* Add trailing slash for next directory. */ 319 *bup++ = '/'; 320 321 /* 322 * If it's a mount point, have to stat each element because 323 * the inode number in the directory is for the entry in the 324 * parent directory, not the inode number of the mounted file. 325 */ 326 save_errno = 0; 327 if (s.st_dev == dev) { 328 for (;;) { 329 if (!(dp = readdir(dir))) 330 goto notfound; 331 if (dp->d_fileno == ino) 332 break; 333 } 334 } else 335 for (;;) { 336 if (!(dp = readdir(dir))) 337 goto notfound; 338 if (ISDOT(dp)) 339 continue; 340 bcopy(dp->d_name, bup, 341 (size_t)(dp->d_namlen + 1)); 342 343 /* Save the first error for later. */ 344 if (lstat(up, &s)) { 345 if (!save_errno) 346 save_errno = errno; 347 errno = 0; 348 continue; 349 } 350 if (s.st_dev == dev && s.st_ino == ino) 351 break; 352 } 353 354 /* 355 * Check for length of the current name, preceding slash, 356 * leading slash. 357 */ 358 if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) { 359 size_t len, off; 360 361 if (!ptsize) { 362 errno = ERANGE; 363 goto err; 364 } 365 off = bpt - pt; 366 len = ept - bpt; 367 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 368 goto err; 369 bpt = pt + off; 370 ept = pt + ptsize; 371 bcopy(bpt, ept - len, len); 372 bpt = ept - len; 373 } 374 if (!first) 375 *--bpt = '/'; 376 bpt -= dp->d_namlen; 377 bcopy(dp->d_name, bpt, (size_t)dp->d_namlen); 378 (void)closedir(dir); 379 380 /* Truncate any file name. */ 381 *bup = '\0'; 382 } 383 384 notfound: 385 /* 386 * If readdir set errno, use it, not any saved error; otherwise, 387 * didn't find the current directory in its parent directory, set 388 * errno to ENOENT. 389 */ 390 if (!errno) 391 errno = save_errno ? save_errno : ENOENT; 392 /* FALLTHROUGH */ 393 err: 394 if (ptsize) 395 free(pt); 396 free(up); 397 return (NULL); 398 } 399