getcwd.c revision 1573
11638Srgrimes/* 21638Srgrimes * Copyright (c) 1989, 1991, 1993 31638Srgrimes * The Regents of the University of California. All rights reserved. 41638Srgrimes * 51638Srgrimes * Redistribution and use in source and binary forms, with or without 61638Srgrimes * modification, are permitted provided that the following conditions 71638Srgrimes * are met: 81638Srgrimes * 1. Redistributions of source code must retain the above copyright 91638Srgrimes * notice, this list of conditions and the following disclaimer. 101638Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 111638Srgrimes * notice, this list of conditions and the following disclaimer in the 121638Srgrimes * documentation and/or other materials provided with the distribution. 131638Srgrimes * 3. All advertising materials mentioning features or use of this software 141638Srgrimes * must display the following acknowledgement: 151638Srgrimes * This product includes software developed by the University of 161638Srgrimes * California, Berkeley and its contributors. 171638Srgrimes * 4. Neither the name of the University nor the names of its contributors 181638Srgrimes * may be used to endorse or promote products derived from this software 191638Srgrimes * without specific prior written permission. 201638Srgrimes * 211638Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 221638Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 231638Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 241638Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 251638Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 261638Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 271638Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 281638Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 291638Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 301638Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 311638Srgrimes * SUCH DAMAGE. 321638Srgrimes */ 3350476Speter 341638Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 351638Srgrimesstatic char sccsid[] = "@(#)getcwd.c 8.1 (Berkeley) 6/4/93"; 361638Srgrimes#endif /* LIBC_SCCS and not lint */ 3779538Sru 381638Srgrimes#include <sys/param.h> 391638Srgrimes#include <sys/stat.h> 401638Srgrimes 411638Srgrimes#include <errno.h> 421638Srgrimes#include <dirent.h> 43131530Sru#include <stdio.h> 44131530Sru#include <stdlib.h> 451638Srgrimes#include <string.h> 461638Srgrimes#include <unistd.h> 471638Srgrimes 48131530Sru#define ISDOT(dp) \ 49131530Sru (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 501638Srgrimes dp->d_name[1] == '.' && dp->d_name[2] == '\0')) 511638Srgrimes 521638Srgrimeschar * 531638Srgrimesgetcwd(pt, size) 541638Srgrimes char *pt; 551638Srgrimes size_t size; 561638Srgrimes{ 571638Srgrimes register struct dirent *dp; 581638Srgrimes register DIR *dir; 591638Srgrimes register dev_t dev; 601638Srgrimes register ino_t ino; 611638Srgrimes register int first; 62131530Sru register char *bpt, *bup; 63131530Sru struct stat s; 641638Srgrimes dev_t root_dev; 651638Srgrimes ino_t root_ino; 661638Srgrimes size_t ptsize, upsize; 671638Srgrimes int save_errno; 681638Srgrimes char *ept, *eup, *up; 691638Srgrimes 70131530Sru /* 71131530Sru * If no buffer specified by the user, allocate one as necessary. 721638Srgrimes * If a buffer is specified, the size has to be non-zero. The path 731638Srgrimes * is built from the end of the buffer backwards. 741638Srgrimes */ 751638Srgrimes if (pt) { 761638Srgrimes ptsize = 0; 771638Srgrimes if (!size) { 781638Srgrimes errno = EINVAL; 791638Srgrimes return (NULL); 801638Srgrimes } 811638Srgrimes ept = pt + size; 821638Srgrimes } else { 831638Srgrimes if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 841638Srgrimes return (NULL); 851638Srgrimes ept = pt + ptsize; 861638Srgrimes } 871638Srgrimes bpt = ept - 1; 881638Srgrimes *bpt = '\0'; 891638Srgrimes 901638Srgrimes /* 911638Srgrimes * Allocate bytes (1024 - malloc space) for the string of "../"'s. 921638Srgrimes * Should always be enough (it's 340 levels). If it's not, allocate 931638Srgrimes * as necessary. Special * case the first stat, it's ".", not "..". 941638Srgrimes */ 951638Srgrimes if ((up = malloc(upsize = 1024 - 4)) == NULL) 961638Srgrimes goto err; 971638Srgrimes eup = up + MAXPATHLEN; 98131530Sru bup = up; 99131530Sru up[0] = '.'; 1001638Srgrimes up[1] = '\0'; 1011638Srgrimes 1021638Srgrimes /* Save root values, so know when to stop. */ 1031638Srgrimes if (stat("/", &s)) 104131530Sru goto err; 105131530Sru root_dev = s.st_dev; 1061638Srgrimes root_ino = s.st_ino; 107131530Sru 108131530Sru errno = 0; /* XXX readdir has no error return. */ 1091638Srgrimes 1101638Srgrimes for (first = 1;; first = 0) { 1111638Srgrimes /* Stat the current level. */ 1121638Srgrimes if (lstat(up, &s)) 1131638Srgrimes goto err; 114131530Sru 115131530Sru /* Save current node values. */ 1161638Srgrimes ino = s.st_ino; 1171638Srgrimes dev = s.st_dev; 1181638Srgrimes 119131530Sru /* Check for reaching root. */ 120131530Sru if (root_dev == dev && root_ino == ino) { 1211638Srgrimes *--bpt = '/'; 1221638Srgrimes /* 1231638Srgrimes * It's unclear that it's a requirement to copy the 1241638Srgrimes * path to the beginning of the buffer, but it's always 1251638Srgrimes * been that way and stuff would probably break. 1261638Srgrimes */ 1271638Srgrimes (void)bcopy(bpt, pt, ept - bpt); 1281638Srgrimes free(up); 1291638Srgrimes return (pt); 1301638Srgrimes } 1311638Srgrimes 1321638Srgrimes /* 1331638Srgrimes * Build pointer to the parent directory, allocating memory 1341638Srgrimes * as necessary. Max length is 3 for "../", the largest 1351638Srgrimes * possible component name, plus a trailing NULL. 1361638Srgrimes */ 1371638Srgrimes if (bup + 3 + MAXNAMLEN + 1 >= eup) { 1381638Srgrimes if ((up = realloc(up, upsize *= 2)) == NULL) 1391638Srgrimes goto err; 140131530Sru bup = up; 141131530Sru eup = up + upsize; 1421638Srgrimes } 1431638Srgrimes *bup++ = '.'; 1441638Srgrimes *bup++ = '.'; 14520920Swosch *bup = '\0'; 14620920Swosch 14720920Swosch /* Open and stat parent directory. */ 14820920Swosch if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 14920920Swosch goto err; 15020920Swosch 1511638Srgrimes /* Add trailing slash for next directory. */ 1521638Srgrimes *bup++ = '/'; 15320243Smpp 15420243Smpp /* 1551638Srgrimes * If it's a mount point, have to stat each element because 1561638Srgrimes * the inode number in the directory is for the entry in the 1571638Srgrimes * parent directory, not the inode number of the mounted file. 1581638Srgrimes */ 1591638Srgrimes save_errno = 0; 1601638Srgrimes if (s.st_dev == dev) { 1611638Srgrimes for (;;) { 1621638Srgrimes if (!(dp = readdir(dir))) 163 goto notfound; 164 if (dp->d_fileno == ino) 165 break; 166 } 167 } else 168 for (;;) { 169 if (!(dp = readdir(dir))) 170 goto notfound; 171 if (ISDOT(dp)) 172 continue; 173 bcopy(dp->d_name, bup, dp->d_namlen + 1); 174 175 /* Save the first error for later. */ 176 if (lstat(up, &s)) { 177 if (!save_errno) 178 save_errno = errno; 179 errno = 0; 180 continue; 181 } 182 if (s.st_dev == dev && s.st_ino == ino) 183 break; 184 } 185 186 /* 187 * Check for length of the current name, preceding slash, 188 * leading slash. 189 */ 190 if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) { 191 size_t len, off; 192 193 if (!ptsize) { 194 errno = ERANGE; 195 goto err; 196 } 197 off = bpt - pt; 198 len = ept - bpt; 199 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 200 goto err; 201 bpt = pt + off; 202 ept = pt + ptsize; 203 (void)bcopy(bpt, ept - len, len); 204 bpt = ept - len; 205 } 206 if (!first) 207 *--bpt = '/'; 208 bpt -= dp->d_namlen; 209 bcopy(dp->d_name, bpt, dp->d_namlen); 210 (void)closedir(dir); 211 212 /* Truncate any file name. */ 213 *bup = '\0'; 214 } 215 216notfound: 217 /* 218 * If readdir set errno, use it, not any saved error; otherwise, 219 * didn't find the current directory in its parent directory, set 220 * errno to ENOENT. 221 */ 222 if (!errno) 223 errno = save_errno ? save_errno : ENOENT; 224 /* FALLTHROUGH */ 225err: 226 if (ptsize) 227 free(pt); 228 free(up); 229 return (NULL); 230} 231