1 /* 2 * Copyright (c) 1989, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #if defined(LIBC_SCCS) && !defined(lint) 31 static char rcsid[] = "$OpenBSD: getcwd.c,v 1.10 2005/01/05 19:48:08 otto Exp $"; 32 #endif /* LIBC_SCCS and not lint */ 33 34 #include <sys/param.h> 35 #include <sys/stat.h> 36 37 #include <errno.h> 38 #include <dirent.h> 39 #include <stdio.h> 40 #include <stdlib.h> 41 #include <string.h> 42 #include <unistd.h> 43 44 #define ISDOT(dp) \ 45 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 46 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 47 48 char * 49 getcwd(char *pt, size_t size) 50 { 51 register struct dirent *dp; 52 register DIR *dir = NULL; 53 register dev_t dev; 54 register ino_t ino; 55 register int first; 56 register char *bpt, *bup; 57 struct stat s; 58 dev_t root_dev; 59 ino_t root_ino; 60 size_t ptsize, upsize; 61 int save_errno; 62 char *ept, *eup, *up; 63 64 /* 65 * If no buffer specified by the user, allocate one as necessary. 66 * If a buffer is specified, the size has to be non-zero. The path 67 * is built from the end of the buffer backwards. 68 */ 69 if (pt) { 70 ptsize = 0; 71 if (!size) { 72 errno = EINVAL; 73 return (NULL); 74 } 75 ept = pt + size; 76 } else { 77 if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL) 78 return (NULL); 79 ept = pt + ptsize; 80 } 81 bpt = ept - 1; 82 *bpt = '\0'; 83 84 /* 85 * Allocate bytes for the string of "../"'s. 86 * Should always be enough (it's 340 levels). If it's not, allocate 87 * as necessary. Special * case the first stat, it's ".", not "..". 88 */ 89 if ((up = malloc(upsize = MAXPATHLEN)) == NULL) 90 goto err; 91 eup = up + upsize; 92 bup = up; 93 up[0] = '.'; 94 up[1] = '\0'; 95 96 /* Save root values, so know when to stop. */ 97 if (stat("/", &s)) 98 goto err; 99 root_dev = s.st_dev; 100 root_ino = s.st_ino; 101 102 errno = 0; /* XXX readdir has no error return. */ 103 104 for (first = 1;; first = 0) { 105 /* Stat the current level. */ 106 if (lstat(up, &s)) 107 goto err; 108 109 /* Save current node values. */ 110 ino = s.st_ino; 111 dev = s.st_dev; 112 113 /* Check for reaching root. */ 114 if (root_dev == dev && root_ino == ino) { 115 *--bpt = '/'; 116 /* 117 * It's unclear that it's a requirement to copy the 118 * path to the beginning of the buffer, but it's always 119 * been that way and stuff would probably break. 120 */ 121 bcopy(bpt, pt, ept - bpt); 122 free(up); 123 return (pt); 124 } 125 126 /* 127 * Build pointer to the parent directory, allocating memory 128 * as necessary. Max length is 3 for "../", the largest 129 * possible component name, plus a trailing NUL. 130 */ 131 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 132 char *nup; 133 134 if ((nup = realloc(up, upsize *= 2)) == NULL) 135 goto err; 136 bup = nup + (bup - up); 137 up = nup; 138 eup = up + upsize; 139 } 140 *bup++ = '.'; 141 *bup++ = '.'; 142 *bup = '\0'; 143 144 /* Open and stat parent directory. */ 145 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 146 goto err; 147 148 /* Add trailing slash for next directory. */ 149 *bup++ = '/'; 150 151 /* 152 * If it's a mount point, have to stat each element because 153 * the inode number in the directory is for the entry in the 154 * parent directory, not the inode number of the mounted file. 155 */ 156 save_errno = 0; 157 if (s.st_dev == dev) { 158 for (;;) { 159 if (!(dp = readdir(dir))) 160 goto notfound; 161 if (dp->d_fileno == ino) 162 break; 163 } 164 } else 165 for (;;) { 166 if (!(dp = readdir(dir))) 167 goto notfound; 168 if (ISDOT(dp)) 169 continue; 170 bcopy(dp->d_name, bup, dp->d_namlen + 1); 171 172 /* Save the first error for later. */ 173 if (lstat(up, &s)) { 174 if (!save_errno) 175 save_errno = errno; 176 errno = 0; 177 continue; 178 } 179 if (s.st_dev == dev && s.st_ino == ino) 180 break; 181 } 182 183 /* 184 * Check for length of the current name, preceding slash, 185 * leading slash. 186 */ 187 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 188 size_t len, off; 189 char *npt; 190 191 if (!ptsize) { 192 errno = ERANGE; 193 goto err; 194 } 195 off = bpt - pt; 196 len = ept - bpt; 197 if ((npt = realloc(pt, ptsize *= 2)) == NULL) 198 goto err; 199 pt = npt; 200 bpt = pt + off; 201 ept = pt + ptsize; 202 bcopy(bpt, ept - len, len); 203 bpt = ept - len; 204 } 205 if (!first) 206 *--bpt = '/'; 207 bpt -= dp->d_namlen; 208 bcopy(dp->d_name, bpt, dp->d_namlen); 209 (void)closedir(dir); 210 211 /* Truncate any file name. */ 212 *bup = '\0'; 213 } 214 215 notfound: 216 /* 217 * If readdir set errno, use it, not any saved error; otherwise, 218 * didn't find the current directory in its parent directory, set 219 * errno to ENOENT. 220 */ 221 if (!errno) 222 errno = save_errno ? save_errno : ENOENT; 223 /* FALLTHROUGH */ 224 err: 225 if (ptsize) 226 free(pt); 227 free(up); 228 if (dir) 229 (void)closedir(dir); 230 return (NULL); 231 } 232