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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #if defined(LIBC_SCCS) && !defined(lint) 35 static char rcsid[] = "$OpenBSD: getcwd.c,v 1.6 2000/07/19 15:25:13 deraadt Exp $"; 36 #endif /* LIBC_SCCS and not lint */ 37 38 #include <sys/param.h> 39 #include <sys/stat.h> 40 41 #include <errno.h> 42 #include <dirent.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 48 #define ISDOT(dp) \ 49 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 50 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 51 52 char * 53 getcwd(pt, size) 54 char *pt; 55 size_t size; 56 { 57 register struct dirent *dp; 58 register DIR *dir = NULL; 59 register dev_t dev; 60 register ino_t ino; 61 register int first; 62 register char *bpt, *bup; 63 struct stat s; 64 dev_t root_dev; 65 ino_t root_ino; 66 size_t ptsize, upsize; 67 int save_errno; 68 char *ept, *eup, *up; 69 70 /* 71 * If no buffer specified by the user, allocate one as necessary. 72 * If a buffer is specified, the size has to be non-zero. The path 73 * is built from the end of the buffer backwards. 74 */ 75 if (pt) { 76 ptsize = 0; 77 if (!size) { 78 errno = EINVAL; 79 return (NULL); 80 } 81 ept = pt + size; 82 } else { 83 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 84 return (NULL); 85 ept = pt + ptsize; 86 } 87 bpt = ept - 1; 88 *bpt = '\0'; 89 90 /* 91 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 92 * Should always be enough (it's 340 levels). If it's not, allocate 93 * as necessary. Special * case the first stat, it's ".", not "..". 94 */ 95 if ((up = malloc(upsize = 1024 - 4)) == NULL) 96 goto err; 97 eup = up + MAXPATHLEN; 98 bup = up; 99 up[0] = '.'; 100 up[1] = '\0'; 101 102 /* Save root values, so know when to stop. */ 103 if (stat("/", &s)) 104 goto err; 105 root_dev = s.st_dev; 106 root_ino = s.st_ino; 107 108 errno = 0; /* XXX readdir has no error return. */ 109 110 for (first = 1;; first = 0) { 111 /* Stat the current level. */ 112 if (lstat(up, &s)) 113 goto err; 114 115 /* Save current node values. */ 116 ino = s.st_ino; 117 dev = s.st_dev; 118 119 /* Check for reaching root. */ 120 if (root_dev == dev && root_ino == ino) { 121 *--bpt = '/'; 122 /* 123 * It's unclear that it's a requirement to copy the 124 * path to the beginning of the buffer, but it's always 125 * been that way and stuff would probably break. 126 */ 127 bcopy(bpt, pt, ept - bpt); 128 free(up); 129 return (pt); 130 } 131 132 /* 133 * Build pointer to the parent directory, allocating memory 134 * as necessary. Max length is 3 for "../", the largest 135 * possible component name, plus a trailing NULL. 136 */ 137 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 138 char *nup; 139 140 if ((nup = realloc(up, upsize *= 2)) == NULL) 141 goto err; 142 up = nup; 143 bup = up; 144 eup = up + upsize; 145 } 146 *bup++ = '.'; 147 *bup++ = '.'; 148 *bup = '\0'; 149 150 /* Open and stat parent directory. */ 151 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 152 goto err; 153 154 /* Add trailing slash for next directory. */ 155 *bup++ = '/'; 156 157 /* 158 * If it's a mount point, have to stat each element because 159 * the inode number in the directory is for the entry in the 160 * parent directory, not the inode number of the mounted file. 161 */ 162 save_errno = 0; 163 if (s.st_dev == dev) { 164 for (;;) { 165 if (!(dp = readdir(dir))) 166 goto notfound; 167 if (dp->d_fileno == ino) 168 break; 169 } 170 } else 171 for (;;) { 172 if (!(dp = readdir(dir))) 173 goto notfound; 174 if (ISDOT(dp)) 175 continue; 176 bcopy(dp->d_name, bup, dp->d_namlen + 1); 177 178 /* Save the first error for later. */ 179 if (lstat(up, &s)) { 180 if (!save_errno) 181 save_errno = errno; 182 errno = 0; 183 continue; 184 } 185 if (s.st_dev == dev && s.st_ino == ino) 186 break; 187 } 188 189 /* 190 * Check for length of the current name, preceding slash, 191 * leading slash. 192 */ 193 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 194 size_t len, off; 195 char *npt; 196 197 if (!ptsize) { 198 errno = ERANGE; 199 goto err; 200 } 201 off = bpt - pt; 202 len = ept - bpt; 203 if ((npt = realloc(pt, ptsize *= 2)) == NULL) 204 goto err; 205 pt = npt; 206 bpt = pt + off; 207 ept = pt + ptsize; 208 bcopy(bpt, ept - len, len); 209 bpt = ept - len; 210 } 211 if (!first) 212 *--bpt = '/'; 213 bpt -= dp->d_namlen; 214 bcopy(dp->d_name, bpt, dp->d_namlen); 215 (void)closedir(dir); 216 217 /* Truncate any file name. */ 218 *bup = '\0'; 219 } 220 221 notfound: 222 /* 223 * If readdir set errno, use it, not any saved error; otherwise, 224 * didn't find the current directory in its parent directory, set 225 * errno to ENOENT. 226 */ 227 if (!errno) 228 errno = save_errno ? save_errno : ENOENT; 229 /* FALLTHROUGH */ 230 err: 231 if (ptsize) 232 free(pt); 233 if (up) 234 free(up); 235 if (dir) 236 (void)closedir(dir); 237 return (NULL); 238 } 239