1 /* $OpenBSD: getcwd.c,v 1.14 2005/08/08 08:05:34 espie Exp */ 2 /* 3 * Copyright (c) 1989, 1991, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 /* OPENBSD ORIGINAL: lib/libc/gen/getcwd.c */ 32 33 #include "includes.h" 34 35 #if !defined(HAVE_GETCWD) 36 37 #include <sys/stat.h> 38 #include <errno.h> 39 #include <dirent.h> 40 #include <sys/dir.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include "includes.h" 45 46 #define ISDOT(dp) \ 47 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 48 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 49 50 char * 51 getcwd(char *pt, size_t size) 52 { 53 struct dirent *dp; 54 DIR *dir = NULL; 55 dev_t dev; 56 ino_t ino; 57 int first; 58 char *bpt, *bup; 59 struct stat s; 60 dev_t root_dev; 61 ino_t root_ino; 62 size_t ptsize, upsize; 63 int save_errno; 64 char *ept, *eup, *up; 65 66 /* 67 * If no buffer specified by the user, allocate one as necessary. 68 * If a buffer is specified, the size has to be non-zero. The path 69 * is built from the end of the buffer backwards. 70 */ 71 if (pt) { 72 ptsize = 0; 73 if (!size) { 74 errno = EINVAL; 75 return (NULL); 76 } 77 ept = pt + size; 78 } else { 79 if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL) 80 return (NULL); 81 ept = pt + ptsize; 82 } 83 bpt = ept - 1; 84 *bpt = '\0'; 85 86 /* 87 * Allocate bytes for the string of "../"'s. 88 * Should always be enough (it's 340 levels). If it's not, allocate 89 * as necessary. Special * case the first stat, it's ".", not "..". 90 */ 91 if ((up = malloc(upsize = MAXPATHLEN)) == NULL) 92 goto err; 93 eup = up + upsize; 94 bup = up; 95 up[0] = '.'; 96 up[1] = '\0'; 97 98 /* Save root values, so know when to stop. */ 99 if (stat("/", &s)) 100 goto err; 101 root_dev = s.st_dev; 102 root_ino = s.st_ino; 103 104 errno = 0; /* XXX readdir has no error return. */ 105 106 for (first = 1;; first = 0) { 107 /* Stat the current level. */ 108 if (lstat(up, &s)) 109 goto err; 110 111 /* Save current node values. */ 112 ino = s.st_ino; 113 dev = s.st_dev; 114 115 /* Check for reaching root. */ 116 if (root_dev == dev && root_ino == ino) { 117 *--bpt = '/'; 118 /* 119 * It's unclear that it's a requirement to copy the 120 * path to the beginning of the buffer, but it's always 121 * been that way and stuff would probably break. 122 */ 123 memmove(pt, bpt, ept - bpt); 124 free(up); 125 return (pt); 126 } 127 128 /* 129 * Build pointer to the parent directory, allocating memory 130 * as necessary. Max length is 3 for "../", the largest 131 * possible component name, plus a trailing NUL. 132 */ 133 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 134 char *nup; 135 136 if ((nup = realloc(up, upsize *= 2)) == NULL) 137 goto err; 138 bup = nup + (bup - up); 139 up = nup; 140 eup = up + upsize; 141 } 142 *bup++ = '.'; 143 *bup++ = '.'; 144 *bup = '\0'; 145 146 /* Open and stat parent directory. */ 147 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 148 goto err; 149 150 /* Add trailing slash for next directory. */ 151 *bup++ = '/'; 152 153 /* 154 * If it's a mount point, have to stat each element because 155 * the inode number in the directory is for the entry in the 156 * parent directory, not the inode number of the mounted file. 157 */ 158 save_errno = 0; 159 if (s.st_dev == dev) { 160 for (;;) { 161 if (!(dp = readdir(dir))) 162 goto notfound; 163 if (dp->d_fileno == ino) 164 break; 165 } 166 } else 167 for (;;) { 168 if (!(dp = readdir(dir))) 169 goto notfound; 170 if (ISDOT(dp)) 171 continue; 172 memcpy(bup, dp->d_name, dp->d_namlen + 1); 173 174 /* Save the first error for later. */ 175 if (lstat(up, &s)) { 176 if (!save_errno) 177 save_errno = errno; 178 errno = 0; 179 continue; 180 } 181 if (s.st_dev == dev && s.st_ino == ino) 182 break; 183 } 184 185 /* 186 * Check for length of the current name, preceding slash, 187 * leading slash. 188 */ 189 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 190 size_t len; 191 char *npt; 192 193 if (!ptsize) { 194 errno = ERANGE; 195 goto err; 196 } 197 len = ept - bpt; 198 if ((npt = realloc(pt, ptsize *= 2)) == NULL) 199 goto err; 200 bpt = npt + (bpt - pt); 201 pt = npt; 202 ept = pt + ptsize; 203 memmove(ept - len, bpt, len); 204 bpt = ept - len; 205 } 206 if (!first) 207 *--bpt = '/'; 208 bpt -= dp->d_namlen; 209 memcpy(bpt, dp->d_name, dp->d_namlen); 210 (void)closedir(dir); 211 212 /* Truncate any file name. */ 213 *bup = '\0'; 214 } 215 216 notfound: 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 */ 225 err: 226 save_errno = errno; 227 228 if (ptsize) 229 free(pt); 230 free(up); 231 if (dir) 232 (void)closedir(dir); 233 234 errno = save_errno; 235 236 return (NULL); 237 } 238 239 #endif /* !defined(HAVE_GETCWD) */ 240