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 == 0) { 74 errno = EINVAL; 75 return (NULL); 76 } else if (size == 1) { 77 errno = ERANGE; 78 return (NULL); 79 } 80 ept = pt + size; 81 } else { 82 if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL) 83 return (NULL); 84 ept = pt + ptsize; 85 } 86 bpt = ept - 1; 87 *bpt = '\0'; 88 89 /* 90 * Allocate bytes for the string of "../"'s. 91 * Should always be enough (it's 340 levels). If it's not, allocate 92 * as necessary. Special * case the first stat, it's ".", not "..". 93 */ 94 if ((up = malloc(upsize = MAXPATHLEN)) == NULL) 95 goto err; 96 eup = up + upsize; 97 bup = up; 98 up[0] = '.'; 99 up[1] = '\0'; 100 101 /* Save root values, so know when to stop. */ 102 if (stat("/", &s)) 103 goto err; 104 root_dev = s.st_dev; 105 root_ino = s.st_ino; 106 107 errno = 0; /* XXX readdir has no error return. */ 108 109 for (first = 1;; first = 0) { 110 /* Stat the current level. */ 111 if (lstat(up, &s)) 112 goto err; 113 114 /* Save current node values. */ 115 ino = s.st_ino; 116 dev = s.st_dev; 117 118 /* Check for reaching root. */ 119 if (root_dev == dev && root_ino == ino) { 120 *--bpt = '/'; 121 /* 122 * It's unclear that it's a requirement to copy the 123 * path to the beginning of the buffer, but it's always 124 * been that way and stuff would probably break. 125 */ 126 memmove(pt, bpt, ept - bpt); 127 free(up); 128 return (pt); 129 } 130 131 /* 132 * Build pointer to the parent directory, allocating memory 133 * as necessary. Max length is 3 for "../", the largest 134 * possible component name, plus a trailing NUL. 135 */ 136 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 137 char *nup; 138 139 if ((nup = realloc(up, upsize *= 2)) == NULL) 140 goto err; 141 bup = nup + (bup - up); 142 up = nup; 143 eup = up + upsize; 144 } 145 *bup++ = '.'; 146 *bup++ = '.'; 147 *bup = '\0'; 148 149 /* Open and stat parent directory. */ 150 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 151 goto err; 152 153 /* Add trailing slash for next directory. */ 154 *bup++ = '/'; 155 156 /* 157 * If it's a mount point, have to stat each element because 158 * the inode number in the directory is for the entry in the 159 * parent directory, not the inode number of the mounted file. 160 */ 161 save_errno = 0; 162 if (s.st_dev == dev) { 163 for (;;) { 164 if (!(dp = readdir(dir))) 165 goto notfound; 166 if (dp->d_fileno == ino) 167 break; 168 } 169 } else 170 for (;;) { 171 if (!(dp = readdir(dir))) 172 goto notfound; 173 if (ISDOT(dp)) 174 continue; 175 memcpy(bup, dp->d_name, dp->d_namlen + 1); 176 177 /* Save the first error for later. */ 178 if (lstat(up, &s)) { 179 if (!save_errno) 180 save_errno = errno; 181 errno = 0; 182 continue; 183 } 184 if (s.st_dev == dev && s.st_ino == ino) 185 break; 186 } 187 188 /* 189 * Check for length of the current name, preceding slash, 190 * leading slash. 191 */ 192 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 193 size_t len; 194 char *npt; 195 196 if (!ptsize) { 197 errno = ERANGE; 198 goto err; 199 } 200 len = ept - bpt; 201 if ((npt = realloc(pt, ptsize *= 2)) == NULL) 202 goto err; 203 bpt = npt + (bpt - pt); 204 pt = npt; 205 ept = pt + ptsize; 206 memmove(ept - len, bpt, len); 207 bpt = ept - len; 208 } 209 if (!first) 210 *--bpt = '/'; 211 bpt -= dp->d_namlen; 212 memcpy(bpt, dp->d_name, dp->d_namlen); 213 (void)closedir(dir); 214 215 /* Truncate any file name. */ 216 *bup = '\0'; 217 } 218 219 notfound: 220 /* 221 * If readdir set errno, use it, not any saved error; otherwise, 222 * didn't find the current directory in its parent directory, set 223 * errno to ENOENT. 224 */ 225 if (!errno) 226 errno = save_errno ? save_errno : ENOENT; 227 /* FALLTHROUGH */ 228 err: 229 save_errno = errno; 230 231 if (ptsize) 232 free(pt); 233 free(up); 234 if (dir) 235 (void)closedir(dir); 236 237 errno = save_errno; 238 239 return (NULL); 240 } 241 242 #endif /* !defined(HAVE_GETCWD) */ 243