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/param.h> 38 #include <sys/stat.h> 39 #include <errno.h> 40 #include <dirent.h> 41 #include <sys/dir.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include "includes.h" 46 47 #define ISDOT(dp) \ 48 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 49 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 50 51 char * 52 getcwd(char *pt, size_t size) 53 { 54 struct dirent *dp; 55 DIR *dir = NULL; 56 dev_t dev; 57 ino_t ino; 58 int first; 59 char *bpt, *bup; 60 struct stat s; 61 dev_t root_dev; 62 ino_t root_ino; 63 size_t ptsize, upsize; 64 int save_errno; 65 char *ept, *eup, *up; 66 67 /* 68 * If no buffer specified by the user, allocate one as necessary. 69 * If a buffer is specified, the size has to be non-zero. The path 70 * is built from the end of the buffer backwards. 71 */ 72 if (pt) { 73 ptsize = 0; 74 if (!size) { 75 errno = EINVAL; 76 return (NULL); 77 } 78 ept = pt + size; 79 } else { 80 if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL) 81 return (NULL); 82 ept = pt + ptsize; 83 } 84 bpt = ept - 1; 85 *bpt = '\0'; 86 87 /* 88 * Allocate bytes for the string of "../"'s. 89 * Should always be enough (it's 340 levels). If it's not, allocate 90 * as necessary. Special * case the first stat, it's ".", not "..". 91 */ 92 if ((up = malloc(upsize = MAXPATHLEN)) == NULL) 93 goto err; 94 eup = up + upsize; 95 bup = up; 96 up[0] = '.'; 97 up[1] = '\0'; 98 99 /* Save root values, so know when to stop. */ 100 if (stat("/", &s)) 101 goto err; 102 root_dev = s.st_dev; 103 root_ino = s.st_ino; 104 105 errno = 0; /* XXX readdir has no error return. */ 106 107 for (first = 1;; first = 0) { 108 /* Stat the current level. */ 109 if (lstat(up, &s)) 110 goto err; 111 112 /* Save current node values. */ 113 ino = s.st_ino; 114 dev = s.st_dev; 115 116 /* Check for reaching root. */ 117 if (root_dev == dev && root_ino == ino) { 118 *--bpt = '/'; 119 /* 120 * It's unclear that it's a requirement to copy the 121 * path to the beginning of the buffer, but it's always 122 * been that way and stuff would probably break. 123 */ 124 memmove(pt, bpt, ept - bpt); 125 free(up); 126 return (pt); 127 } 128 129 /* 130 * Build pointer to the parent directory, allocating memory 131 * as necessary. Max length is 3 for "../", the largest 132 * possible component name, plus a trailing NUL. 133 */ 134 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 135 char *nup; 136 137 if ((nup = realloc(up, upsize *= 2)) == NULL) 138 goto err; 139 bup = nup + (bup - up); 140 up = nup; 141 eup = up + upsize; 142 } 143 *bup++ = '.'; 144 *bup++ = '.'; 145 *bup = '\0'; 146 147 /* Open and stat parent directory. */ 148 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 149 goto err; 150 151 /* Add trailing slash for next directory. */ 152 *bup++ = '/'; 153 154 /* 155 * If it's a mount point, have to stat each element because 156 * the inode number in the directory is for the entry in the 157 * parent directory, not the inode number of the mounted file. 158 */ 159 save_errno = 0; 160 if (s.st_dev == dev) { 161 for (;;) { 162 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 memcpy(bup, dp->d_name, 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; 192 char *npt; 193 194 if (!ptsize) { 195 errno = ERANGE; 196 goto err; 197 } 198 len = ept - bpt; 199 if ((npt = realloc(pt, ptsize *= 2)) == NULL) 200 goto err; 201 bpt = npt + (bpt - pt); 202 pt = npt; 203 ept = pt + ptsize; 204 memmove(ept - len, bpt, len); 205 bpt = ept - len; 206 } 207 if (!first) 208 *--bpt = '/'; 209 bpt -= dp->d_namlen; 210 memcpy(bpt, dp->d_name, dp->d_namlen); 211 (void)closedir(dir); 212 213 /* Truncate any file name. */ 214 *bup = '\0'; 215 } 216 217 notfound: 218 /* 219 * If readdir set errno, use it, not any saved error; otherwise, 220 * didn't find the current directory in its parent directory, set 221 * errno to ENOENT. 222 */ 223 if (!errno) 224 errno = save_errno ? save_errno : ENOENT; 225 /* FALLTHROUGH */ 226 err: 227 save_errno = errno; 228 229 if (ptsize) 230 free(pt); 231 free(up); 232 if (dir) 233 (void)closedir(dir); 234 235 errno = save_errno; 236 237 return (NULL); 238 } 239 240 #endif /* !defined(HAVE_GETCWD) */ 241