1 /* 2 * Copyright (c) 1989, 1991, 1993, 1995 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 sccsid[] = "@(#)getcwd.c 8.5 (Berkeley) 2/7/95"; 36 #endif /* LIBC_SCCS and not lint */ 37 38 #include <sys/param.h> 39 #include <sys/stat.h> 40 41 #include <dirent.h> 42 #include <errno.h> 43 #include <fcntl.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <unistd.h> 48 49 #define ISDOT(dp) \ 50 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 51 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 52 53 char * 54 getcwd(pt, size) 55 char *pt; 56 size_t size; 57 { 58 register struct dirent *dp; 59 register DIR *dir; 60 register dev_t dev; 61 register ino_t ino; 62 register int first; 63 register char *bpt, *bup; 64 struct stat s; 65 dev_t root_dev; 66 ino_t root_ino; 67 size_t ptsize, upsize; 68 int save_errno; 69 char *ept, *eup, *up; 70 71 /* 72 * If no buffer specified by the user, allocate one as necessary. 73 * If a buffer is specified, the size has to be non-zero. The path 74 * is built from the end of the buffer backwards. 75 */ 76 if (pt) { 77 ptsize = 0; 78 if (!size) { 79 errno = EINVAL; 80 return (NULL); 81 } 82 if (size == 1) { 83 errno = ERANGE; 84 return (NULL); 85 } 86 ept = pt + size; 87 } else { 88 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 89 return (NULL); 90 ept = pt + ptsize; 91 } 92 bpt = ept - 1; 93 *bpt = '\0'; 94 95 /* 96 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 97 * Should always be enough (it's 340 levels). If it's not, allocate 98 * as necessary. Special case the first stat, it's ".", not "..". 99 */ 100 if ((up = malloc(upsize = 1024 - 4)) == NULL) 101 goto err; 102 eup = up + MAXPATHLEN; 103 bup = up; 104 up[0] = '.'; 105 up[1] = '\0'; 106 107 /* Save root values, so know when to stop. */ 108 if (stat("/", &s)) 109 goto err; 110 root_dev = s.st_dev; 111 root_ino = s.st_ino; 112 113 errno = 0; /* XXX readdir has no error return. */ 114 115 for (first = 1;; first = 0) { 116 /* Stat the current level. */ 117 if (lstat(up, &s)) 118 goto err; 119 120 /* Save current node values. */ 121 ino = s.st_ino; 122 dev = s.st_dev; 123 124 /* Check for reaching root. */ 125 if (root_dev == dev && root_ino == ino) { 126 *--bpt = '/'; 127 /* 128 * It's unclear that it's a requirement to copy the 129 * path to the beginning of the buffer, but it's always 130 * been that way and stuff would probably break. 131 */ 132 bcopy(bpt, pt, ept - bpt); 133 free(up); 134 return (pt); 135 } 136 137 /* 138 * Build pointer to the parent directory, allocating memory 139 * as necessary. Max length is 3 for "../", the largest 140 * possible component name, plus a trailing NULL. 141 */ 142 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 143 if ((up = realloc(up, upsize *= 2)) == NULL) 144 goto err; 145 bup = up; 146 eup = up + upsize; 147 } 148 *bup++ = '.'; 149 *bup++ = '.'; 150 *bup = '\0'; 151 152 /* Open and stat parent directory. */ 153 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 154 goto err; 155 156 /* Add trailing slash for next directory. */ 157 *bup++ = '/'; 158 *bup = '\0'; 159 160 /* 161 * If it's a mount point, have to stat each element because 162 * the inode number in the directory is for the entry in the 163 * parent directory, not the inode number of the mounted file. 164 */ 165 save_errno = 0; 166 if (s.st_dev == dev) { 167 for (;;) { 168 if (!(dp = readdir(dir))) 169 goto notfound; 170 if (dp->d_fileno == ino) 171 break; 172 } 173 } else 174 for (;;) { 175 if (!(dp = readdir(dir))) 176 goto notfound; 177 if (ISDOT(dp)) 178 continue; 179 bcopy(dp->d_name, bup, dp->d_namlen + 1); 180 181 /* Save the first error for later. */ 182 if (lstat(up, &s)) { 183 if (!save_errno) 184 save_errno = errno; 185 errno = 0; 186 continue; 187 } 188 if (s.st_dev == dev && s.st_ino == ino) 189 break; 190 } 191 192 /* 193 * Check for length of the current name, preceding slash, 194 * leading slash. 195 */ 196 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 197 size_t len, off; 198 199 if (!ptsize) { 200 errno = ERANGE; 201 goto err; 202 } 203 off = bpt - pt; 204 len = ept - bpt; 205 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 206 goto err; 207 bpt = pt + off; 208 ept = pt + ptsize; 209 bcopy(bpt, ept - len, len); 210 bpt = ept - len; 211 } 212 if (!first) 213 *--bpt = '/'; 214 bpt -= dp->d_namlen; 215 bcopy(dp->d_name, bpt, dp->d_namlen); 216 (void)closedir(dir); 217 218 /* Truncate any file name. */ 219 *bup = '\0'; 220 } 221 222 notfound: 223 /* 224 * If readdir set errno, use it, not any saved error; otherwise, 225 * didn't find the current directory in its parent directory, set 226 * errno to ENOENT. 227 */ 228 if (!errno) 229 errno = save_errno ? save_errno : ENOENT; 230 /* FALLTHROUGH */ 231 err: 232 if (ptsize) 233 free(pt); 234 free(up); 235 return (NULL); 236 } 237