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 * $FreeBSD$ 34 */ 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 static char sccsid[] = "@(#)getcwd.c 8.5 (Berkeley) 2/7/95"; 38 #endif /* LIBC_SCCS and not lint */ 39 40 #include <sys/param.h> 41 #include <sys/stat.h> 42 43 #include <dirent.h> 44 #include <errno.h> 45 #include <fcntl.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <unistd.h> 50 51 #define ISDOT(dp) \ 52 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 53 (dp->d_name[1] == '.' && dp->d_name[2] == '\0'))) 54 55 char * 56 getcwd(pt, size) 57 char *pt; 58 size_t size; 59 { 60 register struct dirent *dp; 61 register DIR *dir = NULL; 62 register dev_t dev; 63 register ino_t ino; 64 register int first; 65 register char *bpt, *bup; 66 struct stat s; 67 dev_t root_dev; 68 ino_t root_ino; 69 size_t ptsize, upsize; 70 int save_errno; 71 char *ept, *eup, *up, c; 72 73 /* 74 * If no buffer specified by the user, allocate one as necessary. 75 * If a buffer is specified, the size has to be non-zero. The path 76 * is built from the end of the buffer backwards. 77 */ 78 if (pt) { 79 ptsize = 0; 80 if (!size) { 81 errno = EINVAL; 82 return (NULL); 83 } 84 if (size == 1) { 85 errno = ERANGE; 86 return (NULL); 87 } 88 ept = pt + size; 89 } else { 90 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 91 return (NULL); 92 ept = pt + ptsize; 93 } 94 #if !defined(__NETBSD_SYSCALLS) 95 if (__getcwd(pt, ept - pt) == 0) { 96 if (*pt != '/') { 97 bpt = pt; 98 ept = pt + strlen(pt) - 1; 99 while (bpt < ept) { 100 c = *bpt; 101 *bpt++ = *ept; 102 *ept-- = c; 103 } 104 } 105 return (pt); 106 } 107 #endif 108 bpt = ept - 1; 109 *bpt = '\0'; 110 111 /* 112 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 113 * Should always be enough (it's 340 levels). If it's not, allocate 114 * as necessary. Special case the first stat, it's ".", not "..". 115 */ 116 if ((up = malloc(upsize = 1024 - 4)) == NULL) 117 goto err; 118 eup = up + MAXPATHLEN; 119 bup = up; 120 up[0] = '.'; 121 up[1] = '\0'; 122 123 /* Save root values, so know when to stop. */ 124 if (stat("/", &s)) 125 goto err; 126 root_dev = s.st_dev; 127 root_ino = s.st_ino; 128 129 errno = 0; /* XXX readdir has no error return. */ 130 131 for (first = 1;; first = 0) { 132 /* Stat the current level. */ 133 if (lstat(up, &s)) 134 goto err; 135 136 /* Save current node values. */ 137 ino = s.st_ino; 138 dev = s.st_dev; 139 140 /* Check for reaching root. */ 141 if (root_dev == dev && root_ino == ino) { 142 *--bpt = '/'; 143 /* 144 * It's unclear that it's a requirement to copy the 145 * path to the beginning of the buffer, but it's always 146 * been that way and stuff would probably break. 147 */ 148 bcopy(bpt, pt, ept - bpt); 149 free(up); 150 return (pt); 151 } 152 153 /* 154 * Build pointer to the parent directory, allocating memory 155 * as necessary. Max length is 3 for "../", the largest 156 * possible component name, plus a trailing NULL. 157 */ 158 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 159 if ((up = reallocf(up, upsize *= 2)) == NULL) 160 goto err; 161 bup = up; 162 eup = up + upsize; 163 } 164 *bup++ = '.'; 165 *bup++ = '.'; 166 *bup = '\0'; 167 168 /* Open and stat parent directory. */ 169 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 170 goto err; 171 172 /* Add trailing slash for next directory. */ 173 *bup++ = '/'; 174 *bup = '\0'; 175 176 /* 177 * If it's a mount point, have to stat each element because 178 * the inode number in the directory is for the entry in the 179 * parent directory, not the inode number of the mounted file. 180 */ 181 save_errno = 0; 182 if (s.st_dev == dev) { 183 for (;;) { 184 if (!(dp = readdir(dir))) 185 goto notfound; 186 if (dp->d_fileno == ino) 187 break; 188 } 189 } else 190 for (;;) { 191 if (!(dp = readdir(dir))) 192 goto notfound; 193 if (ISDOT(dp)) 194 continue; 195 bcopy(dp->d_name, bup, dp->d_namlen + 1); 196 197 /* Save the first error for later. */ 198 if (lstat(up, &s)) { 199 if (!save_errno) 200 save_errno = errno; 201 errno = 0; 202 continue; 203 } 204 if (s.st_dev == dev && s.st_ino == ino) 205 break; 206 } 207 208 /* 209 * Check for length of the current name, preceding slash, 210 * leading slash. 211 */ 212 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 213 size_t len, off; 214 215 if (!ptsize) { 216 errno = ERANGE; 217 goto err; 218 } 219 off = bpt - pt; 220 len = ept - bpt; 221 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 222 goto err; 223 bpt = pt + off; 224 ept = pt + ptsize; 225 bcopy(bpt, ept - len, len); 226 bpt = ept - len; 227 } 228 if (!first) 229 *--bpt = '/'; 230 bpt -= dp->d_namlen; 231 bcopy(dp->d_name, bpt, dp->d_namlen); 232 (void) closedir(dir); 233 dir = NULL; 234 235 /* Truncate any file name. */ 236 *bup = '\0'; 237 } 238 239 notfound: 240 /* 241 * If readdir set errno, use it, not any saved error; otherwise, 242 * didn't find the current directory in its parent directory, set 243 * errno to ENOENT. 244 */ 245 if (!errno) 246 errno = save_errno ? save_errno : ENOENT; 247 /* FALLTHROUGH */ 248 err: 249 save_errno = errno; 250 251 if (ptsize) 252 free(pt); 253 if (dir) 254 (void) closedir(dir); 255 free(up); 256 257 errno = save_errno; 258 return (NULL); 259 } 260