1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1989, 1991, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __SCCSID("@(#)getcwd.c 8.5 (Berkeley) 2/7/95"); 34 #include "namespace.h" 35 #include <sys/param.h> 36 #include <sys/stat.h> 37 38 #include <dirent.h> 39 #include <errno.h> 40 #include <fcntl.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include "un-namespace.h" 46 47 #include "gen-private.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 extern int __getcwd(char *, size_t); 54 55 char * 56 getcwd(char *pt, size_t size) 57 { 58 struct dirent *dp; 59 DIR *dir = NULL; 60 dev_t dev; 61 ino_t ino; 62 int first; 63 char *bpt; 64 struct stat s; 65 dev_t root_dev; 66 ino_t root_ino; 67 size_t ptsize; 68 int save_errno; 69 char *ept, c; 70 int fd; 71 72 /* 73 * If no buffer specified by the user, allocate one as necessary. 74 * If a buffer is specified, the size has to be non-zero. The path 75 * is built from the end of the buffer backwards. 76 */ 77 if (pt) { 78 ptsize = 0; 79 if (!size) { 80 errno = EINVAL; 81 return (NULL); 82 } 83 if (size == 1) { 84 errno = ERANGE; 85 return (NULL); 86 } 87 ept = pt + size; 88 } else { 89 if ((pt = malloc(ptsize = PATH_MAX)) == NULL) 90 return (NULL); 91 ept = pt + ptsize; 92 } 93 if (__getcwd(pt, ept - pt) == 0) { 94 if (*pt != '/') { 95 bpt = pt; 96 ept = pt + strlen(pt) - 1; 97 while (bpt < ept) { 98 c = *bpt; 99 *bpt++ = *ept; 100 *ept-- = c; 101 } 102 } 103 return (pt); 104 } 105 bpt = ept - 1; 106 *bpt = '\0'; 107 108 /* Save root values, so know when to stop. */ 109 if (stat("/", &s)) 110 goto err; 111 root_dev = s.st_dev; 112 root_ino = s.st_ino; 113 114 errno = 0; /* XXX readdir has no error return. */ 115 116 for (first = 1;; first = 0) { 117 /* Stat the current level. */ 118 if (dir != NULL ? _fstat(_dirfd(dir), &s) : lstat(".", &s)) 119 goto err; 120 121 /* Save current node values. */ 122 ino = s.st_ino; 123 dev = s.st_dev; 124 125 /* Check for reaching root. */ 126 if (root_dev == dev && root_ino == ino) { 127 *--bpt = '/'; 128 /* 129 * It's unclear that it's a requirement to copy the 130 * path to the beginning of the buffer, but it's always 131 * been that way and stuff would probably break. 132 */ 133 bcopy(bpt, pt, ept - bpt); 134 if (dir) 135 (void) closedir(dir); 136 return (pt); 137 } 138 139 /* Open and stat parent directory. */ 140 fd = _openat(dir != NULL ? _dirfd(dir) : AT_FDCWD, 141 "..", O_RDONLY | O_CLOEXEC); 142 if (fd == -1) 143 goto err; 144 if (dir) 145 (void) closedir(dir); 146 if (!(dir = fdopendir(fd)) || _fstat(_dirfd(dir), &s)) { 147 _close(fd); 148 goto err; 149 } 150 151 /* 152 * If it's a mount point, have to stat each element because 153 * the inode number in the directory is for the entry in the 154 * parent directory, not the inode number of the mounted file. 155 */ 156 save_errno = 0; 157 if (s.st_dev == dev) { 158 for (;;) { 159 if (!(dp = readdir(dir))) 160 goto notfound; 161 if (dp->d_fileno == ino) 162 break; 163 } 164 } else 165 for (;;) { 166 if (!(dp = readdir(dir))) 167 goto notfound; 168 if (ISDOT(dp)) 169 continue; 170 171 /* Save the first error for later. */ 172 if (fstatat(_dirfd(dir), dp->d_name, &s, 173 AT_SYMLINK_NOFOLLOW)) { 174 if (!save_errno) 175 save_errno = errno; 176 errno = 0; 177 continue; 178 } 179 if (s.st_dev == dev && s.st_ino == ino) 180 break; 181 } 182 183 /* 184 * Check for length of the current name, preceding slash, 185 * leading slash. 186 */ 187 while (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 188 size_t len, off; 189 190 if (!ptsize) { 191 errno = ERANGE; 192 goto err; 193 } 194 off = bpt - pt; 195 len = ept - bpt; 196 if ((pt = reallocf(pt, ptsize *= 2)) == NULL) 197 goto err; 198 bpt = pt + off; 199 ept = pt + ptsize; 200 bcopy(bpt, ept - len, len); 201 bpt = ept - len; 202 } 203 if (!first) 204 *--bpt = '/'; 205 bpt -= dp->d_namlen; 206 bcopy(dp->d_name, bpt, dp->d_namlen); 207 } 208 209 notfound: 210 /* 211 * If readdir set errno, use it, not any saved error; otherwise, 212 * didn't find the current directory in its parent directory, set 213 * errno to ENOENT. 214 */ 215 if (!errno) 216 errno = save_errno ? save_errno : ENOENT; 217 /* FALLTHROUGH */ 218 err: 219 save_errno = errno; 220 221 if (ptsize) 222 free(pt); 223 if (dir) 224 (void) closedir(dir); 225 226 errno = save_errno; 227 return (NULL); 228 } 229