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 "namespace.h" 33 #include <sys/param.h> 34 #include <sys/stat.h> 35 36 #include <dirent.h> 37 #include <errno.h> 38 #include <fcntl.h> 39 #include <stdio.h> 40 #include <stdlib.h> 41 #include <string.h> 42 #include <unistd.h> 43 #include "un-namespace.h" 44 45 #include "gen-private.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 extern int __getcwd(char *, size_t); 52 53 char * 54 getcwd(char *pt, size_t size) 55 { 56 struct dirent *dp; 57 DIR *dir = NULL; 58 dev_t dev; 59 ino_t ino; 60 int first; 61 char *bpt; 62 struct stat s; 63 dev_t root_dev; 64 ino_t root_ino; 65 size_t ptsize; 66 int save_errno; 67 char *ept, c; 68 int fd; 69 70 /* 71 * If no buffer specified by the user, allocate one as necessary. 72 * If a buffer is specified, the size has to be non-zero. The path 73 * is built from the end of the buffer backwards. 74 */ 75 if (pt) { 76 ptsize = 0; 77 if (!size) { 78 errno = EINVAL; 79 return (NULL); 80 } 81 if (size == 1) { 82 errno = ERANGE; 83 return (NULL); 84 } 85 ept = pt + size; 86 } else { 87 if ((pt = malloc(ptsize = PATH_MAX)) == NULL) 88 return (NULL); 89 ept = pt + ptsize; 90 } 91 if (__getcwd(pt, ept - pt) == 0) { 92 if (*pt != '/') { 93 bpt = pt; 94 ept = pt + strlen(pt) - 1; 95 while (bpt < ept) { 96 c = *bpt; 97 *bpt++ = *ept; 98 *ept-- = c; 99 } 100 } 101 return (pt); 102 } 103 bpt = ept - 1; 104 *bpt = '\0'; 105 106 /* Save root values, so know when to stop. */ 107 if (stat("/", &s)) 108 goto err; 109 root_dev = s.st_dev; 110 root_ino = s.st_ino; 111 112 errno = 0; /* XXX readdir has no error return. */ 113 114 for (first = 1;; first = 0) { 115 /* Stat the current level. */ 116 if (dir != NULL ? _fstat(_dirfd(dir), &s) : lstat(".", &s)) 117 goto err; 118 119 /* Save current node values. */ 120 ino = s.st_ino; 121 dev = s.st_dev; 122 123 /* Check for reaching root. */ 124 if (root_dev == dev && root_ino == ino) { 125 *--bpt = '/'; 126 /* 127 * It's unclear that it's a requirement to copy the 128 * path to the beginning of the buffer, but it's always 129 * been that way and stuff would probably break. 130 */ 131 bcopy(bpt, pt, ept - bpt); 132 if (dir) 133 (void) closedir(dir); 134 return (pt); 135 } 136 137 /* Open and stat parent directory. */ 138 fd = _openat(dir != NULL ? _dirfd(dir) : AT_FDCWD, 139 "..", O_RDONLY | O_CLOEXEC); 140 if (fd == -1) 141 goto err; 142 if (dir) 143 (void) closedir(dir); 144 if (!(dir = fdopendir(fd)) || _fstat(_dirfd(dir), &s)) { 145 _close(fd); 146 goto err; 147 } 148 149 /* 150 * If it's a mount point, have to stat each element because 151 * the inode number in the directory is for the entry in the 152 * parent directory, not the inode number of the mounted file. 153 */ 154 save_errno = 0; 155 if (s.st_dev == dev) { 156 for (;;) { 157 if (!(dp = readdir(dir))) 158 goto notfound; 159 if (dp->d_fileno == ino) 160 break; 161 } 162 } else 163 for (;;) { 164 if (!(dp = readdir(dir))) 165 goto notfound; 166 if (ISDOT(dp)) 167 continue; 168 169 /* Save the first error for later. */ 170 if (fstatat(_dirfd(dir), dp->d_name, &s, 171 AT_SYMLINK_NOFOLLOW)) { 172 if (!save_errno) 173 save_errno = errno; 174 errno = 0; 175 continue; 176 } 177 if (s.st_dev == dev && s.st_ino == ino) 178 break; 179 } 180 181 /* 182 * Check for length of the current name, preceding slash, 183 * leading slash. 184 */ 185 while (bpt - pt < dp->d_namlen + (first ? 1 : 2)) { 186 size_t len, off; 187 188 if (!ptsize) { 189 errno = ERANGE; 190 goto err; 191 } 192 off = bpt - pt; 193 len = ept - bpt; 194 if ((pt = reallocf(pt, ptsize *= 2)) == NULL) 195 goto err; 196 bpt = pt + off; 197 ept = pt + ptsize; 198 bcopy(bpt, ept - len, len); 199 bpt = ept - len; 200 } 201 if (!first) 202 *--bpt = '/'; 203 bpt -= dp->d_namlen; 204 bcopy(dp->d_name, bpt, dp->d_namlen); 205 } 206 207 notfound: 208 /* 209 * If readdir set errno, use it, not any saved error; otherwise, 210 * didn't find the current directory in its parent directory, set 211 * errno to ENOENT. 212 */ 213 if (!errno) 214 errno = save_errno ? save_errno : ENOENT; 215 /* FALLTHROUGH */ 216 err: 217 save_errno = errno; 218 219 if (ptsize) 220 free(pt); 221 if (dir) 222 (void) closedir(dir); 223 224 errno = save_errno; 225 return (NULL); 226 } 227