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 *
getcwd(char * pt,size_t size)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