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 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)getcwd.c 8.5 (Berkeley) 2/7/95";
32 #endif /* LIBC_SCCS and not lint */
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35
36 #include "namespace.h"
37 #include <sys/param.h>
38 #include <sys/stat.h>
39
40 #include <dirent.h>
41 #include <errno.h>
42 #include <fcntl.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <unistd.h>
47 #include "un-namespace.h"
48
49 #include "gen-private.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 extern int __getcwd(char *, size_t);
56
57 char *
getcwd(char * pt,size_t size)58 getcwd(char *pt, size_t size)
59 {
60 struct dirent *dp;
61 DIR *dir = NULL;
62 dev_t dev;
63 ino_t ino;
64 int first;
65 char *bpt;
66 struct stat s;
67 dev_t root_dev;
68 ino_t root_ino;
69 size_t ptsize;
70 int save_errno;
71 char *ept, c;
72 int fd;
73
74 /*
75 * If no buffer specified by the user, allocate one as necessary.
76 * If a buffer is specified, the size has to be non-zero. The path
77 * is built from the end of the buffer backwards.
78 */
79 if (pt) {
80 ptsize = 0;
81 if (!size) {
82 errno = EINVAL;
83 return (NULL);
84 }
85 if (size == 1) {
86 errno = ERANGE;
87 return (NULL);
88 }
89 ept = pt + size;
90 } else {
91 if ((pt = malloc(ptsize = PATH_MAX)) == NULL)
92 return (NULL);
93 ept = pt + ptsize;
94 }
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 bpt = ept - 1;
108 *bpt = '\0';
109
110 /* Save root values, so know when to stop. */
111 if (stat("/", &s))
112 goto err;
113 root_dev = s.st_dev;
114 root_ino = s.st_ino;
115
116 errno = 0; /* XXX readdir has no error return. */
117
118 for (first = 1;; first = 0) {
119 /* Stat the current level. */
120 if (dir != NULL ? _fstat(_dirfd(dir), &s) : lstat(".", &s))
121 goto err;
122
123 /* Save current node values. */
124 ino = s.st_ino;
125 dev = s.st_dev;
126
127 /* Check for reaching root. */
128 if (root_dev == dev && root_ino == ino) {
129 *--bpt = '/';
130 /*
131 * It's unclear that it's a requirement to copy the
132 * path to the beginning of the buffer, but it's always
133 * been that way and stuff would probably break.
134 */
135 bcopy(bpt, pt, ept - bpt);
136 if (dir)
137 (void) closedir(dir);
138 return (pt);
139 }
140
141 /* Open and stat parent directory. */
142 fd = _openat(dir != NULL ? _dirfd(dir) : AT_FDCWD,
143 "..", O_RDONLY | O_CLOEXEC);
144 if (fd == -1)
145 goto err;
146 if (dir)
147 (void) closedir(dir);
148 if (!(dir = fdopendir(fd)) || _fstat(_dirfd(dir), &s)) {
149 _close(fd);
150 goto err;
151 }
152
153 /*
154 * If it's a mount point, have to stat each element because
155 * the inode number in the directory is for the entry in the
156 * parent directory, not the inode number of the mounted file.
157 */
158 save_errno = 0;
159 if (s.st_dev == dev) {
160 for (;;) {
161 if (!(dp = readdir(dir)))
162 goto notfound;
163 if (dp->d_fileno == ino)
164 break;
165 }
166 } else
167 for (;;) {
168 if (!(dp = readdir(dir)))
169 goto notfound;
170 if (ISDOT(dp))
171 continue;
172
173 /* Save the first error for later. */
174 if (fstatat(_dirfd(dir), dp->d_name, &s,
175 AT_SYMLINK_NOFOLLOW)) {
176 if (!save_errno)
177 save_errno = errno;
178 errno = 0;
179 continue;
180 }
181 if (s.st_dev == dev && s.st_ino == ino)
182 break;
183 }
184
185 /*
186 * Check for length of the current name, preceding slash,
187 * leading slash.
188 */
189 while (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
190 size_t len, off;
191
192 if (!ptsize) {
193 errno = ERANGE;
194 goto err;
195 }
196 off = bpt - pt;
197 len = ept - bpt;
198 if ((pt = reallocf(pt, ptsize *= 2)) == NULL)
199 goto err;
200 bpt = pt + off;
201 ept = pt + ptsize;
202 bcopy(bpt, ept - len, len);
203 bpt = ept - len;
204 }
205 if (!first)
206 *--bpt = '/';
207 bpt -= dp->d_namlen;
208 bcopy(dp->d_name, bpt, dp->d_namlen);
209 }
210
211 notfound:
212 /*
213 * If readdir set errno, use it, not any saved error; otherwise,
214 * didn't find the current directory in its parent directory, set
215 * errno to ENOENT.
216 */
217 if (!errno)
218 errno = save_errno ? save_errno : ENOENT;
219 /* FALLTHROUGH */
220 err:
221 save_errno = errno;
222
223 if (ptsize)
224 free(pt);
225 if (dir)
226 (void) closedir(dir);
227
228 errno = save_errno;
229 return (NULL);
230 }
231