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 <ssp/ssp.h>
44 #include "un-namespace.h"
45
46 #include "gen-private.h"
47
48 #define ISDOT(dp) \
49 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
50 (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
51
52 extern int __getcwd(char *, size_t);
53
54 char *
__ssp_real(getcwd)55 __ssp_real(getcwd)(char *pt, size_t size)
56 {
57 struct dirent *dp;
58 DIR *dir = NULL;
59 dev_t dev;
60 ino_t ino;
61 int first;
62 char *bpt;
63 struct stat s;
64 dev_t root_dev;
65 ino_t root_ino;
66 size_t ptsize;
67 int save_errno;
68 char *ept, c;
69 int fd;
70
71 /*
72 * If no buffer specified by the user, allocate one as necessary.
73 * If a buffer is specified, the size has to be non-zero. The path
74 * is built from the end of the buffer backwards.
75 */
76 if (pt) {
77 ptsize = 0;
78 if (!size) {
79 errno = EINVAL;
80 return (NULL);
81 }
82 if (size == 1) {
83 errno = ERANGE;
84 return (NULL);
85 }
86 ept = pt + size;
87 } else {
88 if ((pt = malloc(ptsize = PATH_MAX)) == NULL)
89 return (NULL);
90 ept = pt + ptsize;
91 }
92 if (__getcwd(pt, ept - pt) == 0) {
93 if (*pt != '/') {
94 bpt = pt;
95 ept = pt + strlen(pt) - 1;
96 while (bpt < ept) {
97 c = *bpt;
98 *bpt++ = *ept;
99 *ept-- = c;
100 }
101 }
102 return (pt);
103 }
104 bpt = ept - 1;
105 *bpt = '\0';
106
107 /* Save root values, so know when to stop. */
108 if (stat("/", &s))
109 goto err;
110 root_dev = s.st_dev;
111 root_ino = s.st_ino;
112
113 errno = 0; /* XXX readdir has no error return. */
114
115 for (first = 1;; first = 0) {
116 /* Stat the current level. */
117 if (dir != NULL ? _fstat(_dirfd(dir), &s) : lstat(".", &s))
118 goto err;
119
120 /* Save current node values. */
121 ino = s.st_ino;
122 dev = s.st_dev;
123
124 /* Check for reaching root. */
125 if (root_dev == dev && root_ino == ino) {
126 *--bpt = '/';
127 /*
128 * It's unclear that it's a requirement to copy the
129 * path to the beginning of the buffer, but it's always
130 * been that way and stuff would probably break.
131 */
132 bcopy(bpt, pt, ept - bpt);
133 if (dir)
134 (void) closedir(dir);
135 return (pt);
136 }
137
138 /* Open and stat parent directory. */
139 fd = _openat(dir != NULL ? _dirfd(dir) : AT_FDCWD,
140 "..", O_RDONLY | O_CLOEXEC);
141 if (fd == -1)
142 goto err;
143 if (dir)
144 (void) closedir(dir);
145 if (!(dir = fdopendir(fd)) || _fstat(_dirfd(dir), &s)) {
146 _close(fd);
147 goto err;
148 }
149
150 /*
151 * If it's a mount point, have to stat each element because
152 * the inode number in the directory is for the entry in the
153 * parent directory, not the inode number of the mounted file.
154 */
155 save_errno = 0;
156 if (s.st_dev == dev) {
157 for (;;) {
158 if (!(dp = readdir(dir)))
159 goto notfound;
160 if (dp->d_fileno == ino)
161 break;
162 }
163 } else
164 for (;;) {
165 if (!(dp = readdir(dir)))
166 goto notfound;
167 if (ISDOT(dp))
168 continue;
169
170 /* Save the first error for later. */
171 if (fstatat(_dirfd(dir), dp->d_name, &s,
172 AT_SYMLINK_NOFOLLOW)) {
173 if (!save_errno)
174 save_errno = errno;
175 errno = 0;
176 continue;
177 }
178 if (s.st_dev == dev && s.st_ino == ino)
179 break;
180 }
181
182 /*
183 * Check for length of the current name, preceding slash,
184 * leading slash.
185 */
186 while (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
187 size_t len, off;
188
189 if (!ptsize) {
190 errno = ERANGE;
191 goto err;
192 }
193 off = bpt - pt;
194 len = ept - bpt;
195 if ((pt = reallocf(pt, ptsize *= 2)) == NULL)
196 goto err;
197 bpt = pt + off;
198 ept = pt + ptsize;
199 bcopy(bpt, ept - len, len);
200 bpt = ept - len;
201 }
202 if (!first)
203 *--bpt = '/';
204 bpt -= dp->d_namlen;
205 bcopy(dp->d_name, bpt, dp->d_namlen);
206 }
207
208 notfound:
209 /*
210 * If readdir set errno, use it, not any saved error; otherwise,
211 * didn't find the current directory in its parent directory, set
212 * errno to ENOENT.
213 */
214 if (!errno)
215 errno = save_errno ? save_errno : ENOENT;
216 /* FALLTHROUGH */
217 err:
218 save_errno = errno;
219
220 if (ptsize)
221 free(pt);
222 if (dir)
223 (void) closedir(dir);
224
225 errno = save_errno;
226 return (NULL);
227 }
228