1 /* $OpenBSD: getcwd.c,v 1.14 2005/08/08 08:05:34 espie Exp */
2 /*
3 * Copyright (c) 1989, 1991, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 /* OPENBSD ORIGINAL: lib/libc/gen/getcwd.c */
32
33 #include "includes.h"
34
35 #if !defined(HAVE_GETCWD)
36
37 #include <sys/stat.h>
38 #include <errno.h>
39 #include <dirent.h>
40 #include <sys/dir.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include "includes.h"
45
46 #define ISDOT(dp) \
47 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
48 (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
49
50 char *
getcwd(char * pt,size_t size)51 getcwd(char *pt, size_t size)
52 {
53 struct dirent *dp;
54 DIR *dir = NULL;
55 dev_t dev;
56 ino_t ino;
57 int first;
58 char *bpt, *bup;
59 struct stat s;
60 dev_t root_dev;
61 ino_t root_ino;
62 size_t ptsize, upsize;
63 int save_errno;
64 char *ept, *eup, *up;
65
66 /*
67 * If no buffer specified by the user, allocate one as necessary.
68 * If a buffer is specified, the size has to be non-zero. The path
69 * is built from the end of the buffer backwards.
70 */
71 if (pt) {
72 ptsize = 0;
73 if (size == 0) {
74 errno = EINVAL;
75 return (NULL);
76 } else if (size == 1) {
77 errno = ERANGE;
78 return (NULL);
79 }
80 ept = pt + size;
81 } else {
82 if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL)
83 return (NULL);
84 ept = pt + ptsize;
85 }
86 bpt = ept - 1;
87 *bpt = '\0';
88
89 /*
90 * Allocate bytes for the string of "../"'s.
91 * Should always be enough (it's 340 levels). If it's not, allocate
92 * as necessary. Special * case the first stat, it's ".", not "..".
93 */
94 if ((up = malloc(upsize = MAXPATHLEN)) == NULL)
95 goto err;
96 eup = up + upsize;
97 bup = up;
98 up[0] = '.';
99 up[1] = '\0';
100
101 /* Save root values, so know when to stop. */
102 if (stat("/", &s))
103 goto err;
104 root_dev = s.st_dev;
105 root_ino = s.st_ino;
106
107 errno = 0; /* XXX readdir has no error return. */
108
109 for (first = 1;; first = 0) {
110 /* Stat the current level. */
111 if (lstat(up, &s))
112 goto err;
113
114 /* Save current node values. */
115 ino = s.st_ino;
116 dev = s.st_dev;
117
118 /* Check for reaching root. */
119 if (root_dev == dev && root_ino == ino) {
120 *--bpt = '/';
121 /*
122 * It's unclear that it's a requirement to copy the
123 * path to the beginning of the buffer, but it's always
124 * been that way and stuff would probably break.
125 */
126 memmove(pt, bpt, ept - bpt);
127 free(up);
128 return (pt);
129 }
130
131 /*
132 * Build pointer to the parent directory, allocating memory
133 * as necessary. Max length is 3 for "../", the largest
134 * possible component name, plus a trailing NUL.
135 */
136 if (bup + 3 + MAXNAMLEN + 1 >= eup) {
137 char *nup;
138
139 if ((nup = realloc(up, upsize *= 2)) == NULL)
140 goto err;
141 bup = nup + (bup - up);
142 up = nup;
143 eup = up + upsize;
144 }
145 *bup++ = '.';
146 *bup++ = '.';
147 *bup = '\0';
148
149 /* Open and stat parent directory. */
150 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
151 goto err;
152
153 /* Add trailing slash for next directory. */
154 *bup++ = '/';
155
156 /*
157 * If it's a mount point, have to stat each element because
158 * the inode number in the directory is for the entry in the
159 * parent directory, not the inode number of the mounted file.
160 */
161 save_errno = 0;
162 if (s.st_dev == dev) {
163 for (;;) {
164 if (!(dp = readdir(dir)))
165 goto notfound;
166 if (dp->d_fileno == ino)
167 break;
168 }
169 } else
170 for (;;) {
171 if (!(dp = readdir(dir)))
172 goto notfound;
173 if (ISDOT(dp))
174 continue;
175 memcpy(bup, dp->d_name, dp->d_namlen + 1);
176
177 /* Save the first error for later. */
178 if (lstat(up, &s)) {
179 if (!save_errno)
180 save_errno = errno;
181 errno = 0;
182 continue;
183 }
184 if (s.st_dev == dev && s.st_ino == ino)
185 break;
186 }
187
188 /*
189 * Check for length of the current name, preceding slash,
190 * leading slash.
191 */
192 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
193 size_t len;
194 char *npt;
195
196 if (!ptsize) {
197 errno = ERANGE;
198 goto err;
199 }
200 len = ept - bpt;
201 if ((npt = realloc(pt, ptsize *= 2)) == NULL)
202 goto err;
203 bpt = npt + (bpt - pt);
204 pt = npt;
205 ept = pt + ptsize;
206 memmove(ept - len, bpt, len);
207 bpt = ept - len;
208 }
209 if (!first)
210 *--bpt = '/';
211 bpt -= dp->d_namlen;
212 memcpy(bpt, dp->d_name, dp->d_namlen);
213 (void)closedir(dir);
214
215 /* Truncate any file name. */
216 *bup = '\0';
217 }
218
219 notfound:
220 /*
221 * If readdir set errno, use it, not any saved error; otherwise,
222 * didn't find the current directory in its parent directory, set
223 * errno to ENOENT.
224 */
225 if (!errno)
226 errno = save_errno ? save_errno : ENOENT;
227 /* FALLTHROUGH */
228 err:
229 save_errno = errno;
230
231 if (ptsize)
232 free(pt);
233 free(up);
234 if (dir)
235 (void)closedir(dir);
236
237 errno = save_errno;
238
239 return (NULL);
240 }
241
242 #endif /* !defined(HAVE_GETCWD) */
243