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/param.h>
38 #include <sys/stat.h>
39 #include <errno.h>
40 #include <dirent.h>
41 #include <sys/dir.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include "includes.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 char *
getcwd(char * pt,size_t size)52 getcwd(char *pt, size_t size)
53 {
54 struct dirent *dp;
55 DIR *dir = NULL;
56 dev_t dev;
57 ino_t ino;
58 int first;
59 char *bpt, *bup;
60 struct stat s;
61 dev_t root_dev;
62 ino_t root_ino;
63 size_t ptsize, upsize;
64 int save_errno;
65 char *ept, *eup, *up;
66
67 /*
68 * If no buffer specified by the user, allocate one as necessary.
69 * If a buffer is specified, the size has to be non-zero. The path
70 * is built from the end of the buffer backwards.
71 */
72 if (pt) {
73 ptsize = 0;
74 if (!size) {
75 errno = EINVAL;
76 return (NULL);
77 }
78 ept = pt + size;
79 } else {
80 if ((pt = malloc(ptsize = MAXPATHLEN)) == NULL)
81 return (NULL);
82 ept = pt + ptsize;
83 }
84 bpt = ept - 1;
85 *bpt = '\0';
86
87 /*
88 * Allocate bytes for the string of "../"'s.
89 * Should always be enough (it's 340 levels). If it's not, allocate
90 * as necessary. Special * case the first stat, it's ".", not "..".
91 */
92 if ((up = malloc(upsize = MAXPATHLEN)) == NULL)
93 goto err;
94 eup = up + upsize;
95 bup = up;
96 up[0] = '.';
97 up[1] = '\0';
98
99 /* Save root values, so know when to stop. */
100 if (stat("/", &s))
101 goto err;
102 root_dev = s.st_dev;
103 root_ino = s.st_ino;
104
105 errno = 0; /* XXX readdir has no error return. */
106
107 for (first = 1;; first = 0) {
108 /* Stat the current level. */
109 if (lstat(up, &s))
110 goto err;
111
112 /* Save current node values. */
113 ino = s.st_ino;
114 dev = s.st_dev;
115
116 /* Check for reaching root. */
117 if (root_dev == dev && root_ino == ino) {
118 *--bpt = '/';
119 /*
120 * It's unclear that it's a requirement to copy the
121 * path to the beginning of the buffer, but it's always
122 * been that way and stuff would probably break.
123 */
124 memmove(pt, bpt, ept - bpt);
125 free(up);
126 return (pt);
127 }
128
129 /*
130 * Build pointer to the parent directory, allocating memory
131 * as necessary. Max length is 3 for "../", the largest
132 * possible component name, plus a trailing NUL.
133 */
134 if (bup + 3 + MAXNAMLEN + 1 >= eup) {
135 char *nup;
136
137 if ((nup = realloc(up, upsize *= 2)) == NULL)
138 goto err;
139 bup = nup + (bup - up);
140 up = nup;
141 eup = up + upsize;
142 }
143 *bup++ = '.';
144 *bup++ = '.';
145 *bup = '\0';
146
147 /* Open and stat parent directory. */
148 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
149 goto err;
150
151 /* Add trailing slash for next directory. */
152 *bup++ = '/';
153
154 /*
155 * If it's a mount point, have to stat each element because
156 * the inode number in the directory is for the entry in the
157 * parent directory, not the inode number of the mounted file.
158 */
159 save_errno = 0;
160 if (s.st_dev == dev) {
161 for (;;) {
162 if (!(dp = readdir(dir)))
163 goto notfound;
164 if (dp->d_fileno == ino)
165 break;
166 }
167 } else
168 for (;;) {
169 if (!(dp = readdir(dir)))
170 goto notfound;
171 if (ISDOT(dp))
172 continue;
173 memcpy(bup, dp->d_name, dp->d_namlen + 1);
174
175 /* Save the first error for later. */
176 if (lstat(up, &s)) {
177 if (!save_errno)
178 save_errno = errno;
179 errno = 0;
180 continue;
181 }
182 if (s.st_dev == dev && s.st_ino == ino)
183 break;
184 }
185
186 /*
187 * Check for length of the current name, preceding slash,
188 * leading slash.
189 */
190 if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
191 size_t len;
192 char *npt;
193
194 if (!ptsize) {
195 errno = ERANGE;
196 goto err;
197 }
198 len = ept - bpt;
199 if ((npt = realloc(pt, ptsize *= 2)) == NULL)
200 goto err;
201 bpt = npt + (bpt - pt);
202 pt = npt;
203 ept = pt + ptsize;
204 memmove(ept - len, bpt, len);
205 bpt = ept - len;
206 }
207 if (!first)
208 *--bpt = '/';
209 bpt -= dp->d_namlen;
210 memcpy(bpt, dp->d_name, dp->d_namlen);
211 (void)closedir(dir);
212
213 /* Truncate any file name. */
214 *bup = '\0';
215 }
216
217 notfound:
218 /*
219 * If readdir set errno, use it, not any saved error; otherwise,
220 * didn't find the current directory in its parent directory, set
221 * errno to ENOENT.
222 */
223 if (!errno)
224 errno = save_errno ? save_errno : ENOENT;
225 /* FALLTHROUGH */
226 err:
227 save_errno = errno;
228
229 if (ptsize)
230 free(pt);
231 free(up);
232 if (dir)
233 (void)closedir(dir);
234
235 errno = save_errno;
236
237 return (NULL);
238 }
239
240 #endif /* !defined(HAVE_GETCWD) */
241