1 /*
2 * Copyright (c) 1989, 1991, 1993
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 *
14 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include "includes.h"
28
29 #if !defined(HAVE_GETCWD)
30
31 #if defined(LIBC_SCCS) && !defined(lint)
32 static char rcsid[] = "$OpenBSD: getcwd.c,v 1.6 2000/07/19 15:25:13 deraadt Exp $";
33 #endif /* LIBC_SCCS and not lint */
34
35 #include <sys/param.h>
36 #include <sys/stat.h>
37 #include <errno.h>
38 #include <dirent.h>
39 #include <sys/dir.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include "includes.h"
44
45 #define ISDOT(dp) \
46 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
47 (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
48
49 char *
50 getcwd(char *pt,size_t size)
51 {
52 register struct dirent *dp;
53 register DIR *dir = NULL;
54 register dev_t dev;
55 register ino_t ino;
56 register int first;
57 register char *bpt, *bup;
58 struct stat s;
59 dev_t root_dev;
60 ino_t root_ino;
61 size_t ptsize, upsize;
62 int save_errno;
63 char *ept, *eup, *up;
64
65 /*
66 * If no buffer specified by the user, allocate one as necessary.
67 * If a buffer is specified, the size has to be non-zero. The path
68 * is built from the end of the buffer backwards.
69 */
70 if (pt) {
71 ptsize = 0;
72 if (!size) {
73 errno = EINVAL;
74 return (NULL);
75 }
76 ept = pt + size;
77 } else {
78 if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
79 return (NULL);
80 ept = pt + ptsize;
81 }
82 bpt = ept - 1;
83 *bpt = '\0';
84
85 /*
86 * Allocate bytes (1024 - malloc space) for the string of "../"'s.
87 * Should always be enough (it's 340 levels). If it's not, allocate
88 * as necessary. Special * case the first stat, it's ".", not "..".
89 */
90 if ((up = malloc(upsize = 1024 - 4)) == NULL)
91 goto err;
92 eup = up + MAXPATHLEN;
93 bup = up;
94 up[0] = '.';
95 up[1] = '\0';
96
97 /* Save root values, so know when to stop. */
98 if (stat("/", &s))
99 goto err;
100 root_dev = s.st_dev;
101 root_ino = s.st_ino;
102
103 errno = 0; /* XXX readdir has no error return. */
104
105 for (first = 1;; first = 0) {
106 /* Stat the current level. */
107 if (lstat(up, &s))
108 goto err;
109
110 /* Save current node values. */
111 ino = s.st_ino;
112 dev = s.st_dev;
113
114 /* Check for reaching root. */
115 if (root_dev == dev && root_ino == ino) {
116 *--bpt = '/';
117 /*
118 * It's unclear that it's a requirement to copy the
119 * path to the beginning of the buffer, but it's always
120 * been that way and stuff would probably break.
121 */
122 memmove(pt, bpt, ept - bpt);
123 free(up);
124 return (pt);
125 }
126
127 /*
128 * Build pointer to the parent directory, allocating memory
129 * as necessary. Max length is 3 for "../", the largest
130 * possible component name, plus a trailing NULL.
131 */
132 if (bup + 3 + MAXNAMLEN + 1 >= eup) {
133 char *nup;
134
135 if ((nup = realloc(up, upsize *= 2)) == NULL)
136 goto err;
137 up = nup;
138 bup = up;
139 eup = up + upsize;
140 }
141 *bup++ = '.';
142 *bup++ = '.';
143 *bup = '\0';
144
145 /* Open and stat parent directory.
146 * RACE?? - replaced fstat(dirfd(dir), &s) w/ lstat(up,&s)
147 */
148 if (!(dir = opendir(up)) || lstat(up,&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 memmove(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, off;
192 char *npt;
193
194 if (!ptsize) {
195 errno = ERANGE;
196 goto err;
197 }
198 off = bpt - pt;
199 len = ept - bpt;
200 if ((npt = realloc(pt, ptsize *= 2)) == NULL)
201 goto err;
202 pt = npt;
203 bpt = pt + off;
204 ept = pt + ptsize;
205 memmove(ept - len, bpt, len);
206 bpt = ept - len;
207 }
208 if (!first)
209 *--bpt = '/';
210 bpt -= dp->d_namlen;
211 memmove(bpt, dp->d_name, dp->d_namlen);
212 (void)closedir(dir);
213
214 /* Truncate any file name. */
215 *bup = '\0';
216 }
217
218 notfound:
219 /*
220 * If readdir set errno, use it, not any saved error; otherwise,
221 * didn't find the current directory in its parent directory, set
222 * errno to ENOENT.
223 */
224 if (!errno)
225 errno = save_errno ? save_errno : ENOENT;
226 /* FALLTHROUGH */
227 err:
228 if (ptsize)
229 free(pt);
230 if (up)
231 free(up);
232 if (dir)
233 (void)closedir(dir);
234 return (NULL);
235 }
236
237 #endif /* !defined(HAVE_GETCWD) */
238
239 #pragma ident "%Z%%M% %I% %E% SMI"