xref: /netbsd/regress/sys/kern/getcwd/old_getcwd.c (revision 6550d01e)
1 /*	$NetBSD: old_getcwd.c,v 1.3 2003/08/07 09:51:08 agc Exp $	*/
2 
3 /*
4  * Copyright (c) 1989, 1991, 1993, 1995
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * Jan-Simon Pendry.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. Neither the name of the University nor the names of its contributors
19  *    may be used to endorse or promote products derived from this software
20  *    without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  */
34 
35 /*
36  * This file copied from NetBSD's src/lib/libc/gen/getcwd.c 1.15, and edited
37  * to remove namespace stuff and the unused realpath function.
38  */
39 
40 
41 #include <sys/cdefs.h>
42 #if defined(LIBC_SCCS) && !defined(lint)
43 #if 0
44 static char sccsid[] = "@(#)getcwd.c	8.5 (Berkeley) 2/7/95";
45 #else
46 __RCSID("$NetBSD: old_getcwd.c,v 1.3 2003/08/07 09:51:08 agc Exp $");
47 #endif
48 #endif /* LIBC_SCCS and not lint */
49 
50 #include <sys/param.h>
51 #include <sys/stat.h>
52 
53 #include <dirent.h>
54 #include <errno.h>
55 #include <fcntl.h>
56 #include <stdio.h>
57 #include <stdlib.h>
58 #include <string.h>
59 #include <unistd.h>
60 
61 #include "getcwd.h"
62 
63 #define	ISDOT(dp) \
64 	(dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
65 	    (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
66 
67 
68 #if defined(__SVR4) || defined(__svr4__)
69 #define d_fileno d_ino
70 #endif
71 
72 char *
73 old_getcwd(pt, size)
74 	char *pt;
75 	size_t size;
76 {
77 	struct dirent *dp;
78 	DIR *dir;
79 	dev_t dev;
80 	ino_t ino;
81 	int first;
82 	char *bpt, *bup;
83 	struct stat s;
84 	dev_t root_dev;
85 	ino_t root_ino;
86 	size_t ptsize, upsize;
87 	int save_errno;
88 	char *ept, *eup, *up;
89 	size_t dlen;
90 
91 	/*
92 	 * If no buffer specified by the user, allocate one as necessary.
93 	 * If a buffer is specified, the size has to be non-zero.  The path
94 	 * is built from the end of the buffer backwards.
95 	 */
96 	if (pt) {
97 		ptsize = 0;
98 		if (!size) {
99 			errno = EINVAL;
100 			return (NULL);
101 		}
102 		ept = pt + size;
103 	} else {
104 		if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
105 			return (NULL);
106 		ept = pt + ptsize;
107 	}
108 	bpt = ept - 1;
109 	*bpt = '\0';
110 
111 	/*
112 	 * Allocate bytes (1024 - malloc space) for the string of "../"'s.
113 	 * Should always be enough (it's 340 levels).  If it's not, allocate
114 	 * as necessary.  Special case the first stat, it's ".", not "..".
115 	 */
116 	if ((up = malloc(upsize = 1024 - 4)) == NULL)
117 		goto err;
118 	eup = up + MAXPATHLEN;
119 	bup = up;
120 	up[0] = '.';
121 	up[1] = '\0';
122 
123 	/* Save root values, so know when to stop. */
124 	if (stat("/", &s))
125 		goto err;
126 	root_dev = s.st_dev;
127 	root_ino = s.st_ino;
128 
129 	errno = 0;			/* XXX readdir has no error return. */
130 
131 	for (first = 1;; first = 0) {
132 		/* Stat the current level. */
133 		if (lstat(up, &s))
134 			goto err;
135 
136 		/* Save current node values. */
137 		ino = s.st_ino;
138 		dev = s.st_dev;
139 
140 		/* Check for reaching root. */
141 		if (root_dev == dev && root_ino == ino) {
142 			*--bpt = '/';
143 			/*
144 			 * It's unclear that it's a requirement to copy the
145 			 * path to the beginning of the buffer, but it's always
146 			 * been that way and stuff would probably break.
147 			 */
148 			memmove(pt, bpt,  (size_t)(ept - bpt));
149 			free(up);
150 			return (pt);
151 		}
152 
153 		/*
154 		 * Build pointer to the parent directory, allocating memory
155 		 * as necessary.  Max length is 3 for "../", the largest
156 		 * possible component name, plus a trailing NULL.
157 		 */
158 		if (bup + 3  + MAXNAMLEN + 1 >= eup) {
159 			if ((up = realloc(up, upsize *= 2)) == NULL)
160 				goto err;
161 			bup = up;
162 			eup = up + upsize;
163 		}
164 		*bup++ = '.';
165 		*bup++ = '.';
166 		*bup = '\0';
167 
168 		/* Open and stat parent directory. */
169 		if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
170 			goto err;
171 
172 		/* Add trailing slash for next directory. */
173 		*bup++ = '/';
174 
175 		/*
176 		 * If it's a mount point, have to stat each element because
177 		 * the inode number in the directory is for the entry in the
178 		 * parent directory, not the inode number of the mounted file.
179 		 */
180 		save_errno = 0;
181 		if (s.st_dev == dev) {
182 			for (;;) {
183 				if (!(dp = readdir(dir)))
184 					goto notfound;
185 				if (dp->d_fileno == ino) {
186 #if defined(__SVR4) || defined(__svr4__)
187 					dlen = strlen(dp->d_name);
188 #else
189 					dlen = dp->d_namlen;
190 #endif
191 					break;
192 				}
193 			}
194 		} else
195 			for (;;) {
196 				if (!(dp = readdir(dir)))
197 					goto notfound;
198 				if (ISDOT(dp))
199 					continue;
200 #if defined(__SVR4) || defined(__svr4__)
201 				dlen = strlen(dp->d_name);
202 #else
203 				dlen = dp->d_namlen;
204 #endif
205 				memmove(bup, dp->d_name, dlen + 1);
206 
207 				/* Save the first error for later. */
208 				if (lstat(up, &s)) {
209 					if (!save_errno)
210 						save_errno = errno;
211 					errno = 0;
212 					continue;
213 				}
214 				if (s.st_dev == dev && s.st_ino == ino)
215 					break;
216 			}
217 
218 		/*
219 		 * Check for length of the current name, preceding slash,
220 		 * leading slash.
221 		 */
222 		if (bpt - pt <= dlen + (first ? 1 : 2)) {
223 			size_t len, off;
224 
225 			if (!ptsize) {
226 				errno = ERANGE;
227 				goto err;
228 			}
229 			off = bpt - pt;
230 			len = ept - bpt;
231 			if ((pt = realloc(pt, ptsize *= 2)) == NULL)
232 				goto err;
233 			bpt = pt + off;
234 			ept = pt + ptsize;
235 			memmove(ept - len, bpt, len);
236 			bpt = ept - len;
237 		}
238 		if (!first)
239 			*--bpt = '/';
240 		bpt -= dlen;
241 		memmove(bpt, dp->d_name, dlen);
242 		(void)closedir(dir);
243 
244 		/* Truncate any file name. */
245 		*bup = '\0';
246 	}
247 
248 notfound:
249 	/*
250 	 * If readdir set errno, use it, not any saved error; otherwise,
251 	 * didn't find the current directory in its parent directory, set
252 	 * errno to ENOENT.
253 	 */
254 	if (!errno)
255 		errno = save_errno ? save_errno : ENOENT;
256 	/* FALLTHROUGH */
257 err:
258 	if (ptsize)
259 		free(pt);
260 	free(up);
261 	return (NULL);
262 }
263