xref: /titanic_41/usr/src/cmd/ssh/libopenbsd-compat/common/getcwd.c (revision 7c478bd95313f5f23a4c958a745db2134aa03244)
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 *
getcwd(char * pt,size_t size)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"
240