opendir.c revision 178256
1178253Sdelphij/*-
21573Srgrimes * Copyright (c) 1983, 1993
31573Srgrimes *	The Regents of the University of California.  All rights reserved.
41573Srgrimes *
51573Srgrimes * Redistribution and use in source and binary forms, with or without
61573Srgrimes * modification, are permitted provided that the following conditions
71573Srgrimes * are met:
81573Srgrimes * 1. Redistributions of source code must retain the above copyright
91573Srgrimes *    notice, this list of conditions and the following disclaimer.
101573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright
111573Srgrimes *    notice, this list of conditions and the following disclaimer in the
121573Srgrimes *    documentation and/or other materials provided with the distribution.
131573Srgrimes * 4. Neither the name of the University nor the names of its contributors
141573Srgrimes *    may be used to endorse or promote products derived from this software
151573Srgrimes *    without specific prior written permission.
161573Srgrimes *
171573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
181573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
191573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
201573Srgrimes * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
211573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
221573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
231573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
241573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
251573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
261573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
271573Srgrimes * SUCH DAMAGE.
281573Srgrimes */
291573Srgrimes
301573Srgrimes#if defined(LIBC_SCCS) && !defined(lint)
3123668Speterstatic char sccsid[] = "@(#)opendir.c	8.8 (Berkeley) 5/1/95";
321573Srgrimes#endif /* LIBC_SCCS and not lint */
3390039Sobrien#include <sys/cdefs.h>
3490039Sobrien__FBSDID("$FreeBSD: head/lib/libc/gen/opendir.c 178256 2008-04-16 18:59:36Z delphij $");
351573Srgrimes
3671579Sdeischen#include "namespace.h"
371573Srgrimes#include <sys/param.h>
3823768Sbde#include <sys/mount.h>
397978Sbde#include <sys/stat.h>
401573Srgrimes
411573Srgrimes#include <dirent.h>
427978Sbde#include <errno.h>
431573Srgrimes#include <fcntl.h>
441573Srgrimes#include <stdlib.h>
45108631Stjr#include <string.h>
461573Srgrimes#include <unistd.h>
4771579Sdeischen#include "un-namespace.h"
481573Srgrimes
4969841Sdeischen#include "telldir.h"
50178256Sdelphij
51178256Sdelphijstatic DIR * __opendir_common(int, const char *, int);
52178256Sdelphij
531573Srgrimes/*
5423668Speter * Open a directory.
551573Srgrimes */
561573SrgrimesDIR *
57178253Sdelphijopendir(const char *name)
581573Srgrimes{
5973632Sobrien
6023668Speter	return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
6123668Speter}
621573Srgrimes
63178256Sdelphij/*
64178256Sdelphij * Open a directory with existing file descriptor.
65178256Sdelphij */
6623668SpeterDIR *
67178256Sdelphijfdopendir(int fd)
68178256Sdelphij{
69178256Sdelphij
70178256Sdelphij	return (__opendir_common(fd, NULL, DTF_HIDEW|DTF_NODUP));
71178256Sdelphij}
72178256Sdelphij
73178256SdelphijDIR *
74178253Sdelphij__opendir2(const char *name, int flags)
7523668Speter{
7623668Speter	int fd;
7723668Speter	struct stat statb;
7823668Speter
7914910Sbde	/*
8071579Sdeischen	 * stat() before _open() because opening of special files may be
81178256Sdelphij	 * harmful.
8214910Sbde	 */
8323668Speter	if (stat(name, &statb) != 0)
8423768Sbde		return (NULL);
8523668Speter	if (!S_ISDIR(statb.st_mode)) {
8614910Sbde		errno = ENOTDIR;
8723768Sbde		return (NULL);
8814910Sbde	}
8956698Sjasone	if ((fd = _open(name, O_RDONLY | O_NONBLOCK)) == -1)
9023668Speter		return (NULL);
91178256Sdelphij
92178256Sdelphij	return __opendir_common(fd, name, flags);
93178256Sdelphij}
94178256Sdelphij
95178256Sdelphij/*
96178256Sdelphij * Common routine for opendir(3), __opendir2(3) and fdopendir(3).
97178256Sdelphij */
98178256Sdelphijstatic DIR *
99178256Sdelphij__opendir_common(int fd, const char *name, int flags)
100178256Sdelphij{
101178256Sdelphij	DIR *dirp;
102178256Sdelphij	int incr;
103178256Sdelphij	int saved_errno;
104178256Sdelphij	int unionstack;
105178256Sdelphij	struct stat statb;
106178256Sdelphij
10723768Sbde	dirp = NULL;
108178256Sdelphij	/* _fstat() the open handler because the file may have changed.  */
10971579Sdeischen	if (_fstat(fd, &statb) != 0)
11023768Sbde		goto fail;
11123768Sbde	if (!S_ISDIR(statb.st_mode)) {
1127978Sbde		errno = ENOTDIR;
11323768Sbde		goto fail;
1147978Sbde	}
11556698Sjasone	if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
11669841Sdeischen	    (dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
11723768Sbde		goto fail;
11823668Speter
119133723Sstefanf	dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
12069841Sdeischen	LIST_INIT(&dirp->dd_td->td_locq);
12169841Sdeischen	dirp->dd_td->td_loccnt = 0;
12269841Sdeischen
1231573Srgrimes	/*
12423768Sbde	 * Use the system page size if that is a multiple of DIRBLKSIZ.
12523668Speter	 * Hopefully this can be a big win someday by allowing page
12671579Sdeischen	 * trades to user space to be done by _getdirentries().
1271573Srgrimes	 */
12823668Speter	incr = getpagesize();
12923668Speter	if ((incr % DIRBLKSIZ) != 0)
13023668Speter		incr = DIRBLKSIZ;
13123668Speter
13223668Speter	/*
13323668Speter	 * Determine whether this directory is the top of a union stack.
13423668Speter	 */
13523668Speter	if (flags & DTF_NODUP) {
13623668Speter		struct statfs sfb;
13723668Speter
13871579Sdeischen		if (_fstatfs(fd, &sfb) < 0)
13923768Sbde			goto fail;
140115047Stjr		unionstack = !strcmp(sfb.f_fstypename, "unionfs")
14175860Sjoerg		    || (sfb.f_flags & MNT_UNION);
14223668Speter	} else {
14323668Speter		unionstack = 0;
14423668Speter	}
14523668Speter
14623668Speter	if (unionstack) {
14723668Speter		int len = 0;
14823668Speter		int space = 0;
14923668Speter		char *buf = 0;
15023668Speter		char *ddptr = 0;
15123668Speter		char *ddeptr;
15223668Speter		int n;
15323668Speter		struct dirent **dpv;
15423668Speter
15523668Speter		/*
15623668Speter		 * The strategy here is to read all the directory
15723668Speter		 * entries into a buffer, sort the buffer, and
15823668Speter		 * remove duplicate entries by setting the inode
15923668Speter		 * number to zero.
16023668Speter		 */
16123668Speter
16223668Speter		do {
16323668Speter			/*
16423668Speter			 * Always make at least DIRBLKSIZ bytes
16571579Sdeischen			 * available to _getdirentries
16623668Speter			 */
16723668Speter			if (space < DIRBLKSIZ) {
16823668Speter				space += incr;
16923668Speter				len += incr;
17039327Simp				buf = reallocf(buf, len);
17123768Sbde				if (buf == NULL)
17223768Sbde					goto fail;
17323668Speter				ddptr = buf + (len - space);
17423668Speter			}
17523668Speter
17671579Sdeischen			n = _getdirentries(fd, ddptr, space, &dirp->dd_seek);
17723668Speter			if (n > 0) {
17823668Speter				ddptr += n;
17923668Speter				space -= n;
18023668Speter			}
18123668Speter		} while (n > 0);
18223668Speter
18323668Speter		ddeptr = ddptr;
18423668Speter		flags |= __DTF_READALL;
18523668Speter
18623668Speter		/*
18723668Speter		 * Re-open the directory.
18823668Speter		 * This has the effect of rewinding back to the
18923668Speter		 * top of the union stack and is needed by
19023668Speter		 * programs which plan to fchdir to a descriptor
19123668Speter		 * which has also been read -- see fts.c.
19223668Speter		 */
19323668Speter		if (flags & DTF_REWIND) {
19456698Sjasone			(void)_close(fd);
19556698Sjasone			if ((fd = _open(name, O_RDONLY)) == -1) {
19623768Sbde				saved_errno = errno;
19723668Speter				free(buf);
19823668Speter				free(dirp);
19923768Sbde				errno = saved_errno;
20023668Speter				return (NULL);
20123668Speter			}
20223668Speter		}
20323668Speter
20423668Speter		/*
20523668Speter		 * There is now a buffer full of (possibly) duplicate
20623668Speter		 * names.
20723668Speter		 */
20823668Speter		dirp->dd_buf = buf;
20923668Speter
21023668Speter		/*
21123668Speter		 * Go round this loop twice...
21223668Speter		 *
21323668Speter		 * Scan through the buffer, counting entries.
21423668Speter		 * On the second pass, save pointers to each one.
21523668Speter		 * Then sort the pointers and remove duplicate names.
21623668Speter		 */
21723668Speter		for (dpv = 0;;) {
21823668Speter			n = 0;
21923668Speter			ddptr = buf;
22023668Speter			while (ddptr < ddeptr) {
22123668Speter				struct dirent *dp;
22223668Speter
22323668Speter				dp = (struct dirent *) ddptr;
22434357Sjb				if ((long)dp & 03L)
22523668Speter					break;
22623668Speter				if ((dp->d_reclen <= 0) ||
22723668Speter				    (dp->d_reclen > (ddeptr + 1 - ddptr)))
22823668Speter					break;
22923668Speter				ddptr += dp->d_reclen;
23023668Speter				if (dp->d_fileno) {
23123668Speter					if (dpv)
23223668Speter						dpv[n] = dp;
23323668Speter					n++;
23423668Speter				}
23523668Speter			}
23623668Speter
23723668Speter			if (dpv) {
23823668Speter				struct dirent *xp;
23923668Speter
24023668Speter				/*
24123668Speter				 * This sort must be stable.
24223668Speter				 */
24323668Speter				mergesort(dpv, n, sizeof(*dpv), alphasort);
24423668Speter
24523668Speter				dpv[n] = NULL;
24623668Speter				xp = NULL;
24723668Speter
24823668Speter				/*
24923668Speter				 * Scan through the buffer in sort order,
25023668Speter				 * zapping the inode number of any
25123668Speter				 * duplicate names.
25223668Speter				 */
25323668Speter				for (n = 0; dpv[n]; n++) {
25423668Speter					struct dirent *dp = dpv[n];
25523668Speter
25623668Speter					if ((xp == NULL) ||
25723668Speter					    strcmp(dp->d_name, xp->d_name)) {
25823668Speter						xp = dp;
25923668Speter					} else {
26023668Speter						dp->d_fileno = 0;
26123668Speter					}
26223668Speter					if (dp->d_type == DT_WHT &&
26323668Speter					    (flags & DTF_HIDEW))
26423668Speter						dp->d_fileno = 0;
26523668Speter				}
26623668Speter
26723668Speter				free(dpv);
26823668Speter				break;
26923668Speter			} else {
27023668Speter				dpv = malloc((n+1) * sizeof(struct dirent *));
27123668Speter				if (dpv == NULL)
27223668Speter					break;
27323668Speter			}
27423668Speter		}
27523668Speter
27623668Speter		dirp->dd_len = len;
27723668Speter		dirp->dd_size = ddptr - dirp->dd_buf;
27823668Speter	} else {
27923668Speter		dirp->dd_len = incr;
280123861Sdfr		dirp->dd_size = 0;
28123668Speter		dirp->dd_buf = malloc(dirp->dd_len);
28223768Sbde		if (dirp->dd_buf == NULL)
28323768Sbde			goto fail;
28423668Speter		dirp->dd_seek = 0;
28523668Speter		flags &= ~DTF_REWIND;
28623668Speter	}
28723668Speter
28823668Speter	dirp->dd_loc = 0;
2891573Srgrimes	dirp->dd_fd = fd;
29023668Speter	dirp->dd_flags = flags;
29171579Sdeischen	dirp->dd_lock = NULL;
29223668Speter
2931573Srgrimes	/*
2941573Srgrimes	 * Set up seek point for rewinddir.
2951573Srgrimes	 */
2961573Srgrimes	dirp->dd_rewind = telldir(dirp);
2977978Sbde
29823668Speter	return (dirp);
29923768Sbde
30023768Sbdefail:
30123768Sbde	saved_errno = errno;
30223768Sbde	free(dirp);
30356698Sjasone	(void)_close(fd);
30423768Sbde	errno = saved_errno;
30523768Sbde	return (NULL);
3061573Srgrimes}
307