369 lines
8.5 KiB
C
369 lines
8.5 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1983, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__SCCSID("@(#)opendir.c 8.8 (Berkeley) 5/1/95");
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <sys/param.h>
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "un-namespace.h"
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#include "gen-private.h"
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#include "telldir.h"
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static DIR * __opendir_common(int, int, bool);
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/*
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* Open a directory.
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*/
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DIR *
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opendir(const char *name)
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{
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return (__opendir2(name, DTF_HIDEW|DTF_NODUP));
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}
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/*
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* Open a directory with existing file descriptor.
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*/
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DIR *
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fdopendir(int fd)
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{
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if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
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return (NULL);
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return (__opendir_common(fd, DTF_HIDEW|DTF_NODUP, true));
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}
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DIR *
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__opendir2(const char *name, int flags)
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{
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int fd;
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DIR *dir;
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int saved_errno;
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if ((flags & (__DTF_READALL | __DTF_SKIPREAD)) != 0)
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return (NULL);
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if ((fd = _open(name,
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O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC)) == -1)
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return (NULL);
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dir = __opendir_common(fd, flags, false);
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if (dir == NULL) {
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saved_errno = errno;
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_close(fd);
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errno = saved_errno;
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}
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return (dir);
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}
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static int
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opendir_compar(const void *p1, const void *p2)
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{
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return (strcmp((*(const struct dirent * const *)p1)->d_name,
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(*(const struct dirent * const *)p2)->d_name));
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}
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/*
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* For a directory at the top of a unionfs stack, the entire directory's
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* contents are read and cached locally until the next call to rewinddir().
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* For the fdopendir() case, the initial seek position must be preserved.
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* For rewinddir(), the full directory should always be re-read from the
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* beginning.
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*
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* If an error occurs, the existing buffer and state of 'dirp' is left
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* unchanged.
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*/
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bool
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_filldir(DIR *dirp, bool use_current_pos)
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{
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struct dirent **dpv;
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char *buf, *ddptr, *ddeptr;
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off_t pos;
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int fd2, incr, len, n, saved_errno, space;
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len = 0;
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space = 0;
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buf = NULL;
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ddptr = NULL;
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/*
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* Use the system page size if that is a multiple of DIRBLKSIZ.
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* Hopefully this can be a big win someday by allowing page
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* trades to user space to be done by _getdirentries().
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*/
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incr = getpagesize();
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if ((incr % DIRBLKSIZ) != 0)
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incr = DIRBLKSIZ;
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/*
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* The strategy here is to read all the directory
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* entries into a buffer, sort the buffer, and
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* remove duplicate entries by setting the inode
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* number to zero.
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*
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* We reopen the directory because _getdirentries()
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* on a MNT_UNION mount modifies the open directory,
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* making it refer to the lower directory after the
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* upper directory's entries are exhausted.
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* This would otherwise break software that uses
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* the directory descriptor for fchdir or *at
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* functions, such as fts.c.
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*/
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if ((fd2 = _openat(dirp->dd_fd, ".", O_RDONLY | O_CLOEXEC)) == -1)
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return (false);
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if (use_current_pos) {
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pos = lseek(dirp->dd_fd, 0, SEEK_CUR);
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if (pos == -1 || lseek(fd2, pos, SEEK_SET) == -1) {
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saved_errno = errno;
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_close(fd2);
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errno = saved_errno;
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return (false);
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}
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}
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do {
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/*
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* Always make at least DIRBLKSIZ bytes
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* available to _getdirentries
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*/
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if (space < DIRBLKSIZ) {
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space += incr;
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len += incr;
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buf = reallocf(buf, len);
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if (buf == NULL) {
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saved_errno = errno;
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_close(fd2);
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errno = saved_errno;
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return (false);
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}
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ddptr = buf + (len - space);
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}
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n = _getdirentries(fd2, ddptr, space, &dirp->dd_seek);
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if (n > 0) {
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ddptr += n;
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space -= n;
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}
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if (n < 0) {
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saved_errno = errno;
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_close(fd2);
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errno = saved_errno;
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return (false);
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}
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} while (n > 0);
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_close(fd2);
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ddeptr = ddptr;
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/*
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* There is now a buffer full of (possibly) duplicate
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* names.
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*/
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dirp->dd_buf = buf;
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/*
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* Go round this loop twice...
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*
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* Scan through the buffer, counting entries.
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* On the second pass, save pointers to each one.
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* Then sort the pointers and remove duplicate names.
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*/
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for (dpv = NULL;;) {
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n = 0;
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ddptr = buf;
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while (ddptr < ddeptr) {
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struct dirent *dp;
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dp = (struct dirent *) ddptr;
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if ((long)dp & 03L)
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break;
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if ((dp->d_reclen <= 0) ||
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(dp->d_reclen > (ddeptr + 1 - ddptr)))
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break;
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ddptr += dp->d_reclen;
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if (dp->d_fileno) {
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if (dpv)
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dpv[n] = dp;
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n++;
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}
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}
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if (dpv) {
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struct dirent *xp;
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/*
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* This sort must be stable.
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*/
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mergesort(dpv, n, sizeof(*dpv), opendir_compar);
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dpv[n] = NULL;
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xp = NULL;
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/*
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* Scan through the buffer in sort order,
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* zapping the inode number of any
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* duplicate names.
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*/
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for (n = 0; dpv[n]; n++) {
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struct dirent *dp = dpv[n];
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if ((xp == NULL) ||
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strcmp(dp->d_name, xp->d_name)) {
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xp = dp;
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} else {
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dp->d_fileno = 0;
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}
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if (dp->d_type == DT_WHT &&
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(dirp->dd_flags & DTF_HIDEW))
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dp->d_fileno = 0;
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}
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free(dpv);
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break;
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} else {
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dpv = malloc((n+1) * sizeof(struct dirent *));
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if (dpv == NULL)
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break;
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}
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}
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dirp->dd_len = len;
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dirp->dd_size = ddptr - dirp->dd_buf;
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return (true);
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}
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static bool
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is_unionstack(int fd)
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{
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int unionstack;
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unionstack = _fcntl(fd, F_ISUNIONSTACK, 0);
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if (unionstack != -1)
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return (unionstack);
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/*
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* Should not happen unless running on a kernel without the op,
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* but no use rendering the system useless in such a case.
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*/
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return (0);
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}
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/*
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* Common routine for opendir(3), __opendir2(3) and fdopendir(3).
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*/
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static DIR *
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__opendir_common(int fd, int flags, bool use_current_pos)
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{
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DIR *dirp;
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int incr;
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int saved_errno;
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bool unionstack;
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if ((dirp = malloc(sizeof(DIR) + sizeof(struct _telldir))) == NULL)
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return (NULL);
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dirp->dd_buf = NULL;
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dirp->dd_fd = fd;
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dirp->dd_flags = flags;
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dirp->dd_loc = 0;
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dirp->dd_lock = NULL;
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dirp->dd_td = (struct _telldir *)((char *)dirp + sizeof(DIR));
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LIST_INIT(&dirp->dd_td->td_locq);
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dirp->dd_td->td_loccnt = 0;
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dirp->dd_compat_de = NULL;
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/*
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* Use the system page size if that is a multiple of DIRBLKSIZ.
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* Hopefully this can be a big win someday by allowing page
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* trades to user space to be done by _getdirentries().
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*/
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incr = getpagesize();
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if ((incr % DIRBLKSIZ) != 0)
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incr = DIRBLKSIZ;
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/*
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* Determine whether this directory is the top of a union stack.
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*/
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unionstack = false;
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if (flags & DTF_NODUP) {
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unionstack = is_unionstack(fd);
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}
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if (unionstack) {
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if (!_filldir(dirp, use_current_pos))
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goto fail;
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dirp->dd_flags |= __DTF_READALL;
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} else {
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dirp->dd_len = incr;
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dirp->dd_buf = malloc(dirp->dd_len);
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if (dirp->dd_buf == NULL)
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goto fail;
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if (use_current_pos) {
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/*
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* Read the first batch of directory entries
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* to prime dd_seek. This also checks if the
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* fd passed to fdopendir() is a directory.
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*/
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dirp->dd_size = _getdirentries(dirp->dd_fd,
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dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
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if (dirp->dd_size < 0) {
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if (errno == EINVAL)
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errno = ENOTDIR;
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goto fail;
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}
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dirp->dd_flags |= __DTF_SKIPREAD;
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} else {
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dirp->dd_size = 0;
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dirp->dd_seek = 0;
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}
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}
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return (dirp);
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fail:
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saved_errno = errno;
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free(dirp->dd_buf);
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free(dirp);
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errno = saved_errno;
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return (NULL);
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}
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