/* $NetBSD: initdir.c,v 1.5 2021/07/11 16:30:41 kre Exp $ */
/*
* Copyright (c) 1983, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: initdir.c,v 1.5 2021/07/11 16:30:41 kre Exp $");
#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
#include "reentrant.h"
#include "extern.h"
#include <sys/param.h>
#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "dirent_private.h"
#define MAXITERATIONS 100
int
_initdir(DIR *dirp, int fd, const char *name)
{
int flags = dirp->dd_flags;
int pagesz;
int incr;
/*
* If the machine's page size is an exact multiple of DIRBLKSIZ,
* use a buffer that is cluster boundary aligned.
* Hopefully this can be a big win someday by allowing page trades
* to user space to be done by getdents()
*/
if (((pagesz = getpagesize()) % DIRBLKSIZ) == 0)
incr = pagesz;
else
incr = DIRBLKSIZ;
if ((flags & DTF_REWIND) && name == NULL) {
return EINVAL;
}
if ((flags & __DTF_READALL) != 0) {
size_t len;
size_t space;
char *buf, *nbuf;
char *ddptr;
char *ddeptr;
int n;
struct dirent **dpv;
int i;
/*
* The strategy here for directories on top of a union stack
* is to read all the directory entries into a buffer, sort
* the buffer, and remove duplicate entries by setting the
* inode number to zero.
*
* For directories on an NFS mounted filesystem, we try
* to get a consistent snapshot by trying until we have
* successfully read all of the directory without errors
* (i.e. 'bad cookie' errors from the server because
* the directory was modified). These errors should not
* happen often, but need to be dealt with.
*/
i = 0;
retry:
len = 0;
space = 0;
buf = 0;
ddptr = 0;
do {
/*
* Always make at least DIRBLKSIZ bytes
* available to getdents
*/
if (space < DIRBLKSIZ) {
space += incr;
len += incr;
nbuf = realloc(buf, len);
if (nbuf == NULL) {
dirp->dd_buf = buf;
return errno;
}
buf = nbuf;
ddptr = buf + (len - space);
}
dirp->dd_seek = lseek(fd, (off_t)0, SEEK_CUR);
n = getdents(fd, ddptr, space);
/*
* For NFS: EINVAL means a bad cookie error
* from the server. Keep trying to get a
* consistent view, in this case this means
* starting all over again.
*/
if (n == -1 && errno == EINVAL &&
(flags & __DTF_RETRY_ON_BADCOOKIE) != 0) {
free(buf);
lseek(fd, (off_t)0, SEEK_SET);
if (++i > MAXITERATIONS)
return EINVAL;
goto retry;
}
if (n > 0) {
ddptr += n;
space -= n;
}
} while (n > 0);
ddeptr = ddptr;
/*
* Re-open the directory.
* This has the effect of rewinding back to the
* top of the union stack and is needed by
* programs which plan to fchdir to a descriptor
* which has also been read -- see fts.c.
*/
if (flags & DTF_REWIND) {
(void) close(fd);
if ((fd = open(name, O_RDONLY | O_CLOEXEC)) == -1) {
dirp->dd_buf = buf;
return errno;
}
}
/*
* There is now a buffer full of (possibly) duplicate
* names.
*/
dirp->dd_buf = buf;
/*
* Go round this loop twice...
*
* Scan through the buffer, counting entries.
* On the second pass, save pointers to each one.
* Then sort the pointers and remove duplicate names.
*/
if ((flags & DTF_NODUP) != 0) {
for (dpv = 0;;) {
for (n = 0, ddptr = buf; ddptr < ddeptr;) {
struct dirent *dp;
dp = (struct dirent *)(void *)ddptr;
if ((long)dp & _DIRENT_ALIGN(dp))
break;
/*
* d_reclen is unsigned,
* so no need to compare <= 0
*/
if (dp->d_reclen > (ddeptr + 1 - ddptr))
break;
ddptr += dp->d_reclen;
if (dp->d_fileno) {
if (dpv)
dpv[n] = dp;
n++;
}
}
if (dpv) {
struct dirent *xp;
/*
* This sort must be stable.
*/
mergesort(dpv, (size_t)n, sizeof(*dpv),
(int (*)(const void *,
const void *))alphasort);
dpv[n] = NULL;
xp = NULL;
/*
* Scan through the buffer in sort
* order, zapping the inode number
* of any duplicate names.
*/
for (n = 0; dpv[n]; n++) {
struct dirent *dp = dpv[n];
if ((xp == NULL) ||
strcmp(dp->d_name,
xp->d_name))
xp = dp;
else
dp->d_fileno = 0;
if (dp->d_type == DT_WHT &&
(flags & DTF_HIDEW))
dp->d_fileno = 0;
}
free(dpv);
break;
} else {
dpv = malloc((n + 1) *
sizeof(struct dirent *));
if (dpv == NULL)
break;
}
}
}
_DIAGASSERT(__type_fit(int, len));
dirp->dd_len = (int)len;
dirp->dd_size = ddptr - dirp->dd_buf;
} else {
dirp->dd_len = incr;
dirp->dd_size = 0;
dirp->dd_buf = malloc((size_t)dirp->dd_len);
if (dirp->dd_buf == NULL)
return errno;
dirp->dd_seek = 0;
flags &= ~DTF_REWIND;
}
dirp->dd_loc = 0;
dirp->dd_fd = fd;
dirp->dd_flags = flags;
/*
* Set up seek point for rewinddir.
*/
(void)_telldir_unlocked(dirp);
return 0;
}
void
_finidir(DIR *dirp)
{
struct dirpos *poslist;
free(dirp->dd_buf);
/* free seekdir/telldir storage */
for (poslist = dirp->dd_internal; poslist; ) {
struct dirpos *nextpos = poslist->dp_next;
free(poslist);
poslist = nextpos;
}
dirp->dd_internal = NULL;
}
