311 lines
7.5 KiB
C
311 lines
7.5 KiB
C
/* $NetBSD: opendir.c,v 1.17 1998/11/13 12:31:50 christos Exp $ */
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. 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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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)opendir.c 8.7 (Berkeley) 12/10/94";
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#else
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__RCSID("$NetBSD: opendir.c,v 1.17 1998/11/13 12:31:50 christos Exp $");
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#endif
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#endif /* LIBC_SCCS and not lint */
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#include "namespace.h"
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#include <sys/param.h>
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#include <sys/mount.h>
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#include <sys/stat.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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#ifdef __weak_alias
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__weak_alias(opendir,_opendir);
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#endif
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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(name)
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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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DIR *
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__opendir2(name, flags)
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const char *name;
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int flags;
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{
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DIR *dirp;
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int fd;
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struct stat sb;
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int pagesz;
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int incr;
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int unionstack, nfsdir;
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struct statfs sfb;
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if ((fd = open(name, O_RDONLY | O_NONBLOCK)) == -1)
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return (NULL);
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if (fstat(fd, &sb) || !S_ISDIR(sb.st_mode)) {
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errno = ENOTDIR;
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close(fd);
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return (NULL);
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}
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if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
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(dirp = (DIR *)malloc(sizeof(DIR))) == NULL) {
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close(fd);
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return (NULL);
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}
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/*
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* If the machine's page size is an exact multiple of DIRBLKSIZ,
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* use a buffer that is cluster boundary aligned.
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* Hopefully this can be a big win someday by allowing page trades
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* to user space to be done by getdirentries()
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*/
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if (((pagesz = getpagesize()) % DIRBLKSIZ) == 0)
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incr = pagesz;
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else
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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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if (fstatfs(fd, &sfb) < 0) {
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free(dirp);
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close(fd);
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return (NULL);
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}
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if (flags & DTF_NODUP)
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unionstack = !(strncmp(sfb.f_fstypename, MOUNT_UNION,
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MFSNAMELEN)) || (sfb.f_flags & MNT_UNION);
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else
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unionstack = 0;
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nfsdir = !(strncmp(sfb.f_fstypename, MOUNT_NFS, MFSNAMELEN));
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if (unionstack || nfsdir) {
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size_t len;
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size_t space;
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char *buf;
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char *ddptr;
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char *ddeptr;
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int n;
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struct dirent **dpv;
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/*
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* The strategy here for directories on top of a union stack
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* is to read all the directory entries into a buffer, sort
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* the buffer, and remove duplicate entries by setting the
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* inode number to zero.
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*
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* For directories on an NFS mounted filesystem, we try
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* to get a consistent snapshot by trying until we have
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* successfully read all of the directory without errors
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* (i.e. 'bad cookie' errors from the server because
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* the directory was modified). These errors should not
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* happen often, but need to be dealt with.
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*/
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retry:
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len = 0;
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space = 0;
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buf = 0;
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ddptr = 0;
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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 = realloc(buf, len);
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if (buf == NULL) {
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free(dirp);
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close(fd);
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return (NULL);
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}
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ddptr = buf + (len - space);
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}
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dirp->dd_seek = lseek(fd, (off_t)0, SEEK_CUR);
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n = getdents(fd, ddptr, space);
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/*
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* For NFS: EINVAL means a bad cookie error
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* from the server. Keep trying to get a
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* consistent view, in this case this means
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* starting all over again.
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*/
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if (n == -1 && errno == EINVAL && nfsdir) {
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free(buf);
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lseek(fd, (off_t)0, SEEK_SET);
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goto retry;
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}
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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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} while (n > 0);
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ddeptr = ddptr;
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flags |= __DTF_READALL;
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/*
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* Re-open the directory.
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* This has the effect of rewinding back to the
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* top of the union stack and is needed by
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* programs which plan to fchdir to a descriptor
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* which has also been read -- see fts.c.
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*/
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if (flags & DTF_REWIND) {
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(void) close(fd);
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if ((fd = open(name, O_RDONLY)) == -1) {
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free(buf);
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free(dirp);
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return (NULL);
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}
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}
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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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if (!nfsdir) {
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for (dpv = 0;;) {
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for (n = 0, ddptr = buf; ddptr < ddeptr;) {
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struct dirent *dp;
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dp = (struct dirent *)(void *)ddptr;
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if ((long)dp & 03)
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break;
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/*
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* d_reclen is unsigned,
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* so no need to compare <= 0
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*/
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if (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, (size_t)n, sizeof(*dpv),
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alphasort);
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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
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* order, zapping the inode number
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* of any 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,
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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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if (dp->d_type == DT_WHT &&
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(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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}
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dirp->dd_len = len;
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dirp->dd_size = ddptr - dirp->dd_buf;
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} else {
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dirp->dd_len = incr;
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dirp->dd_buf = malloc((size_t)dirp->dd_len);
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if (dirp->dd_buf == NULL) {
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free(dirp);
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close (fd);
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return (NULL);
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}
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dirp->dd_seek = 0;
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flags &= ~DTF_REWIND;
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}
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dirp->dd_loc = 0;
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dirp->dd_fd = fd;
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dirp->dd_flags = flags;
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/*
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* Set up seek point for rewinddir.
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*/
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dirp->dd_rewind = telldir(dirp);
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return (dirp);
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}
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