fba61ef227
This fixes a race condition where another thread may fork() before CLOEXEC is set, unintentionally passing the descriptor to the child process. This commit only adds O_CLOEXEC flags to open() or openat() calls where no fcntl(fd, F_SETFD, FD_CLOEXEC) follows. The separate fcntl() call still leaves a race window so it should be fixed later.
317 lines
7.1 KiB
C
317 lines
7.1 KiB
C
/*-
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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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* 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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#if defined(LIBC_SCCS) && !defined(lint)
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static char sccsid[] = "@(#)opendir.c 8.8 (Berkeley) 5/1/95";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/cdefs.h>
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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 <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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#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, const char *, int);
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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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struct stat statb;
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/* Check that fd is associated with a directory. */
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if (_fstat(fd, &statb) != 0)
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return (NULL);
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if (!S_ISDIR(statb.st_mode)) {
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errno = ENOTDIR;
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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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return (NULL);
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return (__opendir_common(fd, NULL, DTF_HIDEW|DTF_NODUP));
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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 ((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, name, flags);
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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 **)p1)->d_name,
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(*(const struct dirent **)p2)->d_name));
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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, const char *name, int flags)
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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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int unionstack;
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int fd2;
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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_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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/*
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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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if (flags & DTF_NODUP) {
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struct statfs sfb;
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if (_fstatfs(fd, &sfb) < 0)
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goto fail;
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unionstack = !strcmp(sfb.f_fstypename, "unionfs")
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|| (sfb.f_flags & MNT_UNION);
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} else {
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unionstack = 0;
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}
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if (unionstack) {
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int len = 0;
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int space = 0;
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char *buf = 0;
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char *ddptr = 0;
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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 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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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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goto fail;
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ddptr = buf + (len - space);
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}
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n = _getdirentries(fd, 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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} 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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if ((fd2 = _open(name, O_RDONLY | O_DIRECTORY |
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O_CLOEXEC)) == -1) {
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saved_errno = errno;
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free(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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(void)_dup2(fd2, fd);
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_close(fd2);
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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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for (dpv = 0;;) {
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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),
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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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(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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} else {
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dirp->dd_len = incr;
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dirp->dd_size = 0;
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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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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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dirp->dd_lock = NULL;
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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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fail:
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saved_errno = errno;
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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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