freebsd-skq/lib/libc/gen/telldir.h
John Baldwin 9f72c0322c Fix some edge cases with rewinddir():
- In the unionfs case, opendir() and fdopendir() read the directory's full
  contents and cache it.  This cache is not refreshed when rewinddir() is
  called, so rewinddir() will not notice updates to a directory.  Fix this
  by splitting the code to fetch a directory's contents out of
  __opendir_common() into a new _filldir() function and call this from
  rewinddir() when operating on a unionfs directory.
- If rewinddir() is called on a directory opened with fdopendir() before
  any directory entries are fetched, rewinddir() will not adjust the seek
  location of the backing file descriptor.  If the file descriptor passed
  to fdopendir() had a non-zero offset, the rewinddir() will not rewind to
  the beginning.  Fix this by always seeking back to 0 in rewinddir().
  This means the dd_rewind hack can also be removed.

While here, add missing locking to rewinddir().

CR:   	    	https://phabric.freebsd.org/D312
Reviewed by:	jilles
MFC after:	1 week
2014-07-11 16:16:26 +00:00

69 lines
2.6 KiB
C

/*
* Copyright (c) 1983, 1993
* The Regents of the University of California. All rights reserved.
*
* Copyright (c) 2000
* Daniel Eischen. 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.
*
* $FreeBSD$
*/
#ifndef _TELLDIR_H_
#define _TELLDIR_H_
#include <sys/queue.h>
#include <stdbool.h>
/*
* One of these structures is malloced to describe the current directory
* position each time telldir is called. It records the current magic
* cookie returned by getdirentries and the offset within the buffer
* associated with that return value.
*/
struct ddloc {
LIST_ENTRY(ddloc) loc_lqe; /* entry in list */
long loc_index; /* key associated with structure */
long loc_seek; /* magic cookie returned by getdirentries */
long loc_loc; /* offset of entry in buffer */
};
/*
* One of these structures is malloced for each DIR to record telldir
* positions.
*/
struct _telldir {
LIST_HEAD(, ddloc) td_locq; /* list of locations */
long td_loccnt; /* index of entry for sequential readdir's */
};
bool _filldir(DIR *, bool);
struct dirent *_readdir_unlocked(DIR *, int);
void _reclaim_telldir(DIR *);
void _seekdir(DIR *, long);
#endif