1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1983, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Copyright (c) 2000
8 * 	Daniel Eischen.  All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#ifndef _TELLDIR_H_
36#define	_TELLDIR_H_
37
38#include <sys/queue.h>
39#include <stdbool.h>
40
41/*
42 * telldir will malloc one of these to describe the current directory position,
43 * if it can't fit that information into the packed structure below.  It
44 * records the current magic cookie returned by getdirentries and the offset
45 * within the buffer associated with that return value.
46 */
47struct ddloc_mem {
48	LIST_ENTRY(ddloc_mem) loc_lqe; /* entry in list */
49	long	loc_index;	/* key associated with structure */
50	off_t	loc_seek;	/* magic cookie returned by getdirentries */
51	long	loc_loc;	/* offset of entry in buffer */
52};
53
54#ifdef __LP64__
55#define DD_LOC_BITS	31
56#define DD_SEEK_BITS	32
57#define DD_INDEX_BITS	63
58#else
59#define DD_LOC_BITS	12
60#define DD_SEEK_BITS	19
61#define DD_INDEX_BITS	31
62#endif
63
64/*
65 * This is the real type returned by telldir.  telldir will prefer to return
66 * the packed type, if possible, or the malloced type otherwise.  For msdosfs,
67 * UFS, and NFS, directory positions usually fit within the packed type.  For
68 * ZFS and tmpfs, they usually fit within the packed type on 64-bit
69 * architectures.
70 */
71union ddloc_packed {
72	long	l;		/* Opaque type returned by telldir(3) */
73	struct {
74		/* Identifies union type.  Must be 0. */
75		unsigned long is_packed:1;
76		/* Index into directory's linked list of ddloc_mem */
77		unsigned long index:DD_INDEX_BITS;
78	} __packed i;
79	struct {
80		/* Identifies union type.  Must be 1. */
81		unsigned long is_packed:1;
82		/* offset of entry in buffer*/
83		unsigned long loc:DD_LOC_BITS;
84		/* magic cookie returned by getdirentries */
85		unsigned long seek:DD_SEEK_BITS;
86	} __packed s;
87};
88
89_Static_assert(sizeof(long) == sizeof(union ddloc_packed),
90    "packed telldir size mismatch!");
91
92/*
93 * One of these structures is malloced for each DIR to record telldir
94 * positions.
95 */
96struct _telldir {
97	LIST_HEAD(, ddloc_mem) td_locq; /* list of locations */
98	long	td_loccnt;	/* index of entry for sequential readdir's */
99};
100
101bool		_filldir(DIR *, bool);
102struct dirent	*_readdir_unlocked(DIR *, int);
103void 		_reclaim_telldir(DIR *);
104void 		_seekdir(DIR *, long);
105void		_fixtelldir(DIR *dirp, long oldseek, long oldloc);
106
107#define	RDU_SKIP	0x0001
108#define	RDU_SHORT	0x0002
109
110#endif
111