1/*
2 * Copyright (c) 1983, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Copyright (c) 2000
6 * 	Daniel Eischen.  All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * $FreeBSD: stable/11/lib/libc/gen/telldir.h 327850 2018-01-11 23:57:55Z asomers $
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	long	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#endif
108