fs_dirent.h

 1/* SPDX-License-Identifier: GPL-2.0 */
 2#ifndef _LINUX_FS_DIRENT_H
 3#define _LINUX_FS_DIRENT_H
 4
 5#include <linux/stat.h>
 6#include <linux/types.h>
 7
 8/*
 9 * This is a header for the common implementation of dirent
10 * to fs on-disk file type conversion.  Although the fs on-disk
11 * bits are specific to every file system, in practice, many
12 * file systems use the exact same on-disk format to describe
13 * the lower 3 file type bits that represent the 7 POSIX file
14 * types.
15 *
16 * It is important to note that the definitions in this
17 * header MUST NOT change. This would break both the
18 * userspace ABI and the on-disk format of filesystems
19 * using this code.
20 *
21 * All those file systems can use this generic code for the
22 * conversions.
23 */
24
25/*
26 * struct dirent file types
27 * exposed to user via getdents(2), readdir(3)
28 *
29 * These match bits 12..15 of stat.st_mode
30 * (ie "(i_mode >> 12) & 15").
31 */
32#define S_DT_SHIFT	12
33#define S_DT(mode)	(((mode) & S_IFMT) >> S_DT_SHIFT)
34#define S_DT_MASK	(S_IFMT >> S_DT_SHIFT)
35
36/* these are defined by POSIX and also present in glibc's dirent.h */
37#define DT_UNKNOWN	0
38#define DT_FIFO		1
39#define DT_CHR		2
40#define DT_DIR		4
41#define DT_BLK		6
42#define DT_REG		8
43#define DT_LNK		10
44#define DT_SOCK		12
45#define DT_WHT		14
46
47#define DT_MAX		(S_DT_MASK + 1) /* 16 */
48
49/*
50 * fs on-disk file types.
51 * Only the low 3 bits are used for the POSIX file types.
52 * Other bits are reserved for fs private use.
53 * These definitions are shared and used by multiple filesystems,
54 * and MUST NOT change under any circumstances.
55 *
56 * Note that no fs currently stores the whiteout type on-disk,
57 * so whiteout dirents are exposed to user as DT_CHR.
58 */
59#define FT_UNKNOWN	0
60#define FT_REG_FILE	1
61#define FT_DIR		2
62#define FT_CHRDEV	3
63#define FT_BLKDEV	4
64#define FT_FIFO		5
65#define FT_SOCK		6
66#define FT_SYMLINK	7
67
68#define FT_MAX		8
69
70/*
71 * declarations for helper functions, accompanying implementation
72 * is in fs/fs_dirent.c
73 */
74extern unsigned char fs_ftype_to_dtype(unsigned int filetype);
75extern unsigned char fs_umode_to_ftype(umode_t mode);
76extern unsigned char fs_umode_to_dtype(umode_t mode);
77
78#endif /* _LINUX_FS_DIRENT_H */