xref: /openbmc/linux/include/linux/fs_types.h (revision bbe7449e)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_FS_TYPES_H
3 #define _LINUX_FS_TYPES_H
4 
5 /*
6  * This is a header for the common implementation of dirent
7  * to fs on-disk file type conversion.  Although the fs on-disk
8  * bits are specific to every file system, in practice, many
9  * file systems use the exact same on-disk format to describe
10  * the lower 3 file type bits that represent the 7 POSIX file
11  * types.
12  *
13  * It is important to note that the definitions in this
14  * header MUST NOT change. This would break both the
15  * userspace ABI and the on-disk format of filesystems
16  * using this code.
17  *
18  * All those file systems can use this generic code for the
19  * conversions.
20  */
21 
22 /*
23  * struct dirent file types
24  * exposed to user via getdents(2), readdir(3)
25  *
26  * These match bits 12..15 of stat.st_mode
27  * (ie "(i_mode >> 12) & 15").
28  */
29 #define S_DT_SHIFT	12
30 #define S_DT(mode)	(((mode) & S_IFMT) >> S_DT_SHIFT)
31 #define S_DT_MASK	(S_IFMT >> S_DT_SHIFT)
32 
33 /* these are defined by POSIX and also present in glibc's dirent.h */
34 #define DT_UNKNOWN	0
35 #define DT_FIFO		1
36 #define DT_CHR		2
37 #define DT_DIR		4
38 #define DT_BLK		6
39 #define DT_REG		8
40 #define DT_LNK		10
41 #define DT_SOCK		12
42 #define DT_WHT		14
43 
44 #define DT_MAX		(S_DT_MASK + 1) /* 16 */
45 
46 /*
47  * fs on-disk file types.
48  * Only the low 3 bits are used for the POSIX file types.
49  * Other bits are reserved for fs private use.
50  * These definitions are shared and used by multiple filesystems,
51  * and MUST NOT change under any circumstances.
52  *
53  * Note that no fs currently stores the whiteout type on-disk,
54  * so whiteout dirents are exposed to user as DT_CHR.
55  */
56 #define FT_UNKNOWN	0
57 #define FT_REG_FILE	1
58 #define FT_DIR		2
59 #define FT_CHRDEV	3
60 #define FT_BLKDEV	4
61 #define FT_FIFO		5
62 #define FT_SOCK		6
63 #define FT_SYMLINK	7
64 
65 #define FT_MAX		8
66 
67 /*
68  * declarations for helper functions, accompanying implementation
69  * is in fs/fs_types.c
70  */
71 extern unsigned char fs_ftype_to_dtype(unsigned int filetype);
72 extern unsigned char fs_umode_to_ftype(umode_t mode);
73 extern unsigned char fs_umode_to_dtype(umode_t mode);
74 
75 #endif
76