include/linux/fs_types.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef _LINUX_FS_TYPES_H
0003 #define _LINUX_FS_TYPES_H
0004
0005 /*
0006  * This is a header for the common implementation of dirent
0007  * to fs on-disk file type conversion.  Although the fs on-disk
0008  * bits are specific to every file system, in practice, many
0009  * file systems use the exact same on-disk format to describe
0010  * the lower 3 file type bits that represent the 7 POSIX file
0011  * types.
0012  *
0013  * It is important to note that the definitions in this
0014  * header MUST NOT change. This would break both the
0015  * userspace ABI and the on-disk format of filesystems
0016  * using this code.
0017  *
0018  * All those file systems can use this generic code for the
0019  * conversions.
0020  */
0021
0022 /*
0023  * struct dirent file types
0024  * exposed to user via getdents(2), readdir(3)
0025  *
0026  * These match bits 12..15 of stat.st_mode
0027  * (ie "(i_mode >> 12) & 15").
0028  */
0029 #define S_DT_SHIFT  12
0030 #define S_DT(mode)  (((mode) & S_IFMT) >> S_DT_SHIFT)
0031 #define S_DT_MASK   (S_IFMT >> S_DT_SHIFT)
0032
0033 /* these are defined by POSIX and also present in glibc's dirent.h */
0034 #define DT_UNKNOWN  0
0035 #define DT_FIFO     1
0036 #define DT_CHR      2
0037 #define DT_DIR      4
0038 #define DT_BLK      6
0039 #define DT_REG      8
0040 #define DT_LNK      10
0041 #define DT_SOCK     12
0042 #define DT_WHT      14
0043
0044 #define DT_MAX      (S_DT_MASK + 1) /* 16 */
0045
0046 /*
0047  * fs on-disk file types.
0048  * Only the low 3 bits are used for the POSIX file types.
0049  * Other bits are reserved for fs private use.
0050  * These definitions are shared and used by multiple filesystems,
0051  * and MUST NOT change under any circumstances.
0052  *
0053  * Note that no fs currently stores the whiteout type on-disk,
0054  * so whiteout dirents are exposed to user as DT_CHR.
0055  */
0056 #define FT_UNKNOWN  0
0057 #define FT_REG_FILE 1
0058 #define FT_DIR      2
0059 #define FT_CHRDEV   3
0060 #define FT_BLKDEV   4
0061 #define FT_FIFO     5
0062 #define FT_SOCK     6
0063 #define FT_SYMLINK  7
0064
0065 #define FT_MAX      8
0066
0067 /*
0068  * declarations for helper functions, accompanying implementation
0069  * is in fs/fs_types.c
0070  */
0071 extern unsigned char fs_ftype_to_dtype(unsigned int filetype);
0072 extern unsigned char fs_umode_to_ftype(umode_t mode);
0073 extern unsigned char fs_umode_to_dtype(umode_t mode);
0074
0075 #endif