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Many file systems use a copy&paste implementation of dirent to on-disk file type conversions. Create a common implementation to be used by file systems with some useful conversion helpers to reduce open coded file type conversions in file system code. Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Phillip Potter <phil@philpotter.co.uk> Signed-off-by: Jan Kara <jack@suse.cz>
75 lines
2 KiB
C
75 lines
2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_FS_TYPES_H
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#define _LINUX_FS_TYPES_H
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/*
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* This is a header for the common implementation of dirent
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* to fs on-disk file type conversion. Although the fs on-disk
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* bits are specific to every file system, in practice, many
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* file systems use the exact same on-disk format to describe
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* the lower 3 file type bits that represent the 7 POSIX file
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* types.
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*
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* It is important to note that the definitions in this
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* header MUST NOT change. This would break both the
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* userspace ABI and the on-disk format of filesystems
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* using this code.
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*
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* All those file systems can use this generic code for the
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* conversions.
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*/
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/*
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* struct dirent file types
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* exposed to user via getdents(2), readdir(3)
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*
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* These match bits 12..15 of stat.st_mode
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* (ie "(i_mode >> 12) & 15").
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*/
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#define S_DT_SHIFT 12
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#define S_DT(mode) (((mode) & S_IFMT) >> S_DT_SHIFT)
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#define S_DT_MASK (S_IFMT >> S_DT_SHIFT)
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/* these are defined by POSIX and also present in glibc's dirent.h */
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#define DT_UNKNOWN 0
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#define DT_FIFO 1
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#define DT_CHR 2
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#define DT_DIR 4
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#define DT_BLK 6
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#define DT_REG 8
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#define DT_LNK 10
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#define DT_SOCK 12
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#define DT_WHT 14
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#define DT_MAX (S_DT_MASK + 1) /* 16 */
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/*
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* fs on-disk file types.
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* Only the low 3 bits are used for the POSIX file types.
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* Other bits are reserved for fs private use.
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* These definitions are shared and used by multiple filesystems,
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* and MUST NOT change under any circumstances.
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*
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* Note that no fs currently stores the whiteout type on-disk,
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* so whiteout dirents are exposed to user as DT_CHR.
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*/
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#define FT_UNKNOWN 0
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#define FT_REG_FILE 1
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#define FT_DIR 2
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#define FT_CHRDEV 3
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#define FT_BLKDEV 4
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#define FT_FIFO 5
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#define FT_SOCK 6
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#define FT_SYMLINK 7
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#define FT_MAX 8
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/*
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* declarations for helper functions, accompanying implementation
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* is in fs/fs_types.c
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*/
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extern unsigned char fs_ftype_to_dtype(unsigned int filetype);
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extern unsigned char fs_umode_to_ftype(umode_t mode);
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extern unsigned char fs_umode_to_dtype(umode_t mode);
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#endif
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