LXR linux/include/linux/fs

   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 */
  71extern unsigned char fs_ftype_to_dtype(unsigned int filetype);
  72extern unsigned char fs_umode_to_ftype(umode_t mode);
  73extern unsigned char fs_umode_to_dtype(umode_t mode);
  74
  75#endif
  76