root/include/linux/fs_types.h

INCLUDED FROM

   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