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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - include/uapi/linux/cramfs_fs.h
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _UAPI__CRAMFS_H
3 #define _UAPI__CRAMFS_H
5 #include <linux/types.h>
6 #include <linux/magic.h>
8 #define CRAMFS_SIGNATURE "Compressed ROMFS"
11 * Width of various bitfields in struct cramfs_inode.
12 * Primarily used to generate warnings in mkcramfs.
14 #define CRAMFS_MODE_WIDTH 16
15 #define CRAMFS_UID_WIDTH 16
16 #define CRAMFS_SIZE_WIDTH 24
17 #define CRAMFS_GID_WIDTH 8
18 #define CRAMFS_NAMELEN_WIDTH 6
19 #define CRAMFS_OFFSET_WIDTH 26
22 * Since inode.namelen is a unsigned 6-bit number, the maximum cramfs
23 * path length is 63 << 2 = 252.
25 #define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2)
28 * Reasonably terse representation of the inode data.
31 __u32 mode
:CRAMFS_MODE_WIDTH
, uid
:CRAMFS_UID_WIDTH
;
32 /* SIZE for device files is i_rdev */
33 __u32 size
:CRAMFS_SIZE_WIDTH
, gid
:CRAMFS_GID_WIDTH
;
34 /* NAMELEN is the length of the file name, divided by 4 and
35 rounded up. (cramfs doesn't support hard links.) */
36 /* OFFSET: For symlinks and non-empty regular files, this
37 contains the offset (divided by 4) of the file data in
38 compressed form (starting with an array of block pointers;
39 see README). For non-empty directories it is the offset
40 (divided by 4) of the inode of the first file in that
41 directory. For anything else, offset is zero. */
42 __u32 namelen
:CRAMFS_NAMELEN_WIDTH
, offset
:CRAMFS_OFFSET_WIDTH
;
53 * Superblock information at the beginning of the FS.
56 __u32 magic
; /* 0x28cd3d45 - random number */
57 __u32 size
; /* length in bytes */
58 __u32 flags
; /* feature flags */
59 __u32 future
; /* reserved for future use */
60 __u8 signature
[16]; /* "Compressed ROMFS" */
61 struct cramfs_info fsid
; /* unique filesystem info */
62 __u8 name
[16]; /* user-defined name */
63 struct cramfs_inode root
; /* root inode data */
69 * 0x00000000 - 0x000000ff: features that work for all past kernels
70 * 0x00000100 - 0xffffffff: features that don't work for past kernels
72 #define CRAMFS_FLAG_FSID_VERSION_2 0x00000001 /* fsid version #2 */
73 #define CRAMFS_FLAG_SORTED_DIRS 0x00000002 /* sorted dirs */
74 #define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */
75 #define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */
76 #define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */
79 * Valid values in super.flags. Currently we refuse to mount
80 * if (flags & ~CRAMFS_SUPPORTED_FLAGS). Maybe that should be
81 * changed to test super.future instead.
83 #define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \
85 | CRAMFS_FLAG_WRONG_SIGNATURE \
86 | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET )
89 #endif /* _UAPI__CRAMFS_H */