Christopher Ferris | 2598113 | 2017-11-14 16:53:49 -0800 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ |
Ben Cheng | 30692c6 | 2013-10-15 18:26:18 -0700 | [diff] [blame] | 2 | #ifndef _UAPI__CRAMFS_H |
| 3 | #define _UAPI__CRAMFS_H |
| 4 | |
| 5 | #include <linux/types.h> |
| 6 | #include <linux/magic.h> |
| 7 | |
| 8 | #define CRAMFS_SIGNATURE "Compressed ROMFS" |
| 9 | |
| 10 | /* |
| 11 | * Width of various bitfields in struct cramfs_inode. |
| 12 | * Primarily used to generate warnings in mkcramfs. |
| 13 | */ |
| 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 |
| 20 | |
| 21 | /* |
| 22 | * Since inode.namelen is a unsigned 6-bit number, the maximum cramfs |
| 23 | * path length is 63 << 2 = 252. |
| 24 | */ |
| 25 | #define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2) |
| 26 | |
| 27 | /* |
| 28 | * Reasonably terse representation of the inode data. |
| 29 | */ |
| 30 | struct cramfs_inode { |
| 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; |
| 43 | }; |
| 44 | |
| 45 | struct cramfs_info { |
| 46 | __u32 crc; |
| 47 | __u32 edition; |
| 48 | __u32 blocks; |
| 49 | __u32 files; |
| 50 | }; |
| 51 | |
| 52 | /* |
| 53 | * Superblock information at the beginning of the FS. |
| 54 | */ |
| 55 | struct cramfs_super { |
| 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 */ |
| 64 | }; |
| 65 | |
| 66 | /* |
| 67 | * Feature flags |
| 68 | * |
| 69 | * 0x00000000 - 0x000000ff: features that work for all past kernels |
| 70 | * 0x00000100 - 0xffffffff: features that don't work for past kernels |
| 71 | */ |
| 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 */ |
Christopher Ferris | a1a109e | 2018-01-31 15:03:12 -0800 | [diff] [blame] | 77 | #define CRAMFS_FLAG_EXT_BLOCK_POINTERS 0x00000800 /* block pointer extensions */ |
Ben Cheng | 30692c6 | 2013-10-15 18:26:18 -0700 | [diff] [blame] | 78 | |
| 79 | /* |
| 80 | * Valid values in super.flags. Currently we refuse to mount |
| 81 | * if (flags & ~CRAMFS_SUPPORTED_FLAGS). Maybe that should be |
| 82 | * changed to test super.future instead. |
| 83 | */ |
| 84 | #define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \ |
| 85 | | CRAMFS_FLAG_HOLES \ |
| 86 | | CRAMFS_FLAG_WRONG_SIGNATURE \ |
Christopher Ferris | a1a109e | 2018-01-31 15:03:12 -0800 | [diff] [blame] | 87 | | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET \ |
| 88 | | CRAMFS_FLAG_EXT_BLOCK_POINTERS ) |
Ben Cheng | 30692c6 | 2013-10-15 18:26:18 -0700 | [diff] [blame] | 89 | |
Christopher Ferris | a1a109e | 2018-01-31 15:03:12 -0800 | [diff] [blame] | 90 | /* |
| 91 | * Block pointer flags |
| 92 | * |
| 93 | * The maximum block offset that needs to be represented is roughly: |
| 94 | * |
| 95 | * (1 << CRAMFS_OFFSET_WIDTH) * 4 + |
| 96 | * (1 << CRAMFS_SIZE_WIDTH) / PAGE_SIZE * (4 + PAGE_SIZE) |
| 97 | * = 0x11004000 |
| 98 | * |
| 99 | * That leaves room for 3 flag bits in the block pointer table. |
| 100 | */ |
| 101 | #define CRAMFS_BLK_FLAG_UNCOMPRESSED (1 << 31) |
| 102 | #define CRAMFS_BLK_FLAG_DIRECT_PTR (1 << 30) |
| 103 | |
| 104 | #define CRAMFS_BLK_FLAGS ( CRAMFS_BLK_FLAG_UNCOMPRESSED \ |
| 105 | | CRAMFS_BLK_FLAG_DIRECT_PTR ) |
| 106 | |
| 107 | /* |
| 108 | * Direct blocks are at least 4-byte aligned. |
| 109 | * Pointers to direct blocks are shifted down by 2 bits. |
| 110 | */ |
| 111 | #define CRAMFS_BLK_DIRECT_PTR_SHIFT 2 |
Ben Cheng | 30692c6 | 2013-10-15 18:26:18 -0700 | [diff] [blame] | 112 | |
| 113 | #endif /* _UAPI__CRAMFS_H */ |