xz_stream.h

 1/* SPDX-License-Identifier: 0BSD */
 2
 3/*
 4 * Definitions for handling the .xz file format
 5 *
 6 * Author: Lasse Collin <lasse.collin@tukaani.org>
 7 */
 8
 9#ifndef XZ_STREAM_H
10#define XZ_STREAM_H
11
12#if defined(__KERNEL__) && !XZ_INTERNAL_CRC32
13#	include <linux/crc32.h>
14#	undef crc32
15#	define xz_crc32(buf, size, crc) \
16		(~crc32_le(~(uint32_t)(crc), buf, size))
17#endif
18
19/*
20 * See the .xz file format specification at
21 * https://tukaani.org/xz/xz-file-format.txt
22 * to understand the container format.
23 */
24
25#define STREAM_HEADER_SIZE 12
26
27#define HEADER_MAGIC "\3757zXZ"
28#define HEADER_MAGIC_SIZE 6
29
30#define FOOTER_MAGIC "YZ"
31#define FOOTER_MAGIC_SIZE 2
32
33/*
34 * Variable-length integer can hold a 63-bit unsigned integer or a special
35 * value indicating that the value is unknown.
36 *
37 * Experimental: vli_type can be defined to uint32_t to save a few bytes
38 * in code size (no effect on speed). Doing so limits the uncompressed and
39 * compressed size of the file to less than 256 MiB and may also weaken
40 * error detection slightly.
41 */
42typedef uint64_t vli_type;
43
44#define VLI_MAX ((vli_type)-1 / 2)
45#define VLI_UNKNOWN ((vli_type)-1)
46
47/* Maximum encoded size of a VLI */
48#define VLI_BYTES_MAX (sizeof(vli_type) * 8 / 7)
49
50/* Integrity Check types */
51enum xz_check {
52	XZ_CHECK_NONE = 0,
53	XZ_CHECK_CRC32 = 1,
54	XZ_CHECK_CRC64 = 4,
55	XZ_CHECK_SHA256 = 10
56};
57
58/* Maximum possible Check ID */
59#define XZ_CHECK_MAX 15
60
61#endif