lib/xz/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  */
  42 typedef 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 */
  51 enum 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