1///////////////////////////////////////////////////////////////////////////////
2//
3/// \file       stream_flags_encoder.c
4/// \brief      Encodes Stream Header and Stream Footer for .xz files
5//
6//  Author:     Lasse Collin
7//
8//  This file has been put into the public domain.
9//  You can do whatever you want with this file.
10//
11///////////////////////////////////////////////////////////////////////////////
12
13#include "stream_flags_common.h"
14
15
16static bool
17stream_flags_encode(const lzma_stream_flags *options, uint8_t *out)
18{
19	if ((unsigned int)(options->check) > LZMA_CHECK_ID_MAX)
20		return true;
21
22	out[0] = 0x00;
23	out[1] = options->check;
24
25	return false;
26}
27
28
29extern LZMA_API(lzma_ret)
30lzma_stream_header_encode(const lzma_stream_flags *options, uint8_t *out)
31{
32	assert(sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE
33			+ 4 == LZMA_STREAM_HEADER_SIZE);
34
35	if (options->version != 0)
36		return LZMA_OPTIONS_ERROR;
37
38	// Magic
39	memcpy(out, lzma_header_magic, sizeof(lzma_header_magic));
40
41	// Stream Flags
42	if (stream_flags_encode(options, out + sizeof(lzma_header_magic)))
43		return LZMA_PROG_ERROR;
44
45	// CRC32 of the Stream Header
46	const uint32_t crc = lzma_crc32(out + sizeof(lzma_header_magic),
47			LZMA_STREAM_FLAGS_SIZE, 0);
48
49	unaligned_write32le(out + sizeof(lzma_header_magic)
50			+ LZMA_STREAM_FLAGS_SIZE, crc);
51
52	return LZMA_OK;
53}
54
55
56extern LZMA_API(lzma_ret)
57lzma_stream_footer_encode(const lzma_stream_flags *options, uint8_t *out)
58{
59	assert(2 * 4 + LZMA_STREAM_FLAGS_SIZE + sizeof(lzma_footer_magic)
60			== LZMA_STREAM_HEADER_SIZE);
61
62	if (options->version != 0)
63		return LZMA_OPTIONS_ERROR;
64
65	// Backward Size
66	if (!is_backward_size_valid(options))
67		return LZMA_PROG_ERROR;
68
69	unaligned_write32le(out + 4, options->backward_size / 4 - 1);
70
71	// Stream Flags
72	if (stream_flags_encode(options, out + 2 * 4))
73		return LZMA_PROG_ERROR;
74
75	// CRC32
76	const uint32_t crc = lzma_crc32(
77			out + 4, 4 + LZMA_STREAM_FLAGS_SIZE, 0);
78
79	unaligned_write32le(out, crc);
80
81	// Magic
82	memcpy(out + 2 * 4 + LZMA_STREAM_FLAGS_SIZE,
83			lzma_footer_magic, sizeof(lzma_footer_magic));
84
85	return LZMA_OK;
86}
87