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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
16 static bool
17 stream_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
29 extern LZMA_API(lzma_ret)
30 lzma_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
56 extern LZMA_API(lzma_ret)
57 lzma_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 }