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
stream_flags_encode(const lzma_stream_flags * options,uint8_t * out)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)
lzma_stream_header_encode(const lzma_stream_flags * options,uint8_t * out)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 write32le(out + sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE,
50 crc);
51
52 return LZMA_OK;
53 }
54
55
56 extern LZMA_API(lzma_ret)
lzma_stream_footer_encode(const lzma_stream_flags * options,uint8_t * out)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 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 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