1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
///////////////////////////////////////////////////////////////////////////////
//
/// \file block_header_decoder.c
/// \brief Decodes Block Header from .lzma files
//
// Copyright (C) 2007 Lasse Collin
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
///////////////////////////////////////////////////////////////////////////////
#include "common.h"
#include "check.h"
static void
free_properties(lzma_block *options, lzma_allocator *allocator)
{
// Free allocated filter options. The last array member is not
// touched after the initialization in the beginning of
// lzma_block_header_decode(), so we don't need to touch that here.
for (size_t i = 0; i < LZMA_BLOCK_FILTERS_MAX; ++i) {
lzma_free(options->filters[i].options, allocator);
options->filters[i].id = LZMA_VLI_UNKNOWN;
options->filters[i].options = NULL;
}
return;
}
extern LZMA_API lzma_ret
lzma_block_header_decode(lzma_block *options,
lzma_allocator *allocator, const uint8_t *in)
{
// NOTE: We consider the header to be corrupt not only when the
// CRC32 doesn't match, but also when variable-length integers
// are invalid or over 63 bits, or if the header is too small
// to contain the claimed information.
// Initialize the filter options array. This way the caller can
// safely free() the options even if an error occurs in this function.
for (size_t i = 0; i <= LZMA_BLOCK_FILTERS_MAX; ++i) {
options->filters[i].id = LZMA_VLI_UNKNOWN;
options->filters[i].options = NULL;
}
size_t in_size = options->header_size;
// Validate. The caller must have set options->header_size with
// lzma_block_header_size_decode() macro, so it is a programming error
// if these tests fail.
if (in_size < LZMA_BLOCK_HEADER_SIZE_MIN
|| in_size > LZMA_BLOCK_HEADER_SIZE_MAX
|| (in_size & 3)
|| lzma_block_header_size_decode(in[0]) != in_size)
return LZMA_PROG_ERROR;
// Exclude the CRC32 field.
in_size -= 4;
// Verify CRC32
if (lzma_crc32(in, in_size, 0) != integer_read_32(in + in_size))
return LZMA_DATA_ERROR;
// Check for unsupported flags.
if (in[1] & 0x3C)
return LZMA_OPTIONS_ERROR;
// Start after the Block Header Size and Block Flags fields.
size_t in_pos = 2;
// Compressed Size
if (in[1] & 0x40) {
return_if_error(lzma_vli_decode(&options->compressed_size,
NULL, in, &in_pos, in_size));
if (options->compressed_size > LZMA_VLI_MAX / 4 - 1)
return LZMA_DATA_ERROR;
options->compressed_size = (options->compressed_size + 1) * 4;
// Check that Total Size (that is, size of
// Block Header + Compressed Data + Check) is
// representable as a VLI.
if (lzma_block_total_size_get(options) == 0)
return LZMA_DATA_ERROR;
} else {
options->compressed_size = LZMA_VLI_UNKNOWN;
}
// Uncompressed Size
if (in[1] & 0x80)
return_if_error(lzma_vli_decode(&options->uncompressed_size,
NULL, in, &in_pos, in_size));
else
options->uncompressed_size = LZMA_VLI_UNKNOWN;
// Filter Flags
const size_t filter_count = (in[1] & 3) + 1;
for (size_t i = 0; i < filter_count; ++i) {
const lzma_ret ret = lzma_filter_flags_decode(
&options->filters[i], allocator,
in, &in_pos, in_size);
if (ret != LZMA_OK) {
free_properties(options, allocator);
return ret;
}
}
// Padding
while (in_pos < in_size) {
if (in[in_pos++] != 0x00) {
free_properties(options, allocator);
// Possibly some new field present so use
// LZMA_OPTIONS_ERROR instead of LZMA_DATA_ERROR.
return LZMA_OPTIONS_ERROR;
}
}
return LZMA_OK;
}
|
