aboutsummaryrefslogtreecommitdiff
path: root/src/liblzma/common/auto_decoder.c
blob: 4272dadfdbe2bb973994121ca4dabfcc5fb2d30c (plain) (blame)
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
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
///////////////////////////////////////////////////////////////////////////////
//
/// \file       auto_decoder.c
/// \brief      Autodetect between .lzma Stream and LZMA_Alone formats
//
//  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 "stream_decoder.h"
#include "alone_decoder.h"


struct lzma_coder_s {
	/// Stream decoder or LZMA_Alone decoder
	lzma_next_coder next;

	uint64_t memlimit;
	uint32_t flags;

	enum {
		SEQ_INIT,
		SEQ_CODE,
		SEQ_FINISH,
	} sequence;
};


static lzma_ret
auto_decode(lzma_coder *coder, lzma_allocator *allocator,
		const uint8_t *restrict in, size_t *restrict in_pos,
		size_t in_size, uint8_t *restrict out,
		size_t *restrict out_pos, size_t out_size, lzma_action action)
{
	switch (coder->sequence) {
	case SEQ_INIT:
		if (*in_pos >= in_size)
			return LZMA_OK;

		// Update the sequence now, because we want to continue from
		// SEQ_CODE even if we return some LZMA_*_CHECK.
		coder->sequence = SEQ_CODE;

		// Detect the file format. For now this is simple, since if
		// it doesn't start with 0xFF (the first magic byte of the
		// new format), it has to be LZMA_Alone, or something that
		// we don't support at all.
		if (in[*in_pos] == 0xFF) {
			return_if_error(lzma_stream_decoder_init(
					&coder->next, allocator,
					coder->memlimit, coder->flags));
		} else {
			return_if_error(lzma_alone_decoder_init(&coder->next,
					allocator, coder->memlimit));

			// If the application wants to know about missing
			// integrity check or about the check in general, we
			// need to handle it here, because LZMA_Alone decoder
			// doesn't accept any flags.
			if (coder->flags & LZMA_TELL_NO_CHECK)
				return LZMA_NO_CHECK;

			if (coder->flags & LZMA_TELL_ANY_CHECK)
				return LZMA_GET_CHECK;
		}

	// Fall through

	case SEQ_CODE: {
		const lzma_ret ret = coder->next.code(
				coder->next.coder, allocator,
				in, in_pos, in_size,
				out, out_pos, out_size, action);
		if (ret != LZMA_STREAM_END
				|| (coder->flags & LZMA_CONCATENATED) == 0)
			return ret;

		coder->sequence = SEQ_FINISH;
	}

	// Fall through

	case SEQ_FINISH:
		// When LZMA_DECODE_CONCATENATED was used and we were decoding
		// LZMA_Alone file, we need to check check that there is no
		// trailing garbage and wait for LZMA_FINISH.
		if (*in_pos < in_size)
			return LZMA_DATA_ERROR;

		return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK;

	default:
		assert(0);
		return LZMA_PROG_ERROR;
	}
}


static void
auto_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
{
	lzma_next_end(&coder->next, allocator);
	lzma_free(coder, allocator);
	return;
}


static lzma_check
auto_decoder_get_check(const lzma_coder *coder)
{
	// It is LZMA_Alone if get_check is NULL.
	return coder->next.get_check == NULL ? LZMA_CHECK_NONE
			: coder->next.get_check(coder->next.coder);
}


static lzma_ret
auto_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
		uint64_t memlimit, uint32_t flags)
{
	lzma_next_coder_init(auto_decoder_init, next, allocator);

	if (flags & ~LZMA_SUPPORTED_FLAGS)
		return LZMA_HEADER_ERROR;

	if (next->coder == NULL) {
		next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
		if (next->coder == NULL)
			return LZMA_MEM_ERROR;

		next->code = &auto_decode;
		next->end = &auto_decoder_end;
		next->get_check = &auto_decoder_get_check;
		next->coder->next = LZMA_NEXT_CODER_INIT;
	}

	next->coder->memlimit = memlimit;
	next->coder->flags = flags;
	next->coder->sequence = SEQ_INIT;

	return LZMA_OK;
}


extern LZMA_API lzma_ret
lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
{
	lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags);

	strm->internal->supported_actions[LZMA_RUN] = true;
	strm->internal->supported_actions[LZMA_FINISH] = true;

	return LZMA_OK;
}