stream_buffer_encoder.c revision 292588 
1///////////////////////////////////////////////////////////////////////////////
2//
3/// \file       stream_buffer_encoder.c
4/// \brief      Single-call .xz Stream encoder
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 "index.h"
14
15
16/// Maximum size of Index that has exactly one Record.
17/// Index Indicator + Number of Records + Record + CRC32 rounded up to
18/// the next multiple of four.
19#define INDEX_BOUND ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 4 + 3) & ~3)
20
21/// Stream Header, Stream Footer, and Index
22#define HEADERS_BOUND (2 * LZMA_STREAM_HEADER_SIZE + INDEX_BOUND)
23
24
25extern LZMA_API(size_t)
26lzma_stream_buffer_bound(size_t uncompressed_size)
27{
28	// Get the maximum possible size of a Block.
29	const size_t block_bound = lzma_block_buffer_bound(uncompressed_size);
30	if (block_bound == 0)
31		return 0;
32
33	// Catch the possible integer overflow and also prevent the size of
34	// the Stream exceeding LZMA_VLI_MAX (theoretically possible on
35	// 64-bit systems).
36	if (my_min(SIZE_MAX, LZMA_VLI_MAX) - block_bound < HEADERS_BOUND)
37		return 0;
38
39	return block_bound + HEADERS_BOUND;
40}
41
42
43extern LZMA_API(lzma_ret)
44lzma_stream_buffer_encode(lzma_filter *filters, lzma_check check,
45		const lzma_allocator *allocator,
46		const uint8_t *in, size_t in_size,
47		uint8_t *out, size_t *out_pos_ptr, size_t out_size)
48{
49	// Sanity checks
50	if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX
51			|| (in == NULL && in_size != 0) || out == NULL
52			|| out_pos_ptr == NULL || *out_pos_ptr > out_size)
53		return LZMA_PROG_ERROR;
54
55	if (!lzma_check_is_supported(check))
56		return LZMA_UNSUPPORTED_CHECK;
57
58	// Note for the paranoids: Index encoder prevents the Stream from
59	// getting too big and still being accepted with LZMA_OK, and Block
60	// encoder catches if the input is too big. So we don't need to
61	// separately check if the buffers are too big.
62
63	// Use a local copy. We update *out_pos_ptr only if everything
64	// succeeds.
65	size_t out_pos = *out_pos_ptr;
66
67	// Check that there's enough space for both Stream Header and
68	// Stream Footer.
69	if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)
70		return LZMA_BUF_ERROR;
71
72	// Reserve space for Stream Footer so we don't need to check for
73	// available space again before encoding Stream Footer.
74	out_size -= LZMA_STREAM_HEADER_SIZE;
75
76	// Encode the Stream Header.
77	lzma_stream_flags stream_flags = {
78		.version = 0,
79		.check = check,
80	};
81
82	if (lzma_stream_header_encode(&stream_flags, out + out_pos)
83			!= LZMA_OK)
84		return LZMA_PROG_ERROR;
85
86	out_pos += LZMA_STREAM_HEADER_SIZE;
87
88	// Encode a Block but only if there is at least one byte of input.
89	lzma_block block = {
90		.version = 0,
91		.check = check,
92		.filters = filters,
93	};
94
95	if (in_size > 0)
96		return_if_error(lzma_block_buffer_encode(&block, allocator,
97				in, in_size, out, &out_pos, out_size));
98
99	// Index
100	{
101		// Create an Index. It will have one Record if there was
102		// at least one byte of input to encode. Otherwise the
103		// Index will be empty.
104		lzma_index *i = lzma_index_init(allocator);
105		if (i == NULL)
106			return LZMA_MEM_ERROR;
107
108		lzma_ret ret = LZMA_OK;
109
110		if (in_size > 0)
111			ret = lzma_index_append(i, allocator,
112					lzma_block_unpadded_size(&block),
113					block.uncompressed_size);
114
115		// If adding the Record was successful, encode the Index
116		// and get its size which will be stored into Stream Footer.
117		if (ret == LZMA_OK) {
118			ret = lzma_index_buffer_encode(
119					i, out, &out_pos, out_size);
120
121			stream_flags.backward_size = lzma_index_size(i);
122		}
123
124		lzma_index_end(i, allocator);
125
126		if (ret != LZMA_OK)
127			return ret;
128	}
129
130	// Stream Footer. We have already reserved space for this.
131	if (lzma_stream_footer_encode(&stream_flags, out + out_pos)
132			!= LZMA_OK)
133		return LZMA_PROG_ERROR;
134
135	out_pos += LZMA_STREAM_HEADER_SIZE;
136
137	// Everything went fine, make the new output position available
138	// to the application.
139	*out_pos_ptr = out_pos;
140	return LZMA_OK;
141}
142