stream_buffer_encoder.c revision 213700 
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		lzma_allocator *allocator, const uint8_t *in, size_t in_size,
46		uint8_t *out, size_t *out_pos_ptr, size_t out_size)
47{
48	// Sanity checks
49	if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX
50			|| (in == NULL && in_size != 0) || out == NULL
51			|| out_pos_ptr == NULL || *out_pos_ptr > out_size)
52		return LZMA_PROG_ERROR;
53
54	// Note for the paranoids: Index encoder prevents the Stream from
55	// getting too big and still being accepted with LZMA_OK, and Block
56	// encoder catches if the input is too big. So we don't need to
57	// separately check if the buffers are too big.
58
59	// Use a local copy. We update *out_pos_ptr only if everything
60	// succeeds.
61	size_t out_pos = *out_pos_ptr;
62
63	// Check that there's enough space for both Stream Header and
64	// Stream Footer.
65	if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)
66		return LZMA_BUF_ERROR;
67
68	// Reserve space for Stream Footer so we don't need to check for
69	// available space again before encoding Stream Footer.
70	out_size -= LZMA_STREAM_HEADER_SIZE;
71
72	// Encode the Stream Header.
73	lzma_stream_flags stream_flags = {
74		.version = 0,
75		.check = check,
76	};
77
78	if (lzma_stream_header_encode(&stream_flags, out + out_pos)
79			!= LZMA_OK)
80		return LZMA_PROG_ERROR;
81
82	out_pos += LZMA_STREAM_HEADER_SIZE;
83
84	// Block
85	lzma_block block = {
86		.version = 0,
87		.check = check,
88		.filters = filters,
89	};
90
91	return_if_error(lzma_block_buffer_encode(&block, allocator,
92			in, in_size, out, &out_pos, out_size));
93
94	// Index
95	{
96		// Create an Index with one Record.
97		lzma_index *i = lzma_index_init(allocator);
98		if (i == NULL)
99			return LZMA_MEM_ERROR;
100
101		lzma_ret ret = lzma_index_append(i, allocator,
102				lzma_block_unpadded_size(&block),
103				block.uncompressed_size);
104
105		// If adding the Record was successful, encode the Index
106		// and get its size which will be stored into Stream Footer.
107		if (ret == LZMA_OK) {
108			ret = lzma_index_buffer_encode(
109					i, out, &out_pos, out_size);
110
111			stream_flags.backward_size = lzma_index_size(i);
112		}
113
114		lzma_index_end(i, allocator);
115
116		if (ret != LZMA_OK)
117			return ret;
118	}
119
120	// Stream Footer. We have already reserved space for this.
121	if (lzma_stream_footer_encode(&stream_flags, out + out_pos)
122			!= LZMA_OK)
123		return LZMA_PROG_ERROR;
124
125	out_pos += LZMA_STREAM_HEADER_SIZE;
126
127	// Everything went fine, make the new output position available
128	// to the application.
129	*out_pos_ptr = out_pos;
130	return LZMA_OK;
131}
132