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 
25 extern LZMA_API(size_t)
26 lzma_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 
43 extern LZMA_API(lzma_ret)
44 lzma_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