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 		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 	if (!lzma_check_is_supported(check))
55 		return LZMA_UNSUPPORTED_CHECK;
56 
57 	// Note for the paranoids: Index encoder prevents the Stream from
58 	// getting too big and still being accepted with LZMA_OK, and Block
59 	// encoder catches if the input is too big. So we don't need to
60 	// separately check if the buffers are too big.
61 
62 	// Use a local copy. We update *out_pos_ptr only if everything
63 	// succeeds.
64 	size_t out_pos = *out_pos_ptr;
65 
66 	// Check that there's enough space for both Stream Header and
67 	// Stream Footer.
68 	if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)
69 		return LZMA_BUF_ERROR;
70 
71 	// Reserve space for Stream Footer so we don't need to check for
72 	// available space again before encoding Stream Footer.
73 	out_size -= LZMA_STREAM_HEADER_SIZE;
74 
75 	// Encode the Stream Header.
76 	lzma_stream_flags stream_flags = {
77 		.version = 0,
78 		.check = check,
79 	};
80 
81 	if (lzma_stream_header_encode(&stream_flags, out + out_pos)
82 			!= LZMA_OK)
83 		return LZMA_PROG_ERROR;
84 
85 	out_pos += LZMA_STREAM_HEADER_SIZE;
86 
87 	// Encode a Block but only if there is at least one byte of input.
88 	lzma_block block = {
89 		.version = 0,
90 		.check = check,
91 		.filters = filters,
92 	};
93 
94 	if (in_size > 0)
95 		return_if_error(lzma_block_buffer_encode(&block, allocator,
96 				in, in_size, out, &out_pos, out_size));
97 
98 	// Index
99 	{
100 		// Create an Index. It will have one Record if there was
101 		// at least one byte of input to encode. Otherwise the
102 		// Index will be empty.
103 		lzma_index *i = lzma_index_init(allocator);
104 		if (i == NULL)
105 			return LZMA_MEM_ERROR;
106 
107 		lzma_ret ret = LZMA_OK;
108 
109 		if (in_size > 0)
110 			ret = lzma_index_append(i, allocator,
111 					lzma_block_unpadded_size(&block),
112 					block.uncompressed_size);
113 
114 		// If adding the Record was successful, encode the Index
115 		// and get its size which will be stored into Stream Footer.
116 		if (ret == LZMA_OK) {
117 			ret = lzma_index_buffer_encode(
118 					i, out, &out_pos, out_size);
119 
120 			stream_flags.backward_size = lzma_index_size(i);
121 		}
122 
123 		lzma_index_end(i, allocator);
124 
125 		if (ret != LZMA_OK)
126 			return ret;
127 	}
128 
129 	// Stream Footer. We have already reserved space for this.
130 	if (lzma_stream_footer_encode(&stream_flags, out + out_pos)
131 			!= LZMA_OK)
132 		return LZMA_PROG_ERROR;
133 
134 	out_pos += LZMA_STREAM_HEADER_SIZE;
135 
136 	// Everything went fine, make the new output position available
137 	// to the application.
138 	*out_pos_ptr = out_pos;
139 	return LZMA_OK;
140 }
141