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)
lzma_stream_buffer_bound(size_t uncompressed_size)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)
lzma_stream_buffer_encode(lzma_filter * filters,lzma_check check,lzma_allocator * allocator,const uint8_t * in,size_t in_size,uint8_t * out,size_t * out_pos_ptr,size_t out_size)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