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1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file       block_encoder.c
4 /// \brief      Encodes .xz Blocks
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 "block_encoder.h"
14 #include "filter_encoder.h"
15 #include "check.h"
16
17
18 typedef struct {
19         /// The filters in the chain; initialized with lzma_raw_decoder_init().
20         lzma_next_coder next;
21
22         /// Encoding options; we also write Unpadded Size, Compressed Size,
23         /// and Uncompressed Size back to this structure when the encoding
24         /// has been finished.
25         lzma_block *block;
26
27         enum {
28                 SEQ_CODE,
29                 SEQ_PADDING,
30                 SEQ_CHECK,
31         } sequence;
32
33         /// Compressed Size calculated while encoding
34         lzma_vli compressed_size;
35
36         /// Uncompressed Size calculated while encoding
37         lzma_vli uncompressed_size;
38
39         /// Position in the Check field
40         size_t pos;
41
42         /// Check of the uncompressed data
43         lzma_check_state check;
44 } lzma_block_coder;
45
46
47 static lzma_ret
48 block_encode(void *coder_ptr, const lzma_allocator *allocator,
49                 const uint8_t *restrict in, size_t *restrict in_pos,
50                 size_t in_size, uint8_t *restrict out,
51                 size_t *restrict out_pos, size_t out_size, lzma_action action)
52 {
53         lzma_block_coder *coder = coder_ptr;
54
55         // Check that our amount of input stays in proper limits.
56         if (LZMA_VLI_MAX - coder->uncompressed_size < in_size - *in_pos)
57                 return LZMA_DATA_ERROR;
58
59         switch (coder->sequence) {
60         case SEQ_CODE: {
61                 const size_t in_start = *in_pos;
62                 const size_t out_start = *out_pos;
63
64                 const lzma_ret ret = coder->next.code(coder->next.coder,
65                                 allocator, in, in_pos, in_size,
66                                 out, out_pos, out_size, action);
67
68                 const size_t in_used = *in_pos - in_start;
69                 const size_t out_used = *out_pos - out_start;
70
71                 if (COMPRESSED_SIZE_MAX - coder->compressed_size < out_used)
72                         return LZMA_DATA_ERROR;
73
74                 coder->compressed_size += out_used;
75
76                 // No need to check for overflow because we have already
77                 // checked it at the beginning of this function.
78                 coder->uncompressed_size += in_used;
79
80                 lzma_check_update(&coder->check, coder->block->check,
81                                 in + in_start, in_used);
82
83                 if (ret != LZMA_STREAM_END || action == LZMA_SYNC_FLUSH)
84                         return ret;
85
86                 assert(*in_pos == in_size);
87                 assert(action == LZMA_FINISH);
88
89                 // Copy the values into coder->block. The caller
90                 // may use this information to construct Index.
91                 coder->block->compressed_size = coder->compressed_size;
92                 coder->block->uncompressed_size = coder->uncompressed_size;
93
94                 coder->sequence = SEQ_PADDING;
95         }
96
97         // Fall through
98
99         case SEQ_PADDING:
100                 // Pad Compressed Data to a multiple of four bytes. We can
101                 // use coder->compressed_size for this since we don't need
102                 // it for anything else anymore.
103                 while (coder->compressed_size & 3) {
104                         if (*out_pos >= out_size)
105                                 return LZMA_OK;
106
107                         out[*out_pos] = 0x00;
108                         ++*out_pos;
109                         ++coder->compressed_size;
110                 }
111
112                 if (coder->block->check == LZMA_CHECK_NONE)
113                         return LZMA_STREAM_END;
114
115                 lzma_check_finish(&coder->check, coder->block->check);
116
117                 coder->sequence = SEQ_CHECK;
118
119         // Fall through
120
121         case SEQ_CHECK: {
122                 const size_t check_size = lzma_check_size(coder->block->check);
123                 lzma_bufcpy(coder->check.buffer.u8, &coder->pos, check_size,
124                                 out, out_pos, out_size);
125                 if (coder->pos < check_size)
126                         return LZMA_OK;
127
128                 memcpy(coder->block->raw_check, coder->check.buffer.u8,
129                                 check_size);
130                 return LZMA_STREAM_END;
131         }
132         }
133
134         return LZMA_PROG_ERROR;
135 }
136
137
138 static void
139 block_encoder_end(void *coder_ptr, const lzma_allocator *allocator)
140 {
141         lzma_block_coder *coder = coder_ptr;
142         lzma_next_end(&coder->next, allocator);
143         lzma_free(coder, allocator);
144         return;
145 }
146
147
148 static lzma_ret
149 block_encoder_update(void *coder_ptr, const lzma_allocator *allocator,
150                 const lzma_filter *filters lzma_attribute((__unused__)),
151                 const lzma_filter *reversed_filters)
152 {
153         lzma_block_coder *coder = coder_ptr;
154
155         if (coder->sequence != SEQ_CODE)
156                 return LZMA_PROG_ERROR;
157
158         return lzma_next_filter_update(
159                         &coder->next, allocator, reversed_filters);
160 }
161
162
163 extern lzma_ret
164 lzma_block_encoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
165                 lzma_block *block)
166 {
167         lzma_next_coder_init(&lzma_block_encoder_init, next, allocator);
168
169         if (block == NULL)
170                 return LZMA_PROG_ERROR;
171
172         // The contents of the structure may depend on the version so
173         // check the version first.
174         if (block->version > 1)
175                 return LZMA_OPTIONS_ERROR;
176
177         // If the Check ID is not supported, we cannot calculate the check and
178         // thus not create a proper Block.
179         if ((unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
180                 return LZMA_PROG_ERROR;
181
182         if (!lzma_check_is_supported(block->check))
183                 return LZMA_UNSUPPORTED_CHECK;
184
185         // Allocate and initialize *next->coder if needed.
186         lzma_block_coder *coder = next->coder;
187         if (coder == NULL) {
188                 coder = lzma_alloc(sizeof(lzma_block_coder), allocator);
189                 if (coder == NULL)
190                         return LZMA_MEM_ERROR;
191
192                 next->coder = coder;
193                 next->code = &block_encode;
194                 next->end = &block_encoder_end;
195                 next->update = &block_encoder_update;
196                 coder->next = LZMA_NEXT_CODER_INIT;
197         }
198
199         // Basic initializations
200         coder->sequence = SEQ_CODE;
201         coder->block = block;
202         coder->compressed_size = 0;
203         coder->uncompressed_size = 0;
204         coder->pos = 0;
205
206         // Initialize the check
207         lzma_check_init(&coder->check, block->check);
208
209         // Initialize the requested filters.
210         return lzma_raw_encoder_init(&coder->next, allocator, block->filters);
211 }
212
213
214 extern LZMA_API(lzma_ret)
215 lzma_block_encoder(lzma_stream *strm, lzma_block *block)
216 {
217         lzma_next_strm_init(lzma_block_encoder_init, strm, block);
218
219         strm->internal->supported_actions[LZMA_RUN] = true;
220         strm->internal->supported_actions[LZMA_FINISH] = true;
221
222         return LZMA_OK;
223 }