1 ///////////////////////////////////////////////////////////////////////////////
3 /// \file block_decoder.c
4 /// \brief Decodes .xz Blocks
6 // Author: Lasse Collin
8 // This file has been put into the public domain.
9 // You can do whatever you want with this file.
11 ///////////////////////////////////////////////////////////////////////////////
13 #include "block_decoder.h"
14 #include "filter_decoder.h"
25 /// The filters in the chain; initialized with lzma_raw_decoder_init().
28 /// Decoding options; we also write Compressed Size and Uncompressed
29 /// Size back to this structure when the decoding has been finished.
32 /// Compressed Size calculated while decoding
33 lzma_vli compressed_size;
35 /// Uncompressed Size calculated while decoding
36 lzma_vli uncompressed_size;
38 /// Maximum allowed Compressed Size; this takes into account the
39 /// size of the Block Header and Check fields when Compressed Size
41 lzma_vli compressed_limit;
43 /// Position when reading the Check field
46 /// Check of the uncompressed data
47 lzma_check_state check;
52 update_size(lzma_vli *size, lzma_vli add, lzma_vli limit)
54 if (limit > LZMA_VLI_MAX)
57 if (limit < *size || limit - *size < add)
67 is_size_valid(lzma_vli size, lzma_vli reference)
69 return reference == LZMA_VLI_UNKNOWN || reference == size;
74 block_decode(lzma_coder *coder, lzma_allocator *allocator,
75 const uint8_t *restrict in, size_t *restrict in_pos,
76 size_t in_size, uint8_t *restrict out,
77 size_t *restrict out_pos, size_t out_size, lzma_action action)
79 switch (coder->sequence) {
81 const size_t in_start = *in_pos;
82 const size_t out_start = *out_pos;
84 const lzma_ret ret = coder->next.code(coder->next.coder,
85 allocator, in, in_pos, in_size,
86 out, out_pos, out_size, action);
88 const size_t in_used = *in_pos - in_start;
89 const size_t out_used = *out_pos - out_start;
91 // NOTE: We compare to compressed_limit here, which prevents
92 // the total size of the Block growing past LZMA_VLI_MAX.
93 if (update_size(&coder->compressed_size, in_used,
94 coder->compressed_limit)
95 || update_size(&coder->uncompressed_size,
97 coder->block->uncompressed_size))
98 return LZMA_DATA_ERROR;
100 lzma_check_update(&coder->check, coder->block->check,
101 out + out_start, out_used);
103 if (ret != LZMA_STREAM_END)
106 // Compressed and Uncompressed Sizes are now at their final
107 // values. Verify that they match the values given to us.
108 if (!is_size_valid(coder->compressed_size,
109 coder->block->compressed_size)
110 || !is_size_valid(coder->uncompressed_size,
111 coder->block->uncompressed_size))
112 return LZMA_DATA_ERROR;
114 // Copy the values into coder->block. The caller
115 // may use this information to construct Index.
116 coder->block->compressed_size = coder->compressed_size;
117 coder->block->uncompressed_size = coder->uncompressed_size;
119 coder->sequence = SEQ_PADDING;
125 // Compressed Data is padded to a multiple of four bytes.
126 while (coder->compressed_size & 3) {
127 if (*in_pos >= in_size)
130 // We use compressed_size here just get the Padding
131 // right. The actual Compressed Size was stored to
132 // coder->block already, and won't be modified by
134 ++coder->compressed_size;
136 if (in[(*in_pos)++] != 0x00)
137 return LZMA_DATA_ERROR;
140 if (coder->block->check == LZMA_CHECK_NONE)
141 return LZMA_STREAM_END;
143 lzma_check_finish(&coder->check, coder->block->check);
144 coder->sequence = SEQ_CHECK;
149 const size_t check_size = lzma_check_size(coder->block->check);
150 lzma_bufcpy(in, in_pos, in_size, coder->block->raw_check,
151 &coder->check_pos, check_size);
152 if (coder->check_pos < check_size)
155 // Validate the Check only if we support it.
156 // coder->check.buffer may be uninitialized
157 // when the Check ID is not supported.
158 if (lzma_check_is_supported(coder->block->check)
159 && memcmp(coder->block->raw_check,
160 coder->check.buffer.u8,
162 return LZMA_DATA_ERROR;
164 return LZMA_STREAM_END;
168 return LZMA_PROG_ERROR;
173 block_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
175 lzma_next_end(&coder->next, allocator);
176 lzma_free(coder, allocator);
182 lzma_block_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
185 lzma_next_coder_init(&lzma_block_decoder_init, next, allocator);
187 // Validate the options. lzma_block_unpadded_size() does that for us
188 // except for Uncompressed Size and filters. Filters are validated
189 // by the raw decoder.
190 if (lzma_block_unpadded_size(block) == 0
191 || !lzma_vli_is_valid(block->uncompressed_size))
192 return LZMA_PROG_ERROR;
194 // Allocate and initialize *next->coder if needed.
195 if (next->coder == NULL) {
196 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
197 if (next->coder == NULL)
198 return LZMA_MEM_ERROR;
200 next->code = &block_decode;
201 next->end = &block_decoder_end;
202 next->coder->next = LZMA_NEXT_CODER_INIT;
205 // Basic initializations
206 next->coder->sequence = SEQ_CODE;
207 next->coder->block = block;
208 next->coder->compressed_size = 0;
209 next->coder->uncompressed_size = 0;
211 // If Compressed Size is not known, we calculate the maximum allowed
212 // value so that encoded size of the Block (including Block Padding)
213 // is still a valid VLI and a multiple of four.
214 next->coder->compressed_limit
215 = block->compressed_size == LZMA_VLI_UNKNOWN
216 ? (LZMA_VLI_MAX & ~LZMA_VLI_C(3))
218 - lzma_check_size(block->check)
219 : block->compressed_size;
221 // Initialize the check. It's caller's problem if the Check ID is not
222 // supported, and the Block decoder cannot verify the Check field.
223 // Caller can test lzma_check_is_supported(block->check).
224 next->coder->check_pos = 0;
225 lzma_check_init(&next->coder->check, block->check);
227 // Initialize the filter chain.
228 return lzma_raw_decoder_init(&next->coder->next, allocator,
233 extern LZMA_API(lzma_ret)
234 lzma_block_decoder(lzma_stream *strm, lzma_block *block)
236 lzma_next_strm_init(lzma_block_decoder_init, strm, block);
238 strm->internal->supported_actions[LZMA_RUN] = true;
239 strm->internal->supported_actions[LZMA_FINISH] = true;