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837 lines
19 KiB
837 lines
19 KiB
/* |
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* .xz Stream decoder |
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* |
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* Author: Lasse Collin <[email protected]> |
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* |
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* This file has been put into the public domain. |
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* You can do whatever you want with this file. |
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*/ |
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|
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#include "xz_private.h" |
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#include "xz_stream.h" |
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|
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/* Hash used to validate the Index field */ |
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struct xz_dec_hash { |
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vli_type unpadded; |
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vli_type uncompressed; |
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uint32_t crc32; |
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}; |
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|
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struct xz_dec { |
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/* Position in dec_main() */ |
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enum { |
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SEQ_STREAM_HEADER, |
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SEQ_BLOCK_START, |
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SEQ_BLOCK_HEADER, |
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SEQ_BLOCK_UNCOMPRESS, |
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SEQ_BLOCK_PADDING, |
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SEQ_BLOCK_CHECK, |
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SEQ_INDEX, |
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SEQ_INDEX_PADDING, |
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SEQ_INDEX_CRC32, |
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SEQ_STREAM_FOOTER |
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} sequence; |
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|
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/* Position in variable-length integers and Check fields */ |
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uint32_t pos; |
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|
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/* Variable-length integer decoded by dec_vli() */ |
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vli_type vli; |
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|
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/* Saved in_pos and out_pos */ |
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size_t in_start; |
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size_t out_start; |
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|
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/* CRC32 value in Block or Index */ |
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uint32_t crc32; |
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|
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/* Type of the integrity check calculated from uncompressed data */ |
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enum xz_check check_type; |
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|
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/* Operation mode */ |
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enum xz_mode mode; |
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|
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/* |
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* True if the next call to xz_dec_run() is allowed to return |
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* XZ_BUF_ERROR. |
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*/ |
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bool allow_buf_error; |
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|
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/* Information stored in Block Header */ |
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struct { |
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/* |
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* Value stored in the Compressed Size field, or |
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* VLI_UNKNOWN if Compressed Size is not present. |
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*/ |
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vli_type compressed; |
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|
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/* |
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* Value stored in the Uncompressed Size field, or |
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* VLI_UNKNOWN if Uncompressed Size is not present. |
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*/ |
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vli_type uncompressed; |
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|
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/* Size of the Block Header field */ |
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uint32_t size; |
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} block_header; |
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|
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/* Information collected when decoding Blocks */ |
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struct { |
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/* Observed compressed size of the current Block */ |
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vli_type compressed; |
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|
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/* Observed uncompressed size of the current Block */ |
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vli_type uncompressed; |
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|
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/* Number of Blocks decoded so far */ |
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vli_type count; |
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|
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/* |
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* Hash calculated from the Block sizes. This is used to |
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* validate the Index field. |
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*/ |
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struct xz_dec_hash hash; |
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} block; |
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|
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/* Variables needed when verifying the Index field */ |
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struct { |
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/* Position in dec_index() */ |
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enum { |
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SEQ_INDEX_COUNT, |
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SEQ_INDEX_UNPADDED, |
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SEQ_INDEX_UNCOMPRESSED |
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} sequence; |
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|
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/* Size of the Index in bytes */ |
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vli_type size; |
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|
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/* Number of Records (matches block.count in valid files) */ |
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vli_type count; |
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|
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/* |
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* Hash calculated from the Records (matches block.hash in |
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* valid files). |
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*/ |
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struct xz_dec_hash hash; |
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} index; |
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|
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/* |
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* Temporary buffer needed to hold Stream Header, Block Header, |
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* and Stream Footer. The Block Header is the biggest (1 KiB) |
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* so we reserve space according to that. buf[] has to be aligned |
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* to a multiple of four bytes; the size_t variables before it |
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* should guarantee this. |
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*/ |
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struct { |
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size_t pos; |
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size_t size; |
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uint8_t buf[1024]; |
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} temp; |
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|
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struct xz_dec_lzma2 *lzma2; |
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|
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#ifdef XZ_DEC_BCJ |
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struct xz_dec_bcj *bcj; |
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bool bcj_active; |
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#endif |
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}; |
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|
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#ifdef XZ_DEC_ANY_CHECK |
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/* Sizes of the Check field with different Check IDs */ |
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static const uint8_t check_sizes[16] = { |
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0, |
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4, 4, 4, |
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8, 8, 8, |
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16, 16, 16, |
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32, 32, 32, |
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64, 64, 64 |
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}; |
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#endif |
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|
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/* |
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* Fill s->temp by copying data starting from b->in[b->in_pos]. Caller |
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* must have set s->temp.pos to indicate how much data we are supposed |
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* to copy into s->temp.buf. Return true once s->temp.pos has reached |
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* s->temp.size. |
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*/ |
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static bool fill_temp(struct xz_dec *s, struct xz_buf *b) |
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{ |
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size_t copy_size = min_t(size_t, |
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b->in_size - b->in_pos, s->temp.size - s->temp.pos); |
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|
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memcpy(s->temp.buf + s->temp.pos, b->in + b->in_pos, copy_size); |
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b->in_pos += copy_size; |
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s->temp.pos += copy_size; |
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|
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if (s->temp.pos == s->temp.size) { |
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s->temp.pos = 0; |
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return true; |
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} |
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|
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return false; |
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} |
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|
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/* Decode a variable-length integer (little-endian base-128 encoding) */ |
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static enum xz_ret dec_vli(struct xz_dec *s, const uint8_t *in, |
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size_t *in_pos, size_t in_size) |
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{ |
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uint8_t byte; |
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|
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if (s->pos == 0) |
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s->vli = 0; |
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|
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while (*in_pos < in_size) { |
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byte = in[*in_pos]; |
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++*in_pos; |
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|
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s->vli |= (vli_type)(byte & 0x7F) << s->pos; |
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|
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if ((byte & 0x80) == 0) { |
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/* Don't allow non-minimal encodings. */ |
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if (byte == 0 && s->pos != 0) |
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return XZ_DATA_ERROR; |
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|
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s->pos = 0; |
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return XZ_STREAM_END; |
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} |
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|
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s->pos += 7; |
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if (s->pos == 7 * VLI_BYTES_MAX) |
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return XZ_DATA_ERROR; |
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} |
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|
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return XZ_OK; |
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} |
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|
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/* |
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* Decode the Compressed Data field from a Block. Update and validate |
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* the observed compressed and uncompressed sizes of the Block so that |
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* they don't exceed the values possibly stored in the Block Header |
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* (validation assumes that no integer overflow occurs, since vli_type |
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* is normally uint64_t). Update the CRC32 if presence of the CRC32 |
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* field was indicated in Stream Header. |
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* |
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* Once the decoding is finished, validate that the observed sizes match |
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* the sizes possibly stored in the Block Header. Update the hash and |
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* Block count, which are later used to validate the Index field. |
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*/ |
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static enum xz_ret dec_block(struct xz_dec *s, struct xz_buf *b) |
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{ |
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enum xz_ret ret; |
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|
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s->in_start = b->in_pos; |
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s->out_start = b->out_pos; |
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|
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#ifdef XZ_DEC_BCJ |
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if (s->bcj_active) |
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ret = xz_dec_bcj_run(s->bcj, s->lzma2, b); |
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else |
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#endif |
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ret = xz_dec_lzma2_run(s->lzma2, b); |
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|
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s->block.compressed += b->in_pos - s->in_start; |
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s->block.uncompressed += b->out_pos - s->out_start; |
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|
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/* |
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* There is no need to separately check for VLI_UNKNOWN, since |
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* the observed sizes are always smaller than VLI_UNKNOWN. |
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*/ |
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if (s->block.compressed > s->block_header.compressed |
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|| s->block.uncompressed |
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> s->block_header.uncompressed) |
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return XZ_DATA_ERROR; |
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|
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if (s->check_type == XZ_CHECK_CRC32) |
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s->crc32 = xz_crc32(b->out + s->out_start, |
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b->out_pos - s->out_start, s->crc32); |
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|
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if (ret == XZ_STREAM_END) { |
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if (s->block_header.compressed != VLI_UNKNOWN |
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&& s->block_header.compressed |
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!= s->block.compressed) |
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return XZ_DATA_ERROR; |
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|
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if (s->block_header.uncompressed != VLI_UNKNOWN |
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&& s->block_header.uncompressed |
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!= s->block.uncompressed) |
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return XZ_DATA_ERROR; |
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|
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s->block.hash.unpadded += s->block_header.size |
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+ s->block.compressed; |
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|
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#ifdef XZ_DEC_ANY_CHECK |
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s->block.hash.unpadded += check_sizes[s->check_type]; |
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#else |
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if (s->check_type == XZ_CHECK_CRC32) |
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s->block.hash.unpadded += 4; |
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#endif |
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|
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s->block.hash.uncompressed += s->block.uncompressed; |
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s->block.hash.crc32 = xz_crc32( |
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(const uint8_t *)&s->block.hash, |
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sizeof(s->block.hash), s->block.hash.crc32); |
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|
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++s->block.count; |
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} |
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|
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return ret; |
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} |
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|
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/* Update the Index size and the CRC32 value. */ |
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static void index_update(struct xz_dec *s, const struct xz_buf *b) |
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{ |
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size_t in_used = b->in_pos - s->in_start; |
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s->index.size += in_used; |
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s->crc32 = xz_crc32(b->in + s->in_start, in_used, s->crc32); |
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} |
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|
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/* |
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* Decode the Number of Records, Unpadded Size, and Uncompressed Size |
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* fields from the Index field. That is, Index Padding and CRC32 are not |
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* decoded by this function. |
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* |
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* This can return XZ_OK (more input needed), XZ_STREAM_END (everything |
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* successfully decoded), or XZ_DATA_ERROR (input is corrupt). |
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*/ |
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static enum xz_ret dec_index(struct xz_dec *s, struct xz_buf *b) |
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{ |
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enum xz_ret ret; |
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|
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do { |
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ret = dec_vli(s, b->in, &b->in_pos, b->in_size); |
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if (ret != XZ_STREAM_END) { |
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index_update(s, b); |
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return ret; |
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} |
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|
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switch (s->index.sequence) { |
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case SEQ_INDEX_COUNT: |
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s->index.count = s->vli; |
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|
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/* |
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* Validate that the Number of Records field |
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* indicates the same number of Records as |
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* there were Blocks in the Stream. |
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*/ |
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if (s->index.count != s->block.count) |
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return XZ_DATA_ERROR; |
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|
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s->index.sequence = SEQ_INDEX_UNPADDED; |
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break; |
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|
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case SEQ_INDEX_UNPADDED: |
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s->index.hash.unpadded += s->vli; |
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s->index.sequence = SEQ_INDEX_UNCOMPRESSED; |
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break; |
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|
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case SEQ_INDEX_UNCOMPRESSED: |
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s->index.hash.uncompressed += s->vli; |
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s->index.hash.crc32 = xz_crc32( |
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(const uint8_t *)&s->index.hash, |
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sizeof(s->index.hash), |
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s->index.hash.crc32); |
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--s->index.count; |
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s->index.sequence = SEQ_INDEX_UNPADDED; |
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break; |
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} |
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} while (s->index.count > 0); |
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|
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return XZ_STREAM_END; |
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} |
|
|
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/* |
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* Validate that the next four input bytes match the value of s->crc32. |
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* s->pos must be zero when starting to validate the first byte. |
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*/ |
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static enum xz_ret crc32_validate(struct xz_dec *s, struct xz_buf *b) |
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{ |
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do { |
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if (b->in_pos == b->in_size) |
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return XZ_OK; |
|
|
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if (((s->crc32 >> s->pos) & 0xFF) != b->in[b->in_pos++]) |
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return XZ_DATA_ERROR; |
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|
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s->pos += 8; |
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|
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} while (s->pos < 32); |
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|
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s->crc32 = 0; |
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s->pos = 0; |
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|
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return XZ_STREAM_END; |
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} |
|
|
|
#ifdef XZ_DEC_ANY_CHECK |
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/* |
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* Skip over the Check field when the Check ID is not supported. |
|
* Returns true once the whole Check field has been skipped over. |
|
*/ |
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static bool check_skip(struct xz_dec *s, struct xz_buf *b) |
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{ |
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while (s->pos < check_sizes[s->check_type]) { |
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if (b->in_pos == b->in_size) |
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return false; |
|
|
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++b->in_pos; |
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++s->pos; |
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} |
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|
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s->pos = 0; |
|
|
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return true; |
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} |
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#endif |
|
|
|
/* Decode the Stream Header field (the first 12 bytes of the .xz Stream). */ |
|
static enum xz_ret dec_stream_header(struct xz_dec *s) |
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{ |
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if (!memeq(s->temp.buf, HEADER_MAGIC, HEADER_MAGIC_SIZE)) |
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return XZ_FORMAT_ERROR; |
|
|
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if (xz_crc32(s->temp.buf + HEADER_MAGIC_SIZE, 2, 0) |
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!= get_le32(s->temp.buf + HEADER_MAGIC_SIZE + 2)) |
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return XZ_DATA_ERROR; |
|
|
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if (s->temp.buf[HEADER_MAGIC_SIZE] != 0) |
|
return XZ_OPTIONS_ERROR; |
|
|
|
/* |
|
* Of integrity checks, we support only none (Check ID = 0) and |
|
* CRC32 (Check ID = 1). However, if XZ_DEC_ANY_CHECK is defined, |
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* we will accept other check types too, but then the check won't |
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* be verified and a warning (XZ_UNSUPPORTED_CHECK) will be given. |
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*/ |
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s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1]; |
|
|
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#ifdef XZ_DEC_ANY_CHECK |
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if (s->check_type > XZ_CHECK_MAX) |
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return XZ_OPTIONS_ERROR; |
|
|
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if (s->check_type > XZ_CHECK_CRC32) |
|
return XZ_UNSUPPORTED_CHECK; |
|
#else |
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if (s->check_type > XZ_CHECK_CRC32) |
|
return XZ_OPTIONS_ERROR; |
|
#endif |
|
|
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return XZ_OK; |
|
} |
|
|
|
/* Decode the Stream Footer field (the last 12 bytes of the .xz Stream) */ |
|
static enum xz_ret dec_stream_footer(struct xz_dec *s) |
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{ |
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if (!memeq(s->temp.buf + 10, FOOTER_MAGIC, FOOTER_MAGIC_SIZE)) |
|
return XZ_DATA_ERROR; |
|
|
|
if (xz_crc32(s->temp.buf + 4, 6, 0) != get_le32(s->temp.buf)) |
|
return XZ_DATA_ERROR; |
|
|
|
/* |
|
* Validate Backward Size. Note that we never added the size of the |
|
* Index CRC32 field to s->index.size, thus we use s->index.size / 4 |
|
* instead of s->index.size / 4 - 1. |
|
*/ |
|
if ((s->index.size >> 2) != get_le32(s->temp.buf + 4)) |
|
return XZ_DATA_ERROR; |
|
|
|
if (s->temp.buf[8] != 0 || s->temp.buf[9] != s->check_type) |
|
return XZ_DATA_ERROR; |
|
|
|
/* |
|
* Use XZ_STREAM_END instead of XZ_OK to be more convenient |
|
* for the caller. |
|
*/ |
|
return XZ_STREAM_END; |
|
} |
|
|
|
/* Decode the Block Header and initialize the filter chain. */ |
|
static enum xz_ret dec_block_header(struct xz_dec *s) |
|
{ |
|
enum xz_ret ret; |
|
|
|
/* |
|
* Validate the CRC32. We know that the temp buffer is at least |
|
* eight bytes so this is safe. |
|
*/ |
|
s->temp.size -= 4; |
|
if (xz_crc32(s->temp.buf, s->temp.size, 0) |
|
!= get_le32(s->temp.buf + s->temp.size)) |
|
return XZ_DATA_ERROR; |
|
|
|
s->temp.pos = 2; |
|
|
|
/* |
|
* Catch unsupported Block Flags. We support only one or two filters |
|
* in the chain, so we catch that with the same test. |
|
*/ |
|
#ifdef XZ_DEC_BCJ |
|
if (s->temp.buf[1] & 0x3E) |
|
#else |
|
if (s->temp.buf[1] & 0x3F) |
|
#endif |
|
return XZ_OPTIONS_ERROR; |
|
|
|
/* Compressed Size */ |
|
if (s->temp.buf[1] & 0x40) { |
|
if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size) |
|
!= XZ_STREAM_END) |
|
return XZ_DATA_ERROR; |
|
|
|
s->block_header.compressed = s->vli; |
|
} else { |
|
s->block_header.compressed = VLI_UNKNOWN; |
|
} |
|
|
|
/* Uncompressed Size */ |
|
if (s->temp.buf[1] & 0x80) { |
|
if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size) |
|
!= XZ_STREAM_END) |
|
return XZ_DATA_ERROR; |
|
|
|
s->block_header.uncompressed = s->vli; |
|
} else { |
|
s->block_header.uncompressed = VLI_UNKNOWN; |
|
} |
|
|
|
#ifdef XZ_DEC_BCJ |
|
/* If there are two filters, the first one must be a BCJ filter. */ |
|
s->bcj_active = s->temp.buf[1] & 0x01; |
|
if (s->bcj_active) { |
|
if (s->temp.size - s->temp.pos < 2) |
|
return XZ_OPTIONS_ERROR; |
|
|
|
ret = xz_dec_bcj_reset(s->bcj, s->temp.buf[s->temp.pos++]); |
|
if (ret != XZ_OK) |
|
return ret; |
|
|
|
/* |
|
* We don't support custom start offset, |
|
* so Size of Properties must be zero. |
|
*/ |
|
if (s->temp.buf[s->temp.pos++] != 0x00) |
|
return XZ_OPTIONS_ERROR; |
|
} |
|
#endif |
|
|
|
/* Valid Filter Flags always take at least two bytes. */ |
|
if (s->temp.size - s->temp.pos < 2) |
|
return XZ_DATA_ERROR; |
|
|
|
/* Filter ID = LZMA2 */ |
|
if (s->temp.buf[s->temp.pos++] != 0x21) |
|
return XZ_OPTIONS_ERROR; |
|
|
|
/* Size of Properties = 1-byte Filter Properties */ |
|
if (s->temp.buf[s->temp.pos++] != 0x01) |
|
return XZ_OPTIONS_ERROR; |
|
|
|
/* Filter Properties contains LZMA2 dictionary size. */ |
|
if (s->temp.size - s->temp.pos < 1) |
|
return XZ_DATA_ERROR; |
|
|
|
ret = xz_dec_lzma2_reset(s->lzma2, s->temp.buf[s->temp.pos++]); |
|
if (ret != XZ_OK) |
|
return ret; |
|
|
|
/* The rest must be Header Padding. */ |
|
while (s->temp.pos < s->temp.size) |
|
if (s->temp.buf[s->temp.pos++] != 0x00) |
|
return XZ_OPTIONS_ERROR; |
|
|
|
s->temp.pos = 0; |
|
s->block.compressed = 0; |
|
s->block.uncompressed = 0; |
|
|
|
return XZ_OK; |
|
} |
|
|
|
static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b) |
|
{ |
|
enum xz_ret ret; |
|
|
|
/* |
|
* Store the start position for the case when we are in the middle |
|
* of the Index field. |
|
*/ |
|
s->in_start = b->in_pos; |
|
|
|
while (true) { |
|
switch (s->sequence) { |
|
case SEQ_STREAM_HEADER: |
|
/* |
|
* Stream Header is copied to s->temp, and then |
|
* decoded from there. This way if the caller |
|
* gives us only little input at a time, we can |
|
* still keep the Stream Header decoding code |
|
* simple. Similar approach is used in many places |
|
* in this file. |
|
*/ |
|
if (!fill_temp(s, b)) |
|
return XZ_OK; |
|
|
|
/* |
|
* If dec_stream_header() returns |
|
* XZ_UNSUPPORTED_CHECK, it is still possible |
|
* to continue decoding if working in multi-call |
|
* mode. Thus, update s->sequence before calling |
|
* dec_stream_header(). |
|
*/ |
|
s->sequence = SEQ_BLOCK_START; |
|
|
|
ret = dec_stream_header(s); |
|
if (ret != XZ_OK) |
|
return ret; |
|
|
|
fallthrough; |
|
|
|
case SEQ_BLOCK_START: |
|
/* We need one byte of input to continue. */ |
|
if (b->in_pos == b->in_size) |
|
return XZ_OK; |
|
|
|
/* See if this is the beginning of the Index field. */ |
|
if (b->in[b->in_pos] == 0) { |
|
s->in_start = b->in_pos++; |
|
s->sequence = SEQ_INDEX; |
|
break; |
|
} |
|
|
|
/* |
|
* Calculate the size of the Block Header and |
|
* prepare to decode it. |
|
*/ |
|
s->block_header.size |
|
= ((uint32_t)b->in[b->in_pos] + 1) * 4; |
|
|
|
s->temp.size = s->block_header.size; |
|
s->temp.pos = 0; |
|
s->sequence = SEQ_BLOCK_HEADER; |
|
|
|
fallthrough; |
|
|
|
case SEQ_BLOCK_HEADER: |
|
if (!fill_temp(s, b)) |
|
return XZ_OK; |
|
|
|
ret = dec_block_header(s); |
|
if (ret != XZ_OK) |
|
return ret; |
|
|
|
s->sequence = SEQ_BLOCK_UNCOMPRESS; |
|
|
|
fallthrough; |
|
|
|
case SEQ_BLOCK_UNCOMPRESS: |
|
ret = dec_block(s, b); |
|
if (ret != XZ_STREAM_END) |
|
return ret; |
|
|
|
s->sequence = SEQ_BLOCK_PADDING; |
|
|
|
fallthrough; |
|
|
|
case SEQ_BLOCK_PADDING: |
|
/* |
|
* Size of Compressed Data + Block Padding |
|
* must be a multiple of four. We don't need |
|
* s->block.compressed for anything else |
|
* anymore, so we use it here to test the size |
|
* of the Block Padding field. |
|
*/ |
|
while (s->block.compressed & 3) { |
|
if (b->in_pos == b->in_size) |
|
return XZ_OK; |
|
|
|
if (b->in[b->in_pos++] != 0) |
|
return XZ_DATA_ERROR; |
|
|
|
++s->block.compressed; |
|
} |
|
|
|
s->sequence = SEQ_BLOCK_CHECK; |
|
|
|
fallthrough; |
|
|
|
case SEQ_BLOCK_CHECK: |
|
if (s->check_type == XZ_CHECK_CRC32) { |
|
ret = crc32_validate(s, b); |
|
if (ret != XZ_STREAM_END) |
|
return ret; |
|
} |
|
#ifdef XZ_DEC_ANY_CHECK |
|
else if (!check_skip(s, b)) { |
|
return XZ_OK; |
|
} |
|
#endif |
|
|
|
s->sequence = SEQ_BLOCK_START; |
|
break; |
|
|
|
case SEQ_INDEX: |
|
ret = dec_index(s, b); |
|
if (ret != XZ_STREAM_END) |
|
return ret; |
|
|
|
s->sequence = SEQ_INDEX_PADDING; |
|
|
|
fallthrough; |
|
|
|
case SEQ_INDEX_PADDING: |
|
while ((s->index.size + (b->in_pos - s->in_start)) |
|
& 3) { |
|
if (b->in_pos == b->in_size) { |
|
index_update(s, b); |
|
return XZ_OK; |
|
} |
|
|
|
if (b->in[b->in_pos++] != 0) |
|
return XZ_DATA_ERROR; |
|
} |
|
|
|
/* Finish the CRC32 value and Index size. */ |
|
index_update(s, b); |
|
|
|
/* Compare the hashes to validate the Index field. */ |
|
if (!memeq(&s->block.hash, &s->index.hash, |
|
sizeof(s->block.hash))) |
|
return XZ_DATA_ERROR; |
|
|
|
s->sequence = SEQ_INDEX_CRC32; |
|
|
|
fallthrough; |
|
|
|
case SEQ_INDEX_CRC32: |
|
ret = crc32_validate(s, b); |
|
if (ret != XZ_STREAM_END) |
|
return ret; |
|
|
|
s->temp.size = STREAM_HEADER_SIZE; |
|
s->sequence = SEQ_STREAM_FOOTER; |
|
|
|
fallthrough; |
|
|
|
case SEQ_STREAM_FOOTER: |
|
if (!fill_temp(s, b)) |
|
return XZ_OK; |
|
|
|
return dec_stream_footer(s); |
|
} |
|
} |
|
|
|
/* Never reached */ |
|
} |
|
|
|
/* |
|
* xz_dec_run() is a wrapper for dec_main() to handle some special cases in |
|
* multi-call and single-call decoding. |
|
* |
|
* In multi-call mode, we must return XZ_BUF_ERROR when it seems clear that we |
|
* are not going to make any progress anymore. This is to prevent the caller |
|
* from calling us infinitely when the input file is truncated or otherwise |
|
* corrupt. Since zlib-style API allows that the caller fills the input buffer |
|
* only when the decoder doesn't produce any new output, we have to be careful |
|
* to avoid returning XZ_BUF_ERROR too easily: XZ_BUF_ERROR is returned only |
|
* after the second consecutive call to xz_dec_run() that makes no progress. |
|
* |
|
* In single-call mode, if we couldn't decode everything and no error |
|
* occurred, either the input is truncated or the output buffer is too small. |
|
* Since we know that the last input byte never produces any output, we know |
|
* that if all the input was consumed and decoding wasn't finished, the file |
|
* must be corrupt. Otherwise the output buffer has to be too small or the |
|
* file is corrupt in a way that decoding it produces too big output. |
|
* |
|
* If single-call decoding fails, we reset b->in_pos and b->out_pos back to |
|
* their original values. This is because with some filter chains there won't |
|
* be any valid uncompressed data in the output buffer unless the decoding |
|
* actually succeeds (that's the price to pay of using the output buffer as |
|
* the workspace). |
|
*/ |
|
XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b) |
|
{ |
|
size_t in_start; |
|
size_t out_start; |
|
enum xz_ret ret; |
|
|
|
if (DEC_IS_SINGLE(s->mode)) |
|
xz_dec_reset(s); |
|
|
|
in_start = b->in_pos; |
|
out_start = b->out_pos; |
|
ret = dec_main(s, b); |
|
|
|
if (DEC_IS_SINGLE(s->mode)) { |
|
if (ret == XZ_OK) |
|
ret = b->in_pos == b->in_size |
|
? XZ_DATA_ERROR : XZ_BUF_ERROR; |
|
|
|
if (ret != XZ_STREAM_END) { |
|
b->in_pos = in_start; |
|
b->out_pos = out_start; |
|
} |
|
|
|
} else if (ret == XZ_OK && in_start == b->in_pos |
|
&& out_start == b->out_pos) { |
|
if (s->allow_buf_error) |
|
ret = XZ_BUF_ERROR; |
|
|
|
s->allow_buf_error = true; |
|
} else { |
|
s->allow_buf_error = false; |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max) |
|
{ |
|
struct xz_dec *s = kmalloc(sizeof(*s), GFP_KERNEL); |
|
if (s == NULL) |
|
return NULL; |
|
|
|
s->mode = mode; |
|
|
|
#ifdef XZ_DEC_BCJ |
|
s->bcj = xz_dec_bcj_create(DEC_IS_SINGLE(mode)); |
|
if (s->bcj == NULL) |
|
goto error_bcj; |
|
#endif |
|
|
|
s->lzma2 = xz_dec_lzma2_create(mode, dict_max); |
|
if (s->lzma2 == NULL) |
|
goto error_lzma2; |
|
|
|
xz_dec_reset(s); |
|
return s; |
|
|
|
error_lzma2: |
|
#ifdef XZ_DEC_BCJ |
|
xz_dec_bcj_end(s->bcj); |
|
error_bcj: |
|
#endif |
|
kfree(s); |
|
return NULL; |
|
} |
|
|
|
XZ_EXTERN void xz_dec_reset(struct xz_dec *s) |
|
{ |
|
s->sequence = SEQ_STREAM_HEADER; |
|
s->allow_buf_error = false; |
|
s->pos = 0; |
|
s->crc32 = 0; |
|
memzero(&s->block, sizeof(s->block)); |
|
memzero(&s->index, sizeof(s->index)); |
|
s->temp.pos = 0; |
|
s->temp.size = STREAM_HEADER_SIZE; |
|
} |
|
|
|
XZ_EXTERN void xz_dec_end(struct xz_dec *s) |
|
{ |
|
if (s != NULL) { |
|
xz_dec_lzma2_end(s->lzma2); |
|
#ifdef XZ_DEC_BCJ |
|
xz_dec_bcj_end(s->bcj); |
|
#endif |
|
kfree(s); |
|
} |
|
}
|
|
|