mirror of https://git.tukaani.org/xz.git
Block encoder cleanups
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@ -22,21 +22,6 @@
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#include "check.h"
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/// The maximum size of a single Block is limited by the maximum size of
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/// a Stream, which is 2^63 - 1 bytes (i.e. LZMA_VLI_MAX). We could
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/// take into account the headers etc. to determine the exact maximum size
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/// of the Compressed Data field, but the complexity would give us nothing
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/// useful. Instead, limit the size of Compressed Data so that even with
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/// biggest possible Block Header and Check fields the total encoded size of
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/// the Block stays as valid VLI. This way we don't produce incorrect output
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/// if someone will really try creating a Block of 8 EiB.
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///
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/// ~LZMA_VLI_C(3) is to guarantee that if we need padding at the end of
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/// the Compressed Data field, it will still stay in the proper limit.
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#define COMPRESSED_SIZE_MAX ((LZMA_VLI_MAX - LZMA_BLOCK_HEADER_SIZE_MAX \
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- LZMA_CHECK_SIZE_MAX) & ~LZMA_VLI_C(3))
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struct lzma_coder_s {
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/// The filters in the chain; initialized with lzma_raw_decoder_init().
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lzma_next_coder next;
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@ -58,7 +43,7 @@ struct lzma_coder_s {
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/// Uncompressed Size calculated while encoding
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lzma_vli uncompressed_size;
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/// Position in Block Padding and the Check fields
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/// Position in the Check field
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size_t pos;
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/// Check of the uncompressed data
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@ -74,7 +59,7 @@ block_encode(lzma_coder *coder, lzma_allocator *allocator,
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{
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// Check that our amount of input stays in proper limits.
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if (LZMA_VLI_MAX - coder->uncompressed_size < in_size - *in_pos)
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return LZMA_PROG_ERROR;
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return LZMA_DATA_ERROR;
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switch (coder->sequence) {
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case SEQ_CODE: {
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@ -117,14 +102,16 @@ block_encode(lzma_coder *coder, lzma_allocator *allocator,
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// Fall through
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case SEQ_PADDING:
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// Pad Compressed Data to a multiple of four bytes.
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while ((coder->compressed_size + coder->pos) & 3) {
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// Pad Compressed Data to a multiple of four bytes. We can
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// use coder->compressed_size for this since we don't need
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// it for anything else anymore.
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while (coder->compressed_size & 3) {
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if (*out_pos >= out_size)
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return LZMA_OK;
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out[*out_pos] = 0x00;
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++*out_pos;
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++coder->pos;
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++coder->compressed_size;
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}
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if (coder->block->check == LZMA_CHECK_NONE)
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@ -132,7 +119,6 @@ block_encode(lzma_coder *coder, lzma_allocator *allocator,
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lzma_check_finish(&coder->check, coder->block->check);
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coder->pos = 0;
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coder->sequence = SEQ_CHECK;
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// Fall through
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@ -23,6 +23,31 @@
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#include "common.h"
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/// \brief Biggest Compressed Size value that the Block encoder supports
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///
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/// The maximum size of a single Block is limited by the maximum size of
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/// a Stream, which in theory is 2^63 - 3 bytes (i.e. LZMA_VLI_MAX - 3).
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/// While the size is really big and no one should hit it in practice, we
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/// take it into account in some places anyway to catch some errors e.g. if
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/// application passes insanely big value to some function.
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///
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/// We could take into account the headers etc. to determine the exact
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/// maximum size of the Compressed Data field, but the complexity would give
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/// us nothing useful. Instead, limit the size of Compressed Data so that
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/// even with biggest possible Block Header and Check fields the total
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/// encoded size of the Block stays as a valid VLI. This doesn't guarantee
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/// that the size of the Stream doesn't grow too big, but that problem is
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/// taken care outside the Block handling code.
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///
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/// ~LZMA_VLI_C(3) is to guarantee that if we need padding at the end of
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/// the Compressed Data field, it will still stay in the proper limit.
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///
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/// This constant is in this file because it is needed in both
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/// block_encoder.c and block_buffer_encoder.c.
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#define COMPRESSED_SIZE_MAX ((LZMA_VLI_MAX - LZMA_BLOCK_HEADER_SIZE_MAX \
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- LZMA_CHECK_SIZE_MAX) & ~LZMA_VLI_C(3))
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extern lzma_ret lzma_block_encoder_init(lzma_next_coder *next,
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lzma_allocator *allocator, lzma_block *block);
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