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deflate_compress: fix checks for sequence store filled

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This commit is contained in:
Eric Biggers 2022-01-02 19:44:10 -06:00
parent 4dd63ea272
commit d352945791
1 changed files with 21 additions and 27 deletions
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48
lib/deflate_compress.c
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@ -81,12 +81,12 @@
/*
* For the greedy, lazy, and lazy2 compressors: this is the length of the
* sequence store, which is an array where the compressor temporarily stores
* matches that it's going to use in the current block. This value is 1 more
* than the number of matches that can be used in a block. If the sequence
* store fills up, then the compressor will be forced to end the block early.
* This value should be large enough so that this rarely happens, due to the
* block being ended normally before then. Increasing/decreasing this value
* will increase/decrease per-compressor memory usage linearly.
* matches that it's going to use in the current block. This value is the
* maximum number of matches that can be used in a block. If the sequence store
* fills up, then the compressor will be forced to end the block early. This
* value should be large enough so that this rarely happens, due to the block
* being ended normally before then. Increasing/decreasing this value will
* increase/decrease per-compressor memory usage linearly.
*/
#define SEQ_STORE_LENGTH 50000
@ -184,20 +184,16 @@ check_buildtime_parameters(void)
*/
STATIC_ASSERT(SOFT_MAX_BLOCK_LENGTH >= MIN_BLOCK_LENGTH);
STATIC_ASSERT(FAST_SOFT_MAX_BLOCK_LENGTH >= MIN_BLOCK_LENGTH);
STATIC_ASSERT(
(SEQ_STORE_LENGTH - 1) * DEFLATE_MIN_MATCH_LEN >=
MIN_BLOCK_LENGTH);
STATIC_ASSERT(
(FAST_SEQ_STORE_LENGTH - 1) * HT_MATCHFINDER_MIN_MATCH_LEN >=
MIN_BLOCK_LENGTH);
STATIC_ASSERT(SEQ_STORE_LENGTH * DEFLATE_MIN_MATCH_LEN >=
MIN_BLOCK_LENGTH);
STATIC_ASSERT(FAST_SEQ_STORE_LENGTH * HT_MATCHFINDER_MIN_MATCH_LEN >=
MIN_BLOCK_LENGTH);
/* Verify that the sequence stores aren't uselessly large. */
STATIC_ASSERT(
(SEQ_STORE_LENGTH - 1) * DEFLATE_MIN_MATCH_LEN <=
SOFT_MAX_BLOCK_LENGTH + MIN_BLOCK_LENGTH);
STATIC_ASSERT(
(FAST_SEQ_STORE_LENGTH - 1) * HT_MATCHFINDER_MIN_MATCH_LEN <=
FAST_SOFT_MAX_BLOCK_LENGTH + MIN_BLOCK_LENGTH);
STATIC_ASSERT(SEQ_STORE_LENGTH * DEFLATE_MIN_MATCH_LEN <=
SOFT_MAX_BLOCK_LENGTH + MIN_BLOCK_LENGTH);
STATIC_ASSERT(FAST_SEQ_STORE_LENGTH * HT_MATCHFINDER_MIN_MATCH_LEN <=
FAST_SOFT_MAX_BLOCK_LENGTH + MIN_BLOCK_LENGTH);
/* Verify that the maximum codeword lengths are valid. */
STATIC_ASSERT(
@ -488,11 +484,8 @@ struct libdeflate_compressor {
/* Hash chains matchfinder */
struct hc_matchfinder hc_mf;
/*
* The matches and literals that the parser has chosen
* for the current block.
*/
struct deflate_sequence sequences[SEQ_STORE_LENGTH];
/* Matches and literals chosen for the current block */
struct deflate_sequence sequences[SEQ_STORE_LENGTH + 1];
} g; /* (g)reedy */
@ -501,8 +494,9 @@ struct libdeflate_compressor {
/* Hash table matchfinder */
struct ht_matchfinder ht_mf;
/* Matches and literals chosen for the current block */
struct deflate_sequence sequences[
FAST_SEQ_STORE_LENGTH];
FAST_SEQ_STORE_LENGTH + 1];
} f; /* (f)astest */
@ -2320,7 +2314,7 @@ deflate_compress_fastest(struct libdeflate_compressor * restrict c,
/* Check if it's time to output another block. */
} while (in_next < in_max_block_end &&
seq < &c->p.f.sequences[ARRAY_LEN(c->p.f.sequences)]);
seq < &c->p.f.sequences[FAST_SEQ_STORE_LENGTH]);
deflate_flush_block(c, &os, in_block_begin,
in_next - in_block_begin,
@ -2402,7 +2396,7 @@ deflate_compress_greedy(struct libdeflate_compressor * restrict c,
/* Check if it's time to output another block. */
} while (in_next < in_max_block_end &&
seq < &c->p.g.sequences[ARRAY_LEN(c->p.g.sequences)] &&
seq < &c->p.g.sequences[SEQ_STORE_LENGTH] &&
!should_end_block(&c->split_stats,
in_block_begin, in_next, in_end));
@ -2614,7 +2608,7 @@ deflate_compress_lazy_generic(struct libdeflate_compressor * restrict c,
}
/* Check if it's time to output another block. */
} while (in_next < in_max_block_end &&
seq < &c->p.g.sequences[ARRAY_LEN(c->p.g.sequences)] &&
seq < &c->p.g.sequences[SEQ_STORE_LENGTH] &&
!should_end_block(&c->split_stats,
in_block_begin, in_next, in_end));