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Speed up fuzzer_tool_flac #770

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merged 2 commits into from
Dec 4, 2024
Merged

Speed up fuzzer_tool_flac #770

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cbff524
Fix overflow in creation of seektable template
ktmf01 Dec 3, 2024
55b86fe
Speed up bitwriter_grow_ by growing exponentially
ktmf01 Dec 3, 2024
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12 changes: 6 additions & 6 deletions src/libFLAC/bitwriter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -89,8 +89,8 @@ typedef FLAC__uint64 FLAC__bwtemp;
* next one.
*/
static const uint32_t FLAC__BITWRITER_DEFAULT_CAPACITY = 32768u / sizeof(bwword); /* size in words */
/* When growing, increment 4K at a time */
static const uint32_t FLAC__BITWRITER_DEFAULT_INCREMENT = 4096u / sizeof(bwword); /* size in words */
/* When growing, increment with 1/4th at a time */
static const uint32_t FLAC__BITWRITER_DEFAULT_GROW_FRACTION = 2; /* means grow by >> 2 (1/4th) of current size */

#define FLAC__WORDS_TO_BITS(words) ((words) * FLAC__BITS_PER_WORD)
#define FLAC__TOTAL_BITS(bw) (FLAC__WORDS_TO_BITS((bw)->words) + (bw)->bits)
Expand Down Expand Up @@ -131,11 +131,11 @@ FLAC__bool bitwriter_grow_(FLAC__BitWriter *bw, uint32_t bits_to_add)
* To prevent chrashing, give up */
return false;

/* round up capacity increase to the nearest FLAC__BITWRITER_DEFAULT_INCREMENT */
if((new_capacity - bw->capacity) % FLAC__BITWRITER_DEFAULT_INCREMENT)
new_capacity += FLAC__BITWRITER_DEFAULT_INCREMENT - ((new_capacity - bw->capacity) % FLAC__BITWRITER_DEFAULT_INCREMENT);
/* As reallocation can be quite expensive, grow exponentially */
if((new_capacity - bw->capacity) < (bw->capacity >> FLAC__BITWRITER_DEFAULT_GROW_FRACTION))
new_capacity = bw->capacity + (bw->capacity >> FLAC__BITWRITER_DEFAULT_GROW_FRACTION);

/* make sure we got everything right */
FLAC__ASSERT(0 == (new_capacity - bw->capacity) % FLAC__BITWRITER_DEFAULT_INCREMENT);
FLAC__ASSERT(new_capacity > bw->capacity);
FLAC__ASSERT(new_capacity >= bw->words + ((bw->bits + bits_to_add + FLAC__BITS_PER_WORD - 1) / FLAC__BITS_PER_WORD));

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19 changes: 15 additions & 4 deletions src/libFLAC/metadata_object.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1102,10 +1102,21 @@ FLAC_API FLAC__bool FLAC__metadata_object_seektable_template_append_spaced_point
if (!FLAC__metadata_object_seektable_resize_points(object, seek_table->num_points + num))
return false;

for (j = 0; j < num; i++, j++) {
seek_table->points[i].sample_number = total_samples * (FLAC__uint64)j / (FLAC__uint64)num;
seek_table->points[i].stream_offset = 0;
seek_table->points[i].frame_samples = 0;
if(total_samples < UINT64_MAX / num) {
/* No risk of overflow */
for (j = 0; j < num; i++, j++) {
seek_table->points[i].sample_number = total_samples * (FLAC__uint64)j / (FLAC__uint64)num;
seek_table->points[i].stream_offset = 0;
seek_table->points[i].frame_samples = 0;
}
}
else {
/* Less precise, but can handle total_samples near UINT64_MAX */
for (j = 0; j < num; i++, j++) {
seek_table->points[i].sample_number = total_samples / (FLAC__uint64)num * (FLAC__uint64)j;
seek_table->points[i].stream_offset = 0;
seek_table->points[i].frame_samples = 0;
}
}
}

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