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Improve speed of fuzzer_seek #766

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merged 2 commits into from
Dec 2, 2024
Merged

Improve speed of fuzzer_seek #766

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3e0a760
Do not shrink decoding buffer when parameters change
ktmf01 Dec 2, 2024
a4b1cb7
Improve fuzzer_seek performance by imposing limits
ktmf01 Dec 2, 2024
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18 changes: 16 additions & 2 deletions oss-fuzz/seek.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,8 @@
#include "common.h"

int write_abort_check_counter = -1;
int written_uncompressed_bytes = 0;
int errors_received_counter = 0;

#if 0 /* set to 1 to debug */
#define FPRINTF_DEBUG_ONLY(...) fprintf(__VA_ARGS__)
Expand All @@ -46,20 +48,30 @@ int write_abort_check_counter = -1;

static FLAC__StreamDecoderWriteStatus write_callback(const FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32 *const buffer[], void *client_data)
{
(void)decoder, (void)frame, (void)buffer, (void)client_data;
(void)decoder, (void)buffer, (void)client_data;
if(write_abort_check_counter > 0) {
write_abort_check_counter--;
if(write_abort_check_counter == 0)
return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;
} else if(write_abort_check_counter == 0)
/* This must not happen: write callback called after abort is returned */
abort();

written_uncompressed_bytes += frame->header.blocksize * frame->header.channels * frame->header.bits_per_sample / 8;
if(written_uncompressed_bytes > (1 << 24))
return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;


if(errors_received_counter > 10000)
return FLAC__STREAM_DECODER_WRITE_STATUS_ABORT;

return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
}

static void error_callback(const FLAC__StreamDecoder *decoder, FLAC__StreamDecoderErrorStatus error, void *client_data)
{
(void)decoder, (void)error, (void)client_data;
(void)decoder, (void)error, (void)client_data;
errors_received_counter++;
}


Expand All @@ -80,6 +92,8 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
alloc_check_counter = 0;

write_abort_check_counter = -1;
written_uncompressed_bytes = 0;
errors_received_counter = 0;

/* allocate the decoder */
if((decoder = FLAC__stream_decoder_new()) == NULL) {
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5 changes: 5 additions & 0 deletions src/libFLAC/stream_decoder.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1552,6 +1552,11 @@ FLAC__bool allocate_output_(FLAC__StreamDecoder *decoder, uint32_t size, uint32_
decoder->private_->side_subframe = 0;
}

/* Only grow per-channel buffers, even if number of channels increases */
if(decoder->private_->output_capacity > size) {
size = decoder->private_->output_capacity;
}

for(i = 0; i < channels; i++) {
/* WATCHOUT:
* FLAC__lpc_restore_signal_asm_ia32_mmx() and ..._intrin_sseN()
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