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doc/examples: add fuzz target for individual ffmpeg APIs for in-process fuzzing with libFuzzer, AFL, and similar fuzzing engines.
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Thomas Garnier
Michael Niedermayer
parent
fba2a8a254
commit
c06d923410
201
doc/examples/decoder_targeted.c
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doc/examples/decoder_targeted.c
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/*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/* Targeted fuzzer that targets specific codecs depending on two
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compile-time flags.
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INSTRUCTIONS:
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* Get the very fresh clang, e.g. see http://libfuzzer.info#versions
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* Get and build libFuzzer:
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svn co http://llvm.org/svn/llvm-project/llvm/trunk/lib/Fuzzer
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./Fuzzer/build.sh
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* build ffmpeg for fuzzing:
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FLAGS="-fsanitize=address -fsanitize-coverage=trace-pc-guard,trace-cmp -g" CC="clang $FLAGS" CXX="clang++ $FLAGS" ./configure --disable-yasm
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make clean && make -j
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* build the fuzz target.
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Choose the value of FFMPEG_CODEC (e.g. AV_CODEC_ID_DVD_SUBTITLE) and
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choose one of FUZZ_FFMPEG_VIDEO, FUZZ_FFMPEG_AUDIO, FUZZ_FFMPEG_SUBTITLE.
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clang -fsanitize=address -fsanitize-coverage=trace-pc-guard,trace-cmp doc/examples/decoder_targeted.c -o decoder_targeted -I. -DFFMPEG_CODEC=AV_CODEC_ID_MPEG1VIDEO -DFUZZ_FFMPEG_VIDEO ../../libfuzzer/libFuzzer.a -Llibavcodec -Llibavdevice -Llibavfilter -Llibavformat -Llibavresample -Llibavutil -Llibpostproc -Llibswscale -Llibswresample -Wl,--as-needed -Wl,-z,noexecstack -Wl,--warn-common -Wl,-rpath-link=libpostproc:libswresample:libswscale:libavfilter:libavdevice:libavformat:libavcodec:libavutil:libavresample -lavdevice -lavfilter -lavformat -lavcodec -lswresample -lswscale -lavutil -ldl -lxcb -lxcb-shm -lxcb -lxcb-xfixes -lxcb -lxcb-shape -lxcb -lX11 -lasound -lm -lbz2 -lz -pthread
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* create a corpus directory and put some samples there (empty dir is ok too):
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mkdir CORPUS && cp some-files CORPUS
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* Run fuzzing:
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./decoder_targeted -max_len=100000 CORPUS
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More info:
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http://libfuzzer.info
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http://tutorial.libfuzzer.info
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https://github.com/google/oss-fuzz
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http://lcamtuf.coredump.cx/afl/
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https://security.googleblog.com/2016/08/guided-in-process-fuzzing-of-chrome.html
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*/
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#include "libavutil/avassert.h"
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#include "libavcodec/avcodec.h"
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#include "libavformat/avformat.h"
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static void error(const char *err)
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{
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fprintf(stderr, "%s", err);
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exit(1);
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}
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static AVCodec *c = NULL;
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static AVCodec *AVCodecInitialize(enum AVCodecID codec_id)
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{
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AVCodec *res;
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av_register_all();
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av_log_set_level(AV_LOG_PANIC);
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res = avcodec_find_decoder(codec_id);
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if (!res)
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error("Failed to find decoder");
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return res;
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}
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#if defined(FUZZ_FFMPEG_VIDEO)
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#define decode_handler avcodec_decode_video2
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#elif defined(FUZZ_FFMPEG_AUDIO)
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#define decode_handler avcodec_decode_audio4
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#elif defined(FUZZ_FFMPEG_SUBTITLE)
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static int subtitle_handler(AVCodecContext *avctx, void *frame,
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int *got_sub_ptr, AVPacket *avpkt)
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{
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AVSubtitle sub;
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int ret = avcodec_decode_subtitle2(avctx, &sub, got_sub_ptr, avpkt);
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if (ret >= 0 && *got_sub_ptr)
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avsubtitle_free(&sub);
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return ret;
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}
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#define decode_handler subtitle_handler
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#else
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#error "Specify encoder type" // To catch mistakes
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#endif
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// Class to handle buffer allocation and resize for each frame
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typedef struct FuzzDataBuffer {
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size_t size_;
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uint8_t *data_;
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} FuzzDataBuffer;
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void FDBCreate(FuzzDataBuffer *FDB) {
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FDB->size_ = 0x1000;
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FDB->data_ = av_malloc(FDB->size_);
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if (!FDB->data_)
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error("Failed memory allocation");
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}
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void FDBDesroy(FuzzDataBuffer *FDB) { av_free(FDB->data_); }
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void FDBRealloc(FuzzDataBuffer *FDB, size_t size) {
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size_t needed = size + FF_INPUT_BUFFER_PADDING_SIZE;
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av_assert0(needed > size);
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if (needed > FDB->size_) {
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av_free(FDB->data_);
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FDB->size_ = needed;
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FDB->data_ = av_malloc(FDB->size_);
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if (!FDB->data_)
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error("Failed memory allocation");
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}
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}
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void FDBPrepare(FuzzDataBuffer *FDB, AVPacket *dst, const uint8_t *data,
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size_t size)
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{
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FDBRealloc(FDB, size);
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memcpy(FDB->data_, data, size);
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size_t padd = FDB->size_ - size;
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if (padd > FF_INPUT_BUFFER_PADDING_SIZE)
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padd = FF_INPUT_BUFFER_PADDING_SIZE;
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memset(FDB->data_ + size, 0, padd);
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av_init_packet(dst);
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dst->data = FDB->data_;
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dst->size = size;
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}
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// Ensure we don't loop forever
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const uint32_t maxiteration = 8096;
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static const uint64_t FUZZ_TAG = 0x4741542D5A5A5546ULL;
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int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
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const uint64_t fuzz_tag = FUZZ_TAG;
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FuzzDataBuffer buffer;
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const uint8_t *last = data;
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const uint8_t *end = data + size;
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uint32_t it = 0;
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if (!c)
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c = AVCodecInitialize(FFMPEG_CODEC); // Done once.
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AVCodecContext* ctx = avcodec_alloc_context3(NULL);
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if (!ctx)
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error("Failed memory allocation");
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int res = avcodec_open2(ctx, c, NULL);
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if (res < 0)
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return res;
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FDBCreate(&buffer);
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int got_frame;
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AVFrame *frame = av_frame_alloc();
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if (!frame)
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error("Failed memory allocation");
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// Read very simple container
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AVPacket avpkt;
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while (data < end && it < maxiteration) {
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// Search for the TAG
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while (data + sizeof(fuzz_tag) < end) {
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if (data[0] == (fuzz_tag & 0xFF) && *(const uint64_t *)(data) == fuzz_tag)
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break;
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data++;
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}
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if (data + sizeof(fuzz_tag) > end)
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data = end;
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FDBPrepare(&buffer, &avpkt, last, data - last);
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data += sizeof(fuzz_tag);
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last = data;
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// Iterate through all data
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while (avpkt.size > 0 && it++ < maxiteration) {
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av_frame_unref(frame);
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int ret = decode_handler(ctx, frame, &got_frame, &avpkt);
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if (ret <= 0 || ret > avpkt.size)
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break;
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avpkt.data += ret;
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avpkt.size -= ret;
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}
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}
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av_init_packet(&avpkt);
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avpkt.data = NULL;
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avpkt.size = 0;
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do {
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got_frame = 0;
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decode_handler(ctx, frame, &got_frame, &avpkt);
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} while (got_frame == 1 && it++ < maxiteration);
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av_frame_free(&frame);
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avcodec_free_context(&ctx);
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av_freep(&ctx);
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FDBDesroy(&buffer);
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return 0;
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}
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