Adding PFFFT to oss-fuzz (#1718)

* first commit

* comments addressed

projects/pffft/Dockerfile

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+# Copyright 2018 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+
+FROM gcr.io/oss-fuzz-base/base-builder
+MAINTAINER alessiob@webrtc.org
+RUN apt-get update && apt-get install -y mercurial
+RUN hg clone https://bitbucket.org/jpommier/pffft $SRC/pffft
+WORKDIR pffft
+COPY build.sh pffft_fuzzer.cc $SRC/

projects/pffft/build.sh

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+#!/bin/bash -eu
+# Copyright 2018 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+################################################################################
+
+SRC_DIR=$SRC/pffft
+cd $WORK
+
+# Building PFFFT as a static library.
+if [ -f libpffft.a ]; then
+  rm libpffft.a
+fi
+$CXX $CXXFLAGS -c -msse2 -fPIC $SRC_DIR/pffft.c -o pffft.o
+ar rcs libpffft.a pffft.o
+
+# Building PFFFT fuzzers.
+$CXX $CXXFLAGS -std=c++11 -I$SRC_DIR \
+     $SRC/pffft_fuzzer.cc -o $OUT/pffft_real_fwbw_fuzzer \
+     -lFuzzingEngine $WORK/libpffft.a

projects/pffft/pffft_fuzzer.cc

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+// Copyright 2018 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+///////////////////////////////////////////////////////////////////////////
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <cstring>
+
+#include "pffft.h"
+
+namespace {
+
+constexpr size_t kSizeOfFloat = sizeof(float);
+
+bool IsValidSize(size_t n) {
+  if (n == 0) { return false; }
+  // PFFFT only supports transforms for inputs of length N of the form
+  // N = (2^a)*(3^b)*(5^c) where a >= 5, b >=0, c >= 0.
+  constexpr std::array<int, 3> kFactors = {2, 3, 5};
+  std::array<int, kFactors.size()> factorization{};
+  for (size_t i = 0; i < kFactors.size(); ++i) {
+    const int factor = kFactors[i];
+    while (n % factor == 0) {
+      n /= factor;
+      factorization[i]++;
+    }
+  }
+  return factorization[0] >= 5 && n == 1;
+}
+
+}  // namespace
+
+// Entry point for LibFuzzer.
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  // Set the number of FFT points to use |data| as input vector.
+  // The latter is truncated if the number of bytes is not an integer
+  // multiple of the size of a float.
+  const size_t fft_size = size / kSizeOfFloat;
+  if (!IsValidSize(fft_size)) {
+    return 0;
+  }
+
+  const size_t number_of_bytes = fft_size * kSizeOfFloat;
+  assert(number_of_bytes <= size);
+  float* buf = static_cast<float*>(pffft_aligned_malloc(number_of_bytes));
+  std::memcpy(buf, reinterpret_cast<const float*>(data), number_of_bytes);
+
+  PFFFT_Setup* pffft_setup = pffft_new_setup(fft_size, PFFFT_REAL);
+
+  pffft_transform(pffft_setup, buf, buf, NULL, PFFFT_FORWARD);
+  pffft_transform(pffft_setup, buf, buf, NULL, PFFFT_BACKWARD);
+  
+  pffft_aligned_free(buf);
+  pffft_destroy_setup(pffft_setup);
+
+  return 0;
+}

projects/pffft/project.yaml

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+homepage: "https://bitbucket.org/jpommier/pffft"
+primary_contact: "pommier@modartt.com"
+auto_ccs:
+  - "alessiob@webrtc.org"
+  - "mbonadei@webrtc.org"
+sanitizers:
+  - address
+  - memory
+  - undefined