Added g711alaw_dec_fuzzer and g711mlaw_dec_fuzzer

/******************************************************************************

 *

 * Copyright (C) 2020 The Android Open Source Project

 *

 * 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.

 *

 *****************************************************************************

 * Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore

 */

cc_fuzz {

    name: "g711alaw_dec_fuzzer",

    host_supported: true,

    srcs: [

        "g711_dec_fuzzer.cpp",

    ],

    static_libs: [

        "codecs_g711dec",

    ],

    cflags: [

        "-DALAW",

    ],

}

cc_fuzz {

    name: "g711mlaw_dec_fuzzer",

    host_supported: true,

    srcs: [

        "g711_dec_fuzzer.cpp",

    ],

    static_libs: [

        "codecs_g711dec",

    ],

}

# Fuzzer for libstagefright_g711dec decoder

## Plugin Design Considerations

The fuzzer plugin for G711 is designed based on the understanding of the

codec and tries to achieve the following:

##### Maximize code coverage

G711 supports two types of decoding:

1. DecodeALaw

2. DecodeMLaw

These two decoder API's are fuzzed separately using g711alaw_dec_fuzzer and

g711mlaw_dec_fuzzer respectively.

##### Maximize utilization of input data

The plugin feeds the entire input data to the codec as expected by decoder API.

## Build

This describes steps to build g711alaw_dec_fuzzer and g711mlaw_dec_fuzzer binary.

### Android

#### Steps to build

Build the fuzzer

```

  $ mm -j$(nproc) g711alaw_dec_fuzzer

  $ mm -j$(nproc) g711mlaw_dec_fuzzer

```

#### Steps to run

Create a directory CORPUS_DIR and copy some g711 files to that folder

Push this directory to device.

To run on device

```

  $ adb sync data

  $ adb shell /data/fuzz/arm64/g711alaw_dec_fuzzer/g711alaw_dec_fuzzer CORPUS_DIR

  $ adb shell /data/fuzz/arm64/g711mlaw_dec_fuzzer/g711mlaw_dec_fuzzer CORPUS_DIR

```

To run on host

```

  $ $ANDROID_HOST_OUT/fuzz/x86_64/g711alaw_dec_fuzzer/g711alaw_dec_fuzzer CORPUS_DIR

  $ $ANDROID_HOST_OUT/fuzz/x86_64/g711mlaw_dec_fuzzer/g711mlaw_dec_fuzzer CORPUS_DIR

```

## References:

 * http://llvm.org/docs/LibFuzzer.html

 * https://github.com/google/oss-fuzz

/******************************************************************************

 *

 * Copyright (C) 2020 The Android Open Source Project

 *

 * 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.

 *

 *****************************************************************************

 * Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore

 */

#include <stdint.h>

#include <stdlib.h>

#include <string.h>

#include "g711Dec.h"

class Codec {

 public:

  Codec() = default;

  ~Codec() = default;

  void decodeFrames(const uint8_t *data, size_t size);

};

void Codec::decodeFrames(const uint8_t *data, size_t size) {

  size_t outputBufferSize = sizeof(int16_t) * size;

  int16_t *out = new int16_t[outputBufferSize];

  if (!out) {

    return;

  }

#ifdef ALAW

  DecodeALaw(out, data, size);

#else

  DecodeMLaw(out, data, size);

#endif

  delete[] out;

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

  if (size < 1) {

    return 0;

  }

  Codec *codec = new Codec();

  if (!codec) {

    return 0;

  }

  codec->decodeFrames(data, size);

  delete codec;

  return 0;

}