Add an openjpeg libfuzzer.

testing/libfuzzer/pdf_jpx_fuzzer.cc

+// Copyright 2016 The PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <cstdint>
+#include <memory>
+#include <vector>
+
+#include "core/fxcodec/codec/codec_int.h"
+#include "core/include/fxge/fx_dib.h"
+
+CCodec_JpxModule g_module;
+
+struct DecoderDeleter {
+  void operator()(CJPX_Decoder* decoder) { g_module.DestroyDecoder(decoder); }
+};
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  std::unique_ptr<CJPX_Decoder, DecoderDeleter> decoder(
+      g_module.CreateDecoder(data, size, nullptr));
+  if (!decoder)
+    return 0;
+
+  FX_DWORD width;
+  FX_DWORD height;
+  FX_DWORD components;
+  g_module.GetImageInfo(decoder.get(), &width, &height, &components);
+
+  FXDIB_Format format;
+  if (components == 1) {
+    format = FXDIB_8bppRgb;
+  } else if (components <= 3) {
+    format = FXDIB_Rgb;
+  } else if (components == 4) {
+    format = FXDIB_Rgb32;
+  } else {
+    width = (width * components + 2) / 3;
+    format = FXDIB_Rgb;
+  }
+
+  std::unique_ptr<CFX_DIBitmap> bitmap(new CFX_DIBitmap);
+  if (!bitmap->Create(width, height, format))
+    return 0;
+
+  bitmap->Clear(0xFFFFFFFF);

[Tom Sepez, 2016/03/18 20:33:40]

Do we have to do this? We're not going to look at the output -- does any part of
the rendering path depend upon the initial bitmap content?  Otherwise, maybe we
can save some cycles.

[Oliver Chang, 2016/03/18 20:50:26]

Probably not, it would seem logical that it doesn't, but I wasn't sure if there
was some craziness happening somewhere that depended on this.

I'll remove it for now.

+  std::vector<uint8_t> output_offsets(components);
+  for (FX_DWORD i = 0; i < components; ++i)
+    output_offsets[i] = i;
+
+  g_module.Decode(decoder.get(), bitmap->GetBuffer(), bitmap->GetPitch(),
+                  output_offsets);
+  return 0;
+}