[mojo] Add shared buffer support to mojo JavaScript bindings.

mojo/edk/js/core.cc

Index: mojo/edk/js/core.cc
diff --git a/mojo/edk/js/core.cc b/mojo/edk/js/core.cc
index c8ccc37c536db220ef621fa5dc51299515236f24..46cfab6342afc78674fc9a93ed34b29636f00e37 100644
--- a/mojo/edk/js/core.cc
+++ b/mojo/edk/js/core.cc
@@ -289,6 +289,83 @@ bool IsHandle(gin::Arguments* args, v8::Handle<v8::Value> val) {
       args->isolate(), val, &ignore_handle);
 }
 
+gin::Dictionary CreateSharedBuffer(const gin::Arguments& args,
+                                   uint64_t num_bytes,
+                                   MojoCreateSharedBufferOptionsFlags flags) {
+  gin::Dictionary dictionary = gin::Dictionary::CreateEmpty(args.isolate());
+  MojoHandle handle = MOJO_HANDLE_INVALID;
+  MojoCreateSharedBufferOptions options;
+  options.flags = flags;
+  MojoResult result = MojoCreateSharedBuffer(&options, num_bytes, &handle);
+  if (result != MOJO_RESULT_OK) {
+    dictionary.Set("result", result);
+    return dictionary;
+  }
+
+  dictionary.Set("result", result);
+  dictionary.Set("handle", mojo::Handle(handle));
+
+  return dictionary;
+}
+
+gin::Dictionary DuplicateBufferHandle(
+    const gin::Arguments& args,
+    mojo::Handle handle,
+    MojoDuplicateBufferHandleOptionsFlags flags) {
+  gin::Dictionary dictionary = gin::Dictionary::CreateEmpty(args.isolate());
+  MojoHandle duped = MOJO_HANDLE_INVALID;
+  MojoDuplicateBufferHandleOptions options;
+  // The |flags| is mandatory parameter for DuplicateBufferHandle, and it will
+  // be always initialized in MojoDuplicateBufferHandleOptions struct. For now,
+  // since the struct has only one options field (flags), set struct_size to be
+  // equal to the size of MojoDuplicateBufferHandleOptions.
+  options.struct_size =
+      static_cast<uint32_t>(sizeof(MojoDuplicateBufferHandleOptions));
+  options.flags = flags;
+  MojoResult result =
+      MojoDuplicateBufferHandle(handle.value(), &options, &duped);
+  if (result != MOJO_RESULT_OK) {
+    dictionary.Set("result", result);
+    return dictionary;
+  }
+
+  dictionary.Set("result", result);
+  dictionary.Set("handle", mojo::Handle(duped));
+
+  return dictionary;
+}
+
+gin::Dictionary MapBuffer(const gin::Arguments& args,
+                          mojo::Handle handle,
+                          uint64_t offset,
+                          uint64_t num_bytes,
+                          MojoMapBufferFlags flags) {
+  gin::Dictionary dictionary = gin::Dictionary::CreateEmpty(args.isolate());
+  void* data = nullptr;
+  MojoResult result =
+      MojoMapBuffer(handle.value(), offset, num_bytes, &data, flags);
+  if (result != MOJO_RESULT_OK) {
+    dictionary.Set("result", result);
+    return dictionary;
+  }
+
+  v8::Handle<v8::ArrayBuffer> array_buffer =
+      v8::ArrayBuffer::New(args.isolate(), data, num_bytes);
+
+  dictionary.Set("result", result);
+  dictionary.Set("buffer", array_buffer);
+
+  return dictionary;
+}
+
+MojoResult UnmapBuffer(const gin::Arguments& args,
+                       const v8::Handle<v8::ArrayBuffer>& buffer) {
+  // Buffer must be external, created by MapBuffer
+  if (!buffer->IsExternal())
+    return MOJO_RESULT_INVALID_ARGUMENT;
+
+  return MojoUnmapBuffer(buffer->GetContents().Data());
+}
 
 gin::WrapperInfo g_wrapper_info = { gin::kEmbedderNativeGin };
 
@@ -317,6 +394,10 @@ v8::Local<v8::Value> Core::GetModule(v8::Isolate* isolate) {
             .SetMethod("readData", ReadData)
             .SetMethod("drainData", DoDrainData)
             .SetMethod("isHandle", IsHandle)
+            .SetMethod("createSharedBuffer", CreateSharedBuffer)
+            .SetMethod("duplicateBufferHandle", DuplicateBufferHandle)
+            .SetMethod("mapBuffer", MapBuffer)
+            .SetMethod("unmapBuffer", UnmapBuffer)
 
             .SetValue("RESULT_OK", MOJO_RESULT_OK)
             .SetValue("RESULT_CANCELLED", MOJO_RESULT_CANCELLED)
@@ -369,6 +450,16 @@ v8::Local<v8::Value> Core::GetModule(v8::Isolate* isolate) {
             .SetValue("READ_DATA_FLAG_DISCARD", MOJO_READ_DATA_FLAG_DISCARD)
             .SetValue("READ_DATA_FLAG_QUERY", MOJO_READ_DATA_FLAG_QUERY)
             .SetValue("READ_DATA_FLAG_PEEK", MOJO_READ_DATA_FLAG_PEEK)
+            .SetValue("CREATE_SHARED_BUFFER_OPTIONS_FLAG_NONE",
+                      MOJO_CREATE_SHARED_BUFFER_OPTIONS_FLAG_NONE)
+
+            .SetValue("DUPLICATE_BUFFER_HANDLE_OPTIONS_FLAG_NONE",
+                      MOJO_DUPLICATE_BUFFER_HANDLE_OPTIONS_FLAG_NONE)
+
+            .SetValue("DUPLICATE_BUFFER_HANDLE_OPTIONS_FLAG_READ_ONLY",
+                      MOJO_DUPLICATE_BUFFER_HANDLE_OPTIONS_FLAG_READ_ONLY)
+
+            .SetValue("MAP_BUFFER_FLAG_NONE", MOJO_MAP_BUFFER_FLAG_NONE)
             .Build();
 
     data->SetObjectTemplate(&g_wrapper_info, templ);