Creating a pexe content handler to translate and run pexes.

services/nacl/content_handler_main_nonsfi_pexe.cc

+// Copyright 2015 The Chromium 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 <fcntl.h>
+
+#include "base/files/file_util.h"
+#include "mojo/application/application_runner_chromium.h"
+#include "mojo/application/content_handler_factory.h"
+#include "mojo/data_pipe_utils/data_pipe_utils.h"
+#include "mojo/message_pump/message_pump_mojo.h"
+#include "mojo/nacl/nonsfi/nexe_launcher_nonsfi.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_impl.h"
+#include "mojo/services/files/c/lib/template_util.h"
+#include "services/nacl/pnacl_compile.mojom.h"
+#include "services/nacl/pnacl_link.mojom.h"
+
+namespace nacl {
+namespace content_handler {
+namespace {
+
+class CompilerUI {
+ public:
+  explicit CompilerUI(mojo::ScopedMessagePipeHandle handle) {
+    compiler_.Bind(mojo::InterfacePtrInfo<mojo::nacl::PexeCompiler>(
+        handle.Pass(), 0u));
+  }
+
+  // Synchronous method to compile pexe into object file.
+  mojo::String CompilePexe(mojo::String pexe_file_path) {
+    mojo::String output;
+    compiler_->PexeCompile(pexe_file_path, mojio::Capture(&output));
+    if (!compiler_.WaitForIncomingResponse())
+      LOG(FATAL) << "Waiting for pexe compiler failed";
+    return output;
+  }
+
+ private:
+  mojo::nacl::PexeCompilerPtr compiler_;
+};
+
+class LinkerUI {
+ public:
+  explicit LinkerUI(mojo::ScopedMessagePipeHandle handle) {
+    linker_.Bind(mojo::InterfacePtrInfo<mojo::nacl::PexeLinker>(
+        handle.Pass(), 0u));
+  }
+
+  // Synchronous method to link object file into nexe.
+  mojo::String LinkPexe(mojo::String object_file_path) {
+    mojo::String output;
+    linker_->PexeLink(object_file_path, mojio::Capture(&output));
+    if (!linker_.WaitForIncomingResponse())
+      LOG(FATAL) << "Waiting for pexe linker failed";
+    return output;
+  }
+
+ private:
+  mojo::nacl::PexeLinkerPtr linker_;
+};
+
+}  // namespace anonymous
+
+class PexeContentHandler : public mojo::ApplicationDelegate,
+                           public mojo::ContentHandlerFactory::Delegate {
+ public:
+  PexeContentHandler() : content_handler_factory_(this) {}
+
+ private:
+  // Overridden from ApplicationDelegate:
+  void Initialize(mojo::ApplicationImpl* app) override {
+    app->ConnectToService("mojo:pnacl_compile", &compiler_init_);
+    app->ConnectToService("mojo:pnacl_link", &linker_init_);
+  }
+
+  // Overridden from ApplicationDelegate:
+  bool ConfigureIncomingConnection(
+      mojo::ApplicationConnection* connection) override {
+    connection->AddService(&content_handler_factory_);
+    return true;
+  }
+
+  // Overridden from ContentHandlerFactory::ManagedDelegate:

[Sean Klein, 2015/11/03 14:31:01]

Fixed this incorrect comment regarding ManagedDelegate -- actually inheriting
from ContentHandlerFactory::Delegate.

+  void RunApplication(
+      mojo::InterfaceRequest<mojo::Application> application_request,
+      mojo::URLResponsePtr response) override {
+    // Needed to use Mojo interfaces on this thread.
+    base::MessageLoop loop(mojo::common::MessagePumpMojo::Create());

[jamesr, 2015/11/02 23:00:02]

why do you need to create another message loop?  mojo::ApplicationRunnerChromium
creates a mojo message pump for you:

https://github.com/domokit/mojo/blob/master/mojo/application/application_runn...

[Sean Klein, 2015/11/03 14:31:01]

As discussed offline, the ContentHandlerFactory is running RunApplication on a
different thread. Removing the message loop here causes the content handler to
fail on the call to "compiler_init_->PexeCompilerStart(...)".

+    // Create temporary file for pexe
+    base::FilePath pexe_file_path;
+    FILE* pexe_fp = CreateAndOpenTemporaryFile(&pexe_file_path);
+    if (!pexe_fp)
+      LOG(FATAL) << "Could not create temporary file for pexe";
+    // Acquire the pexe.
+    if (!mojo::common::BlockingCopyToFile(response->body.Pass(), pexe_fp))
+      LOG(FATAL) << "Could not copy pexe to file";
+    if (fclose(pexe_fp))
+      LOG(FATAL) << "Could not close pexe file";
+
+    // Compile the pexe into an object file
+    mojo::ScopedMessagePipeHandle parent_compile_pipe;
+    mojo::ScopedMessagePipeHandle child_compile_pipe;
+    if (CreateMessagePipe(nullptr, &parent_compile_pipe, &child_compile_pipe) !=
+        MOJO_RESULT_OK)
+      LOG(FATAL) << "Could not create message pipe to compiler";
+    compiler_init_->PexeCompilerStart(child_compile_pipe.Pass());
+
+    // Communicate with the compiler using a mojom interface.
+    CompilerUI compiler_ui(parent_compile_pipe.Pass());
+    mojo::String object_file = compiler_ui.CompilePexe(pexe_file_path.value());
+
+    // Link the object file into a nexe
+    mojo::ScopedMessagePipeHandle parent_link_pipe;
+    mojo::ScopedMessagePipeHandle child_link_pipe;
+    if (CreateMessagePipe(nullptr, &parent_link_pipe, &child_link_pipe) !=
+        MOJO_RESULT_OK)
+      LOG(FATAL) << "Could not create message pipe to linker";
+    linker_init_->PexeLinkerStart(child_link_pipe.Pass());
+
+    // Communicate with the linker using a mojom interface.
+    LinkerUI linker_ui(parent_link_pipe.Pass());
+    mojo::String nexe_file = linker_ui.LinkPexe(object_file);
+
+    // Open the nexe file and launch it (with our mojo handle)
+    int nexe_fd = open(nexe_file.get().c_str(), O_RDONLY);
+    if (unlink(nexe_file.get().c_str()))
+      LOG(FATAL) << "Could not unlink temporary nexe file";
+    if (nexe_fd < 0)
+      LOG(FATAL) << "Could not open nexe object file";
+
+    // Pass the handle connecting us with mojo_shell to the nexe.
+    MojoHandle handle = application_request.PassMessagePipe().release().value();
+    ::nacl::MojoLaunchNexeNonsfi(nexe_fd, handle,
+                                 false /* enable_translation_irt */);
+  }
+
+ private:
+  mojo::ContentHandlerFactory content_handler_factory_;
+  mojo::nacl::PexeCompilerInitPtr compiler_init_;
+  mojo::nacl::PexeLinkerInitPtr linker_init_;
+
+  DISALLOW_COPY_AND_ASSIGN(PexeContentHandler);
+};
+
+}  // namespace content_handler
+}  // namespace nacl
+
+MojoResult MojoMain(MojoHandle application_request) {
+  mojo::ApplicationRunnerChromium runner(
+      new nacl::content_handler::PexeContentHandler());
+  return runner.Run(application_request);
+}