Creating a pexe content handler to translate and run pexes.

mojo/nacl/nonsfi/irt_pnacl_translator_compile.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 "base/logging.h"
+#include "mojo/nacl/nonsfi/irt_mojo_nonsfi.h"
+#include "mojo/public/cpp/bindings/string.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "mojo/public/cpp/utility/run_loop.h"
+#include "native_client/src/untrusted/irt/irt_dev.h"
+#include "services/nacl/pnacl_compile.mojom.h"
+
+namespace {
+
+// Implements a mojom interface which allows the content handler to communicate
+// with the nexe compiler service.
+class PexeCompilerImpl : public mojo::nacl::PexeCompiler {
+ public:
+  PexeCompilerImpl(mojo::ScopedMessagePipeHandle handle,
+                   const struct nacl_irt_pnacl_compile_funcs* funcs)
+      : funcs_(funcs), strong_binding_(this, handle.Pass()) {}
+  void PexeCompile(const mojo::String& pexe_file_name,
+                   const mojo::Callback<void(mojo::String)>& callback)
+      override {
+    base::FilePath obj_file_name;
+    if (!CreateTemporaryFile(&obj_file_name))
+      LOG(FATAL) << "Could not make temporary object file";
+    // TODO(smklein): Use multiple object files to increase parallelism.
+    int obj_file_fd = open(obj_file_name.value().c_str(), O_RDWR, O_TRUNC);
+
+    if (obj_file_fd < 0)
+      LOG(FATAL) << "Could not create temp file for compiled pexe";
+
+    // TODO(smklein): Is there a less arbitrary number to choose?
+    uint32_t num_threads = 8;
+    size_t obj_file_fd_count = 1;
+    char relocation_model[] = "-relocation-model=pic";

[Mark Seaborn, 2015/10/28 18:31:43]

How about some comments on these options?  For this one: "Non-SFI mode requires
PIC"

[Sean Klein, 2015/10/28 21:39:59]

Done.

+    char force_tls[] = "-force-tls-non-pic";

[Mark Seaborn, 2015/10/28 18:31:43]

This is copied from pnacl-translate.py but I suspect we don't need it any more. 
You could add a comment to that effect or remove it.

[Sean Klein, 2015/10/28 21:39:59]

Removed.

+    char bitcode_format[] = "-bitcode-format=pnacl";
+    char sentinel[] = "\0";

[Mark Seaborn, 2015/10/28 18:31:43]

The sentinel is supposed to be NULL, not an empty string.

(Also, "" would be equivalent to "\0" as a C string.)

[Sean Klein, 2015/10/28 21:39:59]

Updated to nullptr in args.

+    char *args[] = { relocation_model, force_tls, bitcode_format, sentinel };

[Mark Seaborn, 2015/10/28 18:31:43]

Spacing: "char*"

[Sean Klein, 2015/10/28 21:39:59]

Done.

+    size_t argc = 3;
+    funcs_->init_callback(num_threads, &obj_file_fd, obj_file_fd_count,
+                          args, argc);
+
+    // Read the pexe using fread, and write the pexe into the callback function.
+    size_t buf_size = 0x100000;
+    scoped_ptr<char[]> buf(new char[buf_size]);
+    FILE* pexe_file_stream = fopen(pexe_file_name.get().c_str(), "r");
+    // Once the pexe has been opened, it is no longer needed, so we unlink it.
+    if (unlink(pexe_file_name.get().c_str()))
+      LOG(FATAL) << "Could not unlink temporary pexe file";
+    if (pexe_file_stream == nullptr)
+      LOG(FATAL) << "Could not open pexe for reading";
+    for (;;) {
+      size_t num_bytes_from_pexe = fread(&buf[0], 1, buf_size,

[Mark Seaborn, 2015/10/28 18:31:43]

buf.get() is probably more idiomatic for scoped_ptr.  Same below.

[Sean Klein, 2015/10/28 21:39:59]

Done.

+                                         pexe_file_stream);
+      if (ferror(pexe_file_stream)) {
+        LOG(FATAL) << "Error reading from pexe file stream";
+      }
+      if (num_bytes_from_pexe == 0) {
+        break;
+      }
+      funcs_->data_callback(&buf[0], num_bytes_from_pexe);
+    }
+

[Mark Seaborn, 2015/10/28 18:31:43]

You could replace the original "delete[] buf;" with buf.reset() to deallocate
earlier.

[Sean Klein, 2015/10/28 21:39:59]

Done.

+    if (fclose(pexe_file_stream))
+      LOG(FATAL) << "Failed to close pexe file stream from compiler nexe";
+    funcs_->end_callback();
+
+    // Return the name of the object file.
+    callback.Run(mojo::String(obj_file_name.value()));
+  }
+ private:
+  const struct nacl_irt_pnacl_compile_funcs* funcs_;
+  mojo::StrongBinding<mojo::nacl::PexeCompiler> strong_binding_;
+};
+
+void ServeTranslateRequest(const struct nacl_irt_pnacl_compile_funcs* funcs) {
+  // Acquire the handle -- this is our mechanism to contact the
+  // content handler which called us.
+  MojoHandle handle;
+  nacl::MojoGetInitialHandle(&handle);
+
+  // Convert the MojoHandle into a ScopedMessagePipeHandle, and use that to
+  // implement the PexeCompiler interface.
+  PexeCompilerImpl impl(
+      mojo::ScopedMessagePipeHandle(mojo::MessagePipeHandle(handle)).Pass(),
+      funcs);
+  mojo::RunLoop::current()->RunUntilIdle();
+}
+
+}  // namespace anonymous
+
+namespace nacl {
+
+const struct nacl_irt_private_pnacl_translator_compile
+    nacl_irt_private_pnacl_translator_compile = {
+  ServeTranslateRequest
+};
+
+}  // namespace nacl