Content handler for python.

mojo/python/content_handler/content_handler_main.cc

Index: mojo/python/content_handler/content_handler_main.cc
diff --git a/mojo/python/content_handler/content_handler_main.cc b/mojo/python/content_handler/content_handler_main.cc
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+++ b/mojo/python/content_handler/content_handler_main.cc
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+// Copyright 2014 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 <python2.7/Python.h>
+#include <dlfcn.h>
+
+#include "base/files/file_path.h"
+#include "base/files/scoped_temp_dir.h"
+#include "base/i18n/icu_util.h"
+#include "mojo/application/application_runner_chromium.h"
+#include "mojo/application/content_handler_factory.h"
+#include "mojo/common/common_type_converters.h"
+#include "mojo/common/data_pipe_utils.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/public/cpp/application/application_delegate.h"
+#include "mojo/public/cpp/application/application_impl.h"
+#include "mojo/public/cpp/application/interface_factory_impl.h"
+#include "mojo/public/python/src/common.h"
+#include "third_party/zlib/google/zip_reader.h"
+
+char kMojoSystem[] = "mojo_system";
+char kMojoSystemImpl[] = "mojo_system_impl";
+char kMojoMain[] = "MojoMain";
+
+extern "C" {
+  void initmojo_system();
+  void initmojo_system_impl();
+}
+
+namespace mojo {
+namespace python {
+
+class PythonContentHandler : public ApplicationDelegate,
+                             public ContentHandlerFactory::Delegate {
+ public:
+  PythonContentHandler() : content_handler_factory_(this) {}
+
+ private:
+  // Overridden from ApplicationDelegate:
+  bool ConfigureIncomingConnection(ApplicationConnection* connection) override {
+    connection->AddService(&content_handler_factory_);
+    return true;
+  }
+
+  // Extracts the target application into a temporary directory. This directory
+  // is deleted at the end of the life of the PythonContentHandler object.
+  std::unique_ptr<base::ScopedTempDir> ExtractApplication(
+      URLResponsePtr response) {
+    std::unique_ptr<base::ScopedTempDir> temp_dir(new base::ScopedTempDir);
+    MOJO_CHECK(temp_dir->CreateUniqueTempDir());
+
+    zip::ZipReader reader;
+    const std::string input_data = CopyToString(response->body.Pass());
+    MOJO_DCHECK(reader.OpenFromString(input_data));
+    base::FilePath temp_dir_path = temp_dir->path();
+    while (reader.HasMore()) {
+      MOJO_DCHECK(reader.OpenCurrentEntryInZip());
+      MOJO_DCHECK(reader.ExtractCurrentEntryIntoDirectory(temp_dir_path));
+      MOJO_DCHECK(reader.AdvanceToNextEntry());
+    }
+    return temp_dir;
+  }
+
+  // Sets up the Python interpreter and loads mojo system modules. This method
+  // returns the global dictionary for the python environment that should be
+  // used for subsequent calls. Takes as input the path of the unpacked
+  // application files.
+  PyObject* SetupPythonEnvironment(const std::string& application_path) {
+    // TODO(etiennej): Build python ourselves so we don't have to rely on
+    // dynamically loading a system library.
+    dlopen("libpython2.7.so", RTLD_LAZY | RTLD_GLOBAL);
+
+    PyImport_AppendInittab(kMojoSystemImpl, &initmojo_system_impl);
+    PyImport_AppendInittab(kMojoSystem, &initmojo_system);
+
+    Py_Initialize();
+
+    PyObject *m, *d;
+    m = PyImport_AddModule("__main__");
+    if (m == NULL)
+        return NULL;
+    d = PyModule_GetDict(m);
+
+    // Inject the application path into the python search path so that imports
+    // from the application work as expected.
+    std::string search_path_py_command =
+        "import sys; sys.path.append('" + application_path + "');";
+    ScopedPyRef result(
+        PyRun_String(search_path_py_command.c_str(), Py_file_input, d, d));
+
+    if (result == nullptr) {
+      LOG(ERROR) << "Error while configuring path";
+      PyErr_Print();
+      return NULL;
+    }
+
+    return d;
+  }
+
+  // Overridden from ContentHandlerFactory::ManagedDelegate:
+  void RunApplication(ShellPtr shell, URLResponsePtr response) override {
+    std::unique_ptr<base::ScopedTempDir> temp_dir =
+        ExtractApplication(response.Pass());
+    base::FilePath directory_path = temp_dir->path();
+
+    PyObject* d = SetupPythonEnvironment(directory_path.value());
+    MOJO_DCHECK(d);
+
+    base::FilePath entry_path = directory_path.Append("__mojo__.py");
+
+    FILE* entry_file = base::OpenFile(entry_path, "r");
+    MOJO_DCHECK(entry_file);
+
+    // Ensure that all created objects are destroyed before calling Py_Finalize.
+    {
+      // Load the __mojo__.py file into the interpreter. MojoMain hasn't run
+      // yet.
+      ScopedPyRef result(PyRun_File(entry_file, entry_path.value().c_str(),
+                                    Py_file_input, d, d));
+      if (result == nullptr) {
+        LOG(ERROR) << "Error while loading script";
+        PyErr_Print();
+        return;
+      }
+
+      // Find MojoMain.
+      ScopedPyRef py_function(PyMapping_GetItemString(d, kMojoMain));
+
+      if (py_function == NULL) {
+        LOG(ERROR) << "Locals size: " << PyMapping_Size(d);
+        LOG(ERROR) << "MojoMain not found";
+        PyErr_Print();
+        return;
+      }
+
+      if (PyCallable_Check(py_function)) {
+        MojoHandle shell_handle = shell.PassMessagePipe().release().value();
+        ScopedPyRef py_input(PyInt_FromLong(shell_handle));
+        ScopedPyRef py_arguments(PyTuple_New(1));
+        // py_input reference is stolen by py_arguments
+        PyTuple_SetItem(py_arguments, 0, py_input.Release());
+        // Run MojoMain with shell_handle as the first and only argument.
+        ScopedPyRef py_output(PyObject_CallObject(py_function, py_arguments));
+
+        if (!py_output) {
+          LOG(ERROR) << "Error while executing MojoMain";
+          PyErr_Print();
+          return;
+        }
+      } else {
+        LOG(ERROR) << "MojoMain is not callable; it should be a function";
+      }
+    }
+    Py_Finalize();
+  }
+
+  std::string CopyToString(ScopedDataPipeConsumerHandle body) {
+    std::string body_str;
+    bool result = common::BlockingCopyToString(body.Pass(), &body_str);
+    DCHECK(result);
+    return body_str;
+  }
+
+  ContentHandlerFactory content_handler_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PythonContentHandler);
+};
+
+}  // namespace python
+}  // namespace mojo
+
+MojoResult MojoMain(MojoHandle shell_handle) {
+  mojo::ApplicationRunnerChromium runner(
+      new mojo::python::PythonContentHandler());
+  return runner.Run(shell_handle);
+}