Adds an IPython kernel running in NaCl, and a wrapper as a Chrome extension.

ports/ipython-ppapi/kernel.cc

Index: ports/ipython-ppapi/kernel.cc
diff --git a/ports/ipython-ppapi/kernel.cc b/ports/ipython-ppapi/kernel.cc
new file mode 100644
index 0000000000000000000000000000000000000000..e134179e2e53477db32f57bf4ce9ad6342a65339
--- /dev/null
+++ b/ports/ipython-ppapi/kernel.cc
@@ -0,0 +1,173 @@
+/* Copyright (c) 2014 Google Inc. 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 <libtar.h>
+#include <locale.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/mount.h>
+#include <errno.h>
+
+#include "ppapi/cpp/var.h"
+#include "ppapi/cpp/var_array.h"
+#include "ppapi/cpp/var_dictionary.h"
+#include "ppapi_simple/ps_interface.h"
+
+#include "nacl_io/nacl_io.h"
+#include "ppapi_simple/ps_main.h"
+#include "ppapi_simple/ps_instance.h"
+
+#ifdef __pnacl__
+#define DATA_FILE "pydata_pnacl.tar"
+#else
+#error "Unknown arch"
+#endif
+
+static int setup_unix_environment() {
+    int ret = umount("/");
+    if (ret) {
+      printf("unmounting root fs failed\n");
+      return 1;
+    }
+
+    ret = mount("", "/", "memfs", 0, NULL);
+    if (ret) {
+      printf("mounting root fs failed\n");
+      return 1;
+    }
+
+    const char* data_url = getenv("NACL_DATA_URL");
+    if (!data_url)
+      data_url = "./";
+    mkdir("/mnt/http", 0777);
+    ret = mount(data_url, "/mnt/http", "httpfs", 0, "allow_cross_origin_requests:true allow_credentials:false");
+    if (ret) {
+      printf("mounting http filesystem failed\n");
+      return 1;
+    }
+
+    char filename[PATH_MAX];
+    strcpy(filename, "/mnt/http/");
+    strcat(filename, DATA_FILE);
+    TAR* tar;
+    ret = tar_open(&tar, filename, NULL, O_RDONLY, 0, 0);
+    if (ret) {
+      printf("error opening %s\n", filename);
+      return 1;
+    }
+
+    mkdir("/lib", 0777);
+    ret = tar_extract_all(tar, (char *)"/");
+    if (ret) {
+      printf("error extracting %s\n", filename);
+      return 1;
+    }
+
+    ret = tar_close(tar);
+
+    setenv("PYTHONHOME", "", 1);
+    return 0;
+}
+
+extern "C" {
+
+  static PyObject * post_json_message(PyObject * self, PyObject * args) {
+    char * stream;
+    char * json;
+    if (!PyArg_ParseTuple(args, "ss", &stream, &json)) {
+      return NULL;
+    }
+
+    pp::VarDictionary message;
+    message.Set("stream", pp::Var(stream));
+    message.Set("json", pp::Var(json));
+
+    const PPB_Messaging * messaging = PSInterfaceMessaging();
+    PP_Instance instance = PSGetInstanceId();
+    messaging->PostMessage(instance, message.pp_var());
+
+    Py_RETURN_NONE;
+  }
+
+  static PyObject * acquire_json_message_wait(PyObject *self, PyObject * args) {
+    if (!PyArg_ParseTuple(args, "")) {
+      return NULL;
+    }
+
+    const PPB_Messaging * messaging = PSInterfaceMessaging();
+    PP_Instance instance = PSGetInstanceId();
+    PSEventSetFilter(PSE_INSTANCE_HANDLEMESSAGE);
+    PSEvent *event = PSEventWaitAcquire();
+    if (event->type != PSE_INSTANCE_HANDLEMESSAGE)
+      Py_RETURN_NONE;
+
+    pp::Var message(event->as_var);
+
+    if (!message.is_dictionary())
+      Py_RETURN_NONE;
+
+    pp::VarDictionary request(message);
+    pp::Var json(request.Get("json"));
+    if (!json.is_string())
+      Py_RETURN_NONE;
+
+    return PyString_FromString(json.AsString().c_str());
+  }
+
+}
+
+static PyMethodDef PPMessageMethods[] = {
+  {
+    "_PostJSONMessage",
+    post_json_message,
+    METH_VARARGS,
+    "Post a message encoded as JSON"
+  },
+  {
+    "_AcquireJSONMessageWait",
+    acquire_json_message_wait,
+    METH_VARARGS,
+    "Acquire a message encoded as JSON (blocking)"},
+  {NULL, NULL, 0, NULL}
+};
+
+int ipython_kernel_main(int argc, char **argv) {
+  printf("Setting up unix environment...\n");
+  if (setup_unix_environment()) {
+    printf("Error: %s\n", strerror(errno));
+    return -1;
+  }
+  printf("done\n");
+
+  // Initialize Pepper API
+  PSInterfaceInit();
+
+  int quit = 0;
+
+  while(!quit) {
+    // Initialize Python interpreter
+    Py_Initialize();
+
+    // Load module that provides access to Pepper messaging API
+    // from within the interpreter
+    Py_InitModule("ppmessage", PPMessageMethods);
+
+     // Run the interpreter main loop.
+    const char * main_filename = "/mnt/http/kernel.py";
+    FILE *main = fopen(main_filename, "r");
+    if (main == NULL) {
+      printf("failed to load interpreter code\n");
+      return -1;
+    }
+
+    quit = PyRun_SimpleFileEx(main, main_filename, 1);
+
+    Py_Finalize();
+  }
+
+  return 0;
+}
+
+PPAPI_SIMPLE_REGISTER_MAIN(ipython_kernel_main)