Simple shell that loads a dll and calls an entrypoint function passing in a handle to a pipe create…

mojo/shell/sample_app.cc

+// Copyright (c) 2013 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 <stdio.h>
+
+#include "base/basictypes.h"
+#include "mojo/public/system/core.h"
+#include "mojo/system/core_impl.h"
+
+typedef MojoResult (*MojoMainFunction)(MojoHandle pipe);
+
+char* ReadStringFromPipe(MojoHandle pipe) {
+  uint32_t len = 0;
+  char* buf = NULL;
+  MojoResult result = MojoReadMessage(pipe, buf, &len, NULL, NULL,
+                                      MOJO_READ_MESSAGE_FLAG_NONE);
+  if (result == MOJO_RESULT_RESOURCE_EXHAUSTED) {
+    buf = new char[len];
+    result = MojoReadMessage(pipe, buf, &len, NULL, NULL,
+                             MOJO_READ_MESSAGE_FLAG_NONE);
+  }
+  if (result < MOJO_RESULT_OK) {
+    // Failure..
+    if (buf)
+      delete[] buf;
+    return NULL;
+  }
+  return buf;
+}
+
+class SampleMessageWaiter {
+ public:
+  explicit SampleMessageWaiter(MojoHandle pipe) : pipe_(pipe) {}
+  ~SampleMessageWaiter() {}
+
+  void Read() {
+    char* string = ReadStringFromPipe(pipe_);
+    if (string) {
+      printf("Read string from pipe: %s\n", string);
+      delete[] string;
+      string = NULL;
+    }
+  }
+
+  void WaitAndRead() {
+    MojoResult result = MojoWait(pipe_, MOJO_WAIT_FLAG_READABLE, 100);
+    if (result < MOJO_RESULT_OK) {
+      // Failure...

[Ben Goodger (Google), 2013/10/03 17:45:18]

a typical meme in this code. can we have a discussion about error handling?

[darin (slow to review), 2013/10/04 21:47:14]

yeah, we should probably figure out a good canonical way of using these
primitives. porting MessageLoop to mojo is probably part of that.

+    }
+
+    Read();
+  }
+
+ private:
+
+  MojoHandle pipe_;
+  DISALLOW_COPY_AND_ASSIGN(SampleMessageWaiter);
+};
+
+extern "C" __declspec(dllexport) MojoResult __cdecl MojoMain(MojoHandle pipe) {
+  SampleMessageWaiter(pipe).WaitAndRead();
+  return MOJO_RESULT_NOT_FOUND;
+}