Reland: Add some handle read/write helpers to mojo/common/test/test_utils.h

mojo/common/test/test_utils.h

+// 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.
+
+#ifndef MOJO_COMMON_TEST_TEST_UTILS_H_
+#define MOJO_COMMON_TEST_TEST_UTILS_H_
+
+#include <stddef.h>
+
+namespace mojo {
+
+namespace embedder {
+struct PlatformHandle;
+}
+
+namespace test {
+
+// On success, |bytes_written| is updated to the number of bytes written;
+// otherwise it is untouched.
+bool BlockingWrite(const embedder::PlatformHandle& handle,
+                   const void* buffer,
+                   size_t bytes_to_write,
+                   size_t* bytes_written);
+
+// On success, |bytes_read| is updated to the number of bytes read; otherwise it
+// is untouched.
+bool BlockingRead(const embedder::PlatformHandle& handle,
+                  void* buffer,
+                  size_t buffer_size,
+                  size_t* bytes_read);
+
+// If the read is done successfully or would block, the function returns true
+// and updates |bytes_read| to the number of bytes read (0 if the read would
+// block); otherwise it returns false and leaves |bytes_read| untouched.
+// |handle| must already be in non-blocking mode.
+bool NonBlockingRead(const embedder::PlatformHandle& handle,
+                     void* buffer,
+                     size_t buffer_size,
+                     size_t* bytes_read);
+
+}  // namespace test
+}  // namespace mojo
+
+#endif  // MOJO_COMMON_TEST_TEST_UTILS_H_