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

mojo/common/test/test_utils_posix.cc

+// 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 "mojo/common/test/test_utils.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "base/posix/eintr_wrapper.h"
+#include "mojo/system/embedder/platform_handle.h"
+
+namespace mojo {
+namespace test {
+
+bool BlockingWrite(const embedder::PlatformHandle& handle,
+                   const void* buffer,
+                   size_t bytes_to_write,
+                   size_t* bytes_written) {
+  int original_flags = fcntl(handle.fd, F_GETFL);
+  if (original_flags == -1 ||
+      fcntl(handle.fd, F_SETFL, original_flags & (~O_NONBLOCK)) != 0) {
+    return false;
+  }
+
+  ssize_t result = HANDLE_EINTR(write(handle.fd, buffer, bytes_to_write));
+
+  fcntl(handle.fd, F_SETFL, original_flags);
+
+  if (result < 0)
+    return false;
+
+  *bytes_written = result;
+  return true;
+}
+
+bool BlockingRead(const embedder::PlatformHandle& handle,
+                  void* buffer,
+                  size_t buffer_size,
+                  size_t* bytes_read) {
+  int original_flags = fcntl(handle.fd, F_GETFL);
+  if (original_flags == -1 ||
+      fcntl(handle.fd, F_SETFL, original_flags & (~O_NONBLOCK)) != 0) {
+    return false;
+  }
+
+  ssize_t result = HANDLE_EINTR(read(handle.fd, buffer, buffer_size));
+
+  fcntl(handle.fd, F_SETFL, original_flags);
+
+  if (result < 0)
+    return false;
+
+  *bytes_read = result;
+  return true;
+}
+
+bool NonBlockingRead(const embedder::PlatformHandle& handle,
+                     void* buffer,
+                     size_t buffer_size,
+                     size_t* bytes_read) {
+  ssize_t result = HANDLE_EINTR(read(handle.fd, buffer, buffer_size));
+
+  if (result < 0) {
+    if (errno != EAGAIN && errno != EWOULDBLOCK)
+      return false;
+
+    *bytes_read = 0;
+  } else {
+    *bytes_read = result;
+  }
+
+  return true;
+}
+
+}  // namespace test
+}  // namespace mojo