4 files changed, 23 insertions, 0 deletions
diff --git a/base/sync_socket.h b/base/sync_socket.h
index ad181ff..a44c445 100644
--- a/base/sync_socket.h
+++ b/base/sync_socket.h
@@ -51,6 +51,12 @@ class SyncSocket {
   // Returns the number of bytes received, or 0 upon failure.
   size_t Receive(void* buffer, size_t length);
 
+  // Returns the number of bytes available. If non-zero, Receive() will not
+  // not block when called. NOTE: Some implementations cannot reliably
+  // determine the number of bytes available so avoid using the returned
+  // size as a promise and simply test against zero.
+  size_t Peek();
+
   // Extracts the contained handle.  Used for transferring between
   // processes.
   Handle handle() const { return handle_; }
diff --git a/base/sync_socket_posix.cc b/base/sync_socket_posix.cc
index 35d53b2..5390c7d 100644
--- a/base/sync_socket_posix.cc
+++ b/base/sync_socket_posix.cc
@@ -98,4 +98,10 @@ size_t SyncSocket::Receive(void* buffer, size_t length) {
   }
 }
 
+// TODO(port). Some kind of select?
+size_t SyncSocket::Peek() {
+  NOTIMPLEMENTED();
+  return 0;
+}
+
 }  // namespace base
diff --git a/base/sync_socket_win.cc b/base/sync_socket_win.cc
index b591bb0..4e3c35f 100644
--- a/base/sync_socket_win.cc
+++ b/base/sync_socket_win.cc
@@ -141,4 +141,10 @@ size_t SyncSocket::Receive(void* buffer, size_t length) {
   return count;
 }
 
+size_t SyncSocket::Peek() {
+  DWORD available = 0;
+  PeekNamedPipe(handle_, NULL, 0, NULL, &available, NULL);
+  return available;
+}
+
 }  // namespace base
diff --git a/ipc/sync_socket_unittest.cc b/ipc/sync_socket_unittest.cc
index 9820009..7710c09 100644
--- a/ipc/sync_socket_unittest.cc
+++ b/ipc/sync_socket_unittest.cc
@@ -189,6 +189,11 @@ class SyncSocketClientListener : public IPC::Channel::Listener {
   // string as was written on the SyncSocket.  These are compared
   // and a shutdown message is sent back to the server.
   void OnMsgClassResponse(const std::string& str) {
+#if defined(OS_WIN)
+    // We rely on the order of sync_socket.Send() and chan_->Send() in
+    // the SyncSocketServerListener object.
+    EXPECT_EQ(kHelloStringLength, socket_->Peek());
+#endif
     char buf[kHelloStringLength];
     socket_->Receive(static_cast<void*>(buf), kHelloStringLength);
     EXPECT_EQ(strcmp(str.c_str(), buf), 0);