[RFC PATCH 02/11] server: Add a helper function to trigger synchronous completion of I/O via APC_ASYNC_IO.

[Jinoh Kang]

Signed-off-by: Jinoh Kang <jinoh.kang.kr at gmail.com>
---

Notes:
    This patch was necessary since we have to reuse APC for synchronous I/O.
    The previous approach without APC would completely obviate the need for this
    function.

 server/async.c | 17 +++++++++++++++++
 server/file.h  |  1 +
 2 files changed, 18 insertions(+)

diff --git a/server/async.c b/server/async.c
index aa6d50cde75..5d0857f3eec 100644
--- a/server/async.c
+++ b/server/async.c
@@ -383,6 +383,23 @@ obj_handle_t async_handoff( struct async *async, data_size_t *result, int force_
     return async->wait_handle;
 }
 
+/* Set up synchronous completion of I/O via the APC_ASYNC_IO system APC.
+ * This function is intended to be called immediately before async_handoff(),
+ * and expects the last error status to be STATUS_ALERTED.
+ *
+ * The information argument can be used to pass extra information to the client
+ * (e.g. whether the socket is in non-blocking mode).
+ */
+void async_start_sync_io_request( struct async *async, data_size_t information )
+{
+    assert( get_error() == STATUS_ALERTED );
+    assert( async->thread == current );
+    assert( !async->pending );
+
+    async->direct_result = 0;  /* force APC to fire off */
+    async->iosb->result = information;
+}
+
 /* complete a request-based async with a pre-allocated buffer */
 void async_request_complete( struct async *async, unsigned int status, data_size_t result,
                              data_size_t out_size, void *out_data )
diff --git a/server/file.h b/server/file.h
index 1d830cd3d6f..34930b87b5d 100644
--- a/server/file.h
+++ b/server/file.h
@@ -234,6 +234,7 @@ extern void async_set_initial_status( struct async *async, unsigned int status )
 extern void async_wake_obj( struct async *async );
 extern int async_waiting( struct async_queue *queue );
 extern void async_terminate( struct async *async, unsigned int status );
+extern void async_start_sync_io_request( struct async *async, data_size_t information );
 extern void async_request_complete( struct async *async, unsigned int status, data_size_t result,
                                     data_size_t out_size, void *out_data );
 extern void async_request_complete_alloc( struct async *async, unsigned int status, data_size_t result,
-- 
2.31.1