[PATCH v4 3/6] ntdll: Introduce a helper to wait on an server-side sync object.

[Elizabeth Figura]

From: Elizabeth Figura

Some objects like async or completion waits are internal only, and their
sync logic is still a bit complicated as they have various server side
effects. They are only waited on alone, we can keep using server-side
syncs for them.
---
 dlls/ntdll/unix/server.c       | 15 +++++++++++++++
 dlls/ntdll/unix/sync.c         |  4 ++--
 dlls/ntdll/unix/unix_private.h |  3 ++-
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/dlls/ntdll/unix/server.c b/dlls/ntdll/unix/server.c
index e8da94ebc64..25cc9bf0cbf 100644
--- a/dlls/ntdll/unix/server.c
+++ b/dlls/ntdll/unix/server.c
@@ -818,6 +818,21 @@ unsigned int server_wait( const union select_op *select_op, data_size_t size, UI
 }

+/* helper function to perform a server-side wait on an internal handle without
+ * using the fast synchronization path */
+unsigned int server_wait_for_object( HANDLE handle, BOOL alertable, const LARGE_INTEGER *timeout )
+{
+    union select_op select_op;
+    UINT flags = SELECT_INTERRUPTIBLE;
+
+    if (alertable) flags |= SELECT_ALERTABLE;
+
+    select_op.wait.op = SELECT_WAIT;
+    select_op.wait.handles[0] = wine_server_obj_handle( handle );
+    return server_wait( &select_op, offsetof( union select_op, wait.handles[1] ), flags, timeout );
+}
+
+
 /***********************************************************************
  *              NtContinue  (NTDLL.@)
  */
diff --git a/dlls/ntdll/unix/sync.c b/dlls/ntdll/unix/sync.c
index 57e67933cd3..817bca2a649 100644
--- a/dlls/ntdll/unix/sync.c
+++ b/dlls/ntdll/unix/sync.c
@@ -2319,7 +2319,7 @@ NTSTATUS WINAPI NtRemoveIoCompletion( HANDLE handle, ULONG_PTR *key, ULONG_PTR *
     }
     SERVER_END_REQ;
     if (status != STATUS_PENDING) return status;
-    if (!timeout || timeout->QuadPart) status = NtWaitForSingleObject( wait_handle, FALSE, timeout );
+    if (!timeout || timeout->QuadPart) status = server_wait_for_object( wait_handle, FALSE, timeout );
     else                               status = STATUS_TIMEOUT;
     if (status != WAIT_OBJECT_0) return status;

@@ -2383,7 +2383,7 @@ NTSTATUS WINAPI NtRemoveIoCompletionEx( HANDLE handle, FILE_IO_COMPLETION_INFORM
         assert( status == STATUS_USER_APC );
         goto done;
     }
-    if (!timeout || timeout->QuadPart) status = NtWaitForSingleObject( wait_handle, alertable, timeout );
+    if (!timeout || timeout->QuadPart) status = server_wait_for_object( wait_handle, alertable, timeout );
     else                               status = STATUS_TIMEOUT;
     if (status != WAIT_OBJECT_0) goto done;

diff --git a/dlls/ntdll/unix/unix_private.h b/dlls/ntdll/unix/unix_private.h
index 974766b97a7..bd2d6a19334 100644
--- a/dlls/ntdll/unix/unix_private.h
+++ b/dlls/ntdll/unix/unix_private.h
@@ -230,6 +230,7 @@ extern unsigned int server_select( const union select_op *select_op, data_size_t
                                    timeout_t abs_timeout, struct context_data *context, struct user_apc *user_apc );
 extern unsigned int server_wait( const union select_op *select_op, data_size_t size, UINT flags,
                                  const LARGE_INTEGER *timeout );
+extern unsigned int server_wait_for_object( HANDLE handle, BOOL alertable, const LARGE_INTEGER *timeout );
 extern unsigned int server_queue_process_apc( HANDLE process, const union apc_call *call,
                                               union apc_result *result );
 extern int server_get_unix_fd( HANDLE handle, unsigned int wanted_access, int *unix_fd,
@@ -470,7 +471,7 @@ static inline struct async_data server_async( HANDLE handle, struct async_fileio

static inline NTSTATUS wait_async( HANDLE handle, BOOL alertable )
 {
-    return NtWaitForSingleObject( handle, alertable, NULL );
+    return server_wait_for_object( handle, alertable, NULL );
 }

static inline BOOL in_wow64_call(void)