[PATCH v41 8/8] win32u: Use the desktop shared data for GetCursorPos.

[Rémi Bernon]

From: Rémi Bernon

Based on a patch by Huw Davies .
---
 dlls/win32u/input.c          | 18 +++++++++---------
 dlls/win32u/win32u_private.h |  8 ++++++++
 dlls/win32u/winstation.c     | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/dlls/win32u/input.c b/dlls/win32u/input.c
index 04532e7d015..2b0f59095e2 100644
--- a/dlls/win32u/input.c
+++ b/dlls/win32u/input.c
@@ -739,22 +739,22 @@ BOOL WINAPI NtUserSetCursorPos( INT x, INT y )
  */
 BOOL get_cursor_pos( POINT *pt )
 {
+    struct object_lock lock = OBJECT_LOCK_INIT;
+    const desktop_shm_t *desktop_shm;
     BOOL ret;
-    DWORD last_change;
+    DWORD last_change = 0;
+    NTSTATUS status;
     UINT dpi;

if (!pt) return FALSE;

-    SERVER_START_REQ( set_cursor )
+    while ((status = get_shared_desktop( &lock, &desktop_shm )) == STATUS_PENDING)
     {
-        if ((ret = !wine_server_call( req )))
-        {
-            pt->x = reply->new_x;
-            pt->y = reply->new_y;
-            last_change = reply->last_change;
-        }
+        pt->x = desktop_shm->cursor.x;
+        pt->y = desktop_shm->cursor.y;
+        last_change = desktop_shm->cursor.last_change;
     }
-    SERVER_END_REQ;
+    ret = !status;

/* query new position from graphics driver if we haven't updated recently */
     if (ret && NtGetTickCount() - last_change > 100) ret = user_driver->pGetCursorPos( pt );
diff --git a/dlls/win32u/win32u_private.h b/dlls/win32u/win32u_private.h
index 9815e31b899..94078281faa 100644
--- a/dlls/win32u/win32u_private.h
+++ b/dlls/win32u/win32u_private.h
@@ -202,6 +202,14 @@ struct object_lock
 };
 #define OBJECT_LOCK_INIT {0}

+/* Get shared session object's data pointer, must be called in a loop while STATUS_PENDING
+ * is returned, lock must be initialized with OBJECT_LOCK_INIT.
+ *
+ * The data read from the objects may be transient and no logic should be executed based
+ * on it, within the loop, or after, unless the function has returned STATUS_SUCCESS.
+ */
+extern NTSTATUS get_shared_desktop( struct object_lock *lock, const desktop_shm_t **desktop_shm );
+
 extern BOOL is_virtual_desktop(void);

/* window.c */
diff --git a/dlls/win32u/winstation.c b/dlls/win32u/winstation.c
index f5791f84ba6..dbf2573343d 100644
--- a/dlls/win32u/winstation.c
+++ b/dlls/win32u/winstation.c
@@ -184,6 +184,40 @@ static const shared_object_t *find_shared_session_object( obj_locator_t locator
     return NULL;
 }

+NTSTATUS get_shared_desktop( struct object_lock *lock, const desktop_shm_t **desktop_shm )
+{
+    struct session_thread_data *data = get_session_thread_data();
+    const shared_object_t *object;
+
+    TRACE( "lock %p, desktop_shm %p\n", lock, desktop_shm );
+
+    if (!(object = data->shared_desktop))
+    {
+        obj_locator_t locator = {0};
+
+        SERVER_START_REQ( get_thread_desktop )
+        {
+            req->tid = GetCurrentThreadId();
+            if (!wine_server_call( req )) locator = reply->locator;
+        }
+        SERVER_END_REQ;
+
+        data->shared_desktop = find_shared_session_object( locator );
+        if (!(object = data->shared_desktop)) return STATUS_INVALID_HANDLE;
+        memset( lock, 0, sizeof(*lock) );
+    }
+
+    if (!lock->id || !shared_object_release_seqlock( object, lock->seq ))
+    {
+        shared_object_acquire_seqlock( object, &lock->seq );
+        *desktop_shm = &object->shm.desktop;
+        lock->id = object->id;
+        return STATUS_PENDING;
+    }
+
+    return STATUS_SUCCESS;
+}
+
 BOOL is_virtual_desktop(void)
 {
     HANDLE desktop = NtUserGetThreadDesktop( GetCurrentThreadId() );