Initial import of the CDE 2.1.30 sources from the Open Group.

cde/lib/DtSvc/DtUtil2/lock.c

@@ -0,0 +1,79 @@
+/*
+ * File:         lock.c $XConsortium: lock.c /main/4 1995/10/26 15:33:05 rswiston $
+ * Language:     C
+ *
+ * (C) Copyright 1989, Hewlett-Packard, all rights reserved.
+ *
+ * (c) Copyright 1993, 1994 Hewlett-Packard Company			*
+ * (c) Copyright 1993, 1994 International Business Machines Corp.	*
+ * (c) Copyright 1993, 1994 Sun Microsystems, Inc.			*
+ * (c) Copyright 1993, 1994 Novell, Inc.				*
+ */
+
+#include <X11/Xlib.h>
+
+
+/********    Public Function Declarations    ********/
+
+extern int _DtGetLock( Display *display, char *lock_name) ;
+extern void _DtReleaseLock( Display *display, char *lock_name) ;
+extern int _DtTestLock( Display *display, char *lock_name) ;
+
+/********    End Public Function Declarations    ********/
+
+
+int 
+_DtGetLock(
+        Display *display,
+        char *lock_name )
+{
+   Atom lock_atom;
+   Window selection_owner;
+   Window root_window;
+  
+   /* Do as much processing as possible before grabbing the server. */
+   lock_atom = XInternAtom (display, lock_name, False);
+   root_window = DefaultRootWindow (display);
+
+   /* Do an atomic test-and-set of the lock.  To make this atomic we
+      must grab the server. */
+   XGrabServer (display);
+   if ((selection_owner = XGetSelectionOwner (display, lock_atom)) == None)
+      XSetSelectionOwner (display, lock_atom, root_window, CurrentTime);
+   XUngrabServer (display);
+   XFlush (display);
+  
+   /* If the lock was clear then it was successfully acquired. */
+   if (selection_owner == None)
+      return (1);
+   else
+      return (0);
+}
+
+void 
+_DtReleaseLock(
+        Display *display,
+        char *lock_name )
+{
+   Atom lock_atom;
+  
+   lock_atom = XInternAtom (display, lock_name, False);
+   XSetSelectionOwner (display, lock_atom, None, CurrentTime);
+   XFlush (display);  /* added to release lock NOW */
+}
+
+int 
+_DtTestLock(
+        Display *display,
+        char *lock_name )
+{
+   Atom lock_atom;
+  
+   lock_atom = XInternAtom (display, lock_name, False);
+   
+   if (XGetSelectionOwner (display, lock_atom) == None)
+      return (0);
+   else 
+      return (1);
+}
+