handlecall3

Handlecall3 is a term found in documentation and example code for a third variant of a handle-based interface used in some operating systems and microkernel environments. It is not a universal standard, but appears in designs that expose resources through opaque handles and route operations through a single entry point. In these contexts, a handle represents a resource such as a file, socket, device, or capability object, and the handlecall3 invocation specifies an operation to perform on that resource.

The typical concept of handlecall3 involves a function or system call that takes a handle, an operation code, and a set of optional arguments, returning a status code and, when applicable, data via output parameters. The exact signature, number of arguments, and data types vary by implementation. Security is usually enforced through the rights associated with the handle; an operation attempted with insufficient rights results in an access-denied or similar error. Many designs support asynchronous completion, with options for blocking or non-blocking behavior, and permits repeated use of the same handle until it is closed.

Common usage scenarios include input/output operations, device control, or inter-process communication where a uniform path for resource operations is desirable. Compared with handlecall1 or handlecall2, handlecall3 may expand the argument space or introduce additional operation codes while maintaining a capability-oriented, resource-centric model.

See also: handlecall1, handlecall2, capability-based security, microkernel inter-process communication, resource handles.