2002 FREENIX Track Technical Program - Abstract
X Meets Z: Verifying Correctness In
Bart Massey, Computer Science Department, Portland State University; Robert Bauer, Rational Software Corporation
The Presence Of POSIX Threads
The engineering of freely-available UNIX software normally
utilizes an informal analysis and design process coupled
with extensive user testing. While this approach is often
appropriate, there are situations for which it produces
A case study is given of such a situation that arose during
the design and implementation of a thread-safe library for
interaction with the X Window System. XCB is a C binding
library for the X protocol designed to work transparently
with either single-threaded or multi-threaded clients.
Managing XCB client thread access to the X server while
honoring the constraints of both XCB and the X server is
thus a delicate matter.
The problem of ensuring that this complex system is coded
correctly can be attacked through the use of lightweight
formal methods. A model is constructed of the troublesome
portion of the system using the Z formal specification
notation. This model is used to establish important system
properties and produce C code with a high likelihood of
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