Chapter 1. Technology s Impact on Programs

Chapter 1. Technology's Impact on Programs

This chapter introduces the ideas of communication, concurrency and asynchronous operation at the operating system level and at the application level. Handling such program constructs incorrectly can lead to failures with no apparent cause, even for input that previously seemed to work perfectly . Besides their added complexity, many of today's applications run for weeks or months, so they must properly release resources to avoid waste (so-called leaks of resources). Applications must also cope with outrageously malicious user input, and they must recover from errors and continue running. The Portable Operating System Interface (POSIX) standard is an important step toward producing reliable applications. Programmers who write for POSIX-compliant systems no longer need to contend with small but critical variations in the behavior of library functions across platforms. Most popular UNIX versions (including Linux and Mac OS X) are rapidly moving to support the base POSIX standard and various levels of its extensions.

Objectives

• Learn how an operating system manages resources

• Experiment with buffer overflows

• Explore concurrency and asynchronous behavior

• Use basic operating systems terminology

• Understand the serious implications of incorrect code