Crs 470
Systems and Network Programming for Linux

This course focuses on the "virtual machine" provided by the linux kernel to application software. Inherited largely from UNIX, the elegant application programming interface (API) described in this course has been essentially stable for many years.

The course covers all major system programming features of Linux, from basic I/O operations to interprocess and network communications, to the exploitation of concurrency through the use of threads and processes.

The C language bindings are invariably used to document the system call interface, and C is still the language of choice for most Linux systems programming. For these reasons, C is used for the examples in this course.

Course Outline

Getting Started

• The "Hello World" program
• Receiving command line arguments
• Accessing environment variables
• Reading and writing stdin and stdout
• How to detect and handle system call errors

Multiprocessing

• The memory model and life cycle of a process
• Creating processes with fork
• Executing programs with exec
• Waiting for process termination
• Returning and retrieving exit status

Multithreading

• The memory model and life cycle of a thread
• Creating threads with the pthreads API
• Waiting for thread termination
• How are threads and processes different?
• Synchronising access to shared data
• When to use multiple processes and threads

Basic I/O

• Low-level input and output
• Reading and writing files
• Changing file attributes
• Managing files and directories

Interprocess Communication

• Pipes
• Message queues
• Shared Memory
• Semaphores

Signals

• What are signals for?
• Sending signals
• Ignoring and catching signals
• Writing signal handlers

Working with the Linux Security Model

• Changing file permissions and ownerships
• Accessing the user account database
• Setting user identity of a process

Network Communication

• TCP/IP fundamentals
• Client/server programming
• Connection-oriented sockets
• Connectionless sockets
• Name resolution

Writing graphical applications

• The Xlib libraries
• The Tk and Tcl toolkits
• Drag and drop interface construction with glade
• The Gnome and KDE toolkits

The Linux development environment

• The traditional build model
• Header files
• Automating rebuilds with make
• Writing platform-independent code with GNU configure
• Integrated development environments
• Commercial development environments

Intended Audience

The course is intended primarily for software developers writing or porting code in the Linux environment. The course is also valuable for technical managers and system designers wishing to understand the capabilities of Linux at a programming level.

Attendees should have a reasonable understanding of the C language. Although unnecessarily complex language structures are avoided in the course, the design of some of the API calls require that attendees are comfortable with, for example, the notion of a function returning a pointer to a structure. Course 100 Introduction to C, provides adequate background.

Key Skills

After taking this course you will be able to:

• Write programs which interact with the Linux system
• Access and modify file data, permissions and ownership
• Exploit concurrency through processes and threads
• Develop client/server applications that communicate across a network
• Write graphical applications using libraries and toolkits
• Communicate efficiently between processes
• Write and distribute software to run on a variety of platforms

Practical Work

Extensive hands-on exercises help you gain confidence in writing software to exploit the system features of Linux. Exercises include:

• Taking a snapshot of the filesystem and reporting changes
• Creating a simple web server
• Writing a client to transfer files using the TFTP service
• Developing a graphical front end to a linux command-line tool
• Measuring the efficiency of buffered and unbuffered I/O
• Traversing the filesystem to search for world-writable files