Part 1 Getting Started

Chapter 1 History of Linux Development

1.1 A Short History of Free Unix Software

1.2 Development of Linux

1.3 Notional Lineage of Unix Systems

1.4 Linux Lineage

Chapter 2 Licenses and Copyright

2.1 Copyright

2.2 Licensing

2.3 Free Software Licenses

2.3.1 The GNU General Public License

2.3.2 The GNU Library General Public License

2.3.3 MIT/X/BSD-Style Licenses

2.3.4 Old BSD-Style Licensses

2.3.5 Artistic License

2.3.6 License Incompatibilities

Chapter 3 Online System Documentation

3.1 The man Pages

3.2 The Info Pages

3.3 Other Documentation

Part 2 Development Tools and Environment

Chapter 4 Development Tools

4.1 Editors

4.1.1 Emacs

4.1.2 vi

4.2 Make

4.2.1 Complex Command Lines

4.2.2 Variables

4.2.3 Suffix Rules

4.3 The GNU Debugger

4.4 Tracing Program Actions

Chapter 5 gcc Options and Extensions

5.1 gcc Options

5.2 Header Files

5.2.1 long long

5.2.2 Inline Functions

5.2.3 Alternative Extended Keywords

5.2.4 Attributes

Chapter 6 The GNU C Library

6.1 Feature Selection

6.2 POSIX Interfaces

6.2.1 POSIX Required Types

6.2.2 Discovering Run-Time Capabilities

6.2.3 Finding and Setting Basic System Information

6.3 Compatibility

Chapter 7 Memory Debugging Tools

7.1 Buggy Code

7.2 Memory-Checking Tools Included in glibc

7.2.1 Finding Memory Heap Corruption

7.2.2 Using mtrace()to Track Allocations

7.3 Finding Memory Leaks with mpr

7.4 Investigating Memory Errors with Valgrind

7.5 Electric Fence

7.5.1 Using Electric Fence

7.5.2 Memory Alignment

7.5.3 Other Features

7.5.4 Limitations

7.5.5 Resource Consumption

Chapter 8 Creating and Using Libraries

8.1 Static Libraries

8.2 Shared Libraries

8.3 Designing Shared Libraries

8.3.1 Managing Compatibility

8.3.2 Incompatible Libraries

8.3.3 Designing Compatible Libraries

8.4 Building Shared Libraries

8.5 Installing Shared Libraries

8.5.1 Example

8.6 Using Shared Libraries

8.6.1 Using Noninstalled Libraries

8.6.2 Preloading Libraries

Chapter 9 Linux System Environment

9.1 The Process Environment

9.2 Understanding System Calls

9.2.1 System Call Limitations

9.2.2 System Call Return Codes

9.2.3 Using System Calls

9.2.4 Common Error Return Codes

9.3 Finding Header and Library Files

Part 3 System Programming

Chapter 10 The Process Model

10.1 Defining a Process

10.1.1 Complicating Things with Threads

10.1.2 The Linux Approach

10.2 Process Attributes

10.2.1 The pid and Parentage

10.2.2 Credentials

10.2.3 The filesystem uid

10.2.4 User and Group ID Summary

10.3 Process Information

10.3.1 Program Arguments

10.3.2 Resource Usage

10.3.3 Establishing Usage Limits

10.4 Process Primitives

10.4.1 Having Children

10.4.2 Watching Your Children Die

10.4.3 Running New Programs

10.4.4 Faster Process Creation with vfork()

10.4.5 Killing Yourself

10.4.6 Killing Others

10.4.7 Dumping Core

10.5 Simple Children

10.5.1 Running and Waiting with sy stem()

10.5.2 Reading or Writing from a Process

10.6 Sessions and Process Groups

10.6.1 Sessions

10.6.2 Controlling Terminal

10.6.3 Process Groups

10.6.4 Orphaned Process Groups

10.7 Introduction to ladsh

10.7.1 Running External Programs with ladsh

10.8 Creating Clones

Chapter 11 Simple File Handling

11.1 The File Mode

11.1.1 File Access Permissions

11.1.2 File Permission Modifiers

11.1.3 File Types

11.1.4 The Process's umask

11.2 Basic File Operations

11.2.1 File Descriptors

11.2.2 Closing Files

11.2.3 Opening Filesin the FileSystem

11.2.4 Reading,Writing,and Moving Around

11.2.5 Partial Reads and Writes

11.2.6 Shortening Files

11.2.7 Synchronizing Files

11.2.8 Other Operations

11.3 Querying and Changing Inode Information

11.3.1 Finding Inode Information

11.3.2 A Simple Example of stat()

11.3.3 Easily Determining Access Rights

11.3.4 Changing a File's Access Permissions

11.3.5 Changing a File's Owner and Group

11.3.6 Changing a File's Timestamps

11.3.7 Ext3 Extended Attributes

11.4 Manipulating Directory Entries

11.4.1 Creating Device and Named Pipe Entries

11.4.2 Creating Hard Links

11.4.3 Using Symbolic Links

11.4.4 Removing Files

11.4.5 Renaming Files

11.5 Manipulating File Descriptors

11.5.1 Changing the Access Mode for an Open File

11.5.2 Modifiying the close-on-exec Flag

11.5.3 Duplicating File Descriptors

11.6 Creating Unnamed Pipes

11.7 Adding Redirection to ladsh

11.7.1 The Data Structures

11.7.2 Changing the Code

Chapter 12 Signal Processing

12.1 Signal Concepts

12.1.1 Life Cycle of a Signal

12.1.2 Simple Signals

12.1.3 Reliable Signals

12.1.4 Signals and System Calls

12.2 The Linux(and POSIX)Signal API

12.2.1 Sending Signals

12.2.2 Using sigset_t

12.2.3 Catching Signals

12.2.4 Manipulating a Process's Signal Mask

12.2.5 Finding the Set of Pending Signals

12.2.6 Waiting for Signals

12.3 Available Signals

12.3.1 Describing Signals

12.4 Writing Signal Handlers

12.5 Reopening Log Files

12.6 Real-Time Signals

12.6.1 Signal Queueing and Ordering

12.7 Learning About a Signal

12.7.1 Getting a Signal's Context

12.7.2 Sending Data with a Signal

Chapter 13 Advanced File Handling

13.1 Input and Output Multiplexing

13.1.1 Nonblocking I/O

13.1.2 Multiplexing with poll()

13.1.3 Multiplexing with select()

13.1.4 Comparing poll()and select()

13.1.5 Multiplexing with epoll

13.1.6 Comparing poll()and epoll

13.2 Memory Mapping

13.2.1 Page Alignment

13.2.2 Establishing Memory Mappings

13.2.3 Unmapping Regions

13.2.4 Syncing Memory Regions to Disk

13.2.5 Locking Memory Regions

13.3 File Locking

13.3.1 Lock Files

13.3.2 Record Locking

13.3.3 Mandatory Locks

13.3.4 Leasing a File

13.4 Alternatives to read()and write()

13.4.1 Scatter/Gather Reads and Writes

13.4.2 Ignoring the File Pointer

Chapter 14 Directory Operations

14.1 The Current Working Directory

14.1.1 Finding the Current Working Directory

14.1.2 The.and..Special Files

14.1.3 Changing the Current Directory

14.2 Changing the Root Directory

14.3 Creating and Removing Directories

14.3.1 Creating New Directories

14.3.2 Removing Directories

14.4 Reading a Directory's Contents

14.4.1 Starting Over

14.5 File Name Globbing

14.5.1 Use a Subprocess

14.5.2 Internal Globbing

14.6 Adding Directories and Globbing to ladsh

14.6.1 Adding cd and pwd

14.6.2 Adding File Name Globbing

14.7 Walking File System Trees

14.7.1 Using ftw()

14.7.2 File Tree Walks with nftw()

14.7.3 Implementing find

14.8 Directory Change Notification

Chapter 15 Job Control

15.1 Job Control Basics

15.1.1 Restarting Processes

15.1.2 Stopping Processes

15.1.3 Handling Job Control Signals

15.2 Job Control in ladsh

Chapter 16 Terminals and Pseudo Terminals

16.1 tty Operations

16.1.1 Terminal Utility Functions

16.1.2 Controlling Terminals

16.1.3 Terminal Ownership

16.1.4 Recording with utempter

16.1.5 Recording by Hand

16.2 termios Overview

16.3 termios Examples

16.3.1 Passwords

16.3.2 Serial Communications

16.4 termios Debugging

16.5 termios Reference

16.5.1 Functions

16.5.2 Window Sizes

16.5.3 Flags

16.5.4 Input Flags

16.5.5 Output Flags

16.5.6 Control Flags

16.5.7 Control Characters

16.5.8 Local Flags

16.5.9 Controlling read()

16.6 Pseudo ttys

16.6.1 Opening Pseudo ttys

16.6.2 Opening Pseudo ttys the Easy Ways

16.6.3 Opening Pseudo ttys the Hard Ways

16.6.4 Pseudo tty Examples

Chapter 17 Networking with Sockets

17.1 Protocol Support

17.1.1 Nice Networking

17.1.2 Real Networking

17.1.3 Making Reality Play Nice

17.1.4 Addresses

17.2 Utility Functions

17.3 Basic Socket Operations

17.3.1 Creating a Socket

17.3.2 Establishing Connections

17.3.3 Binding an Address to a Socket

17.3.4 Waiting for Connections

17.3.5 Connecting to a Server

17.3.6 Finding Connection Addresses

17.4 Unix Domain Sockets

17.4.1 Unix Domain Addresses

17.4.2 Waiting for a Connection

17.4.3 Connecting to a Server

17.4.4 Running the Unix Domain Examples

17.4.5 Unnamed Unix Domain Sockets

17.4.6 Passing File Descriptors

17.5 Networking Machines with TCP/IP

17.5.1 Byte Ordering

17.5.2 IPv4 Addressing

17.5.3 IPv6 Addressing

17.5.4 Manipulating IP Addresses

17.5.5 Turning Names into Addresses

17.5.6 Turning Addresses into Names

17.5.7 Listening for TCP Connections

17.5.8 TCP Client Applications

17.6 Using UDP Datagrams

17.6.1 Creating a UDP Socket

17.6.2 Sending and Receiving Datagrams

17.6.3 A Simple tftp Server

17.7 Socket Errors

17.8 Legacy Networking Functions

17.8.1 IPv4 Address Manipulation

17.8.2 Hostname Resolution

17.8.3 Legacy Host Information Lookup Example

17.8.4 Looking Up Port Numbers

Chapter 18 Time

18.1 Telling Time and Dates

18.1.1 Representing Time

18.1.2 Converting,Formatting,and Parsing Times

18.1.3 The Limits of Time

18.2 Using Timers

18.2.1 Sleeping

18.2.2 Interval Timers

Chapter 19 Random Numbers

19.1 Pseudo-Random Numbers

19.2 Cryptography and Random Numbers

Chapter 20 Programming Virtual Consoles

20.1 Getting Started

20.2 Beeping

20.3 Determining Whetherthe Terminal Is a VC

20.4 Finding the Current VC

20.5 Managing VC Switching

20.6 Example:The open Command

Chapter 21 The Linux Console

21.1 Capability Databases

21.2 Glyphs,Characters,and Maps

21.3 Linux Console Capabilities

21.3.1 Control Characters

21.3.2 Escape Sequences

21.3.3 Testing Sequences

21.3.4 Complex Escape Sequences

21.4 Direct Screen Writing

Chapter 22 Writing Secure Programs

22.1 When Security Matters

22.1.1 When Security Fails

22.2 Minimizing the Opportunity for Attack

22.2.1 Giving Up Permissions

22.2.2 Getting a Helping Hand

22.2.3 Restricting File System Access

22.3 Common Security Holes

22.3.1 Buffer Overflows

22.3.2 Parsing Filenames

22.3.3 Environment Variables

22.3.4 Running the Shell

22.3.5 Creating Temporary Files

22.3.6 Race Conditions and Signal Handlers

22.3.7 Closing File Descriptors

22.4 Running as a Daemon

Part 4 Development Libraries

Chapter 23 String Matching

23.1 Globbing Arbitrary Strings

23.2 Regular Expressions

23.2.1 Linux Regular Expressions

23.2.2 Regular Expression Matching

23.2.3 A Simple grep

Chapter 24 Terminal Handling with S-Lang

24.1 Input Handling

24.1.1 Initializing S-Lang Input Handling

24.1.2 Restoring the Terminal State

24.1.3 Reading Characters from the Terminal

24.1.4 Checking for Pending Input

24.2 Output Handling

24.2.1 Initializing Screen Management

24.2.2 Updating the Display

24.2.3 Moving the Cursor

24.2.4 Finishing Screen Management

24.2.5 Skeleton Screen Management

24.2.6 Switching Character Sets

24.2.7 Writing to the Screen

24.2.8 Drawing Lines and Boxes

24.2.9 Using Color

Chapter 25 A Hashed Database Library

25.1 Overview

25.2 Basic Operations

25.2.1 Opening a qdbm File

25.2.2 Closing a Database

25.2.3 Obtaining the File Descriptor

25.2.4 Syncing the Database

25.3 Reading Records

25.3.1 Reading a Particular Record

25.3.2 Reading Records Sequentially

25.4 Modifying the Database

25.4.1 Adding Records

25.4.2 Removing Records

25.5 Example

Chapter 26 Parsing Command-Line Options

26.1 The Option Table

26.1.1 Defining the Options

26.1.2 Nesting Option Tables

26.2 Using the Option Table

26.2.1 Creating a Context

26.2.2 Parsing the Command Line

26.2.3 Leftover Arguments

26.2.4 Automatic Help Messages

26.3 Using Callbacks

26.4 Error Handling

26.5 Option Aliasing

26.5.1 Specifying Aliases

26.5.2 Enabling Aliases

26.6 Parsing Argument Strings

26.7 Handling Extra Arguments

26.8 Sample Application

Chapter 27 Dynamic Loading at Run Time

27.1 The dl Interface

27.1.1 Example

Chapter 28 User Identification and Authentication

28.1 ID-to-Name Translation

28.1.1 Example:The id Command

28.2 Pluggable Authentication Modules

28.2.1 PAM Conversations

28.2.2 PAM Actions

Appendices

Appendix A Header Files

Appendix B ladsh Source Code

Glossary

Bibliography

Index