Beginning Linux programming (Neil Matthew, Richard Stones) (Z-Library)

Beginning Linux® Programming 4th Edition Neil Matthew Richard Stones Wiley Publishing, Inc. 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page v

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Beginning Linux® Programming 4th Edition Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxiii Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxv Chapter 1: Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Chapter 2: Shell Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Chapter 3: Working with Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 Chapter 4: The Linux Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Chapter 5: Terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Chapter 6: Managing Text-Based Screens with curses . . . . . . . . . . . . . . . . 211 Chapter 7: Data Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 Chapter 8: MySQL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311 Chapter 9: Development Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377 Chapter 10: Debugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429 Chapter 11: Processes and Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461 Chapter 12: POSIX Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 495 Chapter 13: Inter-Process Communication: Pipes . . . . . . . . . . . . . . . . . . . . 525 Chapter 14: Semaphores, Shared Memory, and Message Queues. . . . . . . . . 577 Chapter 15: Sockets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 607 Chapter 16: Programming GNOME Using GTK+ . . . . . . . . . . . . . . . . . . . . . . 645 Chapter 17: Programming KDE Using Qt. . . . . . . . . . . . . . . . . . . . . . . . . . . 701 Chapter 18: Standards for Linux. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 747 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 761 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page i

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Beginning Linux® Programming 4th Edition 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page iii

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Beginning Linux® Programming 4th Edition Neil Matthew Richard Stones Wiley Publishing, Inc. 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page v

Beginning Linux® Programming, 4th Edition Published by Wiley Publishing, Inc. 10475 Crosspoint Boulevard Indianapolis, IN 46256 www.wiley.com Copyright © 2008 by Wiley Publishing, Inc., Indianapolis, Indiana Published simultaneously in Canada ISBN: 978-0-470-14762-7 Manufactured in the United States of America 10 9 8 7 6 5 4 3 2 1 Library of Congress Cataloging-in-Publication Data is available from the publisher. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except as permit- ted under Sections 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600. Requests to the Publisher for permission should be addressed to the Legal Department, Wiley Publishing, Inc., 10475 Crosspoint Blvd., Indianapolis, IN 46256, (317) 572-3447, fax (317) 572-4355, or online at http://www.wiley.com/go/permissions. LIMIT OF LIABILITY/DISCLAIMER OF WARRANTY: THE PUBLISHER AND THE AUTHOR MAKE NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS WORK AND SPECIFICALLY DISCLAIM ALL WARRANTIES, INCLUDING WITHOUT LIMITATION WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE. NO WARRANTY MAY BE CREATED OR EXTENDED BY SALES OR PROMOTIONAL MATERIALS. THE ADVICE AND STRATEGIES CONTAINED HEREIN MAY NOT BE SUITABLE FOR EVERY SITUATION. THIS WORK IS SOLD WITH THE UNDERSTANDING THAT THE PUBLISHER IS NOT ENGAGED IN RENDERING LEGAL, ACCOUNTING, OR OTHER PROFESSIONAL SERVICES. IF PROFESSIONAL ASSISTANCE IS REQUIRED, THE SERVICES OF A COMPETENT PROFESSIONAL PERSON SHOULD BE SOUGHT. NEITHER THE PUBLISHER NOR THE AUTHOR SHALL BE LIABLE FOR DAMAGES ARISING HEREFROM. THE FACT THAT AN ORGANIZATION OR WEBSITE IS REFERRED TO IN THIS WORK AS A CITATION AND/OR A POTENTIAL SOURCE OF FURTHER INFORMATION DOES NOT MEAN THAT THE AUTHOR OR THE PUBLISHER ENDORSES THE INFORMATION THE ORGANIZATION OR WEBSITE MAY PROVIDE OR RECOMMENDATIONS IT MAY MAKE. FURTHER, READERS SHOULD BE AWARE THAT INTERNET WEBSITES LISTED IN THIS WORK MAY HAVE CHANGED OR DISAPPEARED BETWEEN WHEN THIS WORK WAS WRITTEN AND WHEN IT IS READ. For general information on our other products and services please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Trademarks: Wiley, the Wiley logo, Wrox, the Wrox logo, Wrox Programmer to Programmer, and related trade dress are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affil- iates, in the United States and other countries, and may not be used without written permission. Linux is a trademark of Linus Torvalds. All other trademarks are the property of their respective owners. Wiley Publishing, Inc., is not associated with any product or vendor mentioned in this book. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books. 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page vi

About the Authors Neil Matthew has been interested in and has programmed computers since 1974. A mathematics graduate from the University of Nottingham, Neil is just plain keen on programming languages and likes to explore new ways of solving computing problems. He’s written systems to program in BCPL, FP (Functional Programming), Lisp, Prolog, and a structured BASIC. He even wrote a 6502 microprocessor emulator to run BBC microcomputer programs on UNIX systems. In terms of UNIX experience, Neil has used almost every flavor since the late 1970s, including BSD UNIX, AT&T System V, Sun Solaris, IBM AIX, many others, and of course Linux. He can claim to have been using Linux since August 1993 when he acquired a floppy disk distribution of Soft Landing (SLS) from Canada, with kernel version 0.99.11. He’s used Linux-based computers for hacking C, C++, Icon, Prolog, Tcl, and Java at home and at work. All of Neil’s “home” projects are developed using Linux. He says Linux is much easier because it supports quite a lot of features from other systems, so that both BSD- and System V-targeted pro- grams will generally compile with little or no change. Neil is currently working as an Enterprise Architect specializing in IT strategy at Celesio AG. He has a background in technical consultancy, software development techniques, and quality assur- ance. Neil has also programmed in C and C++ for real-time embedded systems. Neil is married to Christine and has two children, Alexandra and Adrian. He lives in a converted barn in Northamptonshire, England. His interests include solving puzzles by computer, music, science fiction, squash, mountain biking, and not doing it yourself. Rick Stones started programming at school (more years ago than he cares to remember) on a 6502-powered BBC micro, which, with the help of a few spare parts, continued to function for the next 15 years. He graduated from Nottingham University with a degree in Electronic Engineering, but decided software was more fun. Over the years he has worked for a variety of companies, from the very small with just a dozen employees, to the very large, including the IT services giant EDS. Along the way he has worked on a range of projects, from real-time communications to accounting systems, to very large help desk systems. He is currently working as an IT architect, acting as a technical authority on various major projects for a large pan-European company. A bit of a programming linguist, he has programmed in various assemblers, a rather neat proprietary telecommunications language called SL-1, some FORTRAN, Pascal, Perl, SQL, and smidgeons of Python and C++, as well as C. (Under duress he even admits that he was once reasonably proficient in Visual Basic, but tries not to advertise this aberration.) Rick lives in a village in Leicestershire, England, with his wife Ann, children Jennifer and Andrew, and a cat. Outside work his main interests are classical music, especially early religious music, and photography, and he does his best to find time for some piano practice. 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page vii

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Credits Acquisitions Editor Jenny Watson Development Editor Sara Shlaer Technical Editor Timothy Boronczyk Production Editor William A. Barton Copy Editor Kim Cofer Editorial Manager Mary Beth Wakefield Production Manager Tim Tate Vice President and Executive Group Publisher Richard Swadley Vice President and Executive Publisher Joseph B. Wikert Project Coordinator, Cover Adrienne Martinez Graphics and Production Specialists Mike Park, Happenstance-Type-O-Rama Craig Woods, Happenstance-Type-O-Rama Proofreader Amy McCarthy, Word One Indexer Johnna VanHoose Dinse Anniversary Logo Design Richard Pacifico 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page ix

Acknowledgments The authors would like to record their thanks to the many people who helped to make this book possible. Neil would like to thank his wife, Christine, for her understanding and children Alex and Adrian for not complaining too loudly at Dad spending so long in The Den writing. Rick would like to thank his wife, Ann, and their children, Jennifer and Andrew, for their very con- siderable patience during the evenings and weekends while Dad was yet again “doing book work.” As for the publishing team, we’d like to thank the folks at Wiley who helped us get this fourth edition into print. Thanks to Carol Long for getting the process started and sorting out the contracts, and especially to Sara Shlaer for her exceptional editing work and Timothy Boronczyk for his excellent technical reviews. We also wish to thank Jenny Watson for chasing down all those odd bits of extras and generally guiding the book through the administrative layers, Bill Barton for ensuring proper organization and presentation, and Kim Cofer for a thorough copyedit. We are very grateful also to Eric Foster-Johnson for his fantastic work on Chapters 16 and 17. We can say that this is a better book than it would have been without the efforts of all of you. We would also like to thank our employers, Scientific Generics, Mobicom, and Celesio for their support during the production of all four editions of this book. Finally we would also like to pay homage to two important motivators who have helped make this book possible. Firstly, Richard Stallman for the excellent GNU tools and the idea of a free software environment, which is now a reality with GNU/Linux, and secondly, Linus Torvalds for starting and continuing to inspire the co-operative development that gives us the ever-improving Linux kernel. 47627ffirs.qxd:WroxPro 10/1/07 7:07 AM Page x

Contents Acknowledgements x Foreword xxiii Introduction xxv Chapter 1: Getting Started 1 An Introduction to UNIX, Linux, and GNU 1 What Is UNIX? 1 What Is Linux? 3 The GNU Project and the Free Software Foundation 3 Linux Distributions 4 Programming Linux 4 Linux Programs 5 Text Editors 6 The C Compiler 7 Development System Roadmap 8 Getting Help 14 Summary 16 Chapter 2: Shell Programming 17 Why Program with a Shell? 18 A Bit of Philosophy 18 What Is a Shell? 19 Pipes and Redirection 21 Redirecting Output 21 Redirecting Input 22 Pipes 22 The Shell as a Programming Language 23 Interactive Programs 23 Creating a Script 24 Making a Script Executable 25 Shell Syntax 27 Variables 27 Conditions 31 Control Structures 34 Functions 46 Commands 49 Command Execution 68 47627ftoc.qxd:WroxPro 10/1/07 7:11 AM Page xi

xii Contents Here Documents 73 Debugging Scripts 74 Going Graphical — The dialog Utility 75 Putting It All Together 81 Requirements 82 Design 82 Summary 91 Chapter 3: Working with Files 93 Linux File Structure 94 Directories 94 Files and Devices 95 System Calls and Device Drivers 96 Library Functions 97 Low-Level File Access 98 write 98 read 99 open 100 Initial Permissions 101 Other System Calls for Managing Files 106 The Standard I/O Library 109 fopen 110 fread 110 fwrite 111 fclose 111 fflush 111 fseek 112 fgetc, getc, and getchar 112 fputc, putc, and putchar 112 fgets and gets 113 Formatted Input and Output 113 printf, fprintf, and sprintf 113 scanf, fscanf, and sscanf 115 Other Stream Functions 117 Stream Errors 119 Streams and File Descriptors 119 File and Directory Maintenance 120 chmod 120 chown 120 unlink, link, and symlink 121 mkdir and rmdir 121 chdir and getcwd 122 47627ftoc.qxd:WroxPro 10/1/07 7:11 AM Page xii

xiii Contents Scanning Directories 122 opendir 123 readdir 123 telldir 123 seekdir 124 closedir 124 Errors 127 strerror 127 perror 127 The /proc File System 128 Advanced Topics: fcntl and mmap 132 fcntl 132 mmap 133 Summary 135 Chapter 4: The Linux Environment 137 Program Arguments 137 getopt 140 getopt_long 142 Environment Variables 144 Use of Environment Variables 146 The environ Variable 147 Time and Date 148 Temporary Files 156 User Information 158 Host Information 161 Logging 163 Resources and Limits 167 Summary 173 Chapter 5: Terminals 175 Reading from and Writing to the Terminal 175 Talking to the Terminal 180 The Terminal Driver and the General Terminal Interface 182 Overview 183 Hardware Model 183 The termios Structure 184 Input Modes 186 Output Modes 186 Control Modes 187 Local Modes 188 47627ftoc.qxd:WroxPro 10/1/07 7:11 AM Page xiii

xiv Contents Special Control Characters 188 Terminal Speed 192 Additional Functions 192 Terminal Output 196 Terminal Type 197 Identify Your Terminal Type 197 Using terminfo Capabilities 200 Detecting Keystrokes 205 Virtual Consoles 207 Pseudo-Terminals 208 Summary 209 Chapter 6: Managing Text-Based Screens with curses 211 Compiling with curses 212 Curses Terminology and Concepts 213 The Screen 216 Output to the Screen 216 Reading from the Screen 217 Clearing the Screen 218 Moving the Cursor 218 Character Attributes 218 The Keyboard 221 Keyboard Modes 221 Keyboard Input 222 Windows 224 The WINDOW Structure 224 Generalized Functions 225 Moving and Updating a Window 225 Optimizing Screen Refreshes 229 Subwindows 230 The Keypad 232 Using Color 235 Redefining Colors 238 Pads 238 The CD Collection Application 240 Starting a New CD Collection Application 240 Looking at main 243 Building the Menu 243 Database File Manipulation 245 Querying the CD Database 250 Summary 254 47627ftoc.qxd:WroxPro 10/1/07 7:11 AM Page xiv

xv Contents Chapter 7: Data Management 255 Managing Memory 255 Simple Memory Allocation 256 Allocating Lots of Memory 257 Abusing Memory 260 The Null Pointer 261 Freeing Memory 262 Other Memory Allocation Functions 264 File Locking 264 Creating Lock Files 265 Locking Regions 268 Use of read and write with Locking 271 Competing Locks 276 Other Lock Commands 280 Deadlocks 280 Databases 281 The dbm Database 281 The dbm Routines 283 dbm Access Functions 283 Additional dbm Functions 287 The CD Application 289 Updating the Design 289 The CD Database Application Using dbm 290 Summary 309 Chapter 8: MySQL 311 Installation 312 MySQL Packages 312 Post-Install Configuration 314 Post-Installation Troubleshooting 319 MySQL Administration 320 Commands 320 Creating Users and Giving Them Permissions 325 Passwords 327 Creating a Database 328 Data Types 329 Creating a Table 330 Graphical Tools 333 Accessing MySQL Data from C 335 Connection Routines 337 Error Handling 341 47627ftoc.qxd:WroxPro 10/1/07 7:11 AM Page xv

xvi Contents Executing SQL Statements 342 Miscellaneous Functions 357 The CD Database Application 358 Creating the Tables 359 Adding Some Data 362 Accessing the Application Data from C 364 Summary 375 Chapter 9: Development Tools 377 Problems of Multiple Source Files 377 The make Command and Makefiles 378 The Syntax of Makefiles 378 Options and Parameters to make 379 Comments in a Makefile 382 Macros in a Makefile 382 Multiple Targets 384 Built-in Rules 387 Suffix and Pattern Rules 388 Managing Libraries with make 389 Advanced Topic: Makefiles and Subdirectories 391 GNU make and gcc 391 Source Code Control 392 RCS 393 SCCS 399 Comparing RCS and SCCS 399 CVS 400 CVS Front Ends 404 Subversion 405 Writing a Manual Page 406 Distributing Software 409 The patch Program 410 Other Distribution Utilities 411 RPM Packages 413 Working with RPM Package Files 414 Installing RPM Packages 415 Building RPM Packages 415 Other Package Formats 424 Development Environments 424 KDevelop 425 Other Environments 425 Summary 427 47627ftoc.qxd:WroxPro 10/1/07 7:11 AM Page xvi

xvii Contents Chapter 10: Debugging 429 Types of Errors 429 General Debugging Techniques 430 A Program with Bugs 430 Code Inspection 433 Instrumentation 434 Controlled Execution 436 Debugging with gdb 437 Starting gdb 437 Running a Program 438 Stack Trace 438 Examining Variables 439 Listing the Program 440 Setting Breakpoints 441 Patching with the Debugger 444 Learning More about gdb 445 More Debugging Tools 445 Lint: Removing the Fluff from Your Programs 446 Function Call Tools 449 Execution Profiling with prof/gprof 451 Assertions 452 Memory Debugging 453 ElectricFence 454 valgrind 455 Summary 459 Chapter 11: Processes and Signals 461 What Is a Process? 461 Process Structure 462 The Process Table 463 Viewing Processes 463 System Processes 464 Process Scheduling 467 Starting New Processes 468 Waiting for a Process 475 Zombie Processes 477 Input and Output Redirection 479 Threads 480 47627ftoc.qxd:WroxPro 10/1/07 7:11 AM Page xvii