Table Of ContentS E C O N D E D I T I O N
W. RICHARD STEVENS
I
Interprocess Communications
Well-implemented interprocess communications (IPC) are key to the performance of
virtually every non-trivial UNIX program. In UNIX Network Programming,
Udnme 2, Seeond Edition, legendary UNIX expert W . Richard Stevens presents
a comprehensive guide to every form of IPC. including message passing. synchronization.
you'll ever nee& sh-are d memory, and Remote Procedure Calls (RPG.
Stevens heglns with a basic: introduction to IPC and the problems it is intended to solve
b
Slep-by-step you'll learn how to maximize both System V IPC and the new Posix standards.
which offer dramatic improvements in convenience and performance. You'll find extensive
coverage of Pthreads. with many examples rrflecting multiple threads instead of multiple
processes. Alongthe way. you'll master every current IPC technique and technology. including:
Pipes and FlFOs POSIXan d System V Semaphores
Posix and System V Message Queues Poslx and System V Shared Me
St b-Ci aris Doors and Sun RPC
performance Measurements
of IPC Techn~ques
of UNlX Network Programming, 1
of five! You won't just learn about IPC
"from the outside." You'll actually create implemkntatiom of Posix message queues.
read-write locks, and semaphores, gaining an in-de@h understanding of these
capabilities you simply can't get awwhere else.
The book contains extensive new source code--all caqfully optimized and available
on the Web. You'll even find a complete guide to mesuring IPC performance
with message passing bandwidth and laterfcy progrMns, and thread and process
synchronization programs.
The better you understand IPC. the better your UNIX software will run. This book
contains all you need to know. I
ABOUT THE AUTHOR
W. RlCHAR D STEVENS is author of UNIX Network Programming. Firs
widely recognized as the classic text in UNIX networking and UNIX Net
Programming, Wume 1. Second Edition. He is also author of Advanced
in the UNIX Environment and the TCP/IP IIIustrated Series. Stevens
is an acknowledged UNIX and networking expert. sought-after
instructor, and occamnal consultant.
PRENTICE HALL
Upper Saddle River. NJ 07458
Function prototype Page
boolLt clnt-control( CLIENT *d, unsigned int request, char *ptr); 418
CLIENT *clnt-create (const char *host, unsigned long prognum,
unsigned long versnum, const char *protocol);
void clnt-destroy(CL1ENT *c!); 420
int door-bind ( int fd) ; 390
int door-call ( int fd, door-arg-t *argp); 361
int door-create( Door-serverqroc *proc, void *cookie, u-int attr) ; 363
int door-cred (door-cred-t *cred); 365
int door-info( int fd, door-in£ o-t *info); 365
int dooryeturn( char *dataptr, size-t datasize, door-desc-t *descptr. size-t ndesc) ; 365
int door-revoke (int fd) ; 390
Door-createqroc *door~server~create(Door~createqro*pcr Oc); 384
int door-unbind(void); 390
void err-durn (const char *fit, . . . ) ;
void err-msg (const char *fit, . . . ) ;
void err-quit (const char *fit, . . . ) ;
void err-rot (const char *fit, . . . ) ;
void err-sys (const char *fit, . . . ) ;
int fcntl( int fd, int cmd, . . . /* struct flock *arg */ ) ;
int fstat(int fd, struct stat *buf );
key-t ftok(const char *pathname, int id);
int ftruncate( int fd, of f-t length) ;
int qclose( mqd-t mqdes);
int qgetattr (mqd-t mqdes, struct mpattr *attr);
int -notify (mqd-t mqdes, const struct sigevent *notification) ;
mqd-t qopen(const char *name, int oflag, . . .
/* mode-t mode, struct mq-attr *attr */ ).
int -unlink (const char *name) ; 77
int msgctl(int msqid, int cmd, struct msqid-ds *buff);
int msgget( key-t key, int oflag);
FILE *popen (const char *command, const char *type) ; 52
Function prototype Page
int pthread-cancel (pthread-t tid); 187
void pthread-c leanupgop ( int execute) ; 187
void pthread-cleanupgush(void (*function)( void *), void *a%); 187
int pthreahcreate( pthread-t *tid, const pthread-attr-t *attr,
void * (*fu?tc() void *), void *a%); 502
int pthread-detach (pthread-t tid); 504
void pthread-exit (void *status); 504
int pthread-join(pthread-t tid, void **status) ; 503
pthread-t pthread-self(void); 503
int pthread-condattr-destroy(pthread-condattr-t *attr); 172
int pthread-condattr-getpshared(const pthread-condattr-t 'attr, int *valptr); 173
int pthread-condattr-init(pthread-condattr-t *attr); 172
int pthread-condattr-setpshared(pthread-condattr-t *attr, int value); 173
int pthread-cond-broadcast(pthread-cond-t *cptr); 171
int pthreahcond-destroy(pthread-cond-t *cptr); 172
int pthread-cond-init(pthread-cond-t *cptr, const pthread-condattr-t *attr); 172
int pthread-cond-signal(pthread-cond-t *cptr); 167
int pthread-cond-timedwait(pthread-cond-t *cptr, pthread-mutex-t *mptr,
const struct timespec *abstime); 171
int pthread-cond-wait(pthread~cond-t *cptr, pthread-mutex-t *mptr); 167
int pthread-mutaxattr-destroy(pthread-mutexattr-t *attr);
int pthread-mutaxattr-getpsharrd ( const pthread-mutexattr-t *attr, int "valptr);
int pthread-mutaxattr-init (pthread-mutexattr-t *attr);
int pthread-mutaxattr-setpshared(pthread-mutexattr-t *attr, int value);
int pthread-mutex-destroy(pthread-mutex-t *mptr);
int pthread-mutex-init(pthread-mutex-t *mptr, const pthread-mutexattr-t *attr);
int pthread~mutex~lock(pthread~mutex*~mtp tr) ;
int pthrea~mutex~trylock(pthread~mutex*~mtp tr);
int pthread~mutex~unlock(pthread~mutex*~mtp tr);
int pthread~rwlockattr~destroy(pthread~rwlockatt*ra~tttr );
int pthread-rwlockattr-getpshared(const pthread-rwlockattr-t *attr, int *Va!ptr);
int pthread-rwlockattr-init(pthread-rwlockattr-t *attr);
int pthread-rwlockattr-setpshared (pthread-rwlockattr-t *attr, int value);
int pthread-rwlock_destroy(pthread-rwlock-t *noptr);
int pthread-rwlock-init (pthread-rwlock-t *noptr,
const pthread-rwlockattr-t *attr);
int pthread~rwlock~rdlock(pthread~rwlock*~nto ptr);
int pthread~rwlock~tryrdlock(pthread~rwlock*~nto ptr);
int pthread~rwlock~trywr1ock(pthread~rwloc*kn~otp tr);
int pthrea~rwlock~unlock(pthread~rwloc*kn~ut@ ');
int pthread~rw1ock~wrlock(pthread~rwlo*~qk~ttr );
UNIX Network Programming
Volume 2
Second Edition
lnterprocess Communications
by W. Richard Stevens
ISBN 0-23-082082-9
Prentice Hall PTR
Upper Saddle River, NJ 07458
www.phptr.com
Library of Congress Cataloging-in-Publication Data
Stevens, W. Richard.
UNIX network programming I by W. Richard Stevens. -- 2nd ed.
v. <l > : ill. : 25 cm.
Includes bibliographical references and index.
Contents: v. 1. Networking APIs : sockets and XTI.
ISBN 0-13-490012-X (v. 1)
1. UNIX (Computer file) 2. Computer networks. 3. Internet
programming. I. Title.
QA76.76.063S755 1998
005.7' 12768--DC21 97-31 761
Editorial/production supervision: Patti Guerrieri
Cover design director: Jerry Votta
Cover designer: Scott Weiss
Manufacturing manager: Alexis R. Heydl
Marketing manager: Miles Williams
Acquisitions editor: Mary Franz
Editorial assistant: Noreen Regina
01999 by Prentice Hall PTR
Prentice-Hall, Inc.
A Simon & Schuster Company
Upper Saddle River, NJ 07458
Prentice Hall books are widely used by corporations and government agencies
for training, marketing, and resale.
The publisher offers discounts on this book when ordered in bulk quantities.
For more information, contact: Corporate Sales Department, Phone: 800-382-3419;
Fax: 201-236-7141; E-mail: [email protected]; or write: Prentice Hall PTR,
Corp. Sales Dept., One Lake Street, Upper Saddle River, NJ 07458.
All products or services mentioned in this book are the trademarks or service marks of their
respective companies or organizations.
All rights reserved. No part of this book may be reproduced, in any form or by any means, without
permission in writing from the publisher.
Printed in the United States of America
1 0 9 8 7 6 5 4 3 2
ISBN 0-1 3-0810 81 -9
Prentice-Hall lntemational (UK) Limited, London
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To the Usenet community;
for many questions answered,
and many FAQs provided.
Abbreviated Table of Contents
Part 1. Introduction 1
Chapter 1. lntroduction
Chapter 2. Posix IPC
Chapter 3. System V IPC
Part 2. Message Passing 41
Chapter 4. Pipes and FlFOs 43
Chapter 5. Posix Message Queues 75
Chapter 6. System V Message Queues 12 9
Part 3. Synchronization 157
Chapter 7. Mutexes and Condition Variables 159
Chapter 8. Read-Write Locks 17 7
Chapter 9. Record Locking 193
Chapter 10. Posix Semaphores 219
Chapter 11. System V Semaphores 28 1
Part 4. Shared Memory 301
Chapter 12. Shared Memory Introduction 303
Chapter 13. Posix Shared Memory 325
Chapter 14. System V Shared Memory 343
Part 5. Remote Procedure Calls 353
Chapter 15. Doors 355
Chapter 16. Sun RPC 399
Appendix A. Performance Measurements
Appendix 6. A Threads Primer
Appendix C. Miscellaneous Source Code
Appendix D. Solutions to Selected Exercises
Table of Contents
Preface xiii
Part 1. lntroduction 1
Chapter 1. lntroduction
1.1 lntroduction 3
1.2 Processes, Threads, and the Sharing of Information 5
1.3 Persistence of IPC Objects 6
1.4 Name Spaces 7
1.5 Effect of fork, exec, and exit on IPC Objects 9
1.6 Error Handling: Wrapper Functions 11
1.7 Unix Standards 13
1.8 Road Map to IPC Examples in the Text 15
1.9 Summary 16
Chapter 2. Posix IPC
2.1 lntroduction 19
2.2 IPC Names 19
2.3 Creating and Opening IPC Channels 22
2.4 IPC Permissions 25
2.5 Summary 26
vii
viii UNIX Network Programming Contents
Chapter 3. System V IPC
3.1 lntroduction 27
3.2 key-t Keys and ftok Function 28
3.3 i p c q e r m Structure 30
3.4 Creating and Opening IPC Channels 30
3.5 IPC Permissions 32
3.6 Identifier Reuse 34
3.7 ipcs and ipcrm Programs 36
3.8 Kernel Limits 36
3.9 Summary 38
Part 2. Message Passing 41
Chapter 4. Pipes and FlFOs
4.1 lntroduction 43
4.2 A Simple Client-Server Example 43
4.3 Pipes 44
4.4 Full-Duplex Pipes 50
4.5 popen and pclose Functions 52
4.6 FlFOs 54
4.7 Additional Properties of Pipes and FlFOs 58
4.8 One Server, Multiple Clients 60
4.9 Iterative versus Concurrent Servers 66
4.10 Streams and Messages 67
4.1 1 Pipe and FIFO Limits 72
4.1 2 Summary 73
Chapter 5. Posix Message Queues
5.1 lntroduction 75
5.2 maopen, maclose, and mxunlink Functions 76
5.3 m a g e t a t t r and m a s e t a t t r Functions 79
5.4 masend and mareceive Functions 82
5.5 Message Queue Limits 86
5.6 m a n o ti fy Function 87
5.7 Posix Realtime Signals 98
5.8 Implementation Using Memory-Mapped 110 106
5.9 Summary 126
Chapter 6. System V Message Queues
6.1 lntroduction 129
6.2 msgget Function 130
6.3 msgsnd Function 131
6.4 msgrcv Function 132
6.5 msgctl Function 134
6.6 Simple Programs 135
6.7 Client-Server Example 140
6.8 Multiplexing Messages 142
