projects / unix-history / blame
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|---|---|---|
| 53e9b2ee KM |
1 | .\" Copyright (c) 1985 Regents of the University of California. |
| 2 | .\" All rights reserved. The Berkeley software License Agreement | |
| 3 | .\" specifies the terms and conditions for redistribution. | |
| 4 | .\" | |
| 5 | .\" @(#)siginterrupt.3 6.1 (Berkeley) %G% | |
| 6 | .\" | |
| 7 | .TH SIGINTERRUPT 3 "" | |
| 8 | .UC 6 | |
| 9 | .SH NAME | |
| 10 | siginterrupt \- allow signals to interrupt system calls | |
| 11 | .SH SYNOPSIS | |
| 12 | .nf | |
| 13 | .B siginterrupt(sig, flag); | |
| 14 | .B int sig, flag; | |
| 15 | .SH DESCRIPTION | |
| 16 | .I Siginterrupt | |
| 17 | is used to change the system call restart | |
| 18 | behavior when a system call is interrupted by the specified signal. | |
| 19 | If the flag is false (0), then system calls will be restarted if | |
| 20 | they are interrupted by the specified signal | |
| 21 | and no data has been transferred yet. | |
| 22 | System call restart is the default behavior on 4.2 BSD. | |
| 23 | .PP | |
| 24 | If the flag is true (1), then restarting of system calls is disabled. | |
| 25 | If a system call is interrupted by the specified signal | |
| 26 | and no data has been transferred, | |
| 27 | the system call will return -1 with errno set to EINTR. | |
| 28 | Interrupted system calls that have started transferring | |
| 29 | data will return the amount of data actually transferred. | |
| 30 | System call interrupt is the signal behavior found on 4.1 BSD | |
| 31 | and AT&T System V UNIX systems. | |
| 32 | .PP | |
| 33 | Note that the new 4.2 BSD signal handling semantics are not | |
| 34 | altered in any other way. | |
| 35 | Most notably, signal handlers always remain installed until | |
| 36 | explicitly changed by a subsequent | |
| 37 | .IR sigvec (2) | |
| 38 | call, and the signal mask operates as documented in | |
| 39 | .IR sigvec (2). | |
| 40 | Programs may switch between restartable and interruptible | |
| 41 | system call operation as often as desired in the execution of a program. | |
| 42 | .PP | |
| 43 | Issuing a | |
| 44 | .IR siginterrupt (3) | |
| 45 | call during the execution of a signal handler will cause | |
| 46 | the new action to take place on the next signal to be caught. | |
| 47 | .SH NOTES | |
| 48 | This library routine uses an extension of the | |
| 49 | .IR sigvec (2) | |
| 50 | system call that is not available in 4.2BSD, | |
| 51 | hence it should not be used if backward compatibility is needed. | |
| 52 | .SH "RETURN VALUE | |
| 53 | A 0 value indicates that the call succeeded. | |
| 54 | A -1 value indicates that an invalid signal number has been supplied. | |
| 55 | .SH "SEE ALSO" | |
| 56 | sigvec(2), sigblock(2), sigpause(2), sigsetmask(2). |