1.\" $OpenBSD: siginterrupt.3,v 1.11 2001/02/04 22:43:12 millert Exp $ 2.\" 3.\" Copyright (c) 1985, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.Dd February 4, 2001 35.Dt SIGINTERRUPT 3 36.Os 37.Sh NAME 38.Nm siginterrupt 39.Nd allow signals to interrupt system calls 40.Sh SYNOPSIS 41.Fd #include <signal.h> 42.Ft int 43.Fn siginterrupt "int sig" "int flag" 44.Sh DESCRIPTION 45The 46.Fn siginterrupt 47function is used to change the system call restart 48behavior when a system call is interrupted by the specified signal. 49If 50.Fa flag 51is false (0), system calls will be restarted if 52they are interrupted by the specified signal 53.Fa sig 54and no data has been transferred yet. 55System call restart is the default behavior on 56.Ox . 57.Pp 58If 59.Fa flag 60is true (1), 61the restarting of system calls is disabled. 62If a system call is interrupted by the specified signal 63and no data has been transferred, 64the system call will return \-1 with the global variable 65.Va errno 66set to 67.Er EINTR . 68Interrupted system calls that have started transferring 69data will return the amount of data actually transferred. 70System call interrupt is the signal behavior found on 71.Bx 72systems prior to 73.Bx 4.2 74as well as most systems based upon 75.At V . 76.Pp 77Programs may switch between restartable and interruptible 78system call operation as often as desired in the execution of a program. 79Issuing a 80.Fn siginterrupt 81call during the execution of a signal handler will cause 82the new action to take place on the next signal to be caught. 83.Sh RETURN VALUES 84.Fn siginterrupt 85returns 0 on success or \-1 if an invalid signal number has been 86specified. 87.Sh SEE ALSO 88.Xr sigaction 2 , 89.Xr sigprocmask 2 , 90.Xr sigsuspend 2 91.Sh HISTORY 92The 93.Fn siginterrupt 94function appeared in 95.Bx 4.3 . 96