1.\" $OpenBSD: siginterrupt.3,v 1.14 2013/06/05 03:39:22 tedu 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. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd $Mdocdate: June 5 2013 $ 31.Dt SIGINTERRUPT 3 32.Os 33.Sh NAME 34.Nm siginterrupt 35.Nd allow signals to interrupt system calls 36.Sh SYNOPSIS 37.In signal.h 38.Ft int 39.Fn siginterrupt "int sig" "int flag" 40.Sh DESCRIPTION 41The 42.Fn siginterrupt 43function is used to change the system call restart 44behavior when a system call is interrupted by the specified signal. 45If 46.Fa flag 47is false (0), system calls will be restarted if 48they are interrupted by the specified signal 49.Fa sig 50and no data has been transferred yet. 51System call restart is the default behavior on 52.Ox . 53.Pp 54If 55.Fa flag 56is true (1), 57the restarting of system calls is disabled. 58If a system call is interrupted by the specified signal 59and no data has been transferred, 60the system call will return \-1 with the global variable 61.Va errno 62set to 63.Er EINTR . 64Interrupted system calls that have started transferring 65data will return the amount of data actually transferred. 66System call interrupt is the signal behavior found on 67.Bx 68systems prior to 69.Bx 4.2 70as well as most systems based upon 71.At V . 72.Pp 73Programs may switch between restartable and interruptible 74system call operation as often as desired in the execution of a program. 75Issuing a 76.Fn siginterrupt 77call during the execution of a signal handler will cause 78the new action to take place on the next signal to be caught. 79.Sh RETURN VALUES 80.Fn siginterrupt 81returns 0 on success or \-1 if an invalid signal number has been 82specified. 83.Sh SEE ALSO 84.Xr sigaction 2 , 85.Xr sigprocmask 2 , 86.Xr sigsuspend 2 87.Sh HISTORY 88The 89.Fn siginterrupt 90function appeared in 91.Bx 4.3 . 92