.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sun Jul 25 10:40:51 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Sun Apr 14 16:20:34 1996 by Andries Brouwer (aeb@cwi.nl)
.TH SIGINTERRUPT 3 2014-06-13 "" "Linux Programmer's Manual"
.SH NAME
siginterrupt \- allow signals to interrupt system calls
.SH SYNOPSIS
.nf
.B #include <signal.h>
.sp
.BI "int siginterrupt(int " sig ", int " flag );
.fi
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.BR siginterrupt ():
.ad l
.RS 4
_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
_XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
.br
|| /* Since glibc 2.12: */ _POSIX_C_SOURCE\ >=\ 200809L
.RE
.ad
.SH DESCRIPTION
The
.BR siginterrupt ()
function changes the restart behavior when
a system call is interrupted by the signal \fIsig\fP.
If the \fIflag\fP
argument is false (0), then system calls will be restarted if interrupted
by the specified signal \fIsig\fP.
This is the default behavior in Linux.
.PP
If the \fIflag\fP argument is true (1) and no data has been transferred,
then a system call interrupted by the signal \fIsig\fP will return \-1
and \fIerrno\fP will be set to
.BR EINTR .
.PP
If the \fIflag\fP argument is true (1) and data transfer has started,
then the system call will be interrupted and will return the actual
amount of data transferred.
.SH RETURN VALUE
The
.BR siginterrupt ()
function returns 0 on success.
It returns \-1 if the
signal number
.I sig
is invalid, with
.I errno
set to indicate the cause of the error.
.SH ERRORS
.TP
.B EINVAL
The specified signal number is invalid.
.SH ATTRIBUTES
.SS Multithreading (see pthreads(7))
The
.BR siginterrupt ()
function uses a global variable that is not protected,
so it is not thread-safe.
.SH CONFORMING TO
4.3BSD, POSIX.1-2001.
POSIX.1-2008 marks
.BR siginterrupt ()
as obsolete, recommending the use of
.BR sigaction (2)
with the
.B SA_RESTART
flag instead.
.SH SEE ALSO
.BR signal (2)
.SH COLOPHON
This page is part of release 3.74 of the Linux
.I man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
\%http://www.kernel.org/doc/man\-pages/.