NAME
siginterrupt —
allow signals to
interrupt system calls
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <signal.h>
int
siginterrupt(
int
sig,
int flag);
DESCRIPTION
The
siginterrupt() function is used to change the system call
restart behavior when a system call is interrupted by the specified signal. If
the flag is false (0), then system calls will be restarted if they are
interrupted by the specified signal and no data has been transferred yet.
System call restart is the default behavior on
4.2BSD.
If the flag is true (1), then restarting of system calls is disabled. If a
system call is interrupted by the specified signal and no data has been
transferred, the system call will return -1 with the global variable
errno set to
EINTR
. Interrupted
system calls that have started transferring data will return the amount of
data actually transferred. System call interrupt is the signal behavior found
on
4.1BSD and
AT&T System V
UNIX systems.
Note that the new
4.2BSD signal handling semantics are
not altered in any other way. Most notably, signal handlers always remain
installed until explicitly changed by a subsequent
sigaction(2) call, and the
signal mask operates as documented in
sigaction(2). Programs may
switch between restartable and interruptible system call operation as often as
desired in the execution of a program.
Issuing a
siginterrupt(
3) call during
the execution of a signal handler will cause the new action to take place on
the next signal to be caught.
NOTES
This library routine uses an extension of the
sigaction(2) system call that
is not available in
4.2BSD, hence it should not be
used if backward compatibility is needed.
RETURN VALUES
A 0 value indicates that the call succeeded. A -1 value indicates that an
invalid signal number has been supplied.
SEE ALSO
sigaction(2),
sigprocmask(2),
sigsuspend(2)
HISTORY
The
siginterrupt() function appeared in
4.3BSD.