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 has been
the default behavior since 4.2BSD, and is the
default behaviour for signal(3) on FreeBSD.
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
The siginterrupt() function returns the
value 0 if successful; otherwise the value -1 is returned and
the global variable errno is set to indicate the
error.
ERRORS
The siginterrupt() call fails if:
- [
EINVAL] - The sig argument is not a valid signal number.
SEE ALSO
sigaction(2), sigblock(2), sigpause(2), sigsetmask(2), signal(3)
HISTORY
The siginterrupt() function appeared in
4.3BSD.