SIGINTERRUPT(3)                      BSD                       SIGINTERRUPT(3)



NAME
     siginterrupt - allow signals to interrupt system calls

SYNOPSIS
     siginterrupt(sig, flag);
     int sig, flag;

DESCRIPTION
     siginterrupt 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 4.2 BSD.

     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 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 4.1 BSD and AT&T System V UNIX systems.

     Note that the new 4.2 BSD signal handling semantics are not altered in
     any other way.  Most notably, signal handlers always remain installed
     until explicitly changed by a subsequent sigvec(2) call, and the signal
     mask operates as documented in sigvec(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 sigvec(2) system call that
     is not available in 4.2BSD, hence it should not be used if backward
     compatibility is needed.

DIAGNOSTICS
     A 0 value indicates that the call succeeded.  A -1 value indicates that
     an invalid signal number has been supplied.

SEE ALSO
     sigvec(2), sigblock(2), sigpause(2), sigsetmask(2).