siginterrupt - allow signals to interrupt system calls
int siginterrupt(sig, flag)
int sig, flag;
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 4.2BSD, and on SunOS in the 4.2
environment, when the signal (3V) routine is used.
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 older version of the UNIX
operating systems, such as 4.1BSD and System V UNIX. It is the default
behavior on SunOS in the System V environment when the signal() routine
is used; therefore, this routine is useful in that environment only if
a signal that a sigvec(2) specified should restart system calls is to
be changed not to restart them.
Note: 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 sigvec() call, and the signal mask
operates as documented in sigvec(), unless the SV_RESETHAND bit has
been used to specify that the pre-4.2BSD signal behavior is to be used.
Programs may switch between restartable and interruptible system call
operation as often as desired in the execution of a program.
Issuing a siginterrupt() call during the execution of a signal handler
will cause the new action to take place on the next signal to be
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 back-
ward compatibility is needed.
0 on success.
-1 if an invalid signal number was supplied.
sigblock(2), sigpause(2V), sigsetmask(2), sigvec(2), signal(3V)
21 January 1990 SIGINTERRUPT(3V)