SIGINTERRUPT(3)           OpenBSD Programmer's Manual          SIGINTERRUPT(3)

NAME
     siginterrupt - allow signals to interrupt system calls



SYNOPSIS
     #include <signal.h>

     int
     siginterrupt(int sig, int flag);

DESCRIPTION
     The siginterrupt() function is used to change the system call restart be-
     havior when a system call is interrupted by the specified signal.  If
     flag is false (0), system calls will be restarted if they are interrupted
     by the specified signal sig and no data has been transferred yet.  System
     call restart is the default behavior on 4.2BSD.

     If flag is true (1), the 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 transfer-
     ring 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() 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
     siginterrupt() returns 0 on success or -1 if an invalid signal number has
     been specified.

SEE ALSO
     sigaction(2),  sigblock(3),  sigpause(3),  sigsetmask(3)

HISTORY
     The siginterrupt() function appeared in 4.3BSD.

OpenBSD 2.6                      June 4, 1993                                1