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SIGINTERRUPT(3)                         BSD Library Functions Manual                         SIGINTERRUPT(3)

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.

BSD                                             June 4, 1993                                             BSD