DragonFly On-Line Manual Pages
SIGINTERRUPT(3) DragonFly Library Functions Manual SIGINTERRUPT(3)
siginterrupt -- allow signals to interrupt system calls
Standard C Library (libc, -lc)
siginterrupt(int sig, int flag);
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 DragonFly.
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 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
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.
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.
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 siginterrupt() call fails if:
[EINVAL] sig is not a valid signal number.
sigaction(2), sigprocmask(2), sigsuspend(2), signal(3)
The siginterrupt() function appeared in 4.3BSD.
DragonFly 5.3 June 4, 1993 DragonFly 5.3