Manual Pages  — SIGINTERRUPT

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 BSD 4.1 and AT&T V systems.

Note that the new BSD 4.2 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.