[m-dev.] sem_wait and EINTR

[Peter Wang]

Hi,

I noticed that we have calls to MR_SEM_WAIT and MR_SEM_TIMED_WAIT that
do not handle a premature return when the call is interrupted by a
signal. We should wrap the calls like this:

    int err;
    do {
	err = MR_SEM_WAIT(sem, "blah");
    } while (err == -1 && MR_is_eintr(errno));

The MR_SEM_* macros may be implemented with libdispatch.
Does anyone know if libdispatch functions set errno on error?
The dispatch_semaphore_wait manual page does not mention EINTR so I
assume it will not return prematurely (good), but if it doesn't set
errno on error then testing errno there would be incorrect.

Peter