Mark, I think there's a bug in sigtimedwait. I just found the problem while looking into this aio_suspend stuff:
On Jul 17 16:51, Corinna Vinschen wrote:
> > + res = sigtimedwait (&sigmask, &si, to);
You're giving the timeout value verbatim to sigtimedwait().
Let's have a look into sigtimedwait, per your original patch, commit
24ff42d79aab:
+ if (timeout)
+ {
+ if (timeout->tv_sec < 0
+ || timeout->tv_nsec < 0 || timeout->tv_nsec > (NSPERSEC * 100LL))
+ {
+ set_errno (EINVAL);
+ return -1;
+ }
So we're enforcing a positive timeout value.
+ /* convert timespec to 100ns units */
+ waittime.QuadPart = (LONGLONG) timeout->tv_sec * NSPERSEC
+ + ((LONGLONG) timeout->tv_nsec + 99LL) / 100LL;
+ }
...which is converted to a likewise positive 100ns interval ...
+ return sigwait_common (set, info, timeout ? &waittime : cw_infinite);
...given to sigwait_common, which in turn calls
cygwait (NULL, waittime, [flags])
cygwait uses this waittime value verbatim in a call to
NtSetTimer (_my_tls.locals.cw_timer, timeout, [...]);
So NtSetTimer is called with a *positive* waittime value, right?
A positive value given to NtSetTimer is evaluated as a timestamp,
*not* as a time interval. Look at the lpDueTime description of
SetWaitableTimerEx. That's the WIN32 API function exposing the
NtSetTimer function:
https://docs.microsoft.com/en-us/windows/desktop/api/synchapi/nf-synchapi-setwaitabletimerex
However, the POSIX description of sigtimedwait indicates that the
timespec value is evaluated as a time interval, which is a relative
time:
http://pubs.opengroup.org/onlinepubs/9699919799/functions/sigtimedwait.html
So bottom line is, shouldn't timeout be converted to a negative waittime
value in sigtimedwait?
Thanks,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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