On Tue, Apr 23, 2019 at 2:17 PM E. Madison Bray wrote: > > Hello, > > I have had some users of the Jupyter Notebook [1] on Cygwin report an > crash on startup where, when the Notebook server tries to bind() to > the port it will listen on (TCP 8888) the bind() fails and errno is > set to EPERM, which is not an expected errno from bind(). > > Looking at the Cygwin sources, in net.cc I see that in > set_winsock_errno, EPERM is returned by default if there is some WSA > error for which there is no POSIX equivalent mapped. Fine--EPERM is > as good as any other fallback I suppose (?) in that it unambiguously > indicates some unknown WSA error. > > I'm just wondering if anyone has any idea what might cause such an > error. Some third-party firewall or BLODA? I can't reproduce it > myself. Trying to bind to a port already in use correctly returns > EADDRINUSE. > > > [1] https://jupyter.org/
Answering my own question after comparing the list on https://docs.microsoft.com/en-us/windows/desktop/winsock/windows-sockets-error-codes-2 to Cygwin's wsock_errmap table this is a likely culprit: > WSAEACCES > 10013 > Permission denied.An attempt was made to access a socket in a way forbidden > by its access permissions. > An example is using a broadcast address for sendto without broadcast > permission being set using > setsockopt(SO_BROADCAST). > Another possible reason for the WSAEACCES error is that when the bind > function is called (on Windows NT > 4.0 with SP4 and later), another application, service, or kernel mode driver > is bound to the same address > with exclusive access. Such exclusive access is a new feature of Windows NT > 4.0 with SP4 and later, and is > implemented by using the SO_EXCLUSIVEADDRUSE option. This appears to be missing from the wsock_errmap table, but should obviously map to EACCES. I'll supply a patch. -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
