Passing a null pointer to write() is a bad idea any time (in libmythdb)

[Erik Hovland <erik@…>]

The tcp/udp write calls in msocketdevice_unix.cpp can pass a null pointer to write() if the length of the data to write is zero. Although this is unlikely to be a problem, it would be better if we never passed a null pointer to write() ever.

[Erik Hovland <erik@…>]

short ckt zero length buffer writes so null is not passed to write()

[danielk]

I'll keep the ticket open while we are still using msocketdevice, but this code is probably going away. Once we switch completely to Qt4 we won't be initializing the Qt3 network stack at startup and we'll probably need to replace this code.

[Erik Hovland <erik@…>]

Fresh patch for old ticket.

[cpinkham]

(In [21388]) Do a little bit more sanity checking on the input to MSocketDevice::writeData() and MSocketDevice::writeBlock() to guarantee we don't try to pass a null pointer when writing data to the socket.

Closes #5504 using unix patch by Erik Hovland, copied to _win.cpp by myself.