qemu doesn't set vnc port correctly

[Michael Mair-Keimberger]

Qemu Version: 1.1.1

In the past it was possible to set the port for vnc with:
-vnc :1
That would mean the port would be 5901, Starting from 5900 plus the given number. However, it was also possible to set the port directly with a custom given port. Usually i set the port to something like 5801. With qemu-1.1.1 (and maybe prior versions too, i usually use spice) that's not possible anymore. For example:
-vnc 192.168.1.1:5804
Here the 'real' port would be 11704 (that's 5900 + 5804). I'm sure that worked correctly in the past and i'm pretty sure it's easy to fix.

Would be nice if we can fix that.

System Info:
Portage 2.1.11.31 (default/linux/amd64/10.0/no-multilib, gcc-4.5.4, glibc-2.15-r3, 3.5.7-gentoo x86_64)
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[Daniel Berrange (berrange)]

The problem with this is that the behaviour is inherently ambiguous. We have no way to distinguish whether a user specifying ":5804" wants port 11704 or port 5804, so it is not in fact easy to fix.

If we were writing this again from scratch I would avoid the offset concept entirely and always require absolute port, but given where we are, unconditionally treating the port number as an offset relative to 5900 is the only sane approach, unless we introduce completely new syntax.