Now measures over an entire update, which should hopefully give us more
stable values. They are still small values for fast networks though so
increase precision in the values we keep.

Provide some safety checks when directly accessing the underlying
pointer of streams.

Some systems (like TLS) need to send some final data before closing
a connection. Make sure this is properly handled by cleaning up the
security object before closing the underlying network socket.

Otherwise we might send duplicate result codes and other weird things.

External callers don't need to know the exact details, only if there is
data that needs to be flushed or not.

This allows us to handle peaks in input and output streams gracefully
without having to block processing.

The principle can be used in a more general fashion than just TCP
streams.

We can do what we want with the standard methods.

Just have a simply number of bytes argument to avoid a lot of
complexity.

Most streams are backed by a memory buffer. Create common base classes
for this functionality to avoid code duplication.

Makes it more readable to write code that needs to know how much
data/space is available in a stream.

It might leak data depending on what's in the buffer. Use pad() instead
where blank space is needed.

They were accidentally left unused in fbad8a9 so they haven't been used
in some time.

We need to be able to tell this exception came from a decoder.

For readability.

There might be some final handshake data that is still stuck in the
buffers, so make a best effort attempt at getting it to the client.

The socket is closed at this point so we have to rely on a cached
value for the logging.

It's a generic feature that is better handled as part of SConnection's
state machine.

We can't safely use the normal timers in base classes as we cannot
guarantee that subclasses will call the base class' handleTimeout()
properly if the subclass overrides it.

vncsession-start is running in SELinux vnc_session_t domain because of
"SELinuxContext=system_u:system_r:vnc_session_t:s0" option in systemd
vncserver@.service unit file. vncsession-start executing binary
vncsession with SELinux label/type vnc_session_t. This access was not
allowed in vncsession policy.

It seems like many of the X11 operations can end up with no pixels
actually changing. So instead of discovering and adding workarounds for
each individually we'll just check very region added if it's empty.

Otherwise it might fail if the repositories have changed since the image
was generated.

We now require at least 1.16, so remove all code that handled older
versions than that.

We removed support in the code ages ago, but overlooked this part of the
documentation. Also remove some dead code in Xvnc on the same theme.

Most window managers won't like this, and it tends to provoke bugs in
FLTK, so let's avoid it. It's probably not what the user wants anyway.

Created a new subclass of Exception called GAIException() that will
handle error messages from getaddrinfo() instead of letting Exception()
handle it. GAIException() will make use of gai_strerror() to map the
error code to text. On Windows, gai_strerrorW() must be used if the text
is encoded with UTF-8.

The previous error messages did not support Unicode characters. This
commit will use UTF-8 encoding to be able to display error messages in
every language.

No current distribution ship anything this ancient anyway.

This makes our builds directly compatible with most distributions
without packagers/users having to specify extra flags.

Running as a service on a SELinux system requires rules so we can
transition to our own context. We also need the proper permissions
to start new user sessions.

This sets up a more correct session as there are key tasks that
need to be performed by PAM. E.g. systemd will allocate cgroups
and start base services.

In order to easily handle this as a system service the mapping of
displays is now done via a configuration file.

It is present on all UNIX systems anyway, so let's simplify things.
We will need it for more proper session startup anyway.

Assume we are part of a complete and proper installation and encode the
full expected path in to the vncserver script.

It keeps much better track of the X server and startup files than
we can do.

We need to be started as a system service for things to work correctly
anyway, so delegate the work of starting and stopping things to the
system service manager (e.g. systemd).

This is how display managers (e.g. gdm or lightdm) start sessions
and is necessary to get the proper set of environment variables.