The previous commit was incorrect in that it overrides automake's
dependency list, rather than adding to it. So we need to make sure
things are duplicated between Xvnc_DEPENDENCIES and Xvnc_LDADD as
appropriate.

Use the same approach as the Xorg binary to keep things familiar.

These aren't crucial for a clean build, but must be set for Xvnc to be
properly rebuilt if anything in the Xorg tree changes. automake doesn't
properly deduce these automatically from Xvnc_LDADD, unfortunately.

The socket might not be the stream actually used, e.g. when we are using
TLS. Make sure we cork the proper stream to get all the benefits of
corking.

Avoid having to buffer everything we want to discard, and instead do it
piece by piece. This is more efficient, and avoids hitting any limits on
the buffering.

Note that this is safe here because we already know we have all the
compressed data. It would not be safe for a general input stream.

These streams both need to change the corking state temporarily, but it
is important it is restored to the previous state or things might get
messed up.

For the zlib stream it would just leave things uncorked, which still
works but is less efficient.

But for the TLS stream it might make things very unresponsive as the
corking might be left on permanently, delaying packets indefinitely.

Uncorking implicitly flushes, so we don't need this.

There is no point flushing when corking was enabled, as we might then
push out a small buffer that the corking otherwise would have preserved.

It seems MFT h264 decoder does not support frame cropping. Which
means that if frame width or height is not multiple of 16 then
decoded output can potentially be used with wrong offset. This
code adds explicit parsing of SPS to extract cropping information
to use, and will apply cropping if reported size differs from
expected.

This is the standard method of finding it on Unix systems, so make sure
we use it. Still keep a fallback, though, for other systems, e.g.
Windows.

FFMPEG is needed by the RFB library, so all the details about it should
only be applied there and not for other components.

This is the standard method of finding it on Unix systems, so make sure
we use it. Still keep a fallback, though, for other systems, e.g.
Windows.

We need this function to deal with pkgconfig files properly, but
unfortunately it doesn't exist until CMake 3.13, and we need to support
CMake 3.10. So add a hacky compatibility function for older systems.

Modern cmake has better support for adding source files and libraries
incrementally, so let's use that to clean things up.

Our embedded zlib got removed way back in cc8c6a2.

Reduce the icon margins a bit to conform better with other icons. Also
dial back the rounding a bit, again to fit better with other programs.

Some desktop environment, like KDE, need more rastered sizes and cannot
make use of the SVG.

This is already done by vncviewer, so we don't need any rule here.

Have the padding included in the SVGs to make the rules less complex.

This code is never used on Windows, so remove it.

Avoid the risk of the list of sizes and the list of icons getting out of
sync and causing memory corruption.

Minor fixes/future-proofing for SConnection::accessCheck() and 'accessRights'

These checks depend on accessRights being set up, this has only happened
if we have done the QUERYING steps.

Properties should be initialized in order to avoid random values in
case they are used earlier than expected.

FLTK has a lot of synchronous stuff (like dialogs), which mean that the
main loop might be run recursively in some cases. If there is data
available on our socket then CConn::socketEvent() will be called
constantly in a busy loop.

Avoid this by removing socket notifications whilst we are processing
data.

Enable this automatically for developers so we increase the chance of
these problems getting caught. There is a risk of overhead though so
keep them disabled for release builds.

Unfortunately this error can be given by GnuTLS even though the
underlying stream still has data available. So stop trusting this value
and keep track of the underlying stream explicitly.

It's a bit field so it's easier to decode in hex.

The browsers allow users to make an exception for expired certificates,
so we should probably also.

Otherwise we can get crashes on NULL dereference. This should only
happen on reverse connections where we don't have a server address.

We need to get to the point of starting the session script before we
consider things a success. So this can fail in many different ways, not
just the daemonization. Adjust the error message to something more
generic to reflect this.

Ubuntu 20.04
gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0
libx264-dev:amd64 2:0.155.2917+git0a84d98-2

[ 11%] Building CXX object common/rfb/CMakeFiles/rfb.dir/H264LibavDecoderContext.cxx.o
tigervnc/common/rfb/H264LibavDecoderContext.cxx: In member function ‘virtual bool rfb::H264LibavDecoderContext::initCodec()’:
tigervnc/common/rfb/H264LibavDecoderContext.cxx:50:40: error: invalid conversion from ‘const AVCodec*’ to ‘AVCodec*’ [-fpermissive]
   50 |   AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_H264);
      |                    ~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
      |                                        |
      |                                        const AVCodec*
make[2]: *** [common/rfb/CMakeFiles/rfb.dir/build.make:895: common/rfb/CMakeFiles/rfb.dir/H264LibavDecoderContext.cxx.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:597: common/rfb/CMakeFiles/rfb.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

CentOS 8 is EOL and is now replaced with CentOS Stream 8.

This images isn't available on Docker Hub unfortunately, so we grab it
from Quay.

Instead of HOME_ROOT/.vnc, /root/.vnc should be used
for user root's home to specify default file context
as HOME_ROOT actually means base for home dirs (usually /home).