[WIP] Build FLTK for ZynAddSubFX support

[PhysSong]

Per LMMS/lmms#4109 (comment)

[flathubbot]

Started test build 3086

[flathubbot]

Build 3086 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/2949/io.lmms.LMMS.flatpakref

[hfiguiere]

You still have this marked as [WIP]. Anything you'd like to add?

It builds properly and the ZynAddSubFX is there.
However there UI never show when I click on "Show UI"

[PhysSong]

@hfiguiere Did you get some terminal output like this after clicking Show UI?

Could not connect to local server.
Error while writing.

[hfiguiere]

yes I'm getting these.

[PhysSong]

As you can see in https://github.com/LMMS/lmms/blob/ec64de072352c17a025e073114aaaea6ba773822/src/core/RemotePlugin.cpp#L102-L104, LMMS uses local sockets on the temporary directory. I suspect there were some permission issues with the sockets.

	m_socketFile = QDir::tempPath() + QDir::separator() +
						QUuid::createUuid().toString();
	const char * path = m_socketFile.toUtf8().constData();

Edit: The assumption was correct.

[flathubbot]

Started test build 3415

[flathubbot]

Build 3415 failed

[flathubbot]

Started test build 3416

[flathubbot]

Build 3416 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/3263/io.lmms.LMMS.flatpakref

[hfiguiere]

still doesn't work here.

[hfiguiere]

It fails because

bind(33, {sa_family=AF_UNIX, sun_path="/var/tmp/{9879ab2c-c2c8-4a1b-aa28-fa3b5f6276a0}"}, 110) = -1 EROFS (Read-only file system)

[hfiguiere]

Solution is to add "--filesystem=/var/tmp" (since this is what TMPDIR is set to) instead of changing to "--filesystem=host".

[PhysSong]

Solution is to add "--filesystem=/var/tmp" (since this is what TMPDIR is set to) instead of changing to "--filesystem=host".

Okay. BTW, why did you set TMPDIR to /var/tmp? Are there any issues with default /tmp?

[hfiguiere]

Not setting TMPDIR make the additional filesystem permission unneeded.

That is also a reasonable solution.

[hfiguiere]

Cherry-picked the fltk patch to master, added the proper change for plugin socket to work and rolled all out for the 1.2.0 release that should be building right now.

Thanks you so much.