Ship a private copy of OpenSSL for pre Qt 5.10 applications

[claell]

Should fix #209 thought I'd create a separate issue for it in case further discussion is needed.

[probonopd]

Thanks @ciaeli. Do you know what they did in 5.10 to make this unnecessary?

[probonopd]

Maybe we should add an error message in case someone attempts to bundle an application that requires OpenSSL but is using Qt 5 below 5.10?

[claell]

Do you know what they did in 5.10 to make this unnecessary?

I think I do. The description of #209 says that Qt 5.10 uses OpenSSL 1.1, while older versions probably still rely on version 1.0, which is no longer available on most distributions:

Arch Linux has switched to Qt 5.10, which now depends on OpenSSL 1.1 [1], and now OpenSSL 1.0 is not installed by default. See [2] for packages still depending on version 1.0, but there are not many left.

Maybe we should add an error message

Some hint would be good indeed indicating that one should try to switch to Qt 5.10 or later.

However, there are probably cases where that is not easily possible. So I think there should also be the option to continue building and include a private copy of OpenSSL.

As you said on #209 this should be up to linuxdeployqt, not the person actually using it to build software.
So I'd suggest also adding that functionality of automatically bundling a private copy of OpenSSL to linuxdeployqt, not only an error message.

[probonopd]

The description of #209 says that Qt 5.10 uses OpenSSL 1.1, while older versions probably still rely on version 1.0, which is no longer available on most distributions

How does that work for distributions that use OpenSSL 1.0?

Thanks @claell for doing the investigations and for proposing this solution. For now we have updated the documentation to recommend a newer version of Qt, which should be sufficient in most cases to address this issue. Please feel free to reopen if you run into a concrete situation where this is not sufficient.

[claell]

How does that work for distributions that use OpenSSL 1.0?

Good question. I assume there is either a fallback to OpenSSL 1.0 or it won't work for these distributions in that case. But I did not look into this.

which should be sufficient in most cases to address this issue

To address this issue it is probably perfectly sufficient. But there might be other restrictions that keep developers from switching to 5.10. But also here that is just an assumption, I am not developing such applications, but am only a user of one which is affected by this. So maybe @RobertKrajewski and @nurupo can shed some light on this. Both are using older Qt versions and ran into this issue. So is there a reason you did not change to Qt 5.10?

Also ping to @antony-jr @sudden6 @tux3

[nurupo]

It's as simple as qTox AppImage being based on Debian Stretch, which packages Qt 5.7.1.

[claell]

Ah ok, did not get it the first time you wrote that.

Is there a reason to use Debian Stretch (like stability or being backwards compatible)? Also would adding Qt 5.10 from a PPA work?

[antony-jr]

For the most part, shipping the version of OpenSSL that was used to build Qt will fix any problem related to OpenSSL and Qt. And to adjust the LD_LIBRARY_PATH variable because that's what the official documentation says. I think AppRun automatically sets the LD_LIBRARY_PATH ?

So shipping a private copy into the AppImage may not work properly. The OpenSSL version has to be compatible with the Qt version you are bundling. So copying it from the host system is the only choice.

[claell]

So copying it from the host system is the only choice.

Thanks for clarification. So basically the only option how to implement this in linuxdeployqt would be to grab it from the host system when bundling.

However currently that is not planned to be done, at least if there are no projects that need to rely on pre Qt 5.10. So I am currently trying to investigate whether your project is depending on pre Qt 5.10 or could also switch to Qt 5.10 in order to fix this problem.

[probonopd]

I'd recommend to compile on Ubuntu xenial with Qt 5.10+ from https://launchpad.net/~beineri.