WIP: firefox: enable pulseaudio by default in wrapper

[corngood]

Motivation for this change

Firefox 52.0 removed the alsa backend, so without pulseaudio in LD_LIBRARY_PATH you get no audio.

WIP because:

• How does this affect other uses of the wrapper (I only tested firefox 52)?

• Is the predicate correct?
  config.pulseaudio or true is what's used for pulse support in chromium. Wine uses config.pulseaudio or stdenv.isLinux.

• Should we just enable the ALSA backend instead?
  See firefox: reenable ALSA backend #23989

• Should we require the user to set config.pulseaudio?
  Most other packages don't seem to require this. Especially ones without alsa support.

• Should we add a pulseSupport parameter like in chromium and opt in/out where appropriate?

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

---

[mention-bot]

@corngood, thanks for your PR! By analyzing the history of the files in this pull request, we identified @abbradar, @edolstra and @vcunat to be potential reviewers.

[edolstra]

See also #23989, which re-enables the ALSA backend.

[dtzWill]

ALSA backend is enabled, but it still seems useful to include pulseaudio in the wrapper by default?

• ALSA will still work if user does not use pulseaudio
• Worries about closure size can be addressed by users with config.pulseaudio = false, which they need to set anyway since firefox has dependencies that pull it along anyway/by default[1].
• Users on other distributions that default to pulseaudio don't have to discover magical config options to get things working (Firefox doesn't see host pulseaudio, audio doesn't work #34712)

I haven't tested the first point-- but unless that's false (?) then ... can we default to this being enabled for usability's sake?

FWIW a NixOS system with pulseaudio enabled does not necessarily have "config.pulseaudio" set one way or the other.

[1]

$ nix why-depends -f . firefox libpulseaudio --all
/nix/store/6sblfm52hkvzr2b4fp8y5bn8fvj2j6ag-firefox-58.0.1
╠═══bin/firefox: …D_LIBRARY_PATH:+':'}'/nix/store/07gd5ls8bbqz4kkmb5rycvn9cayzqmdh-ffmpeg-3.4.1/lib:/nix/store/22h…
║   => /nix/store/07gd5ls8bbqz4kkmb5rycvn9cayzqmdh-ffmpeg-3.4.1
║   ╠═══lib/libavdevice.so.57.10.100: …mdh-ffmpeg-3.4.1/lib:/nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0/lib:/nix/sto…
║   ║   => /nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0
║   ╚═══lib/libavdevice.so.57.10.100: ….6.libavdevice.so.57./nix/store/mgwv5454g23gh11hcmzc9v7jfh1prwgk-SDL2-2.0.7/lib:/nix/store/07gd5…
║       => /nix/store/mgwv5454g23gh11hcmzc9v7jfh1prwgk-SDL2-2.0.7
║       ╚═══lib/libSDL2-2.0.so.0.7.0: …x-alsa-lib-1.1.5/lib:/nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0/lib:/nix/sto…
║           lib/libSDL2.la: …5/lib/libasound.la -L/nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0/lib /nix/sto…
║           => /nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0
╚═══bin/firefox: …K_PATH${GTK_PATH:+:}'/nix/store/xflgnag4wwc2s0w4chsaggxrf62dc0d1-libcanberra-0.30/lib/gtk-2.0/'.…
    => /nix/store/xflgnag4wwc2s0w4chsaggxrf62dc0d1-libcanberra-0.30
    ╚═══lib/libcanberra-0.30/libcanberra-pulse.la: ….dependency_libs=' -L/nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0/lib /nix/sto…
        lib/libcanberra-0.30/libcanberra-pulse.so: …libcanberra-pulse.so./nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0/lib:/nix/sto…
        => /nix/store/mkcv47viwcy654wgdckja0mkxxvpjs9g-libpulseaudio-11.0

[oxij]

That issue was discussed before. See #29250. My view is still the same: PulseAudio is insecure and horribly broken by design, NixOS shouldn't push it onto users. It should be strictly opt-in, not opt-out.

[dtzWill]

Okay, well I'm just saying it's already included in the closure of firefox so I'm not sure it helps anyone to avoid it in the wrapper. Doing so seems to only break some setups (non-NixOS pulseaudio users) and nothing else... which is why it seems we might as well help firefox find its libraries.

(I would not suggest this if it wasn't already being included)

Does it help anyone to continue with the current behavior?

[oxij]

Okay, well I'm just saying it's *already* included in the closure of firefox (I would not suggest this if it wasn't already being included)

It should not be, so it's a bug which I shall investigate.