Nixpkgs: terminus not found by fontconfig in 18.03

[Ralith]

Issue description

With pkgs.terminus_font, a bitmap font, in fonts.fonts, as of 18.03 fc-match Terminus does not find the font, fc-cache -v |grep fonts/terminus returns existing cache is valid: 0 fonts, 0 dirs, and fontconfig-based programs formerly configured to use it switch to a fallback font.

In 17.09, the font is found correctly, and fc-cache -v |grep fonts/terminus returns existing cache is valid: 18 fonts, 0 dirs. Strangely, xlsfonts is able to find the font in both 17.09 and 18.03. fc-scan seems to successfully process the font files.

The contents of the font directory appear to be the same on both systems:

fonts.dir        ter-x12n.pcf.gz  ter-x16b.pcf.gz  ter-x18n.pcf.gz  ter-x22b.pcf.gz  ter-x24n.pcf.gz  ter-x32b.pcf.gz
fonts.scale      ter-x14b.pcf.gz  ter-x16n.pcf.gz  ter-x20b.pcf.gz  ter-x22n.pcf.gz  ter-x28b.pcf.gz  ter-x32n.pcf.gz
ter-x12b.pcf.gz  ter-x14n.pcf.gz  ter-x18b.pcf.gz  ter-x20n.pcf.gz  ter-x24b.pcf.gz  ter-x28n.pcf.gz

Steps to reproduce

Set fonts.fonts = [ pkgs.terminus_font ]; and attempt to use the font, e.g. with fc-match Terminus.

Technical details

• system: "x86_64-linux"
• host os: Linux 4.14.27, NixOS, 18.03pre131327.0e7c9b32817 (Impala)
• multi-user?: yes
• sandbox: no
• version: nix-env (Nix) 2.0
• channels(root): "nixos-18.03pre131327.0e7c9b32817"
• channels(user): ""
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs

[volhovm]

I confirm that this issue reproduces for me also.

[jwptrs]

Interestingly, fc-match Terminus returns nothing, but sudo fc-match Terminus gives the correct font files. Same issue with pkgs.profont
Issue both in 17.09 and now in 18.03.

[lheckemann]

I can't reproduce this. fc-match as my regular user produces ter-x32n.pcf.gz: "Terminus (ttf)" "Regular" if terminus_font is in fonts.fonts or in the user profile for me.

 - system: `"x86_64-linux"`
 - host os: `Linux 4.15.15, NixOS, 18.03.131807.489a14add9a (Impala)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.0`
 - channels(root): `"nixos-18.03.131807.489a14add9a"`
 - channels(linus): `""`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs`

[Ralith]

This still reproduces for me on latest 18.03. I also confirm that fc-match gives the correct result as root for some reason.

[Ralith]

There's a fix!

Nuking ~/.cache/fontconfig fixed the issue for me. I'm guessing a GC following the update to 18.03 invalidated the path to [an intermediate reference to] terminus and fontconfig silently fell back on another font instead of reporting the error.

To prevent this issue from recurring in the future, fontconfig could be fixed to drop a cache that contains invalid data, or perhaps we could somehow force all user-specific caches to be dropped.

[volhovm]

@Ralith The issue actually reproduces for me after some time -- something in the cache/fontconfig folder is being recreated.

[Ralith]

That seems very strange; where could it be getting invalid/obsolete data from? Still working fine here; I take it you're certain you didn't perform any nix operations that might have affected fonts or fontconfig in the intervening time?

[lheckemann]

fc-cache -f might also be worth trying.

[Ralith]

I just had this issue recur, nuked the cache to fix it, and then had it recur again in the space of a few hours during which I ran no nix operations whatsoever, although a long-running LLVM build required by a nix-shell invocation may have completed. It looks like this isn't (just) an issue with updates: something is actively mangling the cache.

edit: it just happened again in the last ten minutes o_O

[lheckemann]

Which desktop environment are you using? Maybe there's some connection with that.

[Ralith]

I don't use a DE, just i3.

[lheckemann]

The plot thickens…

(same here)

As a hack, maybe try removing the contents of ~/.cache/fontconfig and then setting it read-only?

[volhovm]

I have figured out that the fix works fine for me unless I restart chromium, which then leads to the problem again. I am not sure, how it can be related, but it perfectly reproduces.

[Ralith]

I haven't been restarting chromium at all, but I do make much heavier use of it on the machine where the issue was recurring than on the machine where it doesn't seem to recur...

[vcunat]

Chromium uses its own bundled fontconfig, built during the huge build, just as it does with many other libraries – see CC obj/third_party/fontconfig/fontconfig/... in the logs. I have no idea what differences they have.

[martingms]

I use Firefox, but used chromium for a quick check yesterday and that brought back the issue.

[octalsrc]

Encountered this issue yesterday, with same cause and fix.

[stale[bot]]

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