Fontconfig warning: remove 'blank' configuration

In the log:

Fontconfig warning: line 145: blank doesn't take any effect anymore. please remove it from your fonts.conf

Quickly skimming fontconfig's changelog one finds:

commit 46b2c62faa64250eec3981ee816e91a9a3dee857 Author: Akira TAGOH akira@tagoh.org Date: Wed Jun 17 16:29:08 2015 +0900

Add a warning for blank in fonts.conf

and remove the unnecessary code for parsing blanks

src/fcxml.c | 7 +++++++ 1 file changed, 7 insertions(+)

added component::applications/tor browser in Legacy / Trac owner::tbb-team in Legacy / Trac parent::18097 in Legacy / Trac priority::medium in Legacy / Trac severity::normal in Legacy / Trac status::new in Legacy / Trac tbb-fingerprinting-fonts in Legacy / Trac type::defect in Legacy / Trac labels

I guess we can't remove that part of fonts.conf, though, until all distros we support have updated to a more recent fontconfig?

Trac:
Cc: N/A to dcf

Here is the upstream commit (2015-06-17): https://cgit.freedesktop.org/fontconfig/commit/?id=46b2c62faa64250eec3981ee816e91a9a3dee857

But before that (2015-02-17), they had removed <blank></blank> from the default fonts.conf and made the blanks be hardcoded in the library: https://cgit.freedesktop.org/fontconfig/commit/?id=d6a5cc665a1d7e91332944353e92c83ad114368c https://bugs.freedesktop.org/show_bug.cgi?id=79956

I am sure that when I set up fonts.conf for Tor Browser initially, I cargo-culted most of the config from somewhere, including the <blank> section. I don't really know what it does.

According to fonts.dtd, the <blank> section is optional, so I would guess that we can remove it without causing crashes on old versions of fontconfig.

But we may have to deal with this as a new fingerprinting vector (whether we remove the <blank> or not). If we are using the system fontconfig, and the system fontconfig has a built-in set of blanks that varies across systems (it looks like they update it with new Unicode versions), and it's possible for a web page to detect the difference, then it could be used for fingerprinting.

The set of built-in blanks isn't even under version control, because they have a makefile that fetches a list from unicode.org at build time :( So it's likely to be whatever randomly happened to be there when someone built a release.

To test, we could repurpose the fontfp code and replace the list of code points with the unicode.org list. !https://repo.eecs.berkeley.edu/git-anon/users/fifield/fontfp.git

Trac:
Keywords: N/A deleted, tbb-fingerprinting added

@pierov another reason perhaps to build/bundle our own font config

Interesting. Seems to be worth investigating further.

Trac:
Keywords: tbb-fingerprinting deleted, tbb-fingerprinting-fonts added
Severity: Minor to Normal

Trac:
Parent: N/A to legacy/trac#18097 (moved)

Nowadays we have systems where we get line 85: unknown element "blank" messages. Resolved legacy/trac#28198 (moved) as a duplicate.

Trac:
Cc: dcf to dcf, traumschule

mentioned in issue legacy/trac#28198 (moved)

moved from legacy/trac#22787 (moved)

added Bug label and removed 1 deleted label

added Fingerprinting label and removed 1 deleted label

Too many warning messages in journalctl due to the same issue, This is an e.g:

+ echo 'May 30 12:19:37 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 12:19:38 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 12:19:38 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 12:19:39 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 12:19:39 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 12:19:39 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 12:19:57 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 12:25:35 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:08:30 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:08:30 host qubes.StartApp+janondisttorbrowser-dom0[5637]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:09:30 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:09:30 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:09:30 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:09:31 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:09:32 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:09:32 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:09:36 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:11:32 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:11:36 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:14:14 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:14:18 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:14:20 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:14:26 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:15:47 host qubes.StartApp+janondisttorbrowser-dom0[7098]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:47:48 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:47:48 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:47:49 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:47:50 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:47:50 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:47:50 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:47:52 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:49:00 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br
+ IFS=
+ read -r line
+ echo 'May 30 20:49:27 host qubes.StartApp+janondisttorbrowser-dom0[8073]: Fontconfig warning: "/home/user/.tb/tor-browser/Browser/TorBrowser/Data/fontconfig/fonts.conf", line 85: unknown element "blank"<br />'
+ tee -a /tmp/tmp.Z9hSQqbni1/journalctl_warn.txt_br

added Fonts label

added Icebox label

removed Icebox label

added Backlog label

changed milestone to %Sponsor 131 - Phase 3 - Major ESR 102 Migration

closed

moved to tor-browser-build#40576 (closed)