Re: postinstall: fontconfig abnormal exit

[Ken Brown <kbrown@cornell.edu>]

On 7/20/2021 1:00 PM, Brian Inglis wrote:
 > On 2020-09-12 06:56, Ken Brown via Cygwin wrote:
> For fontconfig fc-cache-1 appears to have been creating thousands (on Cygwin 64 
> millions) of small <1KB 
> /var/cache/fontconfig/%8x-%4x-%4x-%4x-%12x-le{64,32d8}.cache-7 files.
> 
> The problems could have originally been caused by an old bug:
> 
> https://gitlab.freedesktop.org/fontconfig/fontconfig/-/issues/107
> 
> combined with many font additions around that time, mainly working on Cygwin 64, 
> where I use X, and manually run fontconfig postinstall script, to try to avoid 
> long setup postinstalls, whereas on Cygwin 32 I don't use X or manually run 
> postinstall scripts, just get run after setup.
> 
> I have about 200 Windows MS font files, 1000 non-MS font files, and about 800 
> Cygwin font files, from multiple distros and elsewhere, including some with full 
> BMP coverage, some with SMP coverage, some for fallback code points, others with 
> group ranges.
> 
> I rm'ed -rf /var/cache/fontconfig/ with a few thousand files on Cygwin 32 and 
> rebuilt it okay with only 65 cache files.
> 
> I tried rm -rf /var/cache/fontconfig/ on Cygwin 64 but got many permission 
> errors and killed it.

The preremove script for libfontconfig1 should remove all those cache files 
every time libfontconfig1 is updated, so you should have gotten a fresh start 
every once in a while.  Apparently something went wrong.

> I gave up waiting for ls -U to show any results on Cygwin 64 or Explorer on that 
> dir to show any file details, but cmd /c dir | less displays the base info for 
> hundreds of thousands of files, and wc reports millions.
> 
> I am still waiting for an elevated cmd to rmdir /s /q fontconfig there!
> 
> Do you know why fc-cache-1 is run rather than fc-cache and what the difference is?

They're identical.  It's just a packaging issue.  fc-cache is in the fontconfig 
package, and fc-cache-1 is in the libfontconfig1 package.  That way fc-cache-1 
is available for use in postinstall scripts for users who install libfontconfig1 
(probably because something requires it) but not fontconfig.

> What would give you useful information once I have the fontconfig cache cleared?
> Might running FC_DEBUG=65535 fc-cache-1 -fsv provide useful info?
> Or do so with strace?
> Would running file on the font files give enough info about properties to be of 
> any help?

I'm not an expert on fontconfig, so I probably can't help.

> What is the best approach to get the minimal cache files recreated?

I would expect that this would always happen as a result of running setup and 
letting the preremove/postinstall scripts do their job.  I don't know what went 
wrong in your case.

> What is the best approach to avoid thousand of cache files in future?

Again, I don't know why that happened in the first place.

Ken