Bug#909750: applications tries to write to /usr/* directories via libfontconfig1

[Laurent Bigonville]

On Fri, 9 Nov 2018 14:25:12 +0100 Jakub Wilk <jwilk at jwilk.net> wrote:
 > Control: found -1 2.13.1-2
 >
 > It's still reproducible for me:
 >
 > $ strace -o '| grep -w EACCES' /usr/lib/firefox-esr/firefox-bin
 > ...
 > openat(AT_FDCWD, 
"/usr/share/fonts/truetype/mononoki/.uuid.TMP-lrzetE", 
O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES 
(Permission denied)
 > openat(AT_FDCWD, "/usr/share/fonts/truetype/wine/.uuid.TMP-p6l2oU", 
O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES 
(Permission denied)
 > openat(AT_FDCWD, "/usr/share/fonts/woff/mononoki/.uuid.TMP-S9ygla", 
O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES 
(Permission denied)
 > openat(AT_FDCWD, 
"/usr/share/fonts/X11/encodings/large/.uuid.TMP-VcWBhq", 
O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES 
(Permission denied)
 > openat(AT_FDCWD, "/usr/lib/firefox-esr/fonts/.uuid.TMP-uG7neG", 
O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE|O_CLOEXEC, 0600) = -1 EACCES 
(Permission denied)
 > ...

 >

Do you have any .uuid files in these directories? Can you try to run 
"fc-cache -s -f -v" (as root) and see if it helps. What file system do 
you use for /usr/share/fonts/?

The only occurrence I'm seeing on my system is:

openat(AT_FDCWD, "/usr/lib/firefox/fonts/.uuid.TMP-EWjEq0", 
O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC, 0600) = -1 EACCES (Permission denied)

That one I can understand as firefox is not creating a cache for its 
private font.