Your message dated Mon, 11 Jul 2011 01:43:15 +0800
with message-id <[email protected]>
and subject line Re: Bug #261783: doesn't fall back when default fonts are
unreadable
has caused the Debian Bug report #261783,
regarding doesn't fall back when default fonts are unreadable
to be marked as done.
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Bug report if necessary, and/or fix the problem forthwith.
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--
261783: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=261783
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: gdm
Version: 2.6.0.3-1
Severity: grave
Justification: renders package unusable
Summary: GDMGreeter does not gracefully handle the condition whereby it is
trying to open a font file, but
the font file is not readable.
I have put a number of symlinks in /usr/share/fonts/truetype/commercial/,
pointing to TrueType font files
stored in a different filesystem, namely in '/dosc/winnt/Fonts'. This may or
may not be a good idea; for
the purposes of this bugreport it does not matter.
When the /dosc vfat filesystem containing the fonts is mounted with options
that enable all users to read
the font files contained therein (eg umask=0000), gdmgreeter can also read the
fonts and everything works
as expected.
When the filesystem is mounted with options that deny whichever user
'gdmgreeter' runs as access to the
font files, gdmgreeter does the following (from 'strace -f gdm --nodaemon >log
2>&1):
[pid 4003] open("/usr/share/fonts/truetype/commercial/verdana.ttf", O_RDONLY)
= -1 EACCES (Permission
denied)
[pid 4003] getpid() = 4003
[pid 4003] open("/usr/lib/charset.alias", O_RDONLY|O_LARGEFILE) = -1 ENOENT
(No such file or directory)
[pid 4003] write(2, "\n** (gdmgreeter:4003): WARNING *"..., 77) = 77
[pid 4003] open("/usr/share/fonts/truetype/commercial/verdana.ttf", O_RDONLY)
= -1 EACCES (Permission
denied)
[pid 4003] getpid() = 4003
[pid 4003] write(2, "\n** (gdmgreeter:4003): WARNING *"..., 76) = 76
[pid 4003] exit_group(1) = ?
As you can see, gdmgreeter is treating failure to access one of a great many
font files as a fatal error
and is exiting immediately with an error code.
This in turn causes gdm to exit with an error code, which causes the X session
to end, which leads to an
infinite loop of restarting X sessions and an unusable system. Thus, a small
problem regarding one of many
font files becomes a larger problem (no X) which in turn becomes a very serious
problem (entire system
unusable).
I suggest that gdmgreeter should degrade gracefully when font file(s) are
absent, unreadable, or otherwise
unusable, instead of exiting. One way of gracefully handling such conditions
would be to fall back to
another font.
Also, why does gdmgreeter try to open(2) the same font file twice? If open(2)
failed first time with
errno==EACCES, then it will also fail second time - there are no intervening
chmod calls. I could
understand this behaviour if errno==EGAIN or something similar, but it doesn't,
so this seems like a
pointless waste of CPU cycles. But I don't find this important enough to
justify a seperate bug report.
Also, why does 'gdmgreeter' print 'WARNING', when it is about to exit with
status 1? Isn't this behaviour
the very definition of a fatal error, as opposed to merely a warning?
Another problem is that the error messages printed by gdmgreeter (writes to fd
2 in strace output above) go
nowhere - at this point, fd 2 is opened to /dev/null. This makes it very hard
to diagnose problems in
gdmgreeter. The information in syslog from gdm is not sufficient to diagnose
faults in sub-processes such
as gdmgreeter. I think this deserves a seperate bug report.
Cheers,
--m@
-- System Information:
Debian Release: testing/unstable
APT prefers unstable
APT policy: (500, 'unstable')
Architecture: i386 (i686)
Kernel: Linux 2.6.7
Locale: LANG=C, LC_CTYPE=C
Versions of packages gdm depends on:
hi adduser 3.49 Add and remove users and groups
ii debconf 1.4.29 Debian configuration management sy
ii dpkg 1.10.15 Package maintenance system for Deb
ii gksu 1.2.0-2 graphical frontend to su
ii gnome-session 2.4.2-2 The GNOME 2 Session Manager
ii gnome-terminal [x-terminal- 2.2.2-4 The GNOME 2 terminal emulator appl
ii libart-2.0-2 2.3.16-5 Library of functions for 2D graphi
ii libatk1.0-0 1.6.1-2 The ATK accessibility toolkit
ii libattr1 2.4.15-1 Extended attribute shared library
ii libbonobo2-0 2.6.2-4 Bonobo CORBA interfaces library
ii libbonoboui2-0 2.6.1-1 The Bonobo UI library
ii libc6 2.3.2.ds1-11 GNU C Library: Shared libraries an
ii libgconf2-4 2.6.2-1 GNOME configuration database syste
ii libglade2-0 1:2.4.0-1 Library to load .glade files at ru
ii libglib2.0-0 2.4.2-1 The GLib library of C routines
ii libgnome2-0 2.6.1-6 The GNOME 2 library - runtime file
ii libgnomecanvas2-0 2.6.1.1-2 A powerful object-oriented display
ii libgnomeui-0 2.6.1.1-3 The GNOME 2 libraries (User Interf
ii libgnomevfs2-0 2.6.1.1-3 The GNOME virtual file-system libr
ii libgtk2.0-0 2.4.3-1 The GTK+ graphical user interface
ii libice6 4.3.0-7 Inter-Client Exchange library
ii liborbit2 1:2.10.2-1.1 libraries for ORBit2 - a CORBA ORB
hi libpam-modules 0.76-7 Pluggable Authentication Modules f
ii libpam-runtime 0.76-15 Runtime support for the PAM librar
hi libpam0g 0.76-7 Pluggable Authentication Modules l
ii libpango1.0-0 1.4.0-4 Layout and rendering of internatio
hi libpopt0 1.7-2 lib for parsing cmdline parameters
ii librsvg2-2 2.7.2-3 SAX-based renderer library for SVG
ii libselinux1 1.14-2 SELinux shared libraries
ii libsm6 4.3.0-7 X Window System Session Management
ii libwrap0 7.6-ipv6.1-3 Wietse Venema's TCP wrappers libra
ii libx11-6 4.3.0-7 X Window System protocol client li
ii libxext6 4.3.0-7 X Window System miscellaneous exte
ii libxml2 2.6.10-3 GNOME XML library
ii metacity [x-window-manager] 1:2.4.55-2 A lightweight GTK2 based Window Ma
ii xbase-clients 4.3.0-7 miscellaneous X clients
ii xlibs 4.3.0-7 X Window System client libraries m
ii xterm [x-terminal-emulator] 4.2.1-3 X terminal emulator
hi zlib1g 1:1.2.1-4 compression library - runtime
-- debconf information:
gdm/daemon_name: /usr/bin/gdm
shared/default-x-display-manager: gdm
--- End Message ---
--- Begin Message ---
Version: 2.6.0-1
Fontconfig does fall back when default fonts are unreadable at least
since 2.6.0 (not tested for versions even earlier), so closing this bug.
--
Regards,
Aron Xu
--- End Message ---
