xfs(1)xfs(1)NAMExfs - X font server
SYNOPSISxfs [ -config configuration_file ] [ -daemon ] [ -droppriv ] [ -inetd ]
[ -ls listen_socket ] [ -nodaemon ] [ -port tcp_port ] [ -user username
]
DESCRIPTIONxfs is the X Window System font server. It supplies fonts to X Window
System display servers. The server is usually run by a system adminis‐
trator, and started via init(8) or inetd(8). Users may also wish to
start private font servers for specific sets of fonts.
To connect to a font server, see the documentation for your X server;
it likely supports the syntax documented in the “FONT SERVER NAMES”
section of X(7).
OPTIONS-config configuration_file
specifies the configuration file xfs will use. If this parame‐
ter is not specified, xfs will read its configuration from the
default file, /etc/X11/fs/config.
-daemon
instructs xfs to fork and go into the background automatically
at startup. If this option is not specified, xfs will run as a
regular process (unless it was built to daemonize by default).
When running as a daemon, xfs will attempt to create a file in
which it stores its process ID, and will delete that file upon
exit;
-droppriv
instructs xfs to attempt to run as user and group xfs (unless
the -user option is used). This has been implemented for secu‐
rity reasons, as xfs may have undiscovered buffer overflows or
other paths for possible exploit, both local and remote. When
using this option, you may also wish to specify ‘no-listen =
tcp’ in the config file, which ensures that xfs will not to use
a TCP port at all. By default, xfs runs with the user and group
IDs of the user who invoked it.
-inetd informs xfs that it is being started by inetd, and that a lis‐
tening socket on the appropriate port is being passed as stan‐
dard input. Assumes that inetd is configured to "wait" mode,
and will thus allow xfs to handle listening for and accepting
further connections on this port. This allows xfs to be
started on demand when the first font client connects. When
using this option, the -daemon and -port flags are ignored.
-ls listen_socket
specifies a file descriptor which is already set up to be used
as the listen socket. This option is only intended to be used
by the font server itself when automatically spawning another
copy of itself to handle additional connections.
-nodaemon
instructs xfs not to daemonize (fork and detach from its con‐
trolling terminal). This option only has an effect if xfs is
built to daemonize by default, which is not the stock configura‐
tion.
-port tcp_port
specifies the TCP port number on which the server will listen
for connections. The default port number is 7100. This option
is ignored if xfs is configured to not listen to TCP transports
at all (see “Configuration File Format” below).
-user username
instructs xfs to run as the user username. See -droppriv for
why this may be desired. By default, xfs runs with the user and
group IDs of the user who invoked it.
INPUT FILESxfs reads and serves any font file format recognized by the X server
itself. It locates font files through the specification of a cata‐
logue, which is declared in xfs's configuration file.
Configuration File Format
xfs reads its configuration from a text file (see the -config option in
the “OPTIONS” section above). The configuration language is a list of
keyword and value pairs. Each keyword is followed by an equals sign
(‘=’) and then the desired value.
Recognized keywords include:
alternate-servers (list of strings)
lists alternate servers for this font server. See the “FONT
SERVER NAMES” section of X(7) for the syntax of the string.
catalogue (list of strings)
declares as ordered list of font path element names from which
fonts will be served. The current implementation only supports
a single catalogue ("all") containing all of the specified
fonts. A special directory with symlinks to font paths can be
specified using a catalogue:<dir> entry. See the CATALOGUE DIR
section below for details.
client-limit (cardinal)
determines the number of clients this font server will support
before refusing service. This is useful for tuning the load on
each individual font server.
clone-self (boolean)
indicates whether this font server should attempt to clone
itself when the number of connected clients reaches the
client-limit.
default-point-size (cardinal)
The default pointsize (in decipoints) for font requests that
don't specify a point size. The default is 120.
default-resolutions (list of resolutions)
indicates the resolutions the server supports by default. This
information may be used as a hint for pre-rendering, and substi‐
tuted into requests for scaled fonts which do not specify a res‐
olution. A resolution is a comma-separated pair of horizontal
and vertical resolutions in pixels per inch. Multiple resolu‐
tions are separated by commas.
deferglyphs (string)
sets the mode for delayed fetching and caching of glyphs.
string should be one of ‘none’, meaning glyphs deferment is dis‐
abled, ‘all’, meaning it is enabled for all fonts, and ‘16’,
meaning it is enabled only for 16-bit fonts.
error-file (string)
indicates the filename of the error file. All warnings and
errors will be logged here, unless use-syslog is set to a true
value (see below).
no-listen (trans-type)
disables the specified transport type. For example, TCP/IP con‐
nections can be disabled with ‘no-listen = tcp’.
port (cardinal)
indicates the TCP port on which the server will listen for con‐
nections.
use-syslog (boolean)
determines whether errors and diagnostics should be reported via
syslog(3) (on supported systems) instead of being written to the
error-file (see above).
CATALOGUE DIR
You can specify a special kind of font path in the form cata‐
logue:<dir>. The directory specified after the catalogue: prefix will
be scanned for symlinks and each symlink destination will be added as a
local fontfile FPE.
The symlink can be suffixed by attributes such as 'unscaled', which
will be passed through to the underlying fontfile FPE. The only excep‐
tion is the newly introduced 'pri' attribute, which will be used for
ordering the font paths specified by the symlinks.
An example configuration:
75dpi:unscaled:pri=20 -> /usr/share/X11/fonts/75dpi
ghostscript:pri=60 -> /usr/share/fonts/default/ghostscript
misc:unscaled:pri=10 -> /usr/share/X11/fonts/misc
type1:pri=40 -> /usr/share/X11/fonts/Type1
type1:pri=50 -> /usr/share/fonts/default/Type1
This will add /usr/share/X11/fonts/misc as the first FPE with the
attribute the attribute unscaled etc. This is functionally equivalent
to setting the following font path:
/usr/share/X11/fonts/misc:unscaled,
/usr/share/X11/fonts/75dpi:unscaled,
/usr/share/X11/fonts/Type1,
/usr/share/fonts/default/Type1,
/usr/share/fonts/default/ghostscript
Example Configuration File
#
# sample font server configuration file
#
# allow a max of 10 clients to connect to this font server.
client-limit = 10
# When a font server reaches the above limit, start up a new one.
clone-self = on
# Identify alternate font servers for clients to use.
alternate-servers = hansen:7101,hansen:7102
# Look for fonts in the following directories. The first is a set of
# TrueType outlines, the second is a set of misc bitmaps (such as terminal
# and cursor fonts), and the last is a set of 100dpi bitmaps.
#
catalogue = /usr/share/X11/fonts/TTF,
/usr/share/X11/fonts/misc,
/usr/share/X11/fonts/100dpi/
# in 12 points, decipoints
default-point-size = 120
# 100 x 100 and 75 x 75
default-resolutions = 100,100,75,75
# Specify our log filename.
error-file = /var/log/xfs.log
# Direct diagnostics to our own log file instead of using syslog.
use-syslog = off
OUTPUT FILES
When operating in daemon mode, xfs sends diagnostic messages (errors
and warnings) to the log file specified by the error-file configuration
variable by default. However, these messages can be sent to an alter‐
nate location via the error-file and use-syslog configuration vari‐
ables; see “Configuration File Format”, above.
ASYNCHRONOUS EVENTSxfs handles the following signals specially:
SIGTERM
causes the font server to exit cleanly.
SIGUSR1
causes xfs to re-read its configuration file.
SIGUSR2
causes xfs to flush any cached data it may have.
SIGHUP causes xfs to reset, closing all active connections and re-read‐
ing the configuration file.
BUGS
Multiple catalogues should be supported.
FUTURE DIRECTIONS
Significant further development of xfs is unlikely. One of the origi‐
nal motivations behind it was the single-threaded nature of the X
server — a user's X session could seem to ‘freeze up’ while the X
server took a moment to rasterize a font. This problem with the X
server, which remains single-threaded in all popular implementations to
this day, has been mitigated on two fronts: machines have gotten much
faster, and client-side font rendering (particularly via the Xft
library) is the norm in contemporary software.
AUTHORS
Dave Lemke, Network Computing Devices, Inc
Keith Packard, Massachusetts Institute of Technology
SEE ALSOX(7), xfsinfo(1), fslsfonts(1), init(8), inetd(8), syslog(3), The X
Font Service Protocol, Font Server Implementation Overview
X Version 11xfs 1.1.1 xfs(1)
