This reverts commit 1c55f18717.
Ingo Brueckl was assuming that reverting to 1:1 mapping for chars >= 128
was not useful, but it happens to be: due to the limitations of the
Linux console, when a blind user wants to read BIG5 on it, he has no
other way than loading a font without SFM and let the 1:1 mapping permit
the screen reader to get the BIG5 encoding.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During bootup performance tracing I noticed many occurrences of
vca* device creation and removal, leading to the usual userspace
uevent processing, which are, in this case, rather pointless.
A simple test showing the kernel timing (not including all the
work userspace has to do), gives us these numbers:
$ time for i in `seq 1000`; do echo a > /dev/tty2; done
real 0m1.142s
user 0m0.015s
sys 0m0.540s
If we move the hook for the vcs* driver core devices from the
tty "binding" to the vc allocation/deallocation, which is what
the vcs* devices represent, we get the following numbers:
$ time for i in `seq 1000`; do echo a > /dev/tty2; done
real 0m0.152s
user 0m0.030s
sys 0m0.072s
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Building an allnoconfig kernel, sparse asked whether these could be
static, so I checked, and they are only used in the file where they are
declared.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have special case logic for resizing pty/tty pairs. We also have a per
driver resize method so for the pty case we should use it.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes the loss of echoed (and other ldisc-generated characters) when
the tty is stopped or when the driver output buffer is full (happens
frequently for input during continuous program output, such as ^C)
and removes the Big Kernel Lock from the N_TTY line discipline.
Adds an "echo buffer" to the N_TTY line discipline that handles all
ldisc-generated output (including echoed characters). Along with the
loss of characters, this also fixes the associated loss of sync between
tty output and the ldisc state when characters cannot be immediately
written to the tty driver.
The echo buffer stores (in addition to characters) state operations that need
to be done at the time of character output (like management of the column
position). This allows echo to cooperate correctly with program output,
since the ldisc state remains consistent with actual characters written.
Since the echo buffer code now isolates the tty column state code
to the process_out* and process_echoes functions, we can remove the
Big Kernel Lock (BKL) and replace it with mutex locks.
Highlights are:
* Handles echo (and other ldisc output) when tty driver buffer is full
- continuous program output can block echo
* Saves echo when tty is in stopped state (e.g. ^S)
- (e.g.: ^Q will correctly cause held characters to be released for output)
* Control character pairs (e.g. "^C") are treated atomically and not
split up by interleaved program output
* Line discipline state is kept consistent with characters sent to
the tty driver
* Remove the big kernel lock (BKL) from N_TTY line discipline
Signed-off-by: Joe Peterson <joe@skyrush.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For the console, there is a 1:1 mapping of glyphs which cannot be found
in the current font. This seems to be meant as a kind of 'emergency
fallback' for fonts without unicode mapping which otherwise would
display nothing readable on the screen.
At the moment it affects all chars for which no substitution character
is defined. In particular this means that for all chars (>= 128) where
there is no iso88591-1/unicode character (e.g. control character area)
you'll get the very strange 1:1 mapping of the (cp437) graphics card
glyphs.
I'm pretty sure that the 1:1 mapping should only affect strict ASCII
code characters, i.e. chars < 128.
The patch limits the mapping as it probably was meant anyway.
Signed-off-by: Ingo Brueckl <ib@wupperonline.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Egmont Koblinger <egmont@uhulinux.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Problem 1 (see patch below):
vc_tab_stop is declared as an array of 8 unsigned ints in struct
vc_data in include/linux/console_struct.h .
In drivers/char/vt.c only 5 of these 8 unsigned ints get initialized
leading to unintended tabulator placement on displays with more than
160 columns text.
Problem 2 (open):
Upcoming displays will have more than 256 columns of text leading to
invalid memory access in drivers/char/vt.c during tabulator
calculations:
if (vc->vc_tab_stop[vc->vc_x >> 5] & (1 << (vc->vc_x & 31)))
break;
Signed-off-by: Wolfgang Kroworsch <wolfgang@kroworsch.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
People can use the real name an an index into MAINTAINERS to find the
current email address.
Signed-off-by: Francois Cami <francois.cami@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit c9e587abfd, and the
subsequent commits that fixed it up:
- afa9b649 "fbcon: prevent cursor disappearance after switching to 512
character font"
- d850a2fa "vt/fbcon: fix background color on line feed"
- 7fe3915a "vt/fbcon: update scrl_erase_char after 256/512-glyph font
switch"
by request of Alan Cox. Quoth Alan:
"Unfortunately it's wrong and its been causing breakages because
various apps like ncurses expect our previous (and correct)
behaviour."
Alexander sent out a similar patch.
Requested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Tested-by: Jan Engelhardt <jengelh@medozas.de>
Cc: Alexander V. Lukyanov <lav@netis.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Carry on pushing code out of tty_io when it belongs to other drivers. I'm
not 100% happy with some of this and it will be worth revisiting some of the
exports later when the restructuring work is done.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Right now there are various drivers that try to use tty->count to know when
they get the final close. Aristeau Rozanski showed while debugging the vt
sysfs race that this isn't entirely safe.
Instead of driver side tricks to work around this introduce a shutdown which
is called when the tty is being destructed. This also means that the shutdown
method is tied into the refcounting.
Use this to rework the console close/sysfs logic.
Remove lots of special case code from the tty core code. The pty code can now
have a shutdown() method that replaces the special case hackery in the tree
free up paths.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For hysterical raisins the vt layer drops and retakes locks in the write
method. This is a left over from the days when user/kernel data was passed
directly to the tty not pre-buffered.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Right now we have ifdefs and hooks in the core ioctl handler for TIOCLINUX
and then test if its a console. This is brain dead. Instead call the
tioclinux helper from the relevant driver ioctl methods.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This moves it to being a tty operation. That removes special cases and now
also means that resize can be picked up by um and other non vt consoles
which may have a resize operation.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2.6.26 corrected the mutex locking on tty resizing to fix the case where
you could get the tty/vt sizing out of sync. That turns out to have a
deadlock.
The actual fix is really major and I've got it lined up as part of the ops
changes for 2.6.28 so for 2.6.26/2.6.27 it is safer to reintroduce this
ages old minor bug.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vt.c DO_UPDATE macro checks if the console is visible but doesn't check if
the console is blanked.
In fact updating fbcon while the console is blanked is not only
unnecessary but can even cause screen corruption.
Therefore I am adding a simple check on console_blanked in DO_UPDATE.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Hold console sem while creating/destroying sysfs files. Serialisation is
so far done by BKL held in tty release_dev and chrdev_open, but no other
locks are held in open path.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Aristeu Rozanski <aris@ruivo.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
device_create() is race-prone, so use the race-free
device_create_drvdata() instead as device_create() is going away.
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Original report: """I used to force my console to black-on-white by the
command `setterm -inversescreen on`. In 2.6.26-rc4, I get lots of black
background characters."""
Another addendum to commit c9e587ab. This was previously missed out since
I was not aware of what vc_decscnm was for.
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Reported-by: <thunder7@xs4all.nl>
Tested-by: <thunder7@xs4all.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
By turning off the new CONSOLE_TRANSLATIONS option and dropping the
associated code and tables from the kernel, we can save about 7KiB.
Taken from linux-tiny project by Tim Bird and mangled further by dwmw2.
Signed-off-by: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
For e.g. proper TTY canonical support, IUTF8 termios flag has to be set as
appropriate. Linux used to not care about setting that flag for VT TTYs.
This patch fixes that by activating it according to the current mode of the
VT, and sets the default value according to the vt.default_utf8 parameter.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adds a minimalistic braille screen reader support. This is meant to
be used by blind people e.g. on boot failures or when / cannot be mounted
etc and thus the userland screen readers can not work.
[akpm@linux-foundation.org: fix exports]
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Jiri Kosina <jikos@jikos.cz>
Cc: Dmitry Torokhov <dtor@mail.ru>
Acked-by: Alan Cox <alan@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Historically tty->pgrp and friends were pid_t and the code "knew" they were
safe. The change to pid structs opened up a few races and the removal of the
BKL in places made them quite hittable. We put tty->pgrp under the ctrl_lock
for the tty.
Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Push the BKL down into the line disciplines
- Switch the tty layer to unlocked_ioctl
- Introduce a new ctrl_lock spin lock for the control bits
- Eliminate much of the lock_kernel use in n_tty
- Prepare to (but don't yet) call the drivers with the lock dropped
on the paths that historically held the lock
BKL now primarily protects open/close/ldisc change in the tty layer
[jirislaby@gmail.com: a couple of fixes]
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A command that causes a line feed while a background color is active,
such as
perl -e 'print "x" x 60, "\e[44m", "x" x 40, "\e[0m\n"'
and
perl -e 'print "x" x 40, "\e[44m\n", "x" x 40, "\e[0m\n"'
causes the line that was started as a result of the line feed to be completely
filled with the currently active background color instead of the default
color.
When scrolling, part of the current screen is memcpy'd/memmove'd to the new
region, and the new line(s) that will appear as a result are cleared using
memset. However, the lines are cleared with vc->vc_video_erase_char, causing
them to be colored with the currently active background color. This is
different from X11 terminal emulators which always paint the new lines with
the default background color (e.g. `xterm -bg black`).
The clear operation (\e[1J and \e[2J) also use vc_video_erase_char, so a new
vc->vc_scrl_erase_char is introduced with contains the erase character used
for scrolling, which is built from vc->vc_def_color instead of vc->vc_color.
Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some accessibility modules need to be able to catch the output on the
console before the VT interpretation, and possibly swallow it.
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
VT notifier callbacks need to be aware of console switches. This is already
partially done from console_callback(), but at that time fg_console, cursor
positions, etc. are not yet updated and hence screen readers fetch the old
values.
This adds an update notify after all of the values are updated in
redraw_screen(vc, 1).
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vt is missing a memory barrier to close the critical section. Use a real
spinlock for this.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some external modules like Speakup need to monitor console output.
This adds a VT notifier that such modules can use to get console output events:
allocation, deallocation, writes, other updates (cursor position, switch, etc.)
[akpm@linux-foundation.org: fix headers_check]
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since default_utf8 is already a sysfs attribute, having an extra
CONFIG_VT_UNICODE compile-time option is redundant, since sysfs attributes can
be set at boot and run time.
Also let Linux VCs default to UTF-8 (as per the discussion at
http://lkml.org/lkml/2007/9/6/99).
Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Cc: Bill Nottingham <notting@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As of now, the kernel defaults to non-unicode and XLATE for the keyboard.
We've been changing this in Fedora, but that requires patching the defaults
in the kernel.
The attached introduces CONFIG_VT_UNICODE, which sets the console in
unicode mode by default on boot, including both the virtual terminal and
the keyboard driver.
Signed-off-by: Bill Nottingham <notting@redhat.com>
Cc: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Various console drivers are able to resize the screen via the con_resize()
hook. This hook is also visible in userspace via the TIOCWINSZ, VT_RESIZE and
VT_RESIZEX ioctl's. One particular utility, SVGATextMode, expects that
con_resize() of the VGA console will always return success even if the
resulting screen is not compatible with the hardware. However, this
particular behavior of the VGA console, as reported in Kernel Bugzilla Bug
7513, can cause undefined behavior if the user starts with a console size
larger than 80x25.
To work around this problem, add an extra parameter to con_resize(). This
parameter is ignored by drivers except for vgacon. If this parameter is
non-zero, then the resize request came from a VT_RESIZE or VT_RESIZEX ioctl
and vgacon will always return success. If this parameter is zero, vgacon will
return -EINVAL if the requested size is not compatible with the hardware. The
latter is the more correct behavior.
With this change, SVGATextMode should still work correctly while in-kernel and
stty resize calls can expect correct behavior from vgacon.
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
VGA console driver can misunderstand the current mode(Text/Graphic) under
"disable console blanking" setting. When "disable console blank" is set
(blankinterval=0), "do_unblank_screen()" function returns without changing
"blank_state", and when "blank_state" is "blank_off", "do_blank_screen()
function returns without invoking sw->con_blank() function. That's why VGA
console driver can misunderstand the current mode.
Signed-off-by: Nobuhiro Tachino <ntachino@redhat.com>
Signed-off-by: Taku Izumi <izumi2005@soft.fujitsu.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: "Luck, Tony" <tony.luck@intel.com>
Acked-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow fbcon to select the primary display adapter using the
fb_is_primary_device() arch-specific helper. If a a primary adapter is
detected, fbcon will unbind the old adapter from the VT layer, then rebind
using the new adapter. This requires that bind_/unbind_con_driver() be made
public.
Because this feature may produce unexpected behavior (from the user's POV),
this must be explicitly enabled in Kconfig.
[akpm@linux-foundation.org: export unbind_con_driver]
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently my console UTF-8 patch went mainline. Here is an additional patch
that fixes two nasty issues and improves a third one, namely:
1. My patch changed the behavior if a glyph is not found in the Unicode
mapping table. Previously for Unicode values less than 256 or 512 the
kernel tried to display the glyph from that position of the glyph table,
which could lead to a different accented letter being displayed. I
removed this fallback possibility and changed it to display the
replacement symbol.
As Behdad pointed out, some fonts (e.g. sun12x22 from the kbd package)
lack Unicode mapping information, hence all you get is lots of question
marks. Though theoretically it's actually a user-space bug (the font
should be fixed), Behdad and I both believe that it'd be good to work
around in the kernel by re-introducing the fallback solution for ASCII
characters only. This sounds a quite reasonable decision, since all fonts
ship the ASCII characters in the first 128 positions. This way users
won't be surprised by lots of question marks just because s/he issued a
not-so-perfectly parameterized setfont command. As this fallback is only
re-introduced for code points below 128, you still won't see an accented
letter replaced by another, but at least you'll always get the English
letters right.
2. My patch introduced "question mark with inverted color attributes" as a
last resort fallback glyph. Though it perfectly works on VGA console, on
framebuffer you may end up with question marks that are highlighed but
shouldn't be, and normal characters that are accidentally highlighed.
This is caused by missing FLUSHes when changing the color attribute.
3. I've updated the table of double-width character based on Markus's
updated version. Only ten new code poings (one interval) is added.
Signed-off-by: Egmont Koblinger <egmont@uhulinux.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The virtual console driver uses a semaphore as mutex. Use the mutex API
instead of the (binary) semaphore.
Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Create a variable, default_utf8, that defines the system-wide default UTF-8
setting. This variable can be altered via sysfs. If the variable is properly
set, this should mimimize breakage of UTF-8 encoded consoles when doing a
reset or echo -e '\033c' and of newly opened/allocated consoles.
This is based from patches by Jan Engelhardt and Paul LeoNerd Evans.
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: Paul LeoNerd Evans <leonerd@leonerd.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add color support to the "underline" and "italic" attributes as in
OpenBSD/NetBSD-style (vt220) and xterm.
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Acked-by: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Allow for the palette to be exposed and changed via sysfs. A call to
/usr/bin/reset will slurp the new definitions in for the current console.
Already posted at http://lkml.org/lkml/2006/1/15/149
Signed-off-by: Jan Engelhardt <jengelh@gmx.de>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The UTF-8 part of the vt driver suffers from the following issues which are
addressed in my patch:
1) If there's no glyph found for a particular valid UTF-8 character, we try
to display U+FFFD. However if this one is not found either, here's what
the current kernel does:
- First, if the Unicode value is less than the number of glyphs, use the
glyph directly from that position of the glyph table. While it may be a
good idea in the 8-bit world, it has absolutely no sense with Unicode
in mind. For example, if a Latin-2 font is loaded and an application
prints U+00FB ("u with circumflex", not present in Latin-2) then as a
fallback solution the glyph from the 0xFB position of the Latin-2
fontset (which is an "u with double accent" - a different character) is
displayed.
- Second, if this fallback fails too, a simple ASCII question mark is
printed, which is visually undistinguishable from a real question mark.
I changed the code to skip the first step (except if in non-UTF-8 mode),
and changed the second step to print the question mark with inverse color
attributes, so it is visually clear that it's not a real question mark,
and resembles more to the common glyph of U+FFFD.
2) The UTF-8 decoder is buggy in many ways:
- Lone continuation bytes (section 3.1 of Markus Kuhn's UTF-8 stress
test) are not caught, they are displayed as some "random" (taken
directly form the font table, see above) glyphs instead the replacement
character.
- Incomplete sequences (sections 3.2 and 3.3 of the stress test) emit no
replacement character, but rather cause the subsequent valid character
to be displayed more times(!).
- The decoder is not safe: overlong sequences are not caught currently,
they are displayed as if these were valid representations. This may
even have security impacts.
- The decoder does not handle D800..DFFF and FFFE..FFFF specially, it
just emits these code points and lets it be looked up in the glyph
table. Since these are invalid code points, I replace them by U+FFFD
and hence give no chance for them to be looked up in the glyph table.
(Assuming no font ships glyphs for these code points, this change is
not visible to the users since the glyph shown will be the same.)
With my fixes to the decoder it now behaves exactly as Markus Kuhn's
stress test recommends.
3) It has no concept of double-width (CJK) characters. It's way beyond the
scope of my patch to try to display them, but at least I think it's
important for the cursor to jump two positions when printing such
characters, since this is what applications (such as text editors)
expect. Currently the cursor only jumps one position, and hence
applications suffer from displaying and refreshing problems, and editing
some English letters that are preceded by some CJK characters in the same
line is a nightmare. With my patch an additional space is inserted after
the CJK character has been printed (which usually means a replacement
symbol of course). (If U+FFFD isn't availble and hence an inverse
question mark is displayed in the first cell, I keep the inverted state
for the space in the 2nd column so it's quite easy to see that they are
tied together.)
4) There is a small built-in table of zero-width spaces that are not to be
printed but silently skipped. U+200A is included there, but it's not a
zero-width character, so I remove it from there.
Signed-off-by: Egmont Koblinger <egmont@uhulinux.hu>
Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When the console is in VT_AUTO+KD_GRAPHICS mode, switching to the
SUSPEND_CONSOLE fails, resulting in vt_waitactive() waiting indefinitely or
until the task is interrupted. This patch tests if a console switch can
occur in set_console() and returns early if a console switch is not
possible.
[akpm@linux-foundation.org: cleanup]
Signed-off-by: Andrew Johnson <ajohnson@intrinsyc.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Somewhere in the rewrite of the work queues my cleanup of SAK handling
got broken. Maybe I didn't retest it properly or possibly the API
was changing so fast I missed something. Regardless currently
triggering a SAK now generates an ugly BUG_ON and kills the kernel.
Thanks to Alexey Dobriyan <adobriyan@openvz.org> for spotting this.
This modifies the use of SAK_work to initialize it when the data
structure it resides in is initialized, and to simply call
schedule_work when we need to generate a SAK. I update both
data structures that have a SAK_work member for consistency.
All of the old PREPARE_WORK calls that are now gone.
If we call schedule_work again before it has processed it
has generated the first SAK it will simply ignore the duplicate
schedule_work request.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Of kernel subsystems that work with pids the tty layer is probably the largest
consumer. But it has the nice virtue that the assiation with a session only
lasts until the session leader exits. Which means that no reference counting
is required. So using struct pid winds up being a simple optimization to
avoid hash table lookups.
In the long term the use of pid_nr also ensures that when we have multiple pid
spaces mixed everything will work correctly.
Signed-off-by: Eric W. Biederman <eric@maxwell.lnxi.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
