From: Nicolas Pitre <nicolas.pitre@linaro.org>
To: Kees Cook <keescook@chromium.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Dave Mielke <Dave@mielke.cc>,
Samuel Thibault <samuel.thibault@ens-lyon.org>,
Adam Borowski <kilobyte@angband.pl>,
Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
LKML <linux-kernel@vger.kernel.org>,
linux-console@vger.kernel.org
Subject: Re: [PATCH v3 1/3] vt: preserve unicode values corresponding to screen characters
Date: Tue, 10 Jul 2018 23:39:39 -0400 [thread overview]
Message-ID: <79334C7E-6E76-4B5C-9A32-C6DA40D8E88E@linaro.org> (raw)
In-Reply-To: <CAGXu5j+KLvJ-n_QRrfq15E8iO_rqfpp+K7PDAZHZMHcemy9y7g@mail.gmail.com>
I am on vacation away from an actual keyboard until next week. Will look at it then.
> Le 10 juill. 2018 à 20:52, Kees Cook <keescook@chromium.org> a écrit :
>
>> On Tue, Jun 26, 2018 at 8:56 PM, Nicolas Pitre <nicolas.pitre@linaro.org> wrote:
>> The vt code translates UTF-8 strings into glyph index values and stores
>> those glyph values directly in the screen buffer. Because there can only
>> be at most 512 glyphs, it is impossible to represent most unicode
>> characters, in which case a default glyph (often '?') is displayed
>> instead. The original unicode value is then lost.
>>
>> This patch implements the basic screen buffer handling to preserve unicode
>> values alongside corresponding display glyphs. It is not activated by
>> default, meaning that people not relying on that functionality won't get
>> the implied overhead.
>>
>> Signed-off-by: Nicolas Pitre <nico@linaro.org>
>> Tested-by: Dave Mielke <Dave@mielke.cc>
>> Acked-by: Adam Borowski <kilobyte@angband.pl>
>> ---
>> drivers/tty/vt/vt.c | 220 +++++++++++++++++++++++++++++++--
>> include/linux/console_struct.h | 2 +
>> 2 files changed, 211 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
>> index 1eb1a376a0..7b636638b3 100644
>> --- a/drivers/tty/vt/vt.c
>> +++ b/drivers/tty/vt/vt.c
>> [...]
>> +static void vc_uniscr_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
>> + enum con_scroll dir, unsigned int nr)
>> +{
>> + struct uni_screen *uniscr = get_vc_uniscr(vc);
>> +
>> + if (uniscr) {
>> + unsigned int s, d, rescue, clear;
>> + char32_t *save[nr];
>
> Can you adjust this to avoid the VLA here? I've almost gotten all VLAs
> removed from the kernel[1], and this is introducing a new one. :)
>
> Thanks!
>
> -Kees
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
>> +
>> + s = clear = t;
>> + d = t + nr;
>> + rescue = b - nr;
>> + if (dir == SM_UP) {
>> + swap(s, d);
>> + swap(clear, rescue);
>> + }
>> + memcpy(save, uniscr->lines + rescue, nr * sizeof(*save));
>> + memmove(uniscr->lines + d, uniscr->lines + s,
>> + (b - t - nr) * sizeof(*uniscr->lines));
>> + memcpy(uniscr->lines + clear, save, nr * sizeof(*save));
>> + vc_uniscr_clear_lines(vc, clear, nr);
>> + }
>> +}
>
>
> --
> Kees Cook
> Pixel Security
next prev parent reply other threads:[~2018-07-11 3:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-27 3:56 [PATCH v3 0/3] have the vt console preserve unicode characters Nicolas Pitre
2018-06-27 3:56 ` [PATCH v3 1/3] vt: preserve unicode values corresponding to screen characters Nicolas Pitre
2018-07-11 0:52 ` Kees Cook
2018-07-11 3:39 ` Nicolas Pitre [this message]
2018-07-11 20:40 ` Kees Cook
2018-07-11 9:18 ` Greg Kroah-Hartman
2018-07-11 20:39 ` Kees Cook
2018-07-11 21:29 ` Adam Borowski
2018-06-27 3:56 ` [PATCH v3 2/3] vt: introduce unicode mode for /dev/vcs Nicolas Pitre
2018-06-29 8:15 ` Geert Uytterhoeven
2018-06-27 3:56 ` [PATCH v3 3/3] vt: unicode fallback for scrollback Nicolas Pitre
2018-06-28 12:38 ` [PATCH v3 0/3] have the vt console preserve unicode characters Greg Kroah-Hartman
2018-07-18 1:00 ` Nicolas Pitre
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