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vt: convert vc_tab_stop to bitmap 

vc_tab_stop is used as a bitmap, but defined as an unsigned int array.
Switch it to bitmap and convert all users to the bitmap interface.

Note the difference in behavior! We no longer mask the top 24 bits away
from x, hence we do not wrap tabs at 256th column. Instead, we silently
drop attempts to set a tab behind 256 columns. And we will also seek by
'\t' to the rightmost column, when behind that boundary. I do not think
the original behavior was desired and that someone relies on that. If
this turns out to be the case, we can change the added 'if's back to
masks here and there instead...

(Or we can increase the limit as fb consoles now have 240 chars here.
And they could have more with higher than my resolution, of course.)

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200615074910.19267-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2020-06-15 09:48:38 +02:00 committed by Greg Kroah-Hartman
parent b70ec4d97f
commit dbee4cffa1
2 changed files with 20 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
drivers/tty/vt/vt.c
View File

@ -2052,6 +2052,8 @@ enum { ESnormal, ESesc, ESsquare, ESgetpars, ESfunckey,
/* console_lock is held (except via vc_init()) */
static void reset_terminal(struct vc_data *vc, int do_clear)
{
unsigned int i;
vc->vc_top = 0;
vc->vc_bottom = vc->vc_rows;
vc->vc_state = ESnormal;
@ -2082,14 +2084,9 @@ static void reset_terminal(struct vc_data *vc, int do_clear)
default_attr(vc);
update_attr(vc);
vc->vc_tab_stop[0] =
vc->vc_tab_stop[1] =
vc->vc_tab_stop[2] =
vc->vc_tab_stop[3] =
vc->vc_tab_stop[4] =
vc->vc_tab_stop[5] =
vc->vc_tab_stop[6] =
vc->vc_tab_stop[7] = 0x01010101;
bitmap_zero(vc->vc_tab_stop, VC_TABSTOPS_COUNT);
for (i = 0; i < VC_TABSTOPS_COUNT; i += 8)
set_bit(i, vc->vc_tab_stop);
vc->vc_bell_pitch = DEFAULT_BELL_PITCH;
vc->vc_bell_duration = DEFAULT_BELL_DURATION;
@ -2147,11 +2144,13 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
return;
case 9:
vc->vc_pos -= (vc->state.x << 1);
while (vc->state.x < vc->vc_cols - 1) {
vc->state.x++;
if (vc->vc_tab_stop[7 & (vc->state.x >> 5)] & (1 << (vc->state.x & 31)))
break;
}
vc->state.x = find_next_bit(vc->vc_tab_stop,
min(vc->vc_cols - 1, VC_TABSTOPS_COUNT),
vc->state.x + 1);
if (vc->state.x >= VC_TABSTOPS_COUNT)
vc->state.x = vc->vc_cols - 1;
vc->vc_pos += (vc->state.x << 1);
notify_write(vc, '\t');
return;
@ -2210,7 +2209,8 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
lf(vc);
return;
case 'H':
vc->vc_tab_stop[7 & (vc->state.x >> 5)] |= (1 << (vc->state.x & 31));
if (vc->state.x < VC_TABSTOPS_COUNT)
set_bit(vc->state.x, vc->vc_tab_stop);
return;
case 'Z':
respond_ID(tty);
@ -2421,18 +2421,10 @@ static void do_con_trol(struct tty_struct *tty, struct vc_data *vc, int c)
respond_ID(tty);
return;
case 'g':
if (!vc->vc_par[0])
vc->vc_tab_stop[7 & (vc->state.x >> 5)] &= ~(1 << (vc->state.x & 31));
else if (vc->vc_par[0] == 3) {
vc->vc_tab_stop[0] =
vc->vc_tab_stop[1] =
vc->vc_tab_stop[2] =
vc->vc_tab_stop[3] =
vc->vc_tab_stop[4] =
vc->vc_tab_stop[5] =
vc->vc_tab_stop[6] =
vc->vc_tab_stop[7] = 0;
}
if (!vc->vc_par[0] && vc->state.x < VC_TABSTOPS_COUNT)
set_bit(vc->state.x, vc->vc_tab_stop);
else if (vc->vc_par[0] == 3)
bitmap_zero(vc->vc_tab_stop, VC_TABSTOPS_COUNT);
return;
case 'm':
csi_m(vc);

3
include/linux/console_struct.h
View File

@ -21,6 +21,7 @@ struct uni_pagedir;
struct uni_screen;
#define NPAR 16
#define VC_TABSTOPS_COUNT 256U
enum vc_intensity {
VCI_HALF_BRIGHT,
@ -147,7 +148,7 @@ struct vc_data {
unsigned char vc_utf : 1; /* Unicode UTF-8 encoding */
unsigned char vc_utf_count;
int vc_utf_char;
unsigned int vc_tab_stop[8]; /* Tab stops. 256 columns. */
DECLARE_BITMAP(vc_tab_stop, VC_TABSTOPS_COUNT); /* Tab stops. 256 columns. */
unsigned char vc_palette[16*3]; /* Colour palette for VGA+ */
unsigned short * vc_translate;
unsigned int vc_resize_user; /* resize request from user */