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 also means that the /dev/vcs* devices only provide user space with
glyph index values, and then user applications must get hold of the
unicode-to-glyph table the kernel is using in order to back-translate
those into actual characters. It is not possible to get back the original
unicode value when multiple unicode characters map to the same glyph,
especially for the vast majority that maps to the default replacement
glyph.
The 512-glyph limitation is inherent to VGA displays, but users of
/dev/vcs* shouldn't have to be restricted to a narrow unicode space from
lossy screen content because of that. This is especially true for
accessibility applications such as BRLTTY that rely on /dev/vcs to rander
screen content onto braille terminals.
This patch series introduces unicode support to /dev/vcs* devices,
allowing full unicode access from userspace to the vt console which
can, amongst other purposes, appropriately translate actual unicode
screen content into braille. Memory is allocated, and possible CPU
overhead introduced, only if /dev/vcsu is read at least once.
I'm a prime user of this feature, as well as the BRLTTY maintainer Dave Mielke
who implemented support for this in BRLTTY. There is therefore a vested
self interest to maintain this feature as necessary.
Patch #1 has been picked up by Greg already (commit 4b4ecd9cb8 in
linux-next) but it is included here as well, as the rest of the series
depends on it to apply properly.
Patch #5 was used for validation and is included for completeness, however
if people think it is unappropriate for mainline then it can be dropped.
This is also available on top of v4.17-rc7 here:
git://git.linaro.org/people/nicolas.pitre/linux vt-unicode
diffstat:
drivers/tty/vt/vc_screen.c | 90 +++++++--
drivers/tty/vt/vt.c | 366 +++++++++++++++++++++++++++++++++--
include/linux/console_struct.h | 2 +
include/linux/selection.h | 5 +
4 files changed, 429 insertions(+), 34 deletions(-)
Commit f8df13e0a9 ("tty: Clean console safely") added code to clear
both the scrollback buffer and the screen with "\e[3J", then execution
falls through into the code to simply clear the screen. This means
scr_memsetw() and the console driver update callback is called twice
on the whole screen buffer. Let's reorganize the code so the same work
is not performed twice.
Signed-off-by: Nicolas Pitre <[email protected]>
---
drivers/tty/vt/vt.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index f97251f39c..1eb1a376a0 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1178,15 +1178,8 @@ static void csi_J(struct vc_data *vc, int vpar)
count = ((vc->vc_pos - vc->vc_origin) >> 1) + 1;
start = (unsigned short *)vc->vc_origin;
break;
- case 3: /* erase scroll-back buffer (and whole display) */
- scr_memsetw(vc->vc_screenbuf, vc->vc_video_erase_char,
- vc->vc_screenbuf_size);
- flush_scrollback(vc);
- set_origin(vc);
- if (con_is_visible(vc))
- update_screen(vc);
- /* fall through */
case 2: /* erase whole display */
+ case 3: /* (and scrollback buffer later) */
count = vc->vc_cols * vc->vc_rows;
start = (unsigned short *)vc->vc_origin;
break;
@@ -1194,7 +1187,12 @@ static void csi_J(struct vc_data *vc, int vpar)
return;
}
scr_memsetw(start, vc->vc_video_erase_char, 2 * count);
- if (con_should_update(vc))
+ if (vpar == 3) {
+ set_origin(vc);
+ flush_scrollback(vc);
+ if (con_is_visible(vc))
+ update_screen(vc);
+ } else if (con_should_update(vc))
do_update_region(vc, (unsigned long) start, count);
vc->vc_need_wrap = 0;
}
--
2.17.0
Make sure the unicode screen buffer matches the video screen content.
This is provided for debugging convenience and disabled by default.
Signed-off-by: Nicolas Pitre <[email protected]>
---
drivers/tty/vt/vt.c | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index e7c3cabeb1..2f3d528082 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -571,6 +571,45 @@ void vc_uniscr_copy_line(struct vc_data *vc, void *dest, int viewed,
}
}
+/* this is for validation and debugging only */
+static void vc_uniscr_debug_check(struct vc_data *vc)
+{
+ struct uni_screen *uniscr = get_vc_uniscr(vc);
+ unsigned short *p;
+ int x, y, mask;
+
+ if (true)
+ return;
+
+ if (!uniscr)
+ return;
+
+ WARN_CONSOLE_UNLOCKED();
+
+ /*
+ * Make sure our unicode screen translates into the same glyphs
+ * as the actual screen. This is brutal indeed.
+ */
+ p = (unsigned short *)vc->vc_origin;
+ mask = vc->vc_hi_font_mask | 0xff;
+ for (y = 0; y < vc->vc_rows; y++) {
+ char32_t *line = uniscr->lines[y];
+ for (x = 0; x < vc->vc_cols; x++) {
+ u16 glyph = scr_readw(p++) & mask;
+ char32_t uc = line[x];
+ int tc = conv_uni_to_pc(vc, uc);
+ if (tc == -4)
+ tc = conv_uni_to_pc(vc, 0xfffd);
+ if (tc == -4)
+ tc = conv_uni_to_pc(vc, '?');
+ if (tc != glyph)
+ pr_notice("%s: mismatch at %d,%d: "
+ "glyph=%#x tc=%#x\n", __func__,
+ x, y, glyph, tc);
+ }
+ }
+}
+
static void con_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
enum con_scroll dir, unsigned int nr)
@@ -2719,6 +2758,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
do_con_trol(tty, vc, orig);
}
con_flush(vc, draw_from, draw_to, &draw_x);
+ vc_uniscr_debug_check(vc);
console_conditional_schedule();
console_unlock();
notify_update(vc);
--
2.17.0
There is currently no provision for scrollback content in the core code,
leaving that to backend video drivers where this can be highly optimized.
There is currently no common method for those drivers to tell the core
what part of the scrollback is actually displayed and what size the
scrollback buffer is either. Because of that, the unicode screen buffer
has no provision for any scrollback.
At least we can provide backtranslated glyph values when the scrollback
is active which should be plenty good enough for now.
Signed-off-by: Nicolas Pitre <[email protected]>
Tested-by: Dave Mielke <[email protected]>
---
drivers/tty/vt/vc_screen.c | 3 ++-
drivers/tty/vt/vt.c | 31 +++++++++++++++++++++++++++++--
include/linux/selection.h | 2 +-
3 files changed, 32 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index 9c44252e52..2384ea85ff 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -311,7 +311,8 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
do {
if (nr > this_round/4)
nr = this_round/4;
- vc_uniscr_copy_line(vc, con_buf0, row, col, nr);
+ vc_uniscr_copy_line(vc, con_buf0, viewed,
+ row, col, nr);
con_buf0 += nr * 4;
this_round -= nr * 4;
row++;
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 2cba6089ca..e7c3cabeb1 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -535,13 +535,40 @@ int vc_uniscr_check(struct vc_data *vc)
* This must be preceded by a successful call to vc_uniscr_check() once
* the console lock has been taken.
*/
-void vc_uniscr_copy_line(struct vc_data *vc, void *dest,
+void vc_uniscr_copy_line(struct vc_data *vc, void *dest, int viewed,
unsigned int row, unsigned int col, unsigned int nr)
{
struct uni_screen *uniscr = get_vc_uniscr(vc);
+ int offset = row * vc->vc_size_row + col * 2;
+ unsigned long pos;
BUG_ON(!uniscr);
- memcpy(dest, &uniscr->lines[row][col], nr * sizeof(char32_t));
+
+ pos = (unsigned long)screenpos(vc, offset, viewed);
+ if (pos >= vc->vc_origin && pos < vc->vc_scr_end) {
+ /*
+ * Desired position falls in the main screen buffer.
+ * However the actual row/col might be different if
+ * scrollback is active.
+ */
+ row = (pos - vc->vc_origin) / vc->vc_size_row;
+ col = ((pos - vc->vc_origin) % vc->vc_size_row) / 2;
+ memcpy(dest, &uniscr->lines[row][col], nr * sizeof(char32_t));
+ } else {
+ /*
+ * Scrollback is active. For now let's simply backtranslate
+ * the screen glyphs until the unicode screen buffer does
+ * synchronize with console display drivers for a scrollback
+ * buffer of its own.
+ */
+ u16 *p = (u16 *)pos;
+ int mask = vc->vc_hi_font_mask | 0xff;
+ char32_t *uni_buf = dest;
+ while (nr--) {
+ u16 glyph = scr_readw(p++) & mask;
+ *uni_buf++ = inverse_translate(vc, glyph, true);
+ }
+ }
}
diff --git a/include/linux/selection.h b/include/linux/selection.h
index 2b34df9f1e..067d2e99c7 100644
--- a/include/linux/selection.h
+++ b/include/linux/selection.h
@@ -43,7 +43,7 @@ extern void vcs_scr_writew(struct vc_data *vc, u16 val, u16 *org);
extern void vcs_scr_updated(struct vc_data *vc);
extern int vc_uniscr_check(struct vc_data *vc);
-extern void vc_uniscr_copy_line(struct vc_data *vc, void *dest,
+extern void vc_uniscr_copy_line(struct vc_data *vc, void *dest, int viewed,
unsigned int row, unsigned int col,
unsigned int nr);
--
2.17.0
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 <[email protected]>
Tested-by: Dave Mielke <[email protected]>
---
drivers/tty/vt/vt.c | 222 +++++++++++++++++++++++++++++++--
include/linux/console_struct.h | 2 +
2 files changed, 213 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 1eb1a376a0..3a801a60f4 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -317,6 +317,173 @@ void schedule_console_callback(void)
schedule_work(&console_work);
}
+/*
+ * Code to manage unicode-based screen buffers
+ */
+
+#ifdef NO_VC_UNI_SCREEN
+/* this disables and optimizes related code away at compile time */
+#define get_vc_uniscr(vc) NULL
+#else
+#define get_vc_uniscr(vc) vc->vc_uni_screen
+#endif
+
+typedef uint32_t char32_t;
+
+/*
+ * Our screen buffer is preceded by an array of line pointers so that
+ * scrolling only implies some pointer shuffling.
+ */
+struct uni_screen {
+ char32_t *lines[0];
+};
+
+static struct uni_screen *vc_uniscr_alloc(unsigned int cols, unsigned int rows)
+{
+ struct uni_screen *uniscr;
+ void *p;
+ unsigned int memsize, i;
+
+ /* allocate everything in one go */
+ memsize = cols * rows * sizeof(char32_t);
+ memsize += rows * sizeof(char32_t *);
+ p = kmalloc(memsize, GFP_KERNEL);
+ if (!p) {
+ pr_err("unable to allocate unicode screen buffer");
+ return NULL;
+ }
+
+ /* initial line pointers */
+ uniscr = p;
+ p = uniscr->lines + rows;
+ for (i = 0; i < rows; i++) {
+ uniscr->lines[i] = p;
+ p += cols * sizeof(char32_t);
+ }
+ return uniscr;
+}
+
+static void vc_uniscr_set(struct vc_data *vc, struct uni_screen *new_uniscr)
+{
+ kfree(vc->vc_uni_screen);
+ vc->vc_uni_screen = new_uniscr;
+}
+
+static void vc_uniscr_putc(struct vc_data *vc, char32_t uc)
+{
+ struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+ if (uniscr)
+ uniscr->lines[vc->vc_y][vc->vc_x] = uc;
+}
+
+static void vc_uniscr_insert(struct vc_data *vc, unsigned int nr)
+{
+ struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+ if (uniscr) {
+ char32_t *ln = uniscr->lines[vc->vc_y];
+ unsigned int x = vc->vc_x, cols = vc->vc_cols;
+
+ memmove(&ln[x + nr], &ln[x], (cols - x - nr) * sizeof(*ln));
+ memset32(&ln[x], ' ', nr);
+ }
+}
+
+static void vc_uniscr_delete(struct vc_data *vc, unsigned int nr)
+{
+ struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+ if (uniscr) {
+ char32_t *ln = uniscr->lines[vc->vc_y];
+ unsigned int x = vc->vc_x, cols = vc->vc_cols;
+
+ memcpy(&ln[x], &ln[x + nr], (cols - x - nr) * sizeof(*ln));
+ memset32(&ln[cols - nr], ' ', nr);
+ }
+}
+
+static void vc_uniscr_clear_line(struct vc_data *vc, unsigned int x,
+ unsigned int nr)
+{
+ struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+ if (uniscr) {
+ char32_t *ln = uniscr->lines[vc->vc_y];
+
+ memset32(&ln[x], ' ', nr);
+ }
+}
+
+static void vc_uniscr_clear_lines(struct vc_data *vc, unsigned int y,
+ unsigned int nr)
+{
+ struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+ if (uniscr) {
+ unsigned int cols = vc->vc_cols;
+
+ while (nr--)
+ memset32(uniscr->lines[y++], ' ', cols);
+ }
+}
+
+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];
+
+ 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);
+ }
+}
+
+static void vc_uniscr_copy_area(struct uni_screen *dst,
+ unsigned int dst_cols,
+ unsigned int dst_rows,
+ struct uni_screen *src,
+ unsigned int src_cols,
+ unsigned int src_top_row,
+ unsigned int src_bot_row)
+{
+ unsigned int dst_row = 0;
+
+ if (!dst)
+ return;
+
+ while (src_top_row < src_bot_row) {
+ char32_t *src_line = src->lines[src_top_row];
+ char32_t *dst_line = dst->lines[dst_row];
+
+ memcpy(dst_line, src_line, src_cols * sizeof(char32_t));
+ if (dst_cols - src_cols)
+ memset32(dst_line + src_cols, ' ', dst_cols - src_cols);
+ src_top_row++;
+ dst_row++;
+ }
+ while (dst_row < dst_rows) {
+ char32_t *dst_line = dst->lines[dst_row];
+
+ memset32(dst_line, ' ', dst_cols);
+ dst_row++;
+ }
+}
+
+
static void con_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
enum con_scroll dir, unsigned int nr)
{
@@ -326,6 +493,7 @@ static void con_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
nr = b - t - 1;
if (b > vc->vc_rows || t >= b || nr < 1)
return;
+ vc_uniscr_scroll(vc, t, b, dir, nr);
if (con_is_visible(vc) && vc->vc_sw->con_scroll(vc, t, b, dir, nr))
return;
@@ -533,6 +701,7 @@ static void insert_char(struct vc_data *vc, unsigned int nr)
{
unsigned short *p = (unsigned short *) vc->vc_pos;
+ vc_uniscr_insert(vc, nr);
scr_memmovew(p + nr, p, (vc->vc_cols - vc->vc_x - nr) * 2);
scr_memsetw(p, vc->vc_video_erase_char, nr * 2);
vc->vc_need_wrap = 0;
@@ -545,6 +714,7 @@ static void delete_char(struct vc_data *vc, unsigned int nr)
{
unsigned short *p = (unsigned short *) vc->vc_pos;
+ vc_uniscr_delete(vc, nr);
scr_memcpyw(p, p + nr, (vc->vc_cols - vc->vc_x - nr) * 2);
scr_memsetw(p + vc->vc_cols - vc->vc_x - nr, vc->vc_video_erase_char,
nr * 2);
@@ -845,10 +1015,11 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
{
unsigned long old_origin, new_origin, new_scr_end, rlth, rrem, err = 0;
unsigned long end;
- unsigned int old_rows, old_row_size;
+ unsigned int old_rows, old_row_size, first_copied_row;
unsigned int new_cols, new_rows, new_row_size, new_screen_size;
unsigned int user;
unsigned short *newscreen;
+ struct uni_screen *new_uniscr = NULL;
WARN_CONSOLE_UNLOCKED();
@@ -875,6 +1046,14 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
if (!newscreen)
return -ENOMEM;
+ if (get_vc_uniscr(vc)) {
+ new_uniscr = vc_uniscr_alloc(new_cols, new_rows);
+ if (!new_uniscr) {
+ kfree(newscreen);
+ return -ENOMEM;
+ }
+ }
+
if (vc == sel_cons)
clear_selection();
@@ -884,6 +1063,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
err = resize_screen(vc, new_cols, new_rows, user);
if (err) {
kfree(newscreen);
+ kfree(new_uniscr);
return err;
}
@@ -904,18 +1084,24 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
* Cursor near the bottom, copy contents from the
* bottom of buffer
*/
- old_origin += (old_rows - new_rows) * old_row_size;
+ first_copied_row = (old_rows - new_rows);
} else {
/*
* Cursor is in no man's land, copy 1/2 screenful
* from the top and bottom of cursor position
*/
- old_origin += (vc->vc_y - new_rows/2) * old_row_size;
+ first_copied_row = (vc->vc_y - new_rows/2);
}
- }
-
+ old_origin += first_copied_row * old_row_size;
+ } else
+ first_copied_row = 0;
end = old_origin + old_row_size * min(old_rows, new_rows);
+ vc_uniscr_copy_area(new_uniscr, new_cols, new_rows,
+ get_vc_uniscr(vc), rlth/2, first_copied_row,
+ min(old_rows, new_rows));
+ vc_uniscr_set(vc, new_uniscr);
+
update_attr(vc);
while (old_origin < end) {
@@ -1013,6 +1199,7 @@ struct vc_data *vc_deallocate(unsigned int currcons)
vc->vc_sw->con_deinit(vc);
put_pid(vc->vt_pid);
module_put(vc->vc_sw->owner);
+ vc_uniscr_set(vc, NULL);
kfree(vc->vc_screenbuf);
vc_cons[currcons].d = NULL;
}
@@ -1171,15 +1358,22 @@ static void csi_J(struct vc_data *vc, int vpar)
switch (vpar) {
case 0: /* erase from cursor to end of display */
+ vc_uniscr_clear_line(vc, vc->vc_x,
+ vc->vc_cols - vc->vc_x);
+ vc_uniscr_clear_lines(vc, vc->vc_y + 1,
+ vc->vc_rows - vc->vc_y - 1);
count = (vc->vc_scr_end - vc->vc_pos) >> 1;
start = (unsigned short *)vc->vc_pos;
break;
case 1: /* erase from start to cursor */
+ vc_uniscr_clear_line(vc, 0, vc->vc_x + 1);
+ vc_uniscr_clear_lines(vc, 0, vc->vc_y);
count = ((vc->vc_pos - vc->vc_origin) >> 1) + 1;
start = (unsigned short *)vc->vc_origin;
break;
case 2: /* erase whole display */
case 3: /* (and scrollback buffer later) */
+ vc_uniscr_clear_lines(vc, 0, vc->vc_rows);
count = vc->vc_cols * vc->vc_rows;
start = (unsigned short *)vc->vc_origin;
break;
@@ -1200,25 +1394,27 @@ static void csi_J(struct vc_data *vc, int vpar)
static void csi_K(struct vc_data *vc, int vpar)
{
unsigned int count;
- unsigned short * start;
+ unsigned short *start = (unsigned short *)vc->vc_pos;
+ int offset;
switch (vpar) {
case 0: /* erase from cursor to end of line */
+ offset = 0;
count = vc->vc_cols - vc->vc_x;
- start = (unsigned short *)vc->vc_pos;
break;
case 1: /* erase from start of line to cursor */
- start = (unsigned short *)(vc->vc_pos - (vc->vc_x << 1));
+ offset = -vc->vc_x;
count = vc->vc_x + 1;
break;
case 2: /* erase whole line */
- start = (unsigned short *)(vc->vc_pos - (vc->vc_x << 1));
+ offset = -vc->vc_x;
count = vc->vc_cols;
break;
default:
return;
}
- scr_memsetw(start, vc->vc_video_erase_char, 2 * count);
+ vc_uniscr_clear_line(vc, vc->vc_x + offset, count);
+ scr_memsetw(start + offset, vc->vc_video_erase_char, 2 * count);
vc->vc_need_wrap = 0;
if (con_should_update(vc))
do_update_region(vc, (unsigned long) start, count);
@@ -1232,6 +1428,7 @@ static void csi_X(struct vc_data *vc, int vpar) /* erase the following vpar posi
vpar++;
count = (vpar > vc->vc_cols - vc->vc_x) ? (vc->vc_cols - vc->vc_x) : vpar;
+ vc_uniscr_clear_line(vc, vc->vc_x, count);
scr_memsetw((unsigned short *)vc->vc_pos, vc->vc_video_erase_char, 2 * count);
if (con_should_update(vc))
vc->vc_sw->con_clear(vc, vc->vc_y, vc->vc_x, 1, count);
@@ -2188,7 +2385,7 @@ static void con_flush(struct vc_data *vc, unsigned long draw_from,
/* acquires console_lock */
static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
- int c, tc, ok, n = 0, draw_x = -1;
+ int c, next_c, tc, ok, n = 0, draw_x = -1;
unsigned int currcons;
unsigned long draw_from = 0, draw_to = 0;
struct vc_data *vc;
@@ -2382,6 +2579,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
con_flush(vc, draw_from, draw_to, &draw_x);
}
+ next_c = c;
while (1) {
if (vc->vc_need_wrap || vc->vc_decim)
con_flush(vc, draw_from, draw_to,
@@ -2392,6 +2590,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
}
if (vc->vc_decim)
insert_char(vc, 1);
+ vc_uniscr_putc(vc, next_c);
scr_writew(himask ?
((vc_attr << 8) & ~himask) + ((tc & 0x100) ? himask : 0) + (tc & 0xff) :
(vc_attr << 8) + tc,
@@ -2412,6 +2611,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
tc = conv_uni_to_pc(vc, ' '); /* A space is printed in the second column */
if (tc < 0) tc = ' ';
+ next_c = ' ';
}
notify_write(vc, c);
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index c0ec478ea5..2c8d323989 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -19,6 +19,7 @@
struct vt_struct;
struct uni_pagedir;
+struct uni_screen;
#define NPAR 16
@@ -140,6 +141,7 @@ struct vc_data {
struct vc_data **vc_display_fg; /* [!] Ptr to var holding fg console for this display */
struct uni_pagedir *vc_uni_pagedir;
struct uni_pagedir **vc_uni_pagedir_loc; /* [!] Location of uni_pagedir variable for this console */
+ struct uni_screen *vc_uni_screen; /* unicode screen content */
bool vc_panic_force_write; /* when oops/panic this VC can accept forced output/blanking */
/* additional information is in vt_kern.h */
};
--
2.17.0
Now that the core vt code knows how to preserve unicode values for each
displayed character, it is then possible to let user space access it via
/dev/vcs*.
Unicode characters are presented as 32 bit values in native endianity
via the /dev/vcsu* devices, mimicking the simple /dev/vcs* devices.
Unicode with attributes (similarly to /dev/vcsa*) is not supported at
the moment.
Data is available only as long as the console is in UTF-8 mode. ENODATA
is returned otherwise.
This was tested with the latest development version (to become
version 5.7) of BRLTTY. Amongst other things, this allows ⠋⠕⠗ ⠞⠓⠊⠎
⠃⠗⠁⠊⠇⠇⠑⠀⠞⠑⠭⠞⠀to appear directly on braille displays regardless of the
console font being used.
Signed-off-by: Nicolas Pitre <[email protected]>
Tested-by: Dave Mielke <[email protected]>
---
drivers/tty/vt/vc_screen.c | 89 ++++++++++++++++++++++++++++++++------
drivers/tty/vt/vt.c | 61 ++++++++++++++++++++++++++
include/linux/selection.h | 5 +++
3 files changed, 141 insertions(+), 14 deletions(-)
diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
index e4a66e1fd0..9c44252e52 100644
--- a/drivers/tty/vt/vc_screen.c
+++ b/drivers/tty/vt/vc_screen.c
@@ -10,6 +10,12 @@
* Attribute/character pair is in native endianity.
* [minor: N+128]
*
+ * /dev/vcsuN: similar to /dev/vcsaN but using 4-byte unicode values
+ * instead of 1-byte screen glyph values.
+ * [minor: N+64]
+ *
+ * /dev/vcsuaN: same idea as /dev/vcsaN for unicode (not yet implemented).
+ *
* This replaces screendump and part of selection, so that the system
* administrator can control access using file system permissions.
*
@@ -51,6 +57,26 @@
#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
+/*
+ * Our minor space:
+ *
+ * 0 ... 63 glyph mode without attributes
+ * 64 ... 127 unicode mode without attributes
+ * 128 ... 191 glyph mode with attributes
+ * 192 ... 255 unused (reserved for unicode with attributes)
+ *
+ * This relies on MAX_NR_CONSOLES being <= 63, meaning 63 actual consoles
+ * with minors 0, 64, 128 and 192 being proxies for the foreground console.
+ */
+#if MAX_NR_CONSOLES > 63
+#warning "/dev/vcs* devices may not accommodate more than 63 consoles"
+#endif
+
+#define console(inode) (iminor(inode) & 63)
+#define use_unicode(inode) (iminor(inode) & 64)
+#define use_attributes(inode) (iminor(inode) & 128)
+
+
struct vcs_poll_data {
struct notifier_block notifier;
unsigned int cons_num;
@@ -102,7 +128,7 @@ vcs_poll_data_get(struct file *file)
poll = kzalloc(sizeof(*poll), GFP_KERNEL);
if (!poll)
return NULL;
- poll->cons_num = iminor(file_inode(file)) & 127;
+ poll->cons_num = console(file_inode(file));
init_waitqueue_head(&poll->waitq);
poll->notifier.notifier_call = vcs_notifier;
if (register_vt_notifier(&poll->notifier) != 0) {
@@ -140,7 +166,7 @@ vcs_poll_data_get(struct file *file)
static struct vc_data*
vcs_vc(struct inode *inode, int *viewed)
{
- unsigned int currcons = iminor(inode) & 127;
+ unsigned int currcons = console(inode);
WARN_CONSOLE_UNLOCKED();
@@ -164,7 +190,6 @@ static int
vcs_size(struct inode *inode)
{
int size;
- int minor = iminor(inode);
struct vc_data *vc;
WARN_CONSOLE_UNLOCKED();
@@ -175,8 +200,12 @@ vcs_size(struct inode *inode)
size = vc->vc_rows * vc->vc_cols;
- if (minor & 128)
+ if (use_attributes(inode)) {
+ if (use_unicode(inode))
+ return -EOPNOTSUPP;
size = 2*size + HEADER_SIZE;
+ } else if (use_unicode(inode))
+ size *= 4;
return size;
}
@@ -197,12 +226,10 @@ static ssize_t
vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct inode *inode = file_inode(file);
- unsigned int currcons = iminor(inode);
struct vc_data *vc;
struct vcs_poll_data *poll;
- long pos;
- long attr, read;
- int col, maxcol, viewed;
+ long pos, read;
+ int attr, uni_mode, row, col, maxcol, viewed;
unsigned short *org = NULL;
ssize_t ret;
char *con_buf;
@@ -218,7 +245,8 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
*/
console_lock();
- attr = (currcons & 128);
+ uni_mode = use_unicode(inode);
+ attr = use_attributes(inode);
ret = -ENXIO;
vc = vcs_vc(inode, &viewed);
if (!vc)
@@ -227,6 +255,10 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
ret = -EINVAL;
if (pos < 0)
goto unlock_out;
+ /* we enforce 32-bit alignment for pos and count in unicode mode */
+ if (uni_mode && (pos | count) & 3)
+ goto unlock_out;
+
poll = file->private_data;
if (count && poll)
poll->seen_last_update = true;
@@ -266,7 +298,27 @@ vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
con_buf_start = con_buf0 = con_buf;
orig_count = this_round;
maxcol = vc->vc_cols;
- if (!attr) {
+ if (uni_mode) {
+ unsigned int nr;
+
+ ret = vc_uniscr_check(vc);
+ if (ret)
+ break;
+ p /= 4;
+ row = p / vc->vc_cols;
+ col = p % maxcol;
+ nr = maxcol - col;
+ do {
+ if (nr > this_round/4)
+ nr = this_round/4;
+ vc_uniscr_copy_line(vc, con_buf0, row, col, nr);
+ con_buf0 += nr * 4;
+ this_round -= nr * 4;
+ row++;
+ col = 0;
+ nr = maxcol;
+ } while (this_round);
+ } else if (!attr) {
org = screen_pos(vc, p, viewed);
col = p % maxcol;
p += maxcol - col;
@@ -375,7 +427,6 @@ static ssize_t
vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
struct inode *inode = file_inode(file);
- unsigned int currcons = iminor(inode);
struct vc_data *vc;
long pos;
long attr, size, written;
@@ -396,7 +447,7 @@ vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
*/
console_lock();
- attr = (currcons & 128);
+ attr = use_attributes(inode);
ret = -ENXIO;
vc = vcs_vc(inode, &viewed);
if (!vc)
@@ -593,9 +644,15 @@ vcs_fasync(int fd, struct file *file, int on)
static int
vcs_open(struct inode *inode, struct file *filp)
{
- unsigned int currcons = iminor(inode) & 127;
+ unsigned int currcons = console(inode);
+ bool attr = use_attributes(inode);
+ bool uni_mode = use_unicode(inode);
int ret = 0;
-
+
+ /* we currently don't support attributes in unicode mode */
+ if (attr && uni_mode)
+ return -EOPNOTSUPP;
+
console_lock();
if(currcons && !vc_cons_allocated(currcons-1))
ret = -ENXIO;
@@ -628,6 +685,8 @@ void vcs_make_sysfs(int index)
{
device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
"vcs%u", index + 1);
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
+ "vcsu%u", index + 1);
device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
"vcsa%u", index + 1);
}
@@ -635,6 +694,7 @@ void vcs_make_sysfs(int index)
void vcs_remove_sysfs(int index)
{
device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
+ device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
}
@@ -647,6 +707,7 @@ int __init vcs_init(void)
vc_class = class_create(THIS_MODULE, "vc");
device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
+ device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
for (i = 0; i < MIN_NR_CONSOLES; i++)
vcs_make_sysfs(i);
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 3a801a60f4..2cba6089ca 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -483,6 +483,67 @@ static void vc_uniscr_copy_area(struct uni_screen *dst,
}
}
+/*
+ * Called from vcs_read() to make sure unicode screen retrieval is possible.
+ * This will initialize the unicode screen buffer if not already done.
+ * This returns 0 if OK, or a negative error code otherwise.
+ * In particular, -ENODATA is returned if the console is not in UTF-8 mode.
+ */
+int vc_uniscr_check(struct vc_data *vc)
+{
+ struct uni_screen *uniscr;
+ unsigned short *p;
+ int x, y, mask;
+
+ if (__is_defined(NO_VC_UNI_SCREEN))
+ return -EOPNOTSUPP;
+
+ WARN_CONSOLE_UNLOCKED();
+
+ if (!vc->vc_utf)
+ return -ENODATA;
+
+ if (vc->vc_uni_screen)
+ return 0;
+
+ uniscr = vc_uniscr_alloc(vc->vc_cols, vc->vc_rows);
+ if (!uniscr)
+ return -ENOMEM;
+
+ /*
+ * Let's populate it initially with (imperfect) reverse translation.
+ * This is the next best thing we can do short of having it enabled
+ * from the start even when no users rely on this functionality. True
+ * unicode content will be available after a complete screen refresh.
+ */
+ p = (unsigned short *)vc->vc_origin;
+ mask = vc->vc_hi_font_mask | 0xff;
+ for (y = 0; y < vc->vc_rows; y++) {
+ char32_t *line = uniscr->lines[y];
+ for (x = 0; x < vc->vc_cols; x++) {
+ u16 glyph = scr_readw(p++) & mask;
+ line[x] = inverse_translate(vc, glyph, true);
+ }
+ }
+
+ vc->vc_uni_screen = uniscr;
+ return 0;
+}
+
+/*
+ * Called from vcs_read() to get the unicode data from the screen.
+ * This must be preceded by a successful call to vc_uniscr_check() once
+ * the console lock has been taken.
+ */
+void vc_uniscr_copy_line(struct vc_data *vc, void *dest,
+ unsigned int row, unsigned int col, unsigned int nr)
+{
+ struct uni_screen *uniscr = get_vc_uniscr(vc);
+
+ BUG_ON(!uniscr);
+ memcpy(dest, &uniscr->lines[row][col], nr * sizeof(char32_t));
+}
+
static void con_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
enum con_scroll dir, unsigned int nr)
diff --git a/include/linux/selection.h b/include/linux/selection.h
index 5b278ce99d..2b34df9f1e 100644
--- a/include/linux/selection.h
+++ b/include/linux/selection.h
@@ -42,4 +42,9 @@ extern u16 vcs_scr_readw(struct vc_data *vc, const u16 *org);
extern void vcs_scr_writew(struct vc_data *vc, u16 val, u16 *org);
extern void vcs_scr_updated(struct vc_data *vc);
+extern int vc_uniscr_check(struct vc_data *vc);
+extern void vc_uniscr_copy_line(struct vc_data *vc, void *dest,
+ unsigned int row, unsigned int col,
+ unsigned int nr);
+
#endif
--
2.17.0