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 <n...@linaro.org>
Tested-by: Dave Mielke <d...@mielke.cc>
---
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 7b636638b3..062ce6be79 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -481,6 +481,67 @@ 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
--
2.17.1
