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Subject[PATCH]console compatibility fixes to UTF-8 mode
Info:

Fixed inconsistent behaviour with linux terminal definition in UTF-8 mode,
and stick more closely to Unicode standard.
Tested on kernel 2.6.15.4 with lat2-sun16 and latarcyrheb-sun16 console fonts.
Should work without problems with previous kernels too.


Description:

Fixed UTF-8 mode so alternate charset modes always work according
to control sequences interpreted in csm_m and do_con_trol functions:
smpch = '\e[11m', rmpch='\e[10m',
smacs = '\x0e' and rmacs = '\x0f' if vt100 translation map for alternate
charset is active which means enacs = '\e)0'
which supports IBM-PC and VT100 semigraphics compatibility,
and matches the same terminal definition for normal and UTF-8 mode;
malformed UTF sequences represented as sequences of replacement glyphs,
original codes or '?' as a last resort if replacement glyph is undefined
and UCS-2 code does not fit in 0-127 code range

Signed-off-by: Adam Tla/lka <atlka@pg.gda.pl>

--- /usr/src/linux-2.6.15.4/drivers/char/vt_orig.c 2006-02-27 08:43:57.000000000 +0100
+++ /usr/src/linux-2.6.15.4/drivers/char/vt.c 2006-02-27 09:52:47.000000000 +0100
@@ -63,6 +63,10 @@
*
* Removed console_lock, enabled interrupts across all console operations
* 13 March 2001, Andrew Morton
+ *
+ * Fixed UTF-8 mode so alternate charset modes always work,
+ * added showing replacement glyphs in case of malformed UTF-8 sequences
+ * by Adam Tla/lka <atlka@pg.gda.pl>, Feb 2006
*/

#include <linux/module.h>
@@ -1991,17 +1995,23 @@ static int do_con_write(struct tty_struc
/* Do no translation at all in control states */
if (vc->vc_state != ESnormal) {
tc = c;
- } else if (vc->vc_utf) {
+ } else if (vc->vc_utf && !vc->vc_disp_ctrl) {
/* Combine UTF-8 into Unicode */
- /* Incomplete characters silently ignored */
+ /* Malformed sequences as replacement glyphs */
+rescan_last_byte:
if(c > 0x7f) {
- if (vc->vc_utf_count > 0 && (c & 0xc0) == 0x80) {
- vc->vc_utf_char = (vc->vc_utf_char << 6) | (c & 0x3f);
- vc->vc_utf_count--;
- if (vc->vc_utf_count == 0)
- tc = c = vc->vc_utf_char;
- else continue;
+ if (vc->vc_utf_count) {
+ if ((c & 0xc0) == 0x80) {
+ vc->vc_utf_char = (vc->vc_utf_char << 6) | (c & 0x3f);
+ if (--vc->vc_utf_count) {
+ vc->vc_npar++;
+ continue;
+ }
+ tc = c = vc->vc_utf_char;
+ } else
+ goto insert_replacement_glyph;
} else {
+ vc->vc_npar = 0;
if ((c & 0xe0) == 0xc0) {
vc->vc_utf_count = 1;
vc->vc_utf_char = (c & 0x1f);
@@ -2018,12 +2028,13 @@ static int do_con_write(struct tty_struc
vc->vc_utf_count = 5;
vc->vc_utf_char = (c & 0x01);
} else
- vc->vc_utf_count = 0;
+ goto insert_replacement_glyph;
continue;
}
} else {
+ if (vc->vc_utf_count)
+ goto insert_replacement_glyph;
tc = c;
- vc->vc_utf_count = 0;
}
} else { /* no utf */
tc = vc->vc_translate[vc->vc_toggle_meta ? (c | 0x80) : c];
@@ -2040,31 +2051,41 @@ static int do_con_write(struct tty_struc
* direct-to-font zone in UTF-8 mode.
*/
ok = tc && (c >= 32 ||
- (!vc->vc_utf && !(((vc->vc_disp_ctrl ? CTRL_ALWAYS
- : CTRL_ACTION) >> c) & 1)))
+ !(vc->vc_disp_ctrl ? (CTRL_ALWAYS >> c) & 1 :
+ vc->vc_utf || ((CTRL_ACTION >> c) & 1)))
&& (c != 127 || vc->vc_disp_ctrl)
&& (c != 128+27);

if (vc->vc_state == ESnormal && ok) {
/* Now try to find out how to display it */
tc = conv_uni_to_pc(vc, tc);
- if ( tc == -4 ) {
+ if ( tc & ~charmask ) {
+ if ( tc == -4 ) {
/* If we got -4 (not found) then see if we have
defined a replacement character (U+FFFD) */
- tc = conv_uni_to_pc(vc, 0xfffd);
+insert_replacement_glyph:
+ tc = conv_uni_to_pc(vc, 0xfffd);

/* One reason for the -4 can be that we just
did a clear_unimap();
try at least to show something. */
- if (tc == -4)
- tc = c;
- } else if ( tc == -3 ) {
+ if (tc & ~charmask) {
+ if ( c & ~0x7f )
+ tc = '?';
+ else
+ tc = c;
+ }
+ } else if ( tc == -3 ) {
/* Bad hash table -- hope for the best */
- tc = c;
- }
- if (tc & ~charmask)
- continue; /* Conversion failed */
+ if ( c & ~0x7f )
+ tc = '?';
+ else
+ tc = c;
+ } else
+ continue; /* nothing to display */
+ }

+repeat_replacement_glyph:
if (vc->vc_need_wrap || vc->vc_decim)
FLUSH
if (vc->vc_need_wrap) {
@@ -2088,6 +2109,15 @@ static int do_con_write(struct tty_struc
vc->vc_x++;
draw_to = (vc->vc_pos += 2);
}
+ if (vc->vc_utf_count) {
+ if (vc->vc_npar) {
+ vc->vc_npar--;
+ goto repeat_replacement_glyph;
+ }
+ vc->vc_utf_count = 0;
+ c = orig;
+ goto rescan_last_byte;
+ }
continue;
}
FLUSH
-
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