Bug#763731: terminfo: linux (linux-basic: CP437), linux-vt entries vs. ACS support

2014-10-04 Thread Thomas Dickey 
On Thu, Oct 02, 2014 at 08:51:32AM +, Ivan Shmakov wrote:
 Source:   ncurses
 Version:  5.9+20140913-1
 Control:  affects -1  console-setup
 Tags: patch
 Severity: minor
 
   As of the current version of the Terminfo database, the ‘linux’
   terminal entry implies the use of the CP437 encoding for the
   box-drawing characters and the like (also known as “alternate
   character set”, or ACS):
...
   This is hardly a safe assumption these days, especially taking
   into account the widespread use of UTF-8, /including/ on ttys.

several comments.

a) this should be merged with #515609

b) no progress has been observed in upstream (Linux kernel of course) in
   making the SCS patch referred to in #515609 an official part of Linux.

   When I investigated this earlier, I found that it wasn't - in fact did
   _not_ work for the kernels which Debian provided.  We can discuss this if
   the situation has changed.

c) the documentation in console_codes hasn't been updated for instance.
   The only recent (past 6 years) change there was the note about erase
   with 3 parameter since Linux 3.0.

d) this report does prescribe a change, but lacks the patch which is indicated
   in the flags.

e) the choice of enacs is problematic since the documentation (console_codes
   manpage) is pretty clear:

   ESC ( B   Select default (ISO 8859-1 mapping)
   ESC ( 0   Select VT100 graphics mapping

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Bug#763731: terminfo: linux (linux-basic: CP437), linux-vt entries vs. ACS support

2014-10-04 Thread Thomas Dickey 
On Sat, Oct 04, 2014 at 01:34:37PM -0400, Thomas Dickey wrote:
When I investigated this earlier, I found that it wasn't - in fact did
_not_ work for the kernels which Debian provided.  We can discuss this if
the situation has changed.

In a quick check (using TERM=linux-vt tack), the Debian7 configuration does
not show line-drawing).  Likewise Debian/testing.

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Bug#763731: terminfo: linux (linux-basic: CP437), linux-vt entries vs. ACS support

2014-10-04 Thread Ivan Shmakov 
 Thomas Dickey dic...@his.com writes:
 On Thu, Oct 02, 2014 at 08:51:32AM +, Ivan Shmakov wrote:

  Cc: 763731-submit...@bugs.debian.org

(No need to Cc: me, as I’m “on the list.”)

[…]

  As of the current version of the Terminfo database, the ‘linux’
  terminal entry implies the use of the CP437 encoding for the
  box-drawing characters and the like (also known as “alternate
  character set”, or ACS):

  This is hardly a safe assumption these days, especially taking into
  account the widespread use of UTF-8, /including/ on ttys.

  several comments.

  a) this should be merged with #515609

No objection on my part.

[…]

  d) this report does prescribe a change, but lacks the patch which is
  indicated in the flags.

The report surely /provides/ “… some other easy procedure for
fixing the bug”, as per http://www.debian.org/Bugs/Developer:

  patch

  A patch or some other easy procedure for fixing the bug is included
  in the bug logs.  If there’s a patch, but it doesn’t resolve the bug
  adequately or causes some other problems, this tag should not be
  used.

But I stand corrected, – the procedure I’ve suggested does /not/
resolve the bug, and thus this tag is indeed /not/ applicable.

Apparently, the proper “fix” for the issue is just to use the
‘linux2.6’ terminfo entry:

linux2.6|linux 2.6.x console,
rmacs=^O,

sgr=\E[0;10%?%p1%t;7%;%?%p2%t;4%;%?%p3%t;7%;%?%p4%t;5%;%?%p5%t;2%;%?%p6%t;1%;m%?%p9%t\016%e\017%;,
sgr0=\E[m\017, smacs=^N, use=linux2.2,

I hereby suggest that, given that Debian currently only supports
Linux versions 2.6 or later, the ‘linux’ terminfo entry be made
synonymous to ‘linux2.6’.

  • move the current variants of the ‘acsc’, ‘smacs’, ‘rmacs’
capabilities from linux-basic to a dedicated linux-cp437 entry
(following the suit of linux-koi8, linux-koi8r, linux-lat);

… And I still think it makes sense to provide a dedicated
‘linux-cp437’ entry per the above, just in case.

[…]

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Bug#763731: terminfo: linux (linux-basic: CP437), linux-vt entries vs. ACS support

2014-10-02 Thread Ivan Shmakov 
Source:   ncurses
Version:  5.9+20140913-1
Control:  affects -1  console-setup
Tags: patch
Severity: minor

As of the current version of the Terminfo database, the ‘linux’
terminal entry implies the use of the CP437 encoding for the
box-drawing characters and the like (also known as “alternate
character set”, or ACS):

$ nl -ba  misc/terminfo.src 
…
  1577  linux-basic|linux console,
  1578  am, bce, eo, mir, msgr, xenl, xon,
  1579  it#8, ncv#18, U8#1,
  1580  
acsc=+\020\,\021-\030.^Y0\333`\004a\261f\370g\361h\260i\316j\331k\277l\332m\300n\305o~p\304q\304r\304s_t\303u\264v\301w\302x\263y\363z\362{\343|\330}\234~\376,

(Read:  
acsc=+\020\,\021-\030.^Y0█`\004a▒f°g±h░i╬j┘k┐l┌m└n┼o~p─q─r─s_t├u┤v┴w┬x│y≤z≥{π|╪}£~■.
And no, that’s /not/ line noise.)

This is hardly a safe assumption these days, especially taking
into account the widespread use of UTF-8, /including/ on ttys.

(Please also note that the console-setup Debconf scripts will
assume UTF-8 mode for ttys provided that the locale is a UTF-8
one, – which, I believe, are default with D-I installs.)

There’s a separate ‘linux-vt’ entry that’s intended to be used
when the terminal encoding is not known, or non-unibyte, and
which emits ACS characters using VT100 ESC sequences instead:

  1678  # This uses graphics from VT codeset instead of from cp437.
  1679  # reason: cp437 (aka straight to font) is not functional under luit.
  1680  # from: Andrey V Lukyanov l...@long.yar.ru.
  1681  linux-vt|linux console using VT codes for graphics,
  1682  
acsc=++\,\,--..00``aaffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz~~,
  1683  rmacs=\E(K, rmpch@, sgr@, sgr0=\E[0m\E(K\017, smacs=\E(0,
  1684  smpch@, use=linux,

Unfortunately, this entry misses the ‘enacs’ capability, so its
use doesn’t result in the proper ACS rendering, as in:

$ export TERM=linux-vt 
$ tput  enacs ; tput  smacs ; printf %s\\n lk mj ; tput  rmacs ; 
lk
mj

Expected:

┌┐
└┘

The /minimal/ solution for the issue is to fix the linux-vt
entry by adding the missing ‘enacs’ capability:

linux-vt|linux console using VT codes for graphics,
acsc=++\,\,--..00``aaffgghhiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz~~,
enacs=\E(B\E)0, rmacs=\E(K, rmpch@, sgr@, sgr0=\E[0m\E(K\017,
smacs=\E(0, smpch@, use=linux,

This could just as well be combined with explicitly passing
‘linux-vt’ to the getty(8) invocations in the default
/etc/inittab for the new GNU/Linux installations, – or similar
measures for the systems using different means to start up the
gettys.

The “proper” solution, in my opinion, is to:

• move the current variants of the ‘acsc’, ‘smacs’, ‘rmacs’
  capabilities from linux-basic to a dedicated linux-cp437 entry
  (following the suit of linux-koi8, linux-koi8r, linux-lat);

• replace them with the encoding-insensitive ‘acsc’, ‘smacs’,
  ‘rmacs’ variants from linux-vt, along with adding ‘enacs’ per
  above;

• the linux-vt entry is then to be cut down to just ‘use=linux’
  (and ‘sgr@’?), but otherwise retained for compatibility.

TIA.

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