Re: screen and curses problem

[Thomas Dickey]

On Tue, Jul 03, 2007 at 02:06:08PM +0200, Miroslaw Dach wrote:
> Hi Thomas,
> 
>       Thanks a lot for your hint. I have set the NCURSES_TRACE variable 
> to TRACE_MAXIMUM.
> 
> Next what I did, I have started my server:
> export TERM=linux-m
> ../screen  -t MYSERVER -d -m myServer

ok.  To make a comparison, I built a tracing ncurses and statically linked
screen to that, calling trace(0xffff) from the main program.  (I also
turned on screen's debug feature, thinking I could get some separate
tracing - find that screen writes to the same stream as ncurses's trace,
perhaps because it assumes too much about the file descriptor).

> The trace file looked like that:
> ------------------------------------------------------------------------
> TRACING NCURSES version 5.4.20050122 (tracelevel=0x1fff)
> called {tgetent()
> + called {setupterm("screen",1,0x7f9601e8)
> your terminal name is screen
> cannot open terminfo /root/.terminfo/s/screen (errno=2)
> cannot open terminfo /usr/share/terminfo/s/screen (errno=2)
> TERMPATH is /etc/termcap:/usr/share/misc/termcap
> Adding termpath /etc/termcap
> Looking for screen in /etc/termcap
> cannot open terminfo /root/.terminfo/a/ansi-m (errno=2)
> cannot open terminfo /usr/share/terminfo/a/ansi-m (errno=2)

I've assuming there is some missing text here.
If I force screen to read the termcap file, I get a very long listing
showing the parsing of the termcap, e.g., text starting with

        TERMPATH is /tmp/BUILD/etc/termcap
        Adding termpath /tmp/BUILD/etc/termcap
        Looking for linux-m in /tmp/BUILD/etc/termcap
        Token: Names; value='dumb|80-column dumb tty'
        token: `dumb|80-column dumb tty', class 4

That also fails (I'm not sure why at the moment - it is a long trace), with a

        Clear screen capability required.

message.

When it reads the terminfo, there's no "Looking for", etc.
But there should still be some data:

        read terminfo /tmp/BUILD/share/terminfo/l/linux
        READ termtype header @0
        TERMTYPE name_size=20, bool=29/44, num=16/39 str=381/414(809)
        get Numbers[0]=-1
        get Numbers[1]=8

> _nc_free_termtype(klone+acs|alternate character set for ansi.sys displays)
> _nc_free_termtype(3u264v301w302x263y371z372{373|374}375~376.031-030054021+^P0333p3)
> _nc_free_termtype(04r304y363z362{343|330}234)

There's something wrong here - the parameter to _nc_free_termtype()
should be a list of terminal names.  In the two preceding calls,
it looks like a fragment from an acsc string:

        
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,

> _nc_free_termtype(klone+sgr|attribute control for ansi.sys displays)
> _nc_free_termtype(klone+color|color control for ansi.sys and 
> ISO6429-compatible displays)
> _nc_free_termtype(linux|linux console)
> _nc_free_termtype(linux-m|Linux console no color)
> _nc_free_termtype(xf|xterm-xfree86|XFree86 xterm)
> _nc_free_termtype(xterm-debian|xterm with modifications to follow Debian 
> keyboard policy)
> _nc_free_termtype(xterm-redhat|xterm with modifications to follow Debian 
> keyboard policy)
> _nc_free_termtype(v0|xterm|X11 terminal emulator)
> _nc_free_termtype(ansi|ansi/pc-term compatible with color)
> + + called {del_curterm(0x1006bb08)
> _nc_free_termtype((null))
> + + return }0
> + return }-1
> return }0

These look ok - but as I noted, there seems to be something missing.

> -----------------------------------------------------------------
> 
> Next I have tried to attache to the server:
> 
> screen -r 
> 
> trace file looked like that:
> -----------------------------------------------------------------
> called {tgetent()
> + called {setupterm("linux-m",1,0x7f95fd18)
> your terminal name is linux-m
> cannot open terminfo /root/.terminfo/l/linux-m (errno=2)
> cannot open terminfo /usr/share/terminfo/l/linux-m (errno=2)
> TERMPATH is /etc/termcap:/usr/share/misc/termcap
> Adding termpath /etc/termcap
> Looking for linux-m in /etc/termcap
> cannot open terminfo /root/.terminfo/a/ansi-m (errno=2)
> cannot open terminfo /usr/share/terminfo/a/ansi-m (errno=2)
> _nc_free_termtype(klone+acs|alternate character set for ansi.sys displays)
> _nc_free_termtype(3u264v301w302x263y371z372{373|374}375~376.031-030054021+^P0333p3)
> _nc_free_termtype(04r304y363z362{343|330}234)
> _nc_free_termtype(klone+sgr|attribute control for ansi.sys displays)
> _nc_free_termtype(klone+color|color control for ansi.sys and 
> ISO6429-compatible displays)
> _nc_free_termtype(linux|linux console)
> _nc_free_termtype(linux-m|Linux console no color)
> _nc_free_termtype(xf|xterm-xfree86|XFree86 xterm)
> _nc_free_termtype(xterm-debian|xterm with modifications to follow Debian 
> keyboard policy)
> _nc_free_termtype(xterm-redhat|xterm with modifications to follow Debian 
> keyboard policy)
> _nc_free_termtype(v0|xterm|X11 terminal emulator)
> _nc_free_termtype(ansi|ansi/pc-term compatible with color)
> + + called {set_curterm(0x10074c80)
> + + return }(nil)

Again, there's some missing data.  For comparison here's a fragment of
trace:

        called {tgetent()
        + called {setupterm("screen.linux",1,0xbfb229a8)
        your terminal name is screen.linux
        cannot open terminfo /users/tom/.terminfo/s/screen.linux (errno=13)
        read terminfo /tmp/BUILD/share/terminfo/s/screen.linux
        READ termtype header @0
        TERMTYPE name_size=37, bool=15/44, num=16/39 str=361/414(526)
        get Numbers[0]=80
        get Numbers[1]=8

> screen size: terminfo lines = 4080 columns = 4103

Those numbers don't make any sense to me (decimal/octal/hex):

4080: 4080 07760 0xff0 text "\017\360" utf8 \340\277\260
4103: 4103 010007 0x1007 text "\020\007" utf8 \341\200\207

But I think that if you go back and isolate the apparent data overrun
in the first command, that might give a clue.

> Studding the output I see that LINES and COLUMNS are not correctly set.
> Does ncurses detect that automatically?

ncurses tries to use a system call for getting that information.
But I think that's only a symptom - something is not using a
correct buffer size (or structure size), and is overrunning some
data.  Rereading the database only gets worse.

-- 
Thomas E. Dickey <address@hidden>
http://invisible-island.net
ftp://invisible-island.net

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