Eric Pouech wrote:
Le 22/12/2022 à 05:16, Jacob Bachmeyer a écrit :
I think that it would not be enough. The way Windows consoles work
is that we manage complete internal screen buffer and emit output
that synchronizes the buffer with Unix terminal inside conhost.exe
process. It means that its output heavily processed and may be very
different from what application writes to its console handle. While
escape codes discussed in this thread are the most prominent
difference (and that part could, in theory, be improved on our
side), there are more differences. For example, if application
writes "\rA\rB\rC", conhost will process it, update its internal
buffer which changes just one character and cursor position, and
emit sequence to update it in Unix terminal, which could be just
"\rC" (or even "C" if cursor was already at the beginning of the
line). Another example would be long lines: conhost will emit
additional EOLs instead of depending on embedder to wrap the line.
So conhost is essentially a Wine-specific screen(1) in that sense,
except that it translates Windows screen buffer manipulations instead
of VT100 escape codes? As I understand ncurses also implements most
of this; perhaps simply delegating output to ncurses would solve the
problem? If output were simply delegated to ncurses, (as I
understand) setting TERM=dumb should be effective to eliminate escape
codes from the output, since the "dumb" terminal does not support them.
unfortunately, things are not as simple as that: on one hand we need
to mimic Windows behavior, and on the other hand let apps running in
wine behave like regular posix applications <g>
(Note: conhost(.exe) is not wine specific, it's part of the way
windows handle the console input/output)
Right. So that is the name of the program that manages consoles in
Windows. I knew it was not cmd.exe itself. I was testing an
understanding that conhost.exe in Wine is essentially similar to GNU
screen, in that both emulate a console/terminal using a *nix terminal.
If so, then it should be possible to delegate the actual output
(including reductions like the example "\rA\rB\rC" to "\rC") to the
ncurses library and get proper sensitivity to TERM "for free" as well.
To do that, conhost.exe would need to translate the Windows console
buffer manipulations into curses operations, or possibly lower-level
terminfo operations, if you still want to roll your own optimization
code. If this were done, you could check if the current terminal has
sufficient support to properly emulate a Windows console and switch to
"raw" mode if the needed terminfo capabilities are not found. Setting
TERM=dumb in the environment would then force the use of "raw" mode.
but I agree that wine should provide a (simple) way to disable
windows' console for cases like this
Jacek Caban mentioned Windows pseudo-consoles, apparently a new
feature. Would those be a better "fit" for this type of scenario or are
they considerably more complex than POSIX ptys and the apparent
equivalence is false? Does the pseudo-console appear like a regular
console to the child process or does the child need special support to
run with a pseudo-console?
Alternately, could we have a "transparent" mode in conhost where most
processing is bypassed? Setting TERM=dumb in the environment could
reasonably activate this mode, or some other Wine-specific setting
could be used. (maybe "WINETERM=raw"?)
an alternate solution to Jacob's patch is to run wine with none of the
fd 0,1,2 opened on a (p)tty (assuming dejagnu doesn't require fd 0
from console). So something like ./wine what_ever_you_need | tee
/dev/null 2>1 < /dev/null would do
The problem with this solution in general is that Expect does not
normally use the shell to spawn subprocesses, although the shell could
be explicitly invoked (as "/bin/sh -c '...'"). Fortunately, in the
specific case that is causing this issue at the moment, the programs
tested are not being run interactively, so it would be possible to use
Tcl's open(n), which uses a pipe, instead of Expect's spawn, which uses
a pty. Running the program is done by a callback in testsuite code,
rather than the DejaGnu framework itself, so any patch here needs to be
applied to the testsuite. Note that this workaround only works for
non-interactive programs; it will not work when someone decides they
want to test MinGW GDB using Wine.
-- Jacob
