[Vm-dev] Identify console executable and standard one

[Ben Coman]

On 16 April 2018 at 21:17, Alistair Grant <akgrant0710 at gmail.com> wrote:

>
> Hi Eliot & Subbu,
>
> On 16 April 2018 at 05:50, K K Subbu <kksubbu.ml at gmail.com> wrote:
> >
> > On Sunday 15 April 2018 11:42 PM, Eliot Miranda wrote:
> >>>
> >>>
> >>> On Windows in sqFileStdioHandlesInto() in sqWin32FilePrims.c:
> >>>
> >>> files[0].sessionID = thisSession;
> >>> files[0].file = GetStdHandle(STD_INPUT_HANDLE);
> >>> files[0].writable = false;
> >>> files[0].lastOp = 0; /* unused on win32 */
> >>> files[0].isStdioStream = GetConsoleMode(files[0].file, &mode) != 0;
> >>> AddHandleToTable(win32Files, files[0].file);
> >>
> >>
> >> This could be causing problems, because AFAIA
> >> GetConsoleMode(files[0].file, &mode) is no longer reliable.  Can you
> test?
> >
> >
> > I believe _isatty(fd) from io.h is the syscall on Windows:
> >
> >  https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/isatty
> >
> > HTH .. Subbu
>
> Right, _isatty sounds like the more sensible call.  Just looking at
> the docs, the return value of GetConsoleMode() is simply whether it
> succeeded or not.
>
> However, in some quick tests it appears that both _isatty() and
> GetConsoleMode() return the correct value when called from a cmd.exe
> terminal window (I guess GetConsoleMode() fails if there isn't a
> terminal).  They both fail when called from a cygwin shell (mintty).
> It looks like vim (yes, the text editor) has some MIT licensed code
> that does the check correctly from within mintty.



I've was reading around this topic to see if I could find anything useful.
I haven't really got my head around it yet to tell what is directly related,
but here is the most interesting links I found...

How can I tell whether my console program was launched from Explorer or
from a command prompt?
https://blogs.msdn.microsoft.com/oldnewthing/20160125-00/?p=92922

What Is conhost.exe and Why Is It Running?
https://www.howtogeek.com/howto/4996/what-is-conhost.exe-and-why-is-it-running/

GetConsoleMode fails when input piped
http://comp.os.ms-windows.programmer.win32.narkive.com/xiPamaWm/getconsolemode-fails-when-input-piped

Both isatty() and GetConsoleScreenBufferInfo() fail with mintty 2.1.5 in
MSYS2 [okay with Cygwin]
https://github.com/mintty/mintty/issues/482

MSVC's native _isatty() thinks Cygwin Bash is a pipe, not an interactive
shell, because it just uses GetFileType() deep under the hood.
https://stackoverflow.com/questions/45223868/how-do-i-play-nice-with-cygwin

ReadConsole and WriteConsole can only be used with console handles;
ReadConsole and WriteConsole fail if used with a standard handle that has
been redirected and is no longer a console handle.
ReadFile and WriteFile can be used with other handles (such as files or
pipes).
https://docs.microsoft.com/en-us/windows/console/high-level-console-input-and-output-functions

 "GetConsoleMode error: 6" when running under Unix emulation environments
such as cygwin and msys.
What this means is that GetConsoleMode is being called on an invalid file
handle (STD_INPUT_HANDLE).
https://lists.osuosl.org/pipermail/darcs-users/2004-June/002104.html

Windows: Improve terminal detection mechanism
https://phabricator.haskell.org/D2809
https://github.com/git/git/blob/0767172b9068b225c06fd7ce66422e5936ec60a2/compat/winansi.c#L534-L571
https://fossies.org/linux/vim/src/iscygpty.c
https://hackage.haskell.org/package/base-4.6.0.0/src/cbits/consUtils.c

Cunningly conquering communicated console caveats. Comprende, mon Capitán?
http://archives.miloush.net/michkap/archive/2010/05/07/10008232.html

What does CreateFile(“CONIN$” ..) do?
https://stackoverflow.com/questions/377152/what-does-createfileconin-do?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa

The CreateFile function enables a process to get a handle to its console's
input buffer and active screen buffer, even if STDIN and STDOUT have been
redirected. To open a handle to a console's input buffer, specify the
CONIN$ value in a call to CreateFile
https://docs.microsoft.com/en-us/windows/console/console-handles

Where do writes to stdout go when launched from a cygwin shell, no
redirection
https://stackoverflow.com/questions/4028353/where-do-writes-to-stdout-go-when-launched-from-a-cygwin-shell-no-redirection


How to create a Windows program that works both as a GUI and console
application
https://www.tillett.info/2013/05/13/how-to-create-a-windows-program-that-works-as-both-as-a-gui-and-console-application/


cheers -ben
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