Re: How to detect when a console child process is waiting for input?

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

On Mon, 2 May 2005 15:34:16 +0800, "Alex Hong" <hctiaa@xxxxxxxx>
wrote:

>I am writing a program that tests console programs by creating them as child
>processes and redirecting their input/output. And I would like to know when
>the console child process is waiting for input, so that I can give them
>input at a proper time. But the MSDN library only offers a
>WaitForInputIdle() function which will always return true with a console
>program. Is there any way to decide if the child process is waiting for
>input?

When a console is waiting for input, it is generally in ReadConsoleW()
(I'm not sure if this is true if you've redirected its input to a
pipe, but the same general method should work; more info below.)

1) Create a named event to check in your monitoring program.

2) Make your program a debugger, and when loading the destination
console app, redirect ReadConsoleW in its import table to a routine of
your own (which you have injected into the process). I have seen
articles on MSDN describing how to do this.

3) This injected routine should set an event then call the real
ReadConsoleW(). In your monitoring program, the event will be signaled
when the console is waiting for input.

If a console program reading from a pipe uses a call other than
ReadConsoleW (I haven't checked), you'll need to redirect that call
and verify that it is reading from your pipe (perhaps by using a
named, rather than anonymous, pipe) before calling SetEvent.

Another option would be for your monitoring program to set a
breakpoint on ReadConsoleW; then immediately continue the monitored
process and write to its input.

This is all rather complicated; if I think of an easier method I'll
post again.

--
Phillip Crews aka Severian
Microsoft MVP, Windows SDK
Posting email address is real, but please post replies on the newsgroup.
.

Relevant Pages

  • Re: How to detect when a console child process is waiting for input?
    ... >>>the console child process is waiting for input, so that I can give them ... >> When a console is waiting for input, it is generally in ReadConsoleW() ... you'll need to redirect that call ...
    (microsoft.public.win32.programmer.kernel)
  • Re: How to detect when a console child process is waiting for input?
    ... >>the console child process is waiting for input, so that I can give them ... > When a console is waiting for input, it is generally in ReadConsoleW() ... you'll need to redirect that call ...
    (microsoft.public.win32.programmer.kernel)
  • [RFC][PATCH] fix xconsole.
    ... The console messages may only be redirected once, and root may perform ... TIOCCONS security ... The ioctl TIOCCONS allows any user to redirect console output to another ...
    (Linux-Kernel)
  • Re: Windows CE redirected console
    ... Just like the TELNETD does not replace anything, the CONSOLED is a stand alone Service/Driver instance that doing no more than redirect IO into COM port. ... And it does not depends on OutputTo registry but may need its own way to configure the setting. ... Intel IXP425 line but the console service should be platform neutral) ...
    (microsoft.public.windowsce.platbuilder)
  • Re: How to detect when a console child process is waiting for input?
    ... the console child process is waiting for input, so that I can give them ... WaitForInputIdlefunction which will always return true with a console ... Create a named event to check in your monitoring program. ... you'll need to redirect that call ...
    (microsoft.public.win32.programmer.kernel)