🚀 go-pugleaf

"Duane A." <none@nowhere.com> wrote in message
news:43dfb314$1@newsgroups.borland.com...

> I'm trying to debug a recalcitrant C++Builder 6 app and had the
> brainstorm of writing a separate pipe server task to receive/
> log-to-file debug messages from it. Both programs would reside
> on the same machine.

An easier thing to do is to use the OutputDebugString() function instead.
You can then use a third-party viewer, such as DebugView from
http://www.sysinternals.com.

> I blithely thought that incorporating the client side into the buggy
> app would be a snap, but... I can only perform a single write into
> the pipe, using WriteFile(...) before it seems that I never get another
> I/O event signalling that the write was finished and the API is ready
> for another message.

After you call WriteFile(), DO NOT call GetLastError() in a loop!  Calling
ProcessMessages() can change the value that GetLastError() returns (since
ProcessMessage() calls other API functons internally), and that value will
have nothing to do with the I/O operation at all.  Also, using
GetLastError() to wait for an I/O operation to complete is the completely
wrong approach to take anyway.  If you take out the ProcessMessages() then
GetLastError() would not change value at all, so you would end up in an
endlesss loop.

Call GetLastError() ONCE and then use WaitForSingleObject() or
GetOverlappedResult() to perform the waiting.

Alternatively, get rid of the overlapped I/O altogether.  Then WriteFile()
will not return until the full data has been written (or an error occurs).


Gambit