Overlapped I/O on Win95

Overlapped I/O on Win95

Post by Tim Rober » Tue, 17 Feb 1998 04:00:00

I've forgotten whether I asked this here before...

On Windows NT, a kernel-mode driver can plop an error code into an
asynchronous pending ioctl IRP before completing it, and cause the
user-mode GetOverlappedResult to return a failure; the user can then call
GetLastError to fetch the error code.

I cannot find any way to do this from a Windows 95 VxD.  Is there any way a
VxD with a pending ioctl can cause GetOverlappedResult to return ANYTHING
other than success?

  Providenza & Boekelheide, Inc.


1. Overlapped and Non Overlapped I/O on Win95 and NT 4.0

It seems to me that NT 4.0 doesn't support non-overlapped I/O while Win95
supports both overlapped and non-overlappled I/O. At least it's the case
when using TAPI 1.4 in my test.

Once I connect my machines by TAPI 1.4. ReadFile() and WriteFile() don't
work if I pass null to the last parameter in these functions. The return
error code is 87, which is ERROR_INVALID_PARAMETER. Once I pass a valid
pointer to OVERLAPPED structure, things are fine. Win95 seems to work for

My questions are:
1. Does NT 4.0 have this problem (or feature)?
2. Would it make any differece if I switch to TAPI 2.1?

Thanks for any pointer.

Ping He

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