Named pipes/VDMs

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2 total messages Started by Steven Mathers Wed, 14 Dec 1994 04:30

#21

Author: Steven Mathers
Date: Wed, 14 Dec 1994 04:30

22 lines
1689 bytes

Hi.  Ive got an os2 program communicating via a named pipe with a 
DOS program written in Borland Pascal (I know, I cant help it) 
running in a VDM.

Heres the problem:

The Pascal function I am using in the DOS program to read data from the pipe 
is BlockRead.  This function returns either the number of bytes read
into a buffer, or 0 if there is no data available.  This works fine
in a normal DOS environment, reading from a normal file, but when
I tried it in the VDM talking to the pipe, instead of returning 0 when
there is no data to be read, it just hangs until there is data to be
read, just like a blocking function.  I cant have this - I need the
program doing other stuff while there is no data to be processed in the
pipe.

So:  Why is this happening, and how can I get around it?

Thanks everybody!

Steve Mathers
s.mathers@trl.oz.au

Re: Named pipes/VDMs

#22

Author: Golan Yaniv
Date: Thu, 15 Dec 1994 10:21

30 lines
1909 bytes

Steven Mathers (mathers@sibelius.trl.OZ.AU) wrote:
: Hi.  Ive got an os2 program communicating via a named pipe with a
: DOS program written in Borland Pascal (I know, I cant help it)
: running in a VDM.

: Heres the problem:

: The Pascal function I am using in the DOS program to read data from the pipe
: is BlockRead.  This function returns either the number of bytes read
: into a buffer, or 0 if there is no data available.  This works fine
: in a normal DOS environment, reading from a normal file, but when
: I tried it in the VDM talking to the pipe, instead of returning 0 when
: there is no data to be read, it just hangs until there is data to be
: read, just like a blocking function.  I cant have this - I need the
: program doing other stuff while there is no data to be processed in the
: pipe.

: So:  Why is this happening, and how can I get around it?

: Thanks everybody!

: Steve Mathers
: s.mathers@trl.oz.au

VDMs support a subset of the Named Pipes API. Look in Ralph Brown's 
Interrupts List.

--

Yaniv Golan  | s2942275@techst02.technion.ac.il

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