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From: Brian Inglis <Brian DOT Inglis AT SystematicSw DOT Invalid>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Using DR-DOS fork in DJGPP
Organization: Systematic Software
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Date: Mon, 24 May 2004 08:45:59 GMT
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To: djgpp AT delorie DOT com
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On 24 May 2004 07:49:48 +0200 in comp.os.msdos.djgpp, Eli Zaretskii
<eliz AT gnu DOT org> wrote:

>> From: Brian Inglis <Brian DOT Inglis AT SystematicSw DOT Invalid>
>> Newsgroups: comp.os.msdos.djgpp
>> Date: Mon, 24 May 2004 00:11:44 GMT
>> 
>> Alternatively, the fork routine, after copying the VM, has to look at
>> the child process' file handle table, and reestablish the open file
>> handles. 
>
>I don't see how this could be done, at least not easily.  We don't
>need just to have the same file open, we need their file handles to
>refer to the same entry in the DOS System File Table (SFT), so that if
>the child moves the file position (by, e.g., reading or seeking into
>the file), the file position of the parent is moved as well to the
>same place.  I.e., we need the equivalent of the `dup' system call
>(except that we cannot call `dup' because it doesn't work with handles
>from another process).
>
>Therefore, if the DR-DOS's fork doesn't handle these problems, there's
>no way we could, unless we know enough about DR-DOS internals to
>manipulate the SFT entries directly.

Precisely my point. 

-- 
Thanks. Take care, Brian Inglis 	Calgary, Alberta, Canada

Brian DOT Inglis AT CSi DOT com 	(Brian dot Inglis at SystematicSw dot ab dot ca)
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