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Date: Tue, 8 Apr 2025 16:13:17 +0200
To: cygwin AT cygwin DOT com
Subject: Re: ftruncate() may fail with EISDIR if other process calls open()
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From: Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
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On Apr  8 13:50, Corinna Vinschen via Cygwin wrote:
> On Apr  7 09:59, Christian Franke via Cygwin wrote:
> > Found because 'stress-ng --fcntl 2 --verify' reports "ftruncate failed,
> > errno=21":
> 
> Thanks for the testcase.  I know what happens.  Stay tuned for a patch.

Nice problem.  That's what happens if you try to do what an OS is doing,
without actually being an OS, just a user space lib.  Theoretically we
should never cache any file information but always call the matching OS
functions.  Only... this adds quite a few context switches every time
accessing files.  Sigh.

I just pushed 2d81f6ebe3dc ("Cygwin: open: always fix up cached DOS file
attributes after NtCreateFile").

Try the upcoming cygwin-3.7.0-0.47.g9e6193576f34.


Thanks,
Corinna

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