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Date: Tue, 9 Apr 2024 23:14:54 +0200
To: cygwin AT cygwin DOT com
Subject: Re: Win32 FILE_BASIC_INFORMATION.*Time.QuadPart - which value should
 be used if filesystem does not support it,
 so Cygwin /usr/bin/stat lists the value as '-'?
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From: Corinna Vinschen via Cygwin <cygwin AT cygwin DOT com>
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On Apr  5 04:26, Martin Wege via Cygwin wrote:
> On Fri, Apr 5, 2024 at 2:05 AM Martin Wege <martin DOT l DOT wege AT gmail DOT com> wrote:
> >
> > Hello,
> >
> > I have problems with debugging, so a quick help would be appreciated,
> > as I cannot figure this out after several hours of digging.
> >
> > Cygwin /usr/bin/stat returns "Birth: -" for some files. Which value
> > must the CreationTime member of FILE_BASIC_INFORMATION have to cause
> > /usr/bin/stat ti return "-"? 0, -1, or something else?
> 
> In a related matter:
> The Win32 FILE_BASIC_INFORMATION structure defines four time values:
> 
> LARGE_INTEGER CreationTime;
> LARGE_INTEGER LastAccessTime;
> LARGE_INTEGER LastWriteTime;
> LARGE_INTEGER ChangeTime;
> 
> How can a filesystem indicate if it does not support a particular
> timestamp, such as ChangeTime? Should ChangeTime.QuadPart then be -1,
> -2 or 0, or another value?

I'm not aware of a filesystem not supporting ChangeTime, that is,
st_ctime.  Usually only CreationTime (st_birthtime) is missing.

I think setting the timestamp to 0 works for indicating that this kind
of timestamp is not supported.  Cygwin is handling Windows timestamps
this way, but I can't find this in documentation ATM.

But the FS driver can also just fill the CreationTime field with the
same value as LastWriteTime or ChangeTime.  MSFT NFS does that.


Corinna

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