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RE: [Gnu-arch-users] Arch On Cygwin(Win32)

From: Parker, Ron
Subject: RE: [Gnu-arch-users] Arch On Cygwin(Win32)
Date: Thu, 13 Nov 2003 11:26:25 -0600

> -----Original Message-----
> From: Michael Grubb [mailto:address@hidden

> At 10:12 AM 11/13/2003, Naushit Sakarvadia wrote:
> >I also was working on Cygwin port.
> >and ran into >256 byte path limit
> >
> > > - fix Cygwin to support longer paths
> >
> >So this 256 bye path limit is Cygwin Limitation or Win32 ?
> >If its Cygwin problem. its serious and it should be fixed in Cygwin.

I had mentioned doing the necessary work to fix Cygwin in a previous thread.
However, my time outside of work has been running at about 2-3x overcommit.
Finally last night I noticed a temporary lull in this and began some of the
work on modifying Cygwin.  I still cannot promise a given timeframe but
thought a status update would be appropriate.

The necessary code in cygwin1.dll is now using Create{File,Directory}W
instead of Create{File,Directory} which are defined to be
Create{File,Directory}A.  It is also using the "\\?\" prefix which is
necessary to by pass the Win32-subsystem's file name parsing.  I have not
currently addressed the UNC case, where \\server\share\file needs to be
translated to \\?\UNC\server\share\file.  I will add this in once the
overall concept has proven itself on a local file system.

As an example mkdir and touch are no longer returning the generic system
error message resulting from cygwin1.dll returning an error code, they are
now giving their own error messages, because their internal file name
buffers are not large enough.  For the time being I am going to try to
recompile only those tools that tla directly depends upon, tar and such, and
see what happens.

> >So if we can get this fixed....Do you anybody know of any open issue?

No, but this issue may be a blocking one, with secondary issues lined up
behind it.

> >I dont understand why do you want to modify tar and gzip??
> >I never saw any problem with tar and gzip on cygwin. Am I missing
> >something??

I need to rebuild tar so that it can pick up the new MAXPATH value.  Some
tar files generated by archen have paths exceeding 260 characters, which is
the current Windows/Cygwin limit.  I have arbitrarily raised it to 4096 in
my code to match Linux even though Windows supports somewhere around ~32K.
The MS documentation is in conflict with itself and does not give an exact
limit, and I see no need to determine it experimentally since past
experience shows that various limits are not always consistent across
Windows versions.  Also, if we ever blow the Linux limit, there will be much
more significant issues than "tla doesn't work on Windows".

It may not be necessary to recompile gzip, if it is only being called as a
filter by tar.  However, if tla calls it directly on a file, it may need to
be rebuilt.  (I have not looked into this yet).


I hope this at least shows a glimmer of light at the end of the tunnel for
those wandering in the darkness of Windows.

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