Re: change in handling quotes in cygwin package from 3.1.4-1 to 3.1.5-1

[Josh Thompson <josh_thompson@ncsu.edu>]

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> > On Monday, June 22, 2020 4:11:35 PM EDT Ken Brown wrote:
> > > On 6/15/2020 12:21 PM, Josh Thompson wrote:
> > > > We recently noticed a change in double quote (") handling that is
> > > > causing
> > > > a
> > > 
> > > > command we issue to fail.  The command is:
> > > [...]
> > > 
> > > > 3.1.4:
> > > > $ cmd.exe /c "echo \""
> > > > "
> > > > 
> > > > 3.1.5:
> > > > $ cmd.exe /c "echo \""
> > > > \"
> > > 
> > > I can confirm this change in behavior, and I thought it would be
> > > completely
> > > trivial to do a bisection to find the commit that caused it. 
> > > Unfortunately, it seems that the issue is somehow tied up with the fact
> > > that the toolchain used for building the cygwin package was upgraded
> > > shortly after the release of 3.1.4.
> > > 
> > > An attempt to rebuild 3.1.4 with the current toolchain fails because of
> > > some gcc/binutils changes.  So I applied the attached patches, which
> > > were applied to the Cygwin git master shortly after the release of
> > > 3.1.4, in order to make the build succeed.
> > > 
> > > After installing the rebuilt 3.1.4, however, the cmd.exe call above
> > > exhibits the "3.1.5" behavior rather than the "3.1.4" behavior.  I
> > > can't see anything in the patches that would explain this.  I thought
> > > maybe it was a compiler optimization problem, but rebuilding without
> > > optimization doesn't change anything.
> > > 
> > > I'm stumped.
> > > 
> > > Ken
> > 
> > Hi Ken,
> > 
> > Thanks for your testing on this and for following up.  How strange - I
> > totally wouldn't have expected a toolchain upgrade to have changed how
> > quotes get handled.
> > 
> > It sounds like it will be difficult to change the quote behavior.  So,
> > we'll work to get VCL updated to handle the new behavior.
> 
> I have a fix for that.  It's a long standing bug, a buffer overrun,
> which seem to have had no effect pre-3.1.5 only because the older GCC
> toolchain had a subtily different stack allocation strategy.
> 
> I uploaded developer snapshots to https://cygwin.com/snapshots/
> for testing.  Please give this a try and report back.
> 
> If this fixes your problem, the bug is serious enough to qualify for
> a Cygwin 3.1.6 RSN.
> 
> 
> Thanks,
> Corinna

Hi Corinna,

Thank you for this!  I can confirm that replacing cygwin1.dll with the 
cygwin1-20200706.dll that you uploaded to the snapshot site fixes the quote 
issue.

I upgraded an installation I had to 3.1.5-1 and tested that I was seeing the 
problem by running

cmd.exe /c "echo \""
\"

Next, I downloaded, uncompressed, and overwrote cygwin1.dll with 
cygwin1-20200706.dll and tested again

cmd.exe /c "echo \""
"

Great job working through that issue.

Josh
-- 
-------------------------------
Josh Thompson
Systems Programmer
Virtual Computing Lab (VCL)
North Carolina State University

Josh_Thompson@ncsu.edu
919-515-5323

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