Re: [PATCH] reopen_tempfile(): truncate opened file

> On Tue, Sep 04, 2018 at 12:38:07PM -0400, Jeff King wrote:
> 
> > > And just to be clear I'm looking forward to a patch from Jeff to fix
> > > this since he clearly put more thoughts on this than me. With commit.c
> > > being the only user of reopen_lock_file() I guess it's even ok to just
> > > stick O_TRUNC in there and worry about O_APPEND when a new caller
> > > needs that.
> > 
> > That's the way I'm leaning to. The fix is obviously a one-liner, but I
> > was hoping to construct a minimal test case. I just haven't gotten
> > around to it yet.
> 
> It turned out not to be too bad to write a test. It feels a little like
> black magic, since I empirically determined a way in which the
> cache-tree happens to shrink with the current code. But that assumption
> is tested with a sanity check, so we'll at least know if it becomes a
> noop.
> 
> > The bug is ancient, so I don't think it's important for v2.19.
> 
> The patch below should work on master or maint. We could do a fix
> directly on top of the bug, but merging-up is weird (because the buggy
> code became part of a reusable module).