[PATCH v2 0/3] merge-ll: Cleanup merge driver temporaries after

[Jeff King <peff@peff.net>]

On Fri, Sep 11, 2026 at 04:43:08PM +0200, Michal Koutný wrote:

> > In the worst case we can just call register_tempfile() on each path, but
> > I think this code could be taught to use the actual creation. Something
> > like the patch below (only lightly tested).
> 
> I've tested it and it works (cleans up both after SIGINT and regular
> termination).

Thanks for testing. I considered putting something in the test suite,
but it gets ugly (we'd have the external driver pause, signal a fifo,
then kill git-merge and it with SIGINT). I guess an alternative would be
setting GIT_ALLOC_LIMIT to something low, and then generating a
too-large output, which would cause xmalloc() to fail, which I believe
would also fail. But then we're not really testing the signal handling.

Hmm. I wonder if leaving the files could actually be a _feature_. If you
completed the merge with the external tool but we barfed reading it back
in, would it be useful to leave the file in place? It's possible, I
suppose, but I think it is more likely to be a nuisance (and we already
delete it for things like read() errors, just not anything that would
cause us to die()).

> (There's only a warning about constness, one should not change the
> tempfile's path buffer. But here the ovewrite happens only if there were
> trialing dirseps, which they aren't as the filename is under control.)

Yeah, I've fixed it in this iteration, plus a few tweaks:

 - I did the strbuf cleanup I mentioned (patch 1)

 - we should be using close_tempfile_gently() instead of close() on the
   tempfiles so that they don't get double-closed when deleting

 - that made me notice a small error-checking bug in the original code,
   fixed in patch 2

> Do you want me to send your variant as v2 or will you?

Here it is. I've labeled it v2, and I stole your commit message for the
third patch.

  [1/3]: merge-ll: use strbuf to read back external merge result
  [2/3]: merge-ll: catch close() errors when writing external tempfiles
  [3/3]: merge-ll: use tempfile API for external driver files

 merge-ll.c | 68 +++++++++++++++++++++++++++++-------------------------
 1 file changed, 37 insertions(+), 31 deletions(-)

-Peff