Re: Unable to create temporary file '/var/git/tmv3-target-overlay.git/shallow_Un8ZOR': Permission denied

[Junio C Hamano <gitster@pobox.com>]

Johannes Schindelin <johannes.schindelin@gmx.de> writes:

>> A .git/tmp/ would make housekeeping easier, you would know that every
>> file under .git
>> should be there and if you find something you don't recognize you would react.
>
> No, it would actually make it harder. I seem to recall that there was
> some problem with renaming a file unless it was already in the same
> directory as the destination. If all files were to be written to
> .git/tmp/ first...

I agree with you here.  This "some filesystems do not like
cross-directory renames" was also why I thought the idea to create
everything in $GIT_DIR/tmp and moving to the final destination would
not fly well.

For the specific issue with the shallow-cutoff list temporarily
created, however, it is created, written to, read from and removed
without ever leaving the original place, so we could designate one
writable "temporary" place somewhere under $GIT_DIR, and $GIT_DIR/tmp
could certainly that designated temporary place.

By the way, the temporary shallow-cutoff-list is created by callingy
xmks_tempfile().  I wonder if it can safely changed to use
mks_tempfile() instead.  That way, people can set up a wrapper for
receive-pack that sets up a suitable TMPDIR exported to the real
thing to relocate it.