Re: [PATCH 3/4] repack: use tempfiles for signal cleanup

From: Jeff King <peff@peff.net>
Date: Oct 21, 2022, 23:24 UTC
Message-ID: <Y1MqPjnYoWcOgXo6@coredump.intra.peff.net>
In-Reply-To: <xmqqmt9oizcq.fsf@gitster.g>

On Fri, Oct 21, 2022 at 03:30:29PM -0700, Junio C Hamano wrote:

Show 29 quoted lines

> > @@ -867,8 +860,6 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
> >  		split_pack_geometry(geometry, geometric_factor);
> >  	}
> >  
> > -	sigchain_push_common(remove_pack_on_signal);
> > -
> >  	prepare_pack_objects(&cmd, &po_args);
> >  
> >  	show_progress = !po_args.quiet && isatty(2);
> > @@ -1020,14 +1011,14 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
> >  			fname_old = mkpathdup("%s-%s%s",
> >  					packtmp, item->string, exts[ext].name);
> >  
> > -			if (data->exts[ext]) {
> > +			if (data->tempfiles[ext]) {
> >  				struct stat statbuffer;
> >  				if (!stat(fname_old, &statbuffer)) {
> >  					statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
> >  					chmod(fname_old, statbuffer.st_mode);
> >  				}
> >  
> > -				if (rename(fname_old, fname))
> > +				if (rename_tempfile(&data->tempfiles[ext], fname))
> >  					die_errno(_("renaming '%s' failed"), fname_old);
> 
> It now got a bit confusing that we have 'fname', 'fname_old', and
> the tempfile.  The path.buf used as the argument to register_tempfile()
> matches what is used to compute fname_old above.  I wonder if tempfile
> API does not give us that name so that we can stop using fname_old here?

It does, and we probably should use get_tempfile_path() in the error message here. But sadly we can't get rid of fname_old entirely, as it's used below this for the second block in the if-else chain:

  if (data->tempfiles[ext]) {
     ...do the rename ...
  } else if (!exts[ext].optional)
	  die(_("missing required file: %s"), fname_old);
  else if (unlink(fname) < 0 && errno != ENOENT)
	  die_errno(_("could not unlink: %s"), fname);

OTOH, it would probably be equally readable (or perhaps even better) for that second block to say:

  die("pack-objects did not generate a '%s' file for pack %s",
      exts[ext].name, item->string);

And then we could drop fname_old entirely. Which is nice, because it gets rid of the implicit assumption that the tempfile matches what is in fname_old (which is always true, but since they are generated by individual lines far apart from each other, it's possible for that to change).

-Peff