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

[Taylor Blau <me@ttaylorr.com>]

On Fri, Oct 21, 2022 at 07:24:46PM -0400, Jeff King wrote:
> On Fri, Oct 21, 2022 at 03:30:29PM -0700, Junio C Hamano wrote:
>
> > > @@ -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).

TBH, I've always found fname_old to be a confusing name. It's not really
"old", in fact we just had pack-objects write that file ;-). It really
does pertain to the tempfile, and I think using get_tempfile_path() when
we have a tempfile to rename is sensible.

I think that your proposed error message is good, too, and doubly so
since it lets us get rid of fname_old entirely. Yay :-).

> -Peff

Thanks,
Taylor