Re: [PATCH 3/4] tmp-objdir: preserve errno when directory creation fails

[Patrick Steinhardt <ps@pks.im>]

On Mon, Nov 09, 2026 at 06:22:50PM -0600, Justin Tobler wrote:
> diff --git a/tmp-objdir.c b/tmp-objdir.c
> index 5307717354..4b91d86787 100644
> --- a/tmp-objdir.c
> +++ b/tmp-objdir.c
> @@ -148,10 +148,13 @@ static int setup_tmp_objdir(const char *root)
>  {
>  	char *path;
>  	int ret = 0;
> +	int saved_errno;
>  
>  	path = xstrfmt("%s/pack", root);
>  	ret = mkdir(path, 0777);
> +	saved_errno = errno;
>  	free(path);
> +	errno = saved_errno;
>  
>  	return ret;
>  }

This whole function here is somewhat pointless, it's only really
required because memory handling would otherwise be awkward. That
could've been avoided if its only caller had a single return path, but
it doesn't.

No need to fix that as part of your patch series though, if you ask me.

> @@ -163,6 +166,7 @@ struct tmp_objdir *tmp_objdir_create(struct repository *r,
>  	struct odb_source_files *files = odb_source_files_downcast(r->objects->source);
>  	static int installed_handlers;
>  	struct tmp_objdir *t;
> +	int saved_errno;
>  
>  	if (the_tmp_objdir)
>  		BUG("only one tmp_objdir can be used at a time");

This could've been a local variable in each of the two blocks, but okay.

> @@ -185,8 +189,10 @@ struct tmp_objdir *tmp_objdir_create(struct repository *r,
>  		chdir_notify_register(tmp_objdir_reparent, t);
>  
>  	if (!mkdtemp(t->path.buf)) {
> +		saved_errno = errno;
>  		/* free, not destroy, as we never touched the filesystem */
>  		tmp_objdir_free(t);
> +		errno = saved_errno;
>  		return NULL;
>  	}
>  
> @@ -197,7 +203,9 @@ struct tmp_objdir *tmp_objdir_create(struct repository *r,
>  	}
>  
>  	if (setup_tmp_objdir(t->path.buf)) {
> +		saved_errno = errno;
>  		tmp_objdir_destroy(t);
> +		errno = saved_errno;
>  		return NULL;
>  	}

Okay, both early returns are adapted in the same way. Makes sense.

Patrick