midx: close multi-pack-index on repack

When repacking, we may remove pack-files. This invalidates the
multi-pack-index (if it exists). Previously, we removed the
multi-pack-index file before removing any pack-file. In some cases,
the repack command may load the multi-pack-index into memory. This
may lead to later in-memory references to the non-existent pack-
files.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/repack.c

@@ -431,8 +431,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 			char *fname, *fname_old;
 
 			if (!midx_cleared) {
-				/* if we move a packfile, it will invalidated the midx */
-				clear_midx_file(get_object_directory());
+				clear_midx_file(the_repository);
 				midx_cleared = 1;
 			}
 

midx.c

@@ -180,9 +180,13 @@ cleanup_fail:
 	return NULL;
 }
 
-static void close_midx(struct multi_pack_index *m)
+void close_midx(struct multi_pack_index *m)
 {
 	uint32_t i;
+
+	if (!m)
+		return;
+
 	munmap((unsigned char *)m->data, m->data_len);
 	close(m->fd);
 	m->fd = -1;
@@ -917,9 +921,14 @@ cleanup:
 	return 0;
 }
 
-void clear_midx_file(const char *object_dir)
+void clear_midx_file(struct repository *r)
 {
-	char *midx = get_midx_filename(object_dir);
+	char *midx = get_midx_filename(r->objects->objectdir);
+
+	if (r->objects && r->objects->multi_pack_index) {
+		close_midx(r->objects->multi_pack_index);
+		r->objects->multi_pack_index = NULL;
+	}
 
 	if (remove_path(midx)) {
 		UNLEAK(midx);

midx.h

@@ -42,6 +42,8 @@ int midx_contains_pack(struct multi_pack_index *m, const char *idx_name);
 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local);
 
 int write_midx_file(const char *object_dir);
-void clear_midx_file(const char *object_dir);
+void clear_midx_file(struct repository *r);
+
+void close_midx(struct multi_pack_index *m);
 
 #endif