unpack-trees: improve loading of .gitmodules

When recursing submodules 'check_updates()' needs to have strict control
over the submodule-config subsystem to ensure that the gitmodules file
has been read before checking cache entries which are marked for
removal as well ensuring the proper gitmodules file is read before
updating cache entries.

Because of this let's not rely on callers of 'check_updates()' to read
the gitmodules file before calling 'check_updates()' and handle the
reading explicitly.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

unpack-trees.c

@@ -1,5 +1,6 @@
 #define NO_THE_INDEX_COMPATIBILITY_MACROS
 #include "cache.h"
+#include "repository.h"
 #include "config.h"
 #include "dir.h"
 #include "tree.h"
@@ -268,22 +269,28 @@ static int check_submodule_move_head(const struct cache_entry *ce,
 	return 0;
 }
 
-static void reload_gitmodules_file(struct index_state *index,
-				   struct checkout *state)
+/*
+ * Preform the loading of the repository's gitmodules file.  This function is
+ * used by 'check_update()' to perform loading of the gitmodules file in two
+ * differnt situations:
+ * (1) before removing entries from the working tree if the gitmodules file has
+ *     been marked for removal.  This situation is specified by 'state' == NULL.
+ * (2) before checking out entries to the working tree if the gitmodules file
+ *     has been marked for update.  This situation is specified by 'state' != NULL.
+ */
+static void load_gitmodules_file(struct index_state *index,
+				 struct checkout *state)
 {
-	int i;
-	for (i = 0; i < index->cache_nr; i++) {
-		struct cache_entry *ce = index->cache[i];
-		if (ce->ce_flags & CE_UPDATE) {
-			int r = strcmp(ce->name, GITMODULES_FILE);
-			if (r < 0)
-				continue;
-			else if (r == 0) {
-				submodule_free();
-				checkout_entry(ce, state, NULL);
-				gitmodules_config();
-			} else
-				break;
+	int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
+
+	if (pos >= 0) {
+		struct cache_entry *ce = index->cache[pos];
+		if (!state && ce->ce_flags & CE_WT_REMOVE) {
+			repo_read_gitmodules(the_repository);
+		} else if (state && (ce->ce_flags & CE_UPDATE)) {
+			submodule_free();
+			checkout_entry(ce, state, NULL);
+			repo_read_gitmodules(the_repository);
 		}
 	}
 }
@@ -343,6 +350,10 @@ static int check_updates(struct unpack_trees_options *o)
 
 	if (o->update)
 		git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
+
+	if (should_update_submodules() && o->update && !o->dry_run)
+		load_gitmodules_file(index, NULL);
+
 	for (i = 0; i < index->cache_nr; i++) {
 		const struct cache_entry *ce = index->cache[i];
 
@@ -356,7 +367,7 @@ static int check_updates(struct unpack_trees_options *o)
 	remove_scheduled_dirs();
 
 	if (should_update_submodules() && o->update && !o->dry_run)
-		reload_gitmodules_file(index, &state);
+		load_gitmodules_file(index, &state);
 
 	for (i = 0; i < index->cache_nr; i++) {
 		struct cache_entry *ce = index->cache[i];