branches/zip: Clean up index->to_be_dropped after a failed DROP INDEX.

ha_innobase::final_drop_index(): If row_merge_drop_table() fails, clear
the to_be_dropped flags.  This was the error fixed in this commit; the rest
is just additional safety.

ha_innobase::final_drop_index(): After dropping the flagged indexes,
assert that none of the remaining indexes are flagged to_be_dropped.

ha_innobase::prepare_drop_index(): Assert that no index has been flagged
for deletion.  When checking foreign key constraints, simply traverse the
list of indexes and check if any of the indexes that were just flagged
to_be_dropped.  On error, clear the to_be_dropped flags with simple list
traversal.

handler/handler0alter.cc

@@ -939,6 +939,17 @@ ha_innobase::prepare_drop_index(
 
 	row_mysql_lock_data_dictionary(trx);
 
+	/* Check that none of the indexes have previously been flagged
+	for deletion. */
+	{
+		const dict_index_t*	index
+			= dict_table_get_first_index(prebuilt->table);
+		do {
+			ut_a(!index->to_be_dropped);
+			index = dict_table_get_next_index(index);
+		} while (index);
+	}
+
 	for (n_key = 0; n_key < num_of_keys; n_key++) {
 		const KEY*	key;
 		dict_index_t*	index;
@@ -986,17 +997,16 @@ ha_innobase::prepare_drop_index(
 
 	if (trx->check_foreigns
 	    && thd_sql_command(user_thd) != SQLCOM_CREATE_INDEX) {
-		for (n_key = 0; n_key < num_of_keys; n_key++) {
-			KEY*		key;
-			dict_index_t*	index;
-			dict_foreign_t* foreign;
+		dict_index_t*	index
+			= dict_table_get_first_index(prebuilt->table);
 
-			key = table->key_info + key_num[n_key];
-			index = dict_table_get_index_on_name_and_min_id(
-				prebuilt->table, key->name);
+		do {
+			dict_foreign_t*	foreign;
 
-			ut_a(index);
-			ut_a(index->to_be_dropped);
+			if (!index->to_be_dropped) {
+
+				goto next_index;
+			}
 
 			/* Check if the index is referenced. */
 			foreign = dict_table_get_referenced_constraint(
@@ -1033,24 +1043,22 @@ index_needed:
 					}
 				}
 			}
-		}
+
+next_index:
+			index = dict_table_get_next_index(index);
+		} while (index);
 	}
 
 func_exit:
 	if (err) {
-		/* Undo our changes since there was some sort of error */
-		for (n_key = 0; n_key < num_of_keys; n_key++) {
-			const KEY*	key;
-			dict_index_t*	index;
+		/* Undo our changes since there was some sort of error. */
+		dict_index_t*	index
+			= dict_table_get_first_index(prebuilt->table);
 
-			key = table->key_info + key_num[n_key];
-			index = dict_table_get_index_on_name_and_min_id(
-				prebuilt->table, key->name);
-
-			if (index) {
-				index->to_be_dropped = FALSE;
-			}
-		}
+		do {
+			index->to_be_dropped = FALSE;
+			index = dict_table_get_next_index(index);
+		} while (index);
 	}
 
 	row_mysql_unlock_data_dictionary(trx);
@@ -1107,6 +1115,16 @@ ha_innobase::final_drop_index(
 
 	if (UNIV_UNLIKELY(err)) {
 
+		/* Unmark the indexes to be dropped. */
+		row_mysql_lock_data_dictionary(trx);
+
+		for (index = dict_table_get_first_index(prebuilt->table);
+		     index; index = dict_table_get_next_index(index)) {
+
+			index->to_be_dropped = FALSE;
+		}
+
+		row_mysql_unlock_data_dictionary(trx);
 		goto func_exit;
 	}
 
@@ -1131,6 +1149,12 @@ ha_innobase::final_drop_index(
 		index = next_index;
 	}
 
+	/* Check that all flagged indexes were dropped. */
+	for (index = dict_table_get_first_index(prebuilt->table);
+	     index; index = dict_table_get_next_index(index)) {
+		ut_a(!index->to_be_dropped);
+	}
+
 #ifdef UNIV_DEBUG
 	dict_table_check_for_dup_indexes(prebuilt->table);
 #endif