src/common/backend/catalog/aclchk.cpp

@@ -132,6 +132,9 @@ typedef struct {
     DropBehavior behavior;
 } InternalDefaultACL;
 
+/*
+ * Privileges information corresponding to different object types.
+ */
 const struct AclObjectType {
     GrantObjectType objtype;
     AclMode all_privileges;
@@ -574,6 +577,7 @@ void ExecuteGrantStmt(GrantStmt* stmt)
      * bitmask.  Note: objtype can't be ACL_OBJECT_COLUMN.
      */
     for (size_t idx = 0; idx < sizeof(acl_object_type) / sizeof(acl_object_type[0]); idx++) {
+        /* Set corresponding privileges according to object type. */
         if (acl_object_type[idx].objtype == stmt->objtype) {
             all_privileges = acl_object_type[idx].all_privileges;
             all_ddl_privileges = acl_object_type[idx].all_ddl_privileges;
@@ -672,7 +676,7 @@ void ExecuteGrantStmt(GrantStmt* stmt)
             }
         }
     }
-
+    /* Call privileges management function. */
     ExecGrantStmt_oids(&istmt);
 }
 
@@ -2102,9 +2106,10 @@ static void ExecGrant_Relation(InternalGrant* istmt)
     Relation relation = NULL;
     Relation attRelation = NULL;
     ListCell* cell = NULL;
-
+    /* Open system table pg_class and pg_attribute. */
     relation = heap_open(RelationRelationId, RowExclusiveLock);
     attRelation = heap_open(AttributeRelationId, RowExclusiveLock);
+    /* Loop through each Relation object. */
     foreach (cell, istmt->objects) {
         Oid relOid = lfirst_oid(cell);
         Datum aclDatum;
@@ -2125,10 +2130,12 @@ static void ExecGrant_Relation(InternalGrant* istmt)
         ListCell* cell_colprivs = NULL;
 
         tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relOid));
+        /* Check whether the table object to be operated exists. */
         if (!HeapTupleIsValid(tuple))
             ereport(ERROR, (errmodule(MOD_SEC), errcode(ERRCODE_CACHE_LOOKUP_FAILED),
                 errmsg("cache lookup failed for relation %u", relOid), errdetail("N/A"),
                     errcause("System error."), erraction("Contact engineer to support.")));
+        /* Get the pointer of the table to be operated. */
         pg_class_tuple = (Form_pg_class)GETSTRUCT(tuple);
 
         ExecGrantRelationTypeCheck(pg_class_tuple, istmt, &privileges, &ddl_privileges);
@@ -2381,7 +2388,7 @@ static void ExecGrant_Relation(InternalGrant* istmt)
         /* prevent error when processing duplicate objects */
         CommandCounterIncrement();
     }
-
+    /* Close system table pg_class and pg_attribute. */
     heap_close(attRelation, RowExclusiveLock);
     heap_close(relation, RowExclusiveLock);
 }