MDEV-31521 bzero wipes more bytes than necessary in set_global_from_ddl_log_entry.

'defaults' made into 'constexpr' variables.

Author: Alexey Botchkov

sql/ddl_log.cc

@@ -141,43 +141,43 @@ static st_ddl_recovery   recovery_state;
 mysql_mutex_t LOCK_gdl;
 
 /* Positions to different data in a ddl log block */
-#define DDL_LOG_ENTRY_TYPE_POS 0
+static constexpr unsigned DDL_LOG_ENTRY_TYPE_POS= 0;
 /*
   Note that ACTION_TYPE and PHASE_POS must be after each other.
   See update_phase()
 */
-#define DDL_LOG_ACTION_TYPE_POS 1
-#define DDL_LOG_PHASE_POS 2
-#define DDL_LOG_NEXT_ENTRY_POS 4
+static constexpr unsigned DDL_LOG_ACTION_TYPE_POS= 1;
+static constexpr unsigned DDL_LOG_PHASE_POS= 2;
+static constexpr unsigned DDL_LOG_NEXT_ENTRY_POS= 4;
 /* Flags to remember something unique about the query, like if .frm was used */
-#define DDL_LOG_FLAG_POS 8
+static constexpr unsigned DDL_LOG_FLAG_POS= 8;
 /* Used to store XID entry that was written to binary log */
-#define DDL_LOG_XID_POS 10
+static constexpr unsigned DDL_LOG_XID_POS= 10;
 /* Used to store unique uuid from the .frm file */
-#define DDL_LOG_UUID_POS 18
+static constexpr unsigned DDL_LOG_UUID_POS= 18;
 /* ID_POS can be used to store something unique, like file size (4 bytes) */
-#define DDL_LOG_ID_POS DDL_LOG_UUID_POS + MY_UUID_SIZE
-#define DDL_LOG_END_POS DDL_LOG_ID_POS + 8
+static constexpr unsigned DDL_LOG_ID_POS= DDL_LOG_UUID_POS + MY_UUID_SIZE;
+static constexpr unsigned DDL_LOG_END_POS= DDL_LOG_ID_POS + 8;
 
 /*
   Position to where names are stored in the ddl log blocks. The current
   value is stored in the header and can thus be changed if we need more
   space for constants in the header than what is between DDL_LOG_ID_POS and
   DDL_LOG_TMP_NAME_POS.
 */
-#define DDL_LOG_TMP_NAME_POS 56
+static constexpr unsigned DDL_LOG_TMP_NAME_POS= 56;
 
 /* Definitions for the ddl log header, the first block in the file */
 /* IO_SIZE is stored in the header and can thus be changed */
-#define DDL_LOG_IO_SIZE IO_SIZE
+static constexpr unsigned DDL_LOG_IO_SIZE= IO_SIZE;
 
 /* Header is stored in positions 0-3 */
-#define DDL_LOG_IO_SIZE_POS 4
-#define DDL_LOG_NAME_OFFSET_POS 6
+static constexpr unsigned DDL_LOG_IO_SIZE_POS= 4;
+static constexpr unsigned DDL_LOG_NAME_OFFSET_POS= 6;
 /* Marks if we have done a backup of the ddl log */
-#define DDL_LOG_BACKUP_OFFSET_POS 8
+static constexpr unsigned DDL_LOG_BACKUP_OFFSET_POS= 8;
 /* Sum of the above variables */
-#define DDL_LOG_HEADER_SIZE 4+2+2+1
+static constexpr unsigned DDL_LOG_HEADER_SIZE= 4+2+2+1;
 
 /**
   Sync the ddl log file.