MXS-1203: Improve resultset processing functions

The functions used to track the resultset EOF packets now expose the
position of the end of the result set. This allows the modules that use
them to check if more results exist in the same buffer.

Added the status bits for OK and EOF packets to the mysql.h protocol
header. This can be used to check for various state changes that happen in
the session. Currently the status bits are only used to detect if more
results are expected.

include/maxscale/protocol/mysql.h

@@ -114,6 +114,22 @@ MXS_BEGIN_DECLS
 #define MYSQL_DATABASE_MAXLEN 128
 #define MYSQL_TABLE_MAXLEN    64
 
+/** Response packet status bits for OK and EOF packets */
+#define MXS_MYSQL_STATUS_IN_TRANS             0x0001
+#define MXS_MYSQL_STATUS_AUTOCOMMIT           0x0002
+#define MXS_MYSQL_MORE_RESULTS_EXISTS         0x0008
+#define MXS_MYSQL_STATUS_NO_GOOD_INDEX_USED   0x0010
+#define MXS_MYSQL_STATUS_NO_INDEX_USED        0x0020
+#define MXS_MYSQL_STATUS_CURSOR_EXISTS        0x0040
+#define MXS_MYSQL_STATUS_LAST_ROW_SENT        0x0080
+#define MXS_MYSQL_STATUS_DB_DROPPED           0x0100
+#define MXS_MYSQL_STATUS_NO_BACKSLASH_ESCAPES 0x0200
+#define MXS_MYSQL_STATUS_METADATA_CHANGED     0x0400
+#define MXS_MYSQL_QUERY_WAS_SLOW              0x0800
+#define MXS_MYSQL_PS_OUT_PARAMS               0x1000
+#define MXS_MYSQL_STATUS_IN_TRANS_READONLY    0x2000
+#define MXS_MYSQL_SESSION_STATE_CHANGED       0x4000
+
 #define GW_NOINTR_CALL(A)       do { errno = 0; A; } while (errno == EINTR)
 #define SMALL_CHUNK 1024
 #define MAX_CHUNK SMALL_CHUNK * 8 * 4
@@ -427,8 +443,25 @@ int mxs_mysql_send_ok(DCB *dcb, int sequence, uint8_t affected_rows, const char*
 /** Check for OK packet */
 bool mxs_mysql_is_ok_packet(GWBUF *buffer);
 
-/** Check for result set */
-bool mxs_mysql_is_result_set(GWBUF *buffer);
+/**
+ * @brief Check if a buffer contains a result set
+ *
+ * @param buffer Buffer to check
+ * @param offset Offset into the buffer
+ *
+ * @return True if the @c buffer at @c offset contains the start of a result set
+ */
+bool mxs_mysql_is_result_set(GWBUF *buffer, size_t offset);
+
+/**
+ * @brief Check if the OK packet is followed by another result
+ *
+ * @param buffer Buffer to check
+ * @param offset Offset into the buffer
+ *
+ * @return True if more results are expected
+ */
+bool mxs_mysql_more_results_after_ok(GWBUF *buffer, size_t extra_offset);
 
 /** Get current command for a session */
 mysql_server_cmd_t mxs_mysql_current_command(MXS_SESSION* session);