-Fix MDEV-4878. Table locking is now supported.

modified:
  storage/connect/ha_connect.cc
  storage/connect/ha_connect.h
  storage/connect/plgdbsem.h

- Fiw a bug making records_in_range sometimes return a negative
  value.

modified:
  storage/connect/xindex.cpp

storage/connect/ha_connect.h

@@ -406,6 +406,7 @@ const char *GetValStr(OPVAL vop, bool neg);
   void position(const uchar *record);                           ///< required
   int info(uint);                                               ///< required
   int extra(enum ha_extra_function operation);
+  int start_stmt(THD *thd, thr_lock_type lock_type);
   int external_lock(THD *thd, int lock_type);                   ///< required
   int delete_all_rows(void);
   ha_rows records_in_range(uint inx, key_range *min_key,
@@ -435,6 +436,7 @@ const char *GetValStr(OPVAL vop, bool neg);
 
 protected:
   bool check_privileges(THD *thd, PTOS options);
+  MODE CheckMode(PGLOBAL g, THD *thd, MODE newmode, bool *chk, bool *cras);
 
   // Members
   static ulong  num;                  // Tracable handler number
@@ -452,6 +454,7 @@ const char *GetValStr(OPVAL vop, bool neg);
   bool          valid_info;           // True if xinfo is valid
   bool          stop;                 // Used when creating index
   int           indexing;             // Type of indexing for CONNECT
+  int           locked;               // Table lock
   THR_LOCK_DATA lock_data;
 
 public:

storage/connect/plgdbsem.h

@@ -151,7 +151,8 @@ enum ALGMOD {AMOD_AUTO =  0,          /* PLG chooses best algorithm    */
 #define    NAM_LEN          128
 #endif // !0
 
-enum MODE {MODE_ANY     =  0,         /* Unspecified mode              */
+enum MODE {MODE_ERROR   = -1,         /* Invalid mode                  */
+           MODE_ANY     =  0,         /* Unspecified mode              */
            MODE_READ    = 10,         /* Input/Output mode             */
            MODE_WRITE   = 20,         /* Input/Output mode             */
            MODE_UPDATE  = 30,         /* Input/Output mode             */

storage/connect/xindex.cpp

@@ -1832,8 +1832,9 @@ int XINDXS::Range(PGLOBAL g, int limit, bool incl)
   /*********************************************************************/
   if (xp->GetType() == TYPE_CONST) {
     kp->Valp->SetValue_pval(xp->GetValue(), !kp->Prefix);
+    k = FastFind(Nval);
 
-    if ((k = FastFind(Nval)) < Num_K)
+    if (k < Num_K || Op != OP_EQ)
       if (limit)
         n = (Mul) ? k : kp->Val_K;
       else