MDEV-9949 Connect Engine: long SRCDEF leads to broken table

Two bugs here:
* the server could create an frm (with a long attribute
  value) that it could not read back
* Connect engine opened files from inside DROP TABLE
  and was ignoring the error (correctly) but was not
  hiding it from the server (incorrectly). This caused
  a crash later when DROP TABLE was finishing successfully
  while stmt_da already have seen an error.

Also added a text case for
  MDEV-7935 CREATE TABLE ... AS SELECT ... can cause a Server crash (Assertion `0' in Protocol::end_statement)
because Connect stopped clearing the error status
in stmt_da as a fix for MDEV-7935

sql/create_options.h

@@ -23,7 +23,8 @@
 #define SQL_CREATE_OPTIONS_INCLUDED
 
 #include "sql_class.h"
-//#include "handler.h"
+
+enum { ENGINE_OPTION_MAX_LENGTH=32767 };
 
 class engine_option_value: public Sql_alloc
 {

sql/share/errmsg-utf8.txt

@@ -6506,8 +6506,8 @@ ER_PARTITION_EXCHANGE_FOREIGN_KEY
   swe "Tabellen att byta ut mot partition har foreign key referenser: '%-.64s'"
 ER_NO_SUCH_KEY_VALUE
   eng "Key value '%-.192s' was not found in table '%-.192s.%-.192s'"
-ER_RPL_INFO_DATA_TOO_LONG
-  eng "Data for column '%s' too long"
+ER_VALUE_TOO_LONG
+  eng "Too long value for '%s'"
 ER_NETWORK_READ_EVENT_CHECKSUM_FAILURE
   eng "Replication event checksum verification failed while reading from network."
 ER_BINLOG_READ_EVENT_CHECKSUM_FAILURE

sql/sql_yacc.yy

@@ -5730,12 +5730,16 @@ create_table_option:
           }
         | IDENT_sys equal TEXT_STRING_sys
           {
+            if ($3.length > ENGINE_OPTION_MAX_LENGTH)
+              my_yyabort_error((ER_VALUE_TOO_LONG, MYF(0), $1.str));
             new (thd->mem_root)
               engine_option_value($1, $3, true, &Lex->create_info.option_list,
                                   &Lex->option_list_last);
           }
         | IDENT_sys equal ident
           {
+            if ($3.length > ENGINE_OPTION_MAX_LENGTH)
+              my_yyabort_error((ER_VALUE_TOO_LONG, MYF(0), $1.str));
             new (thd->mem_root)
               engine_option_value($1, $3, false, &Lex->create_info.option_list,
                                   &Lex->option_list_last);
@@ -6440,12 +6444,16 @@ attribute:
           }
         | IDENT_sys equal TEXT_STRING_sys
           {
+            if ($3.length > ENGINE_OPTION_MAX_LENGTH)
+              my_yyabort_error((ER_VALUE_TOO_LONG, MYF(0), $1.str));
             new (thd->mem_root)
               engine_option_value($1, $3, true, &Lex->last_field->option_list,
                                   &Lex->option_list_last);
           }
         | IDENT_sys equal ident
           {
+            if ($3.length > ENGINE_OPTION_MAX_LENGTH)
+              my_yyabort_error((ER_VALUE_TOO_LONG, MYF(0), $1.str));
             new (thd->mem_root)
               engine_option_value($1, $3, false, &Lex->last_field->option_list,
                                   &Lex->option_list_last);
@@ -6834,12 +6842,16 @@ all_key_opt:
           { Lex->last_key->key_create_info.comment= $2; }
         | IDENT_sys equal TEXT_STRING_sys
           {
+            if ($3.length > ENGINE_OPTION_MAX_LENGTH)
+              my_yyabort_error((ER_VALUE_TOO_LONG, MYF(0), $1.str));
             new (thd->mem_root)
               engine_option_value($1, $3, true, &Lex->option_list,
                                   &Lex->option_list_last);
           }
         | IDENT_sys equal ident
           {
+            if ($3.length > ENGINE_OPTION_MAX_LENGTH)
+              my_yyabort_error((ER_VALUE_TOO_LONG, MYF(0), $1.str));
             new (thd->mem_root)
               engine_option_value($1, $3, false, &Lex->option_list,
                                   &Lex->option_list_last);

storage/connect/ha_connect.cc

@@ -4783,7 +4783,11 @@ int ha_connect::delete_or_rename_table(const char *name, const char *to)
       DBUG_RETURN(rc);
 
     // Get the share info from the .frm file
-    if (!open_table_def(thd, share)) {
+    Dummy_error_handler error_handler;
+    thd->push_internal_handler(&error_handler);
+    bool got_error= open_table_def(thd, share);
+    thd->pop_internal_handler();
+    if (!got_error) {
       // Now we can work
       if ((pos= share->option_struct)) {
         if (check_privileges(thd, pos, db))
@@ -4796,12 +4800,6 @@ int ha_connect::delete_or_rename_table(const char *name, const char *to)
 
       } // endif open_table_def
 
-//  This below was done to avoid DBUG_ASSERT in some case that
-//  we don't know anymore what they were. It was suppressed because
-//  it did cause assertion in other cases (see MDEV-7935)
-//  } else       // Avoid infamous DBUG_ASSERT
-//    thd->get_stmt_da()->reset_diagnostics_area();
-
     free_table_share(share);
   } else              // Temporary file
     ok= true;

storage/connect/mysql-test/connect/t/drop-open-error.opt

@@ -0,0 +1 @@
+--secure-file-priv=""