Bug#26030 (Parsing fails for stored routine w/multi-statement execution

enabled)

Before this fix, the lexer and parser would treat the ';' character as a
different token (either ';' or END_OF_INPUT), based on convoluted logic,
which failed in simple cases where a stored procedure is implemented as a
single statement, and used in a multi query.

With this fix:
- the character ';' is always parsed as a ';' token in the lexer,
- parsing multi queries is implemented in the parser, in the 'query:' rules,
- the value of thd->client_capabilities, which is the capabilities
  negotiated between the client and the server during bootstrap,
  is immutable and not arbitrarily modified during parsing (which was the
  root cause of the bug)

1 files changed, 3 insertions, 16 deletions

diff --git a/sql/sql_lex.cc b/sql/sql_lex.cc
index 6bfcd982b04..a1bfc3edc6c 100644
--- a/sql/sql_lex.cc
+++ b/sql/sql_lex.cc
@@ -1010,21 +1010,8 @@ int MYSQLlex(void *arg, void *yythd)
       yySkip();
       return (SET_VAR);
     case MY_LEX_SEMICOLON:			// optional line terminator
-      if (yyPeek())
-      {
-        if ((thd->client_capabilities & CLIENT_MULTI_STATEMENTS) && 
-            !lip->stmt_prepare_mode)
-        {
-	  lex->safe_to_cache_query= 0;
-          lip->found_semicolon= lip->ptr;
-          thd->server_status|= SERVER_MORE_RESULTS_EXISTS;
-          lip->next_state=     MY_LEX_END;
-          return (END_OF_INPUT);
-        }
-        state= MY_LEX_CHAR;		// Return ';'
-	break;
-      }
-      /* fall true */
+      state= MY_LEX_CHAR;               // Return ';'
+      break;
     case MY_LEX_EOL:
       if (lip->ptr >= lip->end_of_query)
       {
@@ -1039,7 +1026,7 @@ int MYSQLlex(void *arg, void *yythd)
     case MY_LEX_END:
       lip->next_state=MY_LEX_END;
       return(0);			// We found end of input last time
-      
+
       /* Actually real shouldn't start with . but allow them anyhow */
     case MY_LEX_REAL_OR_POINT:
       if (my_isdigit(cs,yyPeek()))