A fix and test case for Bug#9478 "mysql_stmt_attr_set mysql_stmt_execute"

(crash on attempt to re-execute a statement with an open cursor) + 
post-review fixes.


include/errmsg.h:
  Add a special error message when we attempt to mysql_stmt_fetch
  from a statement which has no result set.
libmysql/errmsg.c:
  Error message text for CR_NO_RESULT_SET
libmysql/libmysql.c:
  Move the code which frees result sets on client and closes the cursor
  on server, resets long data state on client and server.
  This makes one function out of two (mysql_stmt_reset and
  mysql_stmt_free_result), thus aggregating all related reset work
  in one place.
sql-common/client.c:
  Fix one place where we flushed the pending result set of a statement,
  but didn't set unbuffered_fetch_cancelled flag.
sql/share/errmsg.txt:
  Fix format of ER_UNKNOWN_STMT_HANDLER error message (needs to
  be fixed separately in 4.1). Add two new error messages 
  for the case when we fetch from when there is no cursor
  and for the case when we attempt to execute a statement while there is
  a cursor.
sql/sql_prepare.cc:
  Return error when we fetch while there is no open cursor and
  when we call execute while there is a pending cursor.
  Fix mysql_stmt_reset to close the open cursor if there is any.
sql/sql_select.cc:
  free_items and free_root moved to Cursor::close().
sql/sql_select.h:
  A comment added.
tests/mysql_client_test.c:
  A test case for Bug#9478, test the case of mysql_stmt_reset
  called for client-side cached result set and for the case with open cursor.
  All strcpy replaced with strmov (review request).

4 files changed, 40 insertions, 21 deletions

diff --git a/sql/share/errmsg.txt b/sql/share/errmsg.txt
index 388f47bf96f..848cc422dc2 100644
--- a/sql/share/errmsg.txt
+++ b/sql/share/errmsg.txt
@@ -4766,13 +4766,13 @@ ER_SUBQUERY_NO_1_ROW 21000
 	swe "Subquery returnerade mer än 1 rad"
 	ukr "ð¦ÄÚÁÐÉÔ ÐÏ×ÅÒÔÁ¤ ¦ÌØÛ ÎiÖ 1 ÚÁÐÉÓ"
 ER_UNKNOWN_STMT_HANDLER  
-	dan "Unknown prepared statement handler (%ld) given to %s"
+	dan "Unknown prepared statement handler (%.*s) given to %s"
 	eng "Unknown prepared statement handler (%.*s) given to %s"
 	ger "Unbekannter Prepared-Statement-Handler (%.*s) für %s angegeben"
 	por "Desconhecido manipulador de declaração preparado (%.*s) determinado para %s"
-	spa "Desconocido preparado comando handler (%ld) dado para %s"
-	swe "Okänd PREPARED STATEMENT id (%ld) var given till %s"
-	ukr "Unknown prepared statement handler (%ld) given to %s"
+	spa "Desconocido preparado comando handler (%.*s) dado para %s"
+	swe "Okänd PREPARED STATEMENT id (%.*s) var given till %s"
+	ukr "Unknown prepared statement handler (%.*s) given to %s"
 ER_CORRUPT_HELP_DB  
 	eng "Help database is corrupt or does not exist"
 	ger "Die Hilfe-Datenbank ist beschädigt oder existiert nicht"
@@ -5352,3 +5352,7 @@ ER_BINLOG_UNSAFE_ROUTINE
 	eng "This routine is declared to be non-deterministic and to modify data and binary logging is enabled (you *might* want to use the less safe log_bin_trust_routine_creators variable)"
 ER_BINLOG_CREATE_ROUTINE_NEED_SUPER
 	eng "You do not have SUPER privilege and binary logging is enabled (you *might* want to use the less safe log_bin_trust_routine_creators variable)"
+ER_EXEC_STMT_WITH_OPEN_CURSOR
+	eng "You can't execute a prepared statement which has an open cursor associated with it. Reset the statement to re-execute it."
+ER_STMT_HAS_NO_OPEN_CURSOR
+	eng "The statement (%d) has no open cursor."
diff --git a/sql/sql_prepare.cc b/sql/sql_prepare.cc
index 17c5f51f1e1..03b3df1bc22 100644
--- a/sql/sql_prepare.cc
+++ b/sql/sql_prepare.cc
@@ -135,7 +135,8 @@ find_prepared_statement(THD *thd, ulong id, const char *where)
   if (stmt == 0 || stmt->type() != Item_arena::PREPARED_STATEMENT)
   {
     char llbuf[22];
-    my_error(ER_UNKNOWN_STMT_HANDLER, MYF(0), 22, llstr(id, llbuf), where);
+    my_error(ER_UNKNOWN_STMT_HANDLER, MYF(0), sizeof(llbuf), llstr(id, llbuf),
+             where);
     return 0;
   }
   return (Prepared_statement *) stmt;
@@ -1969,7 +1970,7 @@ void mysql_stmt_execute(THD *thd, char *packet, uint packet_length)
 {
   ulong stmt_id= uint4korr(packet);
   ulong flags= (ulong) ((uchar) packet[4]);
-  Cursor *cursor= 0;
+  Cursor *cursor;
   /*
     Query text for binary log, or empty string if the query is not put into
     binary log.
@@ -1995,6 +1996,13 @@ void mysql_stmt_execute(THD *thd, char *packet, uint packet_length)
     DBUG_VOID_RETURN;
   }
 
+  cursor= stmt->cursor;
+  if (cursor && cursor->is_open())
+  {
+    my_error(ER_EXEC_STMT_WITH_OPEN_CURSOR, MYF(0));
+    DBUG_VOID_RETURN;
+  }
+
   DBUG_ASSERT(thd->free_list == NULL);
   mysql_reset_thd_for_next_command(thd);
   if (flags & (ulong) CURSOR_TYPE_READ_ONLY)
@@ -2013,7 +2021,7 @@ void mysql_stmt_execute(THD *thd, char *packet, uint packet_length)
     else
     {
       DBUG_PRINT("info",("Using READ_ONLY cursor"));
-      if (!stmt->cursor &&
+      if (!cursor &&
           !(cursor= stmt->cursor= new (&stmt->main_mem_root) Cursor()))
         DBUG_VOID_RETURN;
       /* If lex->result is set, mysql_execute_command will use it */
@@ -2208,13 +2216,15 @@ void mysql_stmt_fetch(THD *thd, char *packet, uint packet_length)
   Statement *stmt;
   DBUG_ENTER("mysql_stmt_fetch");
 
-  if (!(stmt= thd->stmt_map.find(stmt_id)) ||
-      !stmt->cursor ||
-      !stmt->cursor->is_open())
+  if (!(stmt= find_prepared_statement(thd, stmt_id, "mysql_stmt_fetch")))
+    DBUG_VOID_RETURN;
+
+  if (!stmt->cursor || !stmt->cursor->is_open())
   {
-    my_error(ER_UNKNOWN_STMT_HANDLER, MYF(0), stmt_id, "fetch");
+    my_error(ER_STMT_HAS_NO_OPEN_CURSOR, MYF(0));
     DBUG_VOID_RETURN;
   }
+
   thd->current_arena= stmt;
   thd->set_n_backup_statement(stmt, &thd->stmt_backup);
   stmt->cursor->init_thd(thd);
@@ -2266,6 +2276,9 @@ void mysql_stmt_reset(THD *thd, char *packet)
   if (!(stmt= find_prepared_statement(thd, stmt_id, "mysql_stmt_reset")))
     DBUG_VOID_RETURN;
 
+  if (stmt->cursor && stmt->cursor->is_open())
+    stmt->cursor->close();
+
   stmt->state= Item_arena::PREPARED;
 
   /* 
diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 47c7de6eba7..84f3bb92a7d 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -1742,6 +1742,7 @@ Cursor::init_from_thd(THD *thd)
   /*
     XXX: thd->locked_tables is not changed.
     What problems can we have with it if cursor is open?
+    TODO: must be fixed because of the prelocked mode.
   */
   /*
     TODO: grab thd->free_list here?
@@ -1871,10 +1872,6 @@ Cursor::fetch(ulong num_rows)
     }
     else if (error != NESTED_LOOP_KILLED)
       my_message(ER_OUT_OF_RESOURCES, ER(ER_OUT_OF_RESOURCES), MYF(0));
-    /* free cursor memory */
-    free_items(free_list);
-    free_list= 0;
-    free_root(&main_mem_root, MYF(0));
   }
 }
 
@@ -1914,6 +1911,13 @@ Cursor::close()
   }
   join= 0;
   unit= 0;
+  free_items(free_list);
+  free_list= 0;
+  /*
+    Must be last, as some memory might be allocated for free purposes,
+    like in free_tmp_table() (TODO: fix this issue)
+  */
+  free_root(mem_root, MYF(0));
   DBUG_VOID_RETURN;
 }
 
@@ -1922,12 +1926,6 @@ Cursor::~Cursor()
 {
   if (is_open())
     close();
-  free_items(free_list);
-  /*
-    Must be last, as some memory might be allocated for free purposes,
-    like in free_tmp_table() (TODO: fix this issue)
-  */
-  free_root(&main_mem_root, MYF(0));
 }
 
 /*********************************************************************/
diff --git a/sql/sql_select.h b/sql/sql_select.h
index a27fbc60856..49ac58e913b 100644
--- a/sql/sql_select.h
+++ b/sql/sql_select.h
@@ -364,6 +364,10 @@ class JOIN :public Sql_alloc
 /*
   Server-side cursor (now stands only for basic read-only cursor)
   See class implementation in sql_select.cc
+  A cursor has its own runtime state - list of used items and memory root of
+  used memory - which is different from Prepared statement runtime: it must
+  be different at least for the purpose of reusing the same prepared
+  statement for many cursors.
 */
 
 class Cursor: public Sql_alloc, public Item_arena