Merge remote-tracking branch 'origin/10.2' into bb-10.2-ext

Conflicts:
	mysql-test/r/cte_recursive.result
	mysql-test/r/derived_cond_pushdown.result
	mysql-test/t/cte_recursive.test
	mysql-test/t/derived_cond_pushdown.test
	sql/datadict.cc
	sql/handler.cc

1 files changed, 18 insertions, 2 deletions

diff --git a/sql/datadict.cc b/sql/datadict.cc
index edc9fe5681b..5b70639174c 100644
--- a/sql/datadict.cc
+++ b/sql/datadict.cc
@@ -46,11 +46,13 @@ static int read_string(File file, uchar**to, size_t length)
 
   engine_name is a LEX_CSTRING, where engine_name->str must point to
   a buffer of at least NAME_CHAR_LEN+1 bytes.
+  If engine_name is 0, then the function will only test if the file is a
+  view or not
 
   @param[out] is_sequence  1 if table is a SEQUENCE, 0 otherwise
 
   @retval  TABLE_TYPE_UNKNOWN   error
-  @retval  TABLE_TYPE_TABLE     table
+  @retval  TABLE_TYPE_NORMAL    table
   @retval  TABLE_TYPE_SEQUENCE  sequence table
   @retval  TABLE_TYPE_VIEW      view
 */
@@ -80,12 +82,26 @@ Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name,
     goto err;
   }
 
+  /*
+    We return TABLE_TYPE_NORMAL if we can read the .frm file. This allows us
+    to drop a bad .frm file with DROP TABLE
+  */
   type= TABLE_TYPE_NORMAL;
 
-  if (!is_binary_frm_header(header) || !engine_name)
+  /* engine_name is 0 if we only want to know if table is view or not */
+  if (!engine_name)
     goto err;
 
+  /*
+    Initialize engine name in case we are not able to find it out
+    The cast is safe, as engine_name->str points to a usable buffer.
+   */
   engine_name->length= 0;
+  ((char*) (engine_name->str))[0]= 0;
+
+  if (!is_binary_frm_header(header))
+    goto err;
+
   dbt= header[3];
 
   if (((header[39] >> 4) & 3) == HA_CHOICE_YES)