cleanup: make dd_frm_type to work as documented

remove redundant argument, return all possible enum values

sql/datadict.cc

@@ -49,16 +49,13 @@ static int read_string(File file, uchar**to, size_t length)
   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  - file can't be opened
   @retval  TABLE_TYPE_NORMAL    table
   @retval  TABLE_TYPE_SEQUENCE  sequence table
   @retval  TABLE_TYPE_VIEW      view
 */
 
-Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name,
-                       bool *is_sequence)
+Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name)
 {
   File file;
   uchar header[40];     //"TYPE=VIEW\n" it is 10 characters
@@ -67,10 +64,8 @@ Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name,
   uchar dbt;
   DBUG_ENTER("dd_frm_type");
 
-  *is_sequence= 0;
-
-  if ((file= mysql_file_open(key_file_frm, path, O_RDONLY | O_SHARE, MYF(0)))
-      < 0)
+  file= mysql_file_open(key_file_frm, path, O_RDONLY | O_SHARE, MYF(0));
+  if (file < 0)
     DBUG_RETURN(TABLE_TYPE_UNKNOWN);
 
   /*
@@ -110,7 +105,7 @@ Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name,
   if (((header[39] >> 4) & 3) == HA_CHOICE_YES)
   {
     DBUG_PRINT("info", ("Sequence found"));
-    *is_sequence= 1;
+    type= TABLE_TYPE_SEQUENCE;
   }
 
   /* cannot use ha_resolve_by_legacy_type without a THD */

sql/datadict.h

@@ -38,13 +38,11 @@ enum Table_type
   To check whether it's an frm of a view, use dd_frm_is_view().
 */
 
-enum Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name,
-                            bool *is_sequence);
+enum Table_type dd_frm_type(THD *thd, char *path, LEX_CSTRING *engine_name);
 
 static inline bool dd_frm_is_view(THD *thd, char *path)
 {
-  bool not_used2;
-  return dd_frm_type(thd, path, NULL, &not_used2) == TABLE_TYPE_VIEW;
+  return dd_frm_type(thd, path, NULL) == TABLE_TYPE_VIEW;
 }
 
 bool dd_recreate_table(THD *thd, const char *db, const char *table_name);

sql/handler.cc

@@ -5837,27 +5837,28 @@ bool ha_table_exists(THD *thd, const LEX_CSTRING *db,
     {
       char engine_buf[NAME_CHAR_LEN + 1];
       LEX_CSTRING engine= { engine_buf, 0 };
-      Table_type type;
+      Table_type type= dd_frm_type(thd, path, &engine);
 
-      if ((type= dd_frm_type(thd, path, &engine, is_sequence)) ==
-          TABLE_TYPE_UNKNOWN)
-      {
-        DBUG_PRINT("exit", ("Does not exist"));
+      switch (type) {
+      case TABLE_TYPE_UNKNOWN:
+        DBUG_PRINT("exit", ("Exist, cannot be opened"));
         DBUG_RETURN(true);                      // Frm exists
-      }
-      if (type != TABLE_TYPE_VIEW)
+      case TABLE_TYPE_VIEW:
+        *hton= view_pseudo_hton;
+        DBUG_PRINT("exit", ("Exist, view"));
+        DBUG_RETURN(true);                      // Frm exists
+      case TABLE_TYPE_SEQUENCE:
+        *is_sequence= true;
+        /* fall through */
+      case TABLE_TYPE_NORMAL:
         {
           plugin_ref p=  plugin_lock_by_name(thd, &engine,
                                              MYSQL_STORAGE_ENGINE_PLUGIN);
           *hton= p ? plugin_hton(p) : NULL;
-        if (*hton)
-        {
-          // verify that the table really exists
+          if (*hton)      // verify that the table really exists
             exists= discover_existence(thd, p, &args);
         }
       }
-      else
-        *hton= view_pseudo_hton;
     }
     DBUG_PRINT("exit", (exists ? "Exists" : "Does not exist"));
     DBUG_RETURN(exists);

sql/sql_plugin.cc

@@ -1720,8 +1720,7 @@ int plugin_init(int *argc, char **argv, int flags)
   {
     char path[FN_REFLEN + 1];
     build_table_filename(path, sizeof(path) - 1, "mysql", "plugin", reg_ext, 0);
-    bool dummy;
-    Table_type ttype= dd_frm_type(0, path, &plugin_table_engine_name, &dummy);
+    Table_type ttype= dd_frm_type(0, path, &plugin_table_engine_name);
     if (ttype != TABLE_TYPE_NORMAL)
       plugin_table_engine_name=empty_clex_str;
   }

sql/sql_show.cc

@@ -4479,8 +4479,7 @@ static void get_table_engine_for_i_s(THD *thd, char *buf, TABLE_LIST *tl,
     char path[FN_REFLEN];
     build_table_filename(path, sizeof(path) - 1,
                          db->str, table->str, reg_ext, 0);
-    bool is_sequence;
-    if (dd_frm_type(thd, path, &engine_name, &is_sequence) == TABLE_TYPE_NORMAL)
+    if (dd_frm_type(thd, path, &engine_name) == TABLE_TYPE_NORMAL)
       tl->option= engine_name.str;
   }
 }

storage/rocksdb/rdb_datadic.cc

@@ -3793,8 +3793,7 @@ bool Rdb_validate_tbls::check_frm_file(const std::string &fullpath,
   */
   char eng_type_buf[NAME_CHAR_LEN+1];
   LEX_CSTRING eng_type_str = {eng_type_buf, 0}; 
-  bool is_sequence;
-  enum Table_type type = dd_frm_type(nullptr, fullfilename.c_ptr(), &eng_type_str, &is_sequence);
+  enum Table_type type = dd_frm_type(nullptr, fullfilename.c_ptr(), &eng_type_str);
   if (type == TABLE_TYPE_UNKNOWN) {
     // NO_LINT_DEBUG
     sql_print_warning("RocksDB: Failed to open/read .from file: %s",