BUG#45638 - Create temporary table with engine innodb fails

Create temporary InnoDB table fails on case insensitive
filesystems, when lower_case_table_names is 2 (e.g. OS X)
and temporary directory path contains upper case letters.

The problem was that tmpdir prefix was converted to lower
case when table was created, but was passed as is when
table was opened.

Fixed by leaving tmpdir prefix part intact.

mysql-test/r/lowercase_mixed_tmpdir_innodb.result

+drop table if exists t1;
+create table t1 (id int) engine=InnoDB;
+insert into t1 values (1);
+create temporary table t2 engine=InnoDB select * from t1;
+drop temporary table t2;
+drop table t1;

mysql-test/t/lowercase_mixed_tmpdir_innodb-master.opt

+--lower-case-table-names=2
+--tmpdir=$MYSQLTEST_VARDIR/tmp/MixedCase

mysql-test/t/lowercase_mixed_tmpdir_innodb-master.sh

+# This test requires a non-lowercase tmpdir directory on a case-sensitive
+# filesystem.
+
+d="$MYSQLTEST_VARDIR/tmp/MixedCase"
+test -d "$d" || mkdir "$d"
+rm -f "$d"/*

mysql-test/t/lowercase_mixed_tmpdir_innodb.test

+--source include/have_lowercase2.inc
+--source include/have_innodb.inc
+
+--disable_warnings
+drop table if exists t1;
+--enable_warnings
+
+create table t1 (id int) engine=InnoDB;
+insert into t1 values (1);
+create temporary table t2 engine=InnoDB select * from t1;
+drop temporary table t2;
+drop table t1;

sql/handler.cc

@@ -1885,12 +1885,42 @@ bool ha_flush_logs(handlerton *db_type)
   return FALSE;
 }
 
+
+/**
+  @brief make canonical filename
+
+  @param[in]  file     table handler
+  @param[in]  path     original path
+  @param[out] tmp_path buffer for canonized path
+
+  @details Lower case db name and table name path parts for
+           non file based tables when lower_case_table_names
+           is 2 (store as is, compare in lower case).
+           Filesystem path prefix (mysql_data_home or tmpdir)
+           is left intact.
+
+  @note tmp_path may be left intact if no conversion was
+        performed.
+
+  @retval canonized path
+
+  @todo This may be done more efficiently when table path
+        gets built. Convert this function to something like
+        ASSERT_CANONICAL_FILENAME.
+*/
 const char *get_canonical_filename(handler *file, const char *path,
                                    char *tmp_path)
 {
+  uint i;
   if (lower_case_table_names != 2 || (file->ha_table_flags() & HA_FILE_BASED))
     return path;
 
+  for (i= 0; i <= mysql_tmpdir_list.max; i++)
+  {
+    if (is_prefix(path, mysql_tmpdir_list.list[i]))
+      return path;
+  }
+
   /* Ensure that table handler get path in lower case */
   if (tmp_path != path)
     strmov(tmp_path, path);