i can confirm that upload from uploaddir fails if base_dir is set to "/htdocs" :
Inserted rows: 1 Warning (1265): Data truncated for column 'c1' at row 1
SQL query:INSERT INTO `blobUplTest` ( `c1` , `DATE` , `blobF` ) VALUES ( 'with base_dir restriktions', '0', '' );
but works well if base_dir is not set.