move_uploaded_file locks?

Can't find this in the PHP docs, so: does anyone know whether move_uploaded_file locks the target file during the process? If move_uploaded_file does a rename within the same filesystem this isn't an issue (on unix, anyway, the O/S just reassigns inodes rather than copying data). But if it does a copy instead, or if it has to rename across filesystems, any process that tries to read or write the file before move_uploaded_file completes could be munging things. -- Matthew H. North mailto:dtlmhn@dtl.net