[Python-Dev] os.rename on windows (original) (raw)

Raghuram Devarakonda draghuram at gmail.com
Tue May 1 16:40:19 CEST 2007

On 5/1/07, Scott Dial <scott+python-dev at scottdial.com> wrote:

The cygwin implementation of rename goes like this:

1) Try to use MoveFile 2) Try to use MoveFileEx(..., MOVEFILEREPLACEEXISTING) 3) Try to unlink destination, then try to use MoveFile And as you say, Cygwin claims it meets POSIX.1. And, POSIX.1 says, "If newpath already exists it will be atomically replaced (subject to a few conditions; see ERRORS below), so that there is no point at which another process attempting to access newpath will find it missing." Clearly, unliking and then calling MoveFile is not atomic. So, cygwin is not being honest here because in these less frequent cases, the rename will not be atomic.

You are right. I just checked cygwin's rename() code and it is convincing enough for me to withdraw the patch.

Thanks for all the comments.

Raghu

More information about the Python-Dev mailing list