internal package
Foswiki::Plugins::BatchUploadPlugin Store callback called before the attachment is further processed. Preliminary attempt to tackle nested zips - does not actually work yet. Each time we fall through beforeUploadHandler to the actual attaching, other attachments get lost.
Checks if a file is a zip file. Returns true if the file has a zip extension, false if not.
Return: 1 if successful, 0 if not successful.
changed to work around a race condition where a symlink could be made in the temp directory pointing to a file writable by the CGI and then a zip uploaded with that filename, also solves the problem if two people are uploading zips with some identical filenames.
Open a zip and perform a sanity check on it. Returns the opened zip object (to be passed to doUnzip) on success, a string saying the reason for failure.