sub is_zip {
   #Load the file
   local $SIG{__WARN__}  = sub { goto CONTINUE };
   $status = $zip->read($file);
   CONTINUE:
   #Check $status
}

##</code><code>##

#Read data into $file
if ($file =~ m/^\x50\x4B\x03\x04/) {
   #Parse as ZIP file
} else {
   #Parse as something else
}