On Tue, 19 Aug 2008 11:07:39 -0700, [EMAIL PROTECTED] wrote: > def do_something(filename): > if not os.access(filename,os.R_OK): > return err(...) > f = open(filename) > ...
You're running on a multitasking modern machine, right? What happens when some other process deletes filename, or changes its permissions, in the time after you check for access but before you actually open it? This isn't just a theoretical risk. There's a whole class of errors and security holes based on similar race conditions. I find it amusing that you consider it "sloppy" to deal with errors raised when actually opening a file, but then recommend a technique that has a well-known failure mode. That's not to say that I never use such techniques myself. For quick and dirty scripts, where I can tolerate the risk of some other process moving a file behind my back, I've been known to do something similar. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
