I am checking for the existence of a file in my main program loop that runs about 4 times a second waiting for keystrokes etc... If I see the file exists, I just want to open the file, read it into a buffer and process it.

This works most of the time, but every once in a while I get EInOutError: Access denied with a return code of 217

I suspect that I happen to see the file is there and try to read it before the program that created the file is done writing it. What is the proper way to detect the file is in use so I don't bother trying to open it until it's done being written?

I'm on a windows system if that makes any difference and this is a console program.

James

AM James Richters wrote

I suspect that I happen to see the file is there and try to read it before the program that created the file is done writing it. What is the proper way to detect the file is in use so I don't bother trying to open it until it's done being written?

Simple approach?
Use filemode = fmOpenRead and use a try..except block to open the file? Opening will fail if the file is locked by another process (triggering the exception).

provided the other program opens the file for creation properly (eg: blahDenyAll), right?

PM wkitty42--- wrote

provided the other program opens the file for creation properly (eg: blahDenyAll), right?

Maybe use fmShareExclusive when opening the file.
That name suggest you can only open if you are the only one?