How to catch the details of the file copy/move event, such as the source file name
.net, events, filesystems, filesystemwatcher, windows
Solution
This is because there is no such operation as "copy a file", as far as the filesystem is concerned.
When you run a file copying command, it actually opens the old file, creates the new file, reads content into memory, writes to the new files, then closes both. All the filesystem sees are writes; there's no taint-tracking system for determining that the data actually came from another file without modification.
The final step, that differentiates the file copy from writing data to a file normally, is that the metadata of the destination are changed to match the source. But again, the filesystem doesn't know why you're changing the attributes or which file you're matching them two.
The filesystem only has special awareness of linking and unlinking. So moving, which consists of "create second link to content; remove first link" is detectable. If copying were implemented as "create new link marked for copy-on-write" then you could discover it, but copy-on-write is not a very popular filesystem feature.
Problem
Just want to write a application to track the relationship between the files in the disk. We know that FileSystemWatcher can fire evetns when creating, renaming or deleting the file. But FileSystemWatcher can not tell us the path of the source file. For example, let's say there is a file `F1` in the `folder1`, and then we copy `F1` to another folder named `folder2`, the new file name is still `F1`. In this case the `FileSystemWatcher` could tell us there is a new file has been created in `folder2`. But it can not tell us the new `F1` is copied from the `F1` in `folder1`, while this information is what we need. Any thoughts?