Dear @acidnik,
Could you be so kind to generate .exe for the rest of us who are mere Windows users w/o compiler?

Your file copy is sound, but I didn't see any switches to adjust the number of threads you copy files with in parallel.

My change request is that you provide a cli clap arg for cpu cores to use . i.e. --cpucorepercenttouse 100
In this use case if your system has 8 cores, then it would use 8 workers to copy 8 files in parallel.
If we want to adjust it to a lower level to all the computer to do other things, that would be useful.

--verifybeforeclosefiles [hashcheckalgo]
In this use case you would want to hashcheck the source against the hashche of the destination after copying the file. There could be a way to hash check while you have all bytes in memory before the write, that would be cheating since it's all about verify after the write and not before.
Technically after all the bytes are written, but before you close the file, you may ftell the position back to the beginning of the file, read all the bytes on the destination device with the bytecount before you close the destination file after writing it. That could save precious time since I believe closefile is an expensive os operation.

If I added the option to verify the checksum of the original and copied file, would it be the sort of thing you would merge?

It'd be great to be able to do cargo install ppcp, thanks!