copy_file implemented for Windows, Linux and Darwin

[Smilex]

I am unable to test it on darwin, but I assumed it's the same as Linux, so I copied it

Linux tested with WSL
Windows tested on Windows 11

This function was inspired by - https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-copyfile

[Tetralux]

Few things to fix up, otherwise decent.

[Kelimion]

It would be nice if on *nix platforms it'd copy permissions (chmod) and ownership (chown) instead of assigning the new file to the current user with some default permissions, or being able to pass in the desired owner and permission.

[Smilex]

It would be nice if on *nix platforms it'd copy permissions (chmod) and ownership (chown) instead of assigning the new file to the current user with some default permissions, or being able to pass in the desired owner and permission.

I did stat for and copy the permissions at first, but decided to simplify
I'm not sure which I prefer

[Smilex]

It would be nice if on *nix platforms it'd copy permissions (chmod) and ownership (chown) instead of assigning the new file to the current user with some default permissions, or being able to pass in the desired owner and permission.

Should I make it possible to pass chmod and chown?

[flysand7]

For a simple implementation copying the original permissions should be enough

[Smilex]

For a simple implementation copying the original permissions should be enough

Ok, now I stat for the mode first and open the new file with that mode

[dvrd]

I tested the implementation on MacOS and it works as expected

[Smilex]

I tested the implementation on MacOS and it works as expected

thanks!

[Yawning]

Some thoughts:

• The Linux and Darwin code could be simplified by using os/stream_from_handle and io/copy.
• Should failure during the copy process, remove the partially copied file? Right now it does.

[laytan]

You probably also want os.O_TRUNC for the destination file, so it truncates the file if it already exists, otherwise it would just add to it

[Tetralux]

Some thoughts:

• The Linux and Darwin code could be simplified by using os/stream_from_handle and io/copy.
• Should failure during the copy process, remove the partially copied file? Right now it does.

It currently doesn't remove a partially copied file - at least not explicitly.