Tar_unix.extract probably leaks file descriptors.

[gravicappa]

It looks like that dst here is leaking unless copy throws an exception: https://github.com/mirage/ocaml-tar/blob/main/unix/tar_unix.ml#L148-L155

[reynir]

Thank you for the report. Looks like you're right! I'll take a look at addressing that in August (due to vacation).

[reynir]

I found that copy never* throws. Instead we should have closed if the result was Error _. However, in the end this seems unnecessary as extract calls fold which calls safe_close in Fun.protect. In fact, this is not desirable as the file descriptor could have been reused for something else in between the two safe_close calls!

ocaml-tar/unix/tar_unix.ml

Lines 116 to 120 in 239a879

	let fold f filename init =
	let* fd = safe Unix.(openfile filename [ O_RDONLY ]) 0 in
	Fun.protect
	~finally:(fun () -> safe_close fd)
	(fun () -> run (Tar.fold f init) fd)

It would be good to go over the file descriptor usage and see if we properly close / don't double close etc.

[reynir]

Sorry, dst is a different file descriptor. Indeed, it can leak. And I think our _ Tar.t type needs error handling hooks.

[gravicappa]

The inability to «protect» around _ Tar.t would be my next issue to report. But I forgot.