Init more carefully and accept enter to terminate user name input

[arvidj]

Fixes #16 and #17.

• passage init bails out if ~/.config/passage exists, unless --force is passed.
• user name input is terminated by newline. I think this is more user friendly, but a consequence is that new lines are no longer accepted in identity names. A change in semantics, but it seems better to me. Actually, I think we should forbid: empty identity names and identity names that are not composed for a-zA-Z_-.@0-9 or some similarly restricted set.

[thatportugueseguy]

looks good, just some minor nitpicks wrt the terms used

[thatportugueseguy]

Maybe some more user-friendly message? 😅

[arvidj]

Hmm, sure! I'm not sure what is more friendly though. You can make this error appear by pressing Ctrl-D in the terminal with no input. Or by redirecting /dev/null to the process:

$ dune exec bin/main.exe -- init --force

Welcome to passage initial setup.

...

What should be the name used for your recipient identity?
E: Passage init failed: Failure("E: username input was terminated by EOF before a newline was encountered. Ensure the username is newline-terminated and try again")

perhaps it should just say:

E: Passage init failed: Empty user name.

?

[thatportugueseguy]

yes, that makes more sense and is understandable by non-techies :)

[arvidj]

Ok, see latest version!

Note that I also moved the try/catch around a bit (here: 56797b9). Before, if we couldn't read the username for some reason, we would remove the config dir (granted that --force had been passed). I changed the code s.t. the config dir is only removed if we actually read the user name successfully and so had started writing to the config dir. This seems a bit more gentle, and less risk for data loss. Makes sense to you?

[thatportugueseguy]

Suggested change

	let line = String.trim line in
	let buf = Buffer.create String.(length line) in
	let buf = Buffer.create String.(length (trim line)) in

[arvidj]

IIUC The var line is read below by String.iter, so if I trim as you suggested initial whitespace would be changed to _ instead of trimmed.

[thatportugueseguy]

ah, you're right, i missed that usage. 👍

[thatportugueseguy]

I think we should forbid: empty identity names and identity names that are not composed for a-zA-Z_-.@0-9

I agree on this one. Probably better on another PR, given the scope?

[arvidj]

Merged after discussion on slack.