Re: [PATCH 0/6] echo usernames as they are typed

On Mon, Nov 28, 2011 at 10:36:21AM +0100, Erik Faye-Lund wrote:

quoted

You really want to open "/dev/tty" on most Unix systems (which is what
getpass() does).

Yes, you're right. Opening "/dev/tty" is much better. But what happens
for processes started by GUI applications (with no easily observable
tty, if any)? Does open simply fail? If so, is it desirable for us to
fail in that case?

Yes, the open will fail (on Linux, I get ENXIO).

And yes, we should fail in that case. getpass() will generally return
NULL in that instance, and the current implementation of git_getpass()
will die(), explaining that we could not get the password.

quoted

I have no idea what would be appropriate on Windows.

It's pretty similar, but not exactly: CreateFile("CONIN$", ...) or
CreateFile("CONOUT$", ...), depending on if you want the read-handle
or the write-handle... I can probably cook up something a bit more
concrete, though.

OK, that maps to the /dev/tty concept quite well. Though I suspect the
code for turning off character echo-ing is going to also be different.

But _getch() that we already use always reads from the console
(according to MSDN, I haven't actually tested this myself:
http://msdn.microsoft.com/en-us/library/078sfkak%28v=VS.80%29.aspx).
But I don't think this allows us to fail when no console is attached.
Question is, should we fail in such cases? Windows does have an API to
prompt for passwords in a GUI window... Perhaps fallbacking to those
are the way to go? Something like:

if (GetConsoleWindow()) {
	/*  normal console-stuff */
} else {
	/* call CredUIPromptForWindowsCredentials(...) instead */
}

Certainly on non-Windows something like that would not be welcome. The
user can already have specified GIT_ASKPASS if they don't have a
terminal. And once the credential-helper code is in, they can use a
platform-specific helper that provides a nice dialog if they want it.

So I would say trying to do something graphical would be surprising and
unwelcome. But then, I am a very Unix-y kind of guy. Maybe on Windows
something like that would be more favorable. I'll leave that decision to
people who know more.

-Peff