Subject: Re: bin/10879: su does not reset terminal settings after Ctrl-C
To: None <email@example.com, firstname.lastname@example.org,>
From: Robert Elz <kre@munnari.OZ.AU>
Date: 08/25/2000 02:19:59
Date: Thu, 24 Aug 2000 11:51:27 -0400 (EDT)
From: email@example.com (Greg A. Woods)
| #2 is possible, but a little yucky as you say. It's also probably about
| as hard to get right as my #5 too.
It shouldn't be, that way (have getpass() catch signals and DTRT) is
the correct solution.
Anything which is messing with the terminal state should be doing that.
| In reality though #3 is the only correct solution, and is the one that's
| been chosen by Unix for a long time now
I don't think so. The difference that is probably causing the
different behaviour is that a read() will be restarted after a signal
in *BSD, without the application noticing it. Perviously the signal
would have caused the read() to return an error (EINTR) which could
then be treated as a "clean up and get out" indicator by getpass().
That and that getpass() is just blocking signals now, instead of
catch, cleanup, and return.
| Of course users of getpass() must be fixed up to catch SIGINT and to
| properly reset the terminal modes when it is triggered....
No, if getpass() is going to meddle it is getpass()'s job to unmeddle.
| We can't be
| relying on interactive shells to restore the terminal modes!
| The code in 4.3BSD-Reno has the comment:
| * note - blocking signals isn't necessarily the
| * right thing, but we leave it for now.
That's also true - it is just the easy way, and close enough...
| My remaining problem with *BSD tty behaviour, which is demonstrated by
| getpass(), is the mis-handling of EOF. Traditionally I recall ^D
| working at any point on a line.
Never. Not ever, not even once. ^D has always meant "end the current
input line here, without including the ^D character". If there's nothing
in the line, that results in a 0 length read, which is EOF. If there's
anything already in the line, the program gets it without a \n on the end.
That is truly ancient behaviour (like 5th edition unix, and probably 1st)>
| beginning of the line so now I have to use ^U^D instead.
Or ^D^D perhaps. But ^C\n works for me (it is certainly close enough).