From: Linus Torvalds <torvalds@osdl.org>
To: Daniel Barkalow <barkalow@iabervon.org>
Cc: Paul Eggert <eggert@CS.UCLA.EDU>, Junio C Hamano <junkio@cox.net>,
Robert Fitzsimons <robfitz@273k.net>,
Alex Riesen <raa.lkml@gmail.com>,
git@vger.kernel.org, Kai Ruemmler <kai.ruemmler@gmx.net>
Subject: Re: [PATCH] Try URI quoting for embedded TAB and LF in pathnames
Date: Wed, 12 Oct 2005 12:52:41 -0700 (PDT) [thread overview]
Message-ID: <Pine.LNX.4.64.0510121220230.15297@g5.osdl.org> (raw)
In-Reply-To: <Pine.LNX.4.63.0510121452030.23242@iabervon.org>
On Wed, 12 Oct 2005, Daniel Barkalow wrote:
>
> I think it's actually sufficient to escape 0x00-0x1f and 0x7f; those
> ranges are both easy
They are indeed easy.
> and, as far as I can tell, include all of the control
> characters that do annoying things.
Nope. The traditional vt100 escape sequence is "ESC" followed by a
character to indicate the type of sequence (the most common one is '[').
That's all 7-bit and fine.
HOWEVER, they made the 8-bit extension be such that any of these vt100
begin sequences where the second character is in the appropriate range can
be instead shortened by one character, by instead using a single 8-bit
character of "0x80+(char-0x40)". Ie the traditional "ESC + '['" (\x1b\x5b)
can also be written as a single '\x9b' character, aka CSI.
In other words, 0x80-0x9f are _all_ just vt100 shorthand for ESC+'@'
through ESC+'_'.
(I guess it's not strictly "vt100" any more - it's the extended vt220
format).
> I think escape, backspace, delete, and
> bell are the only ones we'd rather the terminal not get; beyond that,
> patches with screwy filenames look screwy, but don't screw up anything
> outside of the filename.
Try this on a (non-UTF-8) xterm:
echo -en '\x9b5B---\x9b1A---\x9b4A\r'
and it should do:
- move cursor 5 lines down
- print "---"
- move cursor 1 line up
- print "---"
- move cursor 4 lines up
- return carriage to beginning.
In other words, your screen should end up looking something like this:
[torvalds@g5 ~]$ echo -en '\x9b5B---\x9b1A---\x9b4A\r'
[torvalds@g5 ~]$
---
---
where that "staircase" of two "---" things was done with cursor movements.
And that's a _benign_ sequence. You can do all kinds of funky stuff that
really screws up the user experience. Including have the thing echo keys
to you that you didn't type:
echo -en '\x9b5n'
or lock the keyboard (I don't think any of the terminal emulators
implement the latter, or some of the other stranger sequences - things to
do double-wide characters etc).
Linus
PS. You can do all the same in UTF-8 one, but then you'll have to add a
\xc2 before the \x9b:
echo -en '\xc2\x9b5B---\xc2\x9b1A---\xc2\x9b4A\r'
etc..
next prev parent reply other threads:[~2005-10-12 19:53 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-07 19:35 [RFC] embedded TAB and LF in pathnames Junio C Hamano
2005-10-07 23:29 ` Alex Riesen
2005-10-07 23:44 ` Junio C Hamano
2005-10-08 6:45 ` Alex Riesen
2005-10-08 9:10 ` Junio C Hamano
2005-10-08 13:30 ` [PATCH] Try URI quoting for " Robert Fitzsimons
2005-10-08 18:30 ` Junio C Hamano
2005-10-08 20:19 ` Junio C Hamano
2005-10-11 6:20 ` Paul Eggert
2005-10-11 7:37 ` Junio C Hamano
2005-10-11 15:17 ` Linus Torvalds
2005-10-11 18:03 ` Paul Eggert
2005-10-11 18:37 ` Linus Torvalds
2005-10-11 19:42 ` Paul Eggert
2005-10-11 20:56 ` Linus Torvalds
2005-10-12 6:51 ` Paul Eggert
2005-10-12 14:59 ` Linus Torvalds
2005-10-12 19:07 ` Daniel Barkalow
2005-10-12 19:52 ` Linus Torvalds [this message]
2005-10-12 20:21 ` H. Peter Anvin
[not found] ` <87vf02qy79.fsf@penguin.cs.ucla.edu>
2005-10-12 21:02 ` Junio C Hamano
2005-10-12 21:05 ` Linus Torvalds
2005-10-12 21:09 ` H. Peter Anvin
2005-10-12 21:15 ` Johannes Schindelin
2005-10-12 21:33 ` Junio C Hamano
2005-10-14 0:57 ` Paul Eggert
2005-10-14 5:43 ` Linus Torvalds
2005-10-12 21:24 ` Linus Torvalds
2005-10-14 0:16 ` Paul Eggert
2005-10-14 5:20 ` Linus Torvalds
2005-10-14 17:18 ` H. Peter Anvin
2005-10-14 6:59 ` Junio C Hamano
2005-10-09 10:42 ` Junio C Hamano
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