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From: David Maus <dmaus@ictsoc.de>
To: nicholas.dokos@hp.com
Cc: Jeff Horn <jrhorn424@gmail.com>, Org-mode ml <emacs-orgmode@gnu.org>
Subject: Re: [bug] Org link dialog escapes URL spaces incorrectly
Date: Sat, 05 Nov 2011 15:04:32 +0100	[thread overview]
Message-ID: <87mxcazmvj.wl%dmaus@ictsoc.de> (raw)
In-Reply-To: <26969.1320431142@alphaville.dokosmarshall.org>

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At Fri, 04 Nov 2011 14:25:42 -0400,
Nick Dokos wrote:
>
> Nick Dokos <nicholas.dokos@hp.com> wrote:
>
> > It probably does, but that's probably not the best place to do it: it might be
> > better to do it in the (setq link on line 9090 or thereabouts. Otherwise, in
> > the *other* case (editing the link at point), we'll end up unescaping twice:
> > probably not a problem, since unescaping should be idempotent (in contrast to
> > escaping ;-) ) but why do it twice?
> >
>
> Brian Wightman pointed out to me that the idempotent part of the
> statement above is definitely wrong (d'oh). The original URL that Jeff
> Horn posted, when unescaped once, would be completely free of % signs.
> But if the second (doubly-escaped) form is pasted into the minibuffer,
> then unescaping once would not be enough. So I presume the thing to do
> is to take the URL and unescape it repeatedly until it loses all
> escapes, and then escape it *once* before inserting it in the org
> buffer.
>
> Sounds icky, kludgy, dirty. The question is: 1) is it a solution?
> and 2) is there a better one?

No, this wouldn't be a solution. Consider a link with the sequence
%2525 -- Unescape until no more escapes (or rather "escapes") will
produce a single `%', not %25. Either escape once, or not at all.

What roughly happens is this:

1. The user enters a link via `org-insert-link'
2. Org escapes the link and writes it to the buffer
3. The user opens the link with `org-open-at-poin'
4. Org reads the link from the buffer and unescapes it
5. The link gets escaped and passed to the cosuming application (i.e. browser)

For steps 2 and 4 it is guaranteed that

(string= link (org-link-unescape (org-link-escape link)))

Thus, the problem is not in 2 or 4, but in 1 or 5.

Step 5 assumes, that a link entered by the user in step 1 was an
unescaped link and thus needs escaping before it is passed to the
cosuming application. If you enter a link in step 1 that already is
escaped, this assumption fails and you'll end up with a double-escaped
link that is passed to the consumer.

In other words, the question is: How to decide whether an arbitrary
URL is percent-escaped or not?

Now here's the problem: You can't. Is

"http://example.tld/foo%40bar"

already escaped or not? You can't tell for sure. It depends on the
application you copied the link from.[1]

What we could do in step 5 is... guess. If the (unescaped) link
produced by step 4 does contain characters that need escaping, we
escape the link. Otherwise we don't.

Not quiet sure about the impact of such a change.

Best,
 -- David

[1] Even worse: It may even depend on /how/ or /where/ you copied the
link. E.g. the link to a wikipedia page about set theory is copied as

http://de.wikipedia.org/wiki/Menge_%28Mathematik%29

if C-c'ed from the address bar but copied as

http://de.wikipedia.org/wiki/Menge_(Mathematik)

if C-c'ed via "Copy link to clipboard" at another page (Iceweasel
3.6.23).
--
OpenPGP... 0x99ADB83B5A4478E6
Jabber.... dmjena@jabber.org
Email..... dmaus@ictsoc.de

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  reply	other threads:[~2011-11-05 14:04 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-02  2:02 [bug] Org link dialog escapes URL spaces incorrectly Jeff Horn
2011-11-04 15:59 ` Jeff Horn
2011-11-04 16:14   ` Nick Dokos
2011-11-04 16:33   ` Nick Dokos
2011-11-04 16:52     ` Nick Dokos
     [not found]       ` <CALbR623mDyhC=LRAQBW9-vJxhsFWR0L+xFOKnE3eq5Wn92y04g@mail.gmail.com>
2011-11-04 18:19         ` Nick Dokos
2011-11-04 18:25       ` Nick Dokos
2011-11-05 14:04         ` David Maus [this message]
2011-11-05 15:38           ` Nick Dokos
2011-11-06 14:48             ` David Maus
2011-11-06 22:29               ` Nick Dokos
2011-11-13  9:12                 ` David Maus
2011-11-13 17:32                   ` Nick Dokos
2011-12-15  1:30                     ` Jeff Horn
2011-12-18 17:13                       ` David Maus

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