Re: bug#23750: 25.0.95; bug in url-retrieve or json.el

[Eli Zaretskii <eliz@gnu.org>]

> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Wed, 28 Dec 2016 18:09:52 +0000
> Cc: larsi@gnus.org, dgutov@yandex.ru, kentaro.nakazawa@nifty.com, 
> 	emacs-devel@gnu.org
> 
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> Eli Zaretskii <eliz@gnu.org> schrieb am Mi., 30. Nov. 2016 um 19:45 Uhr:
> 
>  > From: Philipp Stephani <p.stephani2@gmail.com>
>  > Date: Wed, 30 Nov 2016 18:23:14 +0000
>  > Cc: dgutov@yandex.ru, kentaro.nakazawa@nifty.com, emacs-devel@gnu.org
>  >
>  > > Yes, this is not a json.el problem at all. It does the correct thing,
>  > > and shouldn't be changed.
>  >
>  > ??? Why should any code care whether a pure-ASCII string is marked as
>  > unibyte or as multibyte? Both are "correct".
>  >
>  > I guess the problem is that process-send-string cares. If it didn't, we wouldn't have the problem.
> 
>  I don't think I follow. The error we are talking about is signaled
>  from url-http-create-request, not from process-send-string.
> 
> Yes, but url-http-create-request only cares about unibyte strings because the request it creates is passed to
> process-send-string, which special-cases unibyte strings.

How do you see that process-send-string special-cases unibyte strings?

>  > For URL, we'd need functions like
>  > (byte-array-length s) = (length (string-to-unibyte s))
> 
>  Why do you need this? string-to-unibyte is well-defined only for
>  unibyte or ASCII strings (if we forget the raw bytes for a moment), so
>  length will do.
> 
> We need it because we have to send the byte length in a header. We can't just use (length s) because it
> would silently give a wrong result.

We are miscommunicating.  string-to-unibyte can only meaningfully be
called on a pure-ASCII string, and for pure-ASCII strings 'length'
will count bytes.  So I see no need for 'byte-array-length' if its
implementation is as you indicated.

>  > (process-send-bytes s) = (process-send-string (string-to-unibyte s))
> 
>  Why is this needed? process-send-string already encodes its argument,
>  which produces a unibyte string.
> 
> We can't give a multibyte string to process-send-string, because we have to pass the length in bytes in a
> header first. Therefore we have to encode any string before passing it to process-send-string.

Once you encoded the string, why do you need anything except calling
process-send-string?