From: Ted Zlatanov <tzz@lifelogs.com>
To: emacs-devel@gnu.org
Subject: Re: docs for insert-file-contents use 'bytes'
Date: Mon, 29 Sep 2008 16:04:13 -0500 [thread overview]
Message-ID: <86hc7y64vm.fsf@lifelogs.com> (raw)
In-Reply-To: ur672k8xh.fsf@gnu.org
On Mon, 29 Sep 2008 23:12:58 +0300 Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Ted Zlatanov <tzz@lifelogs.com>
>> Date: Mon, 29 Sep 2008 14:58:17 -0500
>>
>> The docs for insert-file-contents say the range is in bytes, but that
>> function does decoding of the contents. Can it, therefore, read from an
>> undesirable position (e.g. the middle of a UTF-8 sequence)?
EZ> The range _is_ in bytes (you will see in fileio.c that Emacs uses
EZ> `lseek' to get to the required file positions). Yes, reading a part
EZ> of a multibyte sequence is a possibility.
>> How does Emacs handle that?
EZ> Like with any other random bytes, I think: it will produce eight-bit-*
EZ> characters in the buffer. IOW, you get garbled text.
This is not a safe operation mode with multibyte sequences; is there a
way to DTRT? I'm specifically thinking about a paged buffer mode where
you only see a small portion of the file (for editing large files, as we
discussed in another newsgroup a while ago).
>> Either way the docs need to state the operation mode clearly.
EZ> Assuming I don't miss anything, and the above is indeed correct, what
EZ> would you like the doc string to say, exactly?
Maybe add:
"Warning: this is not safe with variable-length multibyte encodings such
as UTF-8, because it works by byte offset without encoding awareness, so
you may get garbled data. See ??? instead."
I don't know if this is the right wording, but it's a pretty essential
operation so it should give some warning about this common (nowadays)
case.
Ted
next prev parent reply other threads:[~2008-09-29 21:04 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-29 19:58 docs for insert-file-contents use 'bytes' Ted Zlatanov
2008-09-29 20:12 ` Eli Zaretskii
2008-09-29 21:04 ` Ted Zlatanov [this message]
2008-09-30 6:06 ` Miles Bader
2008-09-30 7:19 ` Eli Zaretskii
2008-09-30 13:48 ` Ted Zlatanov
2008-09-30 15:58 ` Stefan Monnier
2008-09-30 16:29 ` Eli Zaretskii
2008-10-01 0:44 ` Kenichi Handa
2008-10-01 16:54 ` Ted Zlatanov
2008-10-02 1:33 ` Kenichi Handa
2008-10-02 13:42 ` Ted Zlatanov
2008-10-02 18:55 ` Stefan Monnier
2008-10-03 13:55 ` Ted Zlatanov
2008-10-02 1:58 ` Kenichi Handa
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