From mboxrd@z Thu Jan 1 00:00:00 1970 Path: main.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: [HELP] (bug?) Saving a buffer without any conversion? Date: Tue, 14 Jan 2003 08:06:02 +0200 (IST) Sender: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Message-ID: References: <5xk7h8a6lm.fsf@kfs2.cua.dk> NNTP-Posting-Host: main.gmane.org Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: main.gmane.org 1042524413 15916 80.91.224.249 (14 Jan 2003 06:06:53 GMT) X-Complaints-To: usenet@main.gmane.org NNTP-Posting-Date: Tue, 14 Jan 2003 06:06:53 +0000 (UTC) Cc: emacs-devel@gnu.org Return-path: Original-Received: from quimby.gnus.org ([80.91.224.244]) by main.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 18YKDr-00048a-00 for ; Tue, 14 Jan 2003 07:06:51 +0100 Original-Received: from monty-python.gnu.org ([199.232.76.173]) by quimby.gnus.org with esmtp (Exim 3.12 #1 (Debian)) id 18YKLh-0001PV-00 for ; Tue, 14 Jan 2003 07:14:57 +0100 Original-Received: from localhost ([127.0.0.1] helo=monty-python.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.10.13) id 18YKDp-0000eZ-08 for emacs-devel@quimby.gnus.org; Tue, 14 Jan 2003 01:06:49 -0500 Original-Received: from list by monty-python.gnu.org with tmda-scanned (Exim 4.10.13) id 18YKDY-0000ZA-00 for emacs-devel@gnu.org; Tue, 14 Jan 2003 01:06:32 -0500 Original-Received: from mail by monty-python.gnu.org with spam-scanned (Exim 4.10.13) id 18YKDW-0000XF-00 for emacs-devel@gnu.org; Tue, 14 Jan 2003 01:06:31 -0500 Original-Received: from is.elta.co.il ([199.203.121.2]) by monty-python.gnu.org with esmtp (Exim 4.10.13) id 18YKDV-0000Rv-00 for emacs-devel@gnu.org; Tue, 14 Jan 2003 01:06:29 -0500 Original-Received: from is (is [199.203.121.2]) by is.elta.co.il (8.9.3/8.8.8) with SMTP id IAA17974; Tue, 14 Jan 2003 08:06:03 +0200 (IST) X-Sender: eliz@is Original-To: "Kim F. Storm" In-Reply-To: <5xk7h8a6lm.fsf@kfs2.cua.dk> Original-cc: Mario Lang X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1b5 Precedence: list List-Id: Emacs development discussions. List-Help: List-Post: List-Subscribe: , List-Archive: List-Unsubscribe: , Errors-To: emacs-devel-bounces+emacs-devel=quimby.gnus.org@gnu.org Xref: main.gmane.org gmane.emacs.devel:10716 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:10716 On 14 Jan 2003, Kim F. Storm wrote: > > We're receiving binary content via a network process. After the > > transfer is complete, this buffer should be saved to a file. > > > > The effect I'm having is that we receive 1372422 bytes via the process > > filter function STRING argument, and after insertion into a buffer, > > we have a buffer with buffer-size 1372422, but after calling (save-buffer) > > we get this: > > > > -rw-r--r-- 1 root root 1865264 Jan 13 18:35 blah28.mp3 > > > > I'm using: > > > > (set-process-coding-system proc 'binary 'binary) > > (set-buffer-file-coding-system 'no-conversion t) > > > > I have looked at Mario's data before sending it to emacs and after > emacs has written it to a file. > > It seems that every byte in the range 0xa0 .. 0xff that were in the > original file is prefixed with an 0x81 byte in the file containing the > received data. To me, that looks like the internal multi-byte > representation for the binary data. Yes. That's what no-conversion does: it prevents encoding of the internal buffer's contents. I suggest to use raw-text for both coding systems above, and see if that helps. An alternative approach is to (set-buffer-multibyte nil) before reading the data into it and before saving it. > The buffer's coding system for save is no-conversion. How did > that internal data end up in the file? Probably because the buffer was a multibyte buffer, in which case no-conversion writes out the internal representation. That's why I suggested using raw-text to save the buffer. The reason you seem to see the right size is that Emacs tries very hard to conceal the fact that some characters in the 128-255 code range are stored in a multibyte buffer as multibyte sequences. Using no-conversion to save such a buffer exposes the internal representation, so it is exactly the thing _not_to_do_ in this case. > What coding systems should be set on the network process and on the > buffer to make it possible to have the received binary data in the > buffer make its way unmangled into the file on the disk? As I said above, two ways: either force the receiving buffer to be unibyte, or use raw-text to save it. Both ways should have the same effect; however, I'm personally biased towards not using unibyte buffers, so my preference would be to try the raw-text approach first.