From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Juri Linkov Newsgroups: gmane.emacs.devel Subject: Re: Magic MIME Date: Mon, 11 Feb 2008 22:55:33 +0200 Organization: JURTA Message-ID: <87ve4vfc1m.fsf@jurta.org> References: <87prv4h032.fsf@jurta.org> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1202764122 23211 80.91.229.12 (11 Feb 2008 21:08:42 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 11 Feb 2008 21:08:42 +0000 (UTC) Cc: emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Feb 11 22:09:03 2008 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1JOftd-0005w2-24 for ged-emacs-devel@m.gmane.org; Mon, 11 Feb 2008 22:09:01 +0100 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JOft9-00040g-LG for ged-emacs-devel@m.gmane.org; Mon, 11 Feb 2008 16:08:31 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1JOft5-0003yb-2A for emacs-devel@gnu.org; Mon, 11 Feb 2008 16:08:27 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1JOft3-0003yM-JN for emacs-devel@gnu.org; Mon, 11 Feb 2008 16:08:26 -0500 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JOft3-0003yJ-GB for emacs-devel@gnu.org; Mon, 11 Feb 2008 16:08:25 -0500 Original-Received: from relay01.kiev.sovam.com ([62.64.120.200]) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1JOft3-0007jQ-2z for emacs-devel@gnu.org; Mon, 11 Feb 2008 16:08:25 -0500 Original-Received: from [83.170.232.243] (helo=smtp.svitonline.com) by relay01.kiev.sovam.com with esmtp (Exim 4.67) (envelope-from ) id 1JOfsx-0009rl-0N; Mon, 11 Feb 2008 23:08:19 +0200 In-Reply-To: (Stefan Monnier's message of "Sun, 10 Feb 2008 21:24:30 -0500") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) X-Scanner-Signature: e35cef5ed21d82303c208435479e4a86 X-DrWeb-checked: yes X-SpamTest-Envelope-From: juri@jurta.org X-SpamTest-Group-ID: 00000000 X-SpamTest-Header: Not Detected X-SpamTest-Info: Profiles 2223 [Feb 11 2008] X-SpamTest-Info: helo_type=3 X-SpamTest-Info: {HEADERS: header Content-Type found without required header Content-Transfer-Encoding} X-SpamTest-Method: none X-SpamTest-Rate: 11 X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0278], KAS30/Release X-detected-kernel: by monty-python.gnu.org: FreeBSD 4.8-5.1 (or MacOS X 10.2-10.3) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:88786 Archived-At: >> not to fail trying to open it as an archive. Archive files >> have a well-known signature, and using content-based file >> type recognition rather than filename-based is more reliable. > > C'mon Juri, you know better than that. We've been through it with the > image-recognition thingy, so it *should* be clear to everyone on this > list now that content based recognition is no better than filename-based > recognition (and vice versa). We need to use both. Yes, I remember what a mess was the recognition of image files. But I think that for other binary formats this could by simplified. If, say, a file doesn't start with the "0x8080ffff 0x0000081a" signature there is no sense to try treating it as an arc archive even if it has the .arc extension. IIRC, the decision for the image file extensions taking precedence over the image file content was based solely on the security holes that some image libraries reportedly have. So that the user downloaded a .c file somewhere from the Internet actually with an image inside should not take the risk of opening it in image-mode in Emacs. I don't know if such precautions are relevant for other binary formats like archives. -- Juri Linkov http://www.jurta.org/emacs/