From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/6676 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: getopt_long permutation algorithm questions Date: Wed, 3 Dec 2014 14:29:29 -0500 Message-ID: <20141203192929.GA14223@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1417634994 2614 80.91.229.3 (3 Dec 2014 19:29:54 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 3 Dec 2014 19:29:54 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-6689-gllmg-musl=m.gmane.org@lists.openwall.com Wed Dec 03 20:29:46 2014 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1XwFcP-0000tc-F1 for gllmg-musl@m.gmane.org; Wed, 03 Dec 2014 20:29:45 +0100 Original-Received: (qmail 9802 invoked by uid 550); 3 Dec 2014 19:29:43 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 9794 invoked from network); 3 Dec 2014 19:29:43 -0000 Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:6676 Archived-At: As part of resolving the rest of the dist-local changes Alpine is applying to musl, I'm trying to figure out how to add GNU-style argument permutation to getopt_long. The basic concept is simple: when a non-option argument is encountered, skip forward until the next option (argument beginning with '-') and move it (and possibly its argument) before the non-option arguments. However, there are some ugly corner cases like: arg1 -ab foo arg2 where 'a' and 'b' are options, and 'b' takes an argument, foo. Here it seems like, in order to perform the correct permutation, lookahead is required to see that foo also needs to be moved. Is this correct? For long options, it's immediately decidable from the option being processed whether it has no argument, or an argument that's part of the same argv[] string, or a separate option in the next argv[] slot. For short options, it seems necessary to scan each character of the argv[] string to be moved, looking for the first option that takes an argument. If none is found, or if such a character is found in a non-final position, only this string needs to be moved. If an option needing an argument is found in the final position, two argv[] strings need to be moved. Is this correct? Rich