From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 5639 invoked by alias); 11 Jul 2013 20:28:46 -0000 Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Received: (qmail 5596 invoked by uid 89); 11 Jul 2013 20:28:40 -0000 X-Spam-SWARE-Status: No, score=-3.5 required=5.0 tests=AWL,BAYES_00,KHOP_THREADED,RCVD_IN_DNSWL_NONE,RCVD_IN_HOSTKARMA_NO,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.1 Received: from plane.gmane.org (HELO plane.gmane.org) (80.91.229.3) by sourceware.org (qpsmtpd/0.84/v0.84-167-ge50287c) with ESMTP; Thu, 11 Jul 2013 20:28:39 +0000 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1UxNTg-00074c-GD for cygwin@cygwin.com; Thu, 11 Jul 2013 22:28:36 +0200 Received: from c-69-140-37-22.hsd1.md.comcast.net ([69.140.37.22]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 11 Jul 2013 22:28:36 +0200 Received: from schulman.andrew by c-69-140-37-22.hsd1.md.comcast.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 11 Jul 2013 22:28:36 +0200 To: cygwin@cygwin.com From: Andrew Schulman Subject: Re: libargp: argp_program_version does not work Date: Thu, 11 Jul 2013 22:02:00 -0000 Message-ID: <4q4ut8had25hqmo8b0752i8asuv6ism2qh@4ax.com> References: <000001ce7e08$2b866830$82933890$%fedin@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Archive: encrypt X-SW-Source: 2013-07/txt/msg00231.txt.bz2 > > Hello! > > > > I have found a problem: argp_program_version string is ignored by libargp. > > Hi Pavel. Thanks for reporting this. I confirm your observation. For > example, when I compile argp's example #2 > (http://www.gnu.org/software/libc/manual/html_node/Argp-Example-2.html#Argp-Example-2), > the --version option doesn't work. > > > I guess the problem happens because of DLL's nature. DLLs cannot contain > > unresolved symbols, so the DLL has own version of argp_program_version which > > is always initialized to NULL. There's no way to override it. > > Also confirmed. argp.h declares argp_program_version as > > extern const char *argp_program_version; > > But gllib/argp-pv.c initializes it as > > const char *argp_program_version = (const char *) 0 > > Whether there's a way to override that value by one declared in the user's > code, I don't know. Maybe a linker switch? OK, I remembered how this works. To override the initial values in your program, you just have to reassign them at run time. Here's how it's done with argp's example #2. Note the first two lines of main(), which aren't present in the upstream example. /*** Begin modified argp example #2 ***/ #include const char version[] = "argp-ex2 1.0"; const char bug_address[] = ""; /* Program documentation. */ static char doc[] = "Argp example #2 -- a pretty minimal program using argp"; static struct argp argp = { 0, 0, 0, doc }; int main (int argc, char **argv) { argp_program_version = version; argp_program_bug_address = bug_address; argp_parse (&argp, argc, argv, 0, 0, 0); } /*** End modified argp example #2 ***/ If you compile the above version, you'll see that the --version option and bug tracker text are available. I'm sure this problem is familiar to developers and users of shared libraries, but I had forgotten it. I'll add a note to the Cygwin README file, to help all of us remember it next time. Andrew -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple