From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 024E43858406 for ; Mon, 8 Nov 2021 13:42:36 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 024E43858406 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-426-fwow7DxYMSC7AwwNQfB6Ig-1; Mon, 08 Nov 2021 08:42:35 -0500 X-MC-Unique: fwow7DxYMSC7AwwNQfB6Ig-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 942891006AA3; Mon, 8 Nov 2021 13:42:34 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.82]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B99455F4E9; Mon, 8 Nov 2021 13:42:33 +0000 (UTC) From: Florian Weimer To: Jonny Grant Cc: GNU C Library Subject: Re: glibc strerrorname_np References: <874k8nniw4.fsf@oldenburg.str.redhat.com> Date: Mon, 08 Nov 2021 14:42:31 +0100 In-Reply-To: (Jonny Grant's message of "Mon, 8 Nov 2021 13:36:54 +0000") Message-ID: <878rxykblk.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Nov 2021 13:42:38 -0000 * Jonny Grant: > On 08/11/2021 08:36, Florian Weimer wrote: >> * Jonny Grant: >> >>> I noticed on the man page it may return NULL, which is a shame, as then it means we always need to check that before using in every printf etc :- >>> >>> printf("err %s\n", strerrorname_np(myerr)?strerrorname_np(myerr), "Unknown err"); >> >> We can add %#m to printf for this use case. It would print the errno >> constant if known, or a number otherwise. To use it, errno needs to be >> assigned before calling printf. Printing multiple error codes would not >> be possible directly, but such usage is quite rare. > > Hi Florian > > I couldn't find a reference description of %#m - May I ask if you have > a link? I see %m is a GNU printf extension. Sorry, it would be a variant of %m, printing a known error constant or the error number. It's not implemented yet. Thanks, Florian