From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D3CCEC00140 for ; Wed, 10 Aug 2022 18:35:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232673AbiHJSew convert rfc822-to-8bit (ORCPT ); Wed, 10 Aug 2022 14:34:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233772AbiHJSeh (ORCPT ); Wed, 10 Aug 2022 14:34:37 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D0C08C47A for ; Wed, 10 Aug 2022 11:34:33 -0700 (PDT) Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 27AGuS1A003179 for ; Wed, 10 Aug 2022 11:34:32 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3hvdb6asup-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 10 Aug 2022 11:34:32 -0700 Received: from twshared16308.14.prn3.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:21d::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Wed, 10 Aug 2022 11:34:31 -0700 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id A742B1D76C87D; Wed, 10 Aug 2022 11:34:26 -0700 (PDT) From: Andrii Nakryiko To: , , CC: , Subject: [PATCH bpf-next] libbpf: preserve errno across pr_warn/pr_info/pr_debug Date: Wed, 10 Aug 2022 11:34:25 -0700 Message-ID: <20220810183425.1998735-1-andrii@kernel.org> X-Mailer: git-send-email 2.30.2 X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-ORIG-GUID: D0zpFhCGFjpa2t_qnDHPb1RPsrMwklba X-Proofpoint-GUID: D0zpFhCGFjpa2t_qnDHPb1RPsrMwklba Content-Transfer-Encoding: 8BIT X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-10_12,2022-08-10_01,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org As suggested in [0], make sure that libbpf_print saves and restored errno and as such guaranteed that no matter what actual print callback user installs, macros like pr_warn/pr_info/pr_debug are completely transparent as far as errno goes. While libbpf code is pretty careful about not clobbering important errno values accidentally with pr_warn(), it's a trivial change to make sure that pr_warn can be used anywhere without a risk of clobbering errno. No functional changes, just future proofing. [0] https://github.com/libbpf/libbpf/pull/536 Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index f7364ea82ac1..917d975bd4c6 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -223,13 +223,18 @@ __printf(2, 3) void libbpf_print(enum libbpf_print_level level, const char *format, ...) { va_list args; + int old_errno; if (!__libbpf_pr) return; + old_errno = errno; + va_start(args, format); __libbpf_pr(level, format, args); va_end(args); + + errno = old_errno; } static void pr_perm_msg(int err) -- 2.30.2