From patchwork Thu Jun 9 12:27:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12875662 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F4152C43334 for ; Thu, 9 Jun 2022 14:23:37 +0000 (UTC) Received: from localhost ([::1]:40402 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nzJ4S-0004p6-Ts for qemu-devel@archiver.kernel.org; Thu, 09 Jun 2022 10:23:36 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59108) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nzHFq-0003vc-3S for qemu-devel@nongnu.org; Thu, 09 Jun 2022 08:27:14 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:25315) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nzHFo-0007mE-FH for qemu-devel@nongnu.org; Thu, 09 Jun 2022 08:27:13 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1654777631; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iAWVzsa0z1Sj3mziMZiAUPBnAdjatXfpmaGaZ2ZUy5U=; b=QqYL4hfd1s+7kyd3xABSatOuiTvA1VV8rV+Pu4wiRIB3xIk9DtdNbhpICdq/Mp+4Y4Eu+e hsj75UhBTWMSOZlxiwmuiWwpM7Ltwmgj5aDUj6qzFgbDQ8I0HXkkIU60pgbrUJ68BBT4Xo 6tAct0f4hVF/VP3b5/pKuVcUJydxliY= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-414-E-21kFDONRmcjUQXdoZpGw-1; Thu, 09 Jun 2022 08:27:08 -0400 X-MC-Unique: E-21kFDONRmcjUQXdoZpGw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5A1A9803B22; Thu, 9 Jun 2022 12:27:08 +0000 (UTC) Received: from localhost (unknown [10.39.193.99]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1616B2166B26; Thu, 9 Jun 2022 12:27:07 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Hanna Reitz , Kevin Wolf , Paolo Bonzini Subject: [PATCH 3/3] vl: Unlink absolute PID file path Date: Thu, 9 Jun 2022 14:27:01 +0200 Message-Id: <20220609122701.17172-4-hreitz@redhat.com> In-Reply-To: <20220609122701.17172-1-hreitz@redhat.com> References: <20220609122701.17172-1-hreitz@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" After writing the PID file, we register an exit notifier to unlink it when the process terminates. However, if the process has changed its working directory in the meantime (e.g. in os_setup_post() when daemonizing), this will not work when the PID file path was relative. Therefore, pass the absolute path (created with realpath()) to the unlink() call in the exit notifier. (realpath() needs a path pointing to an existing file, so we cannot use it before qemu_write_pidfile().) Reproducer: $ cd /tmp $ qemu-system-x86_64 --daemonize --pidfile qemu.pid $ file qemu.pid qemu.pid: ASCII text $ kill $(cat qemu.pid) $ file qemu.pid qemu.pid: ASCII text (qemu.pid should be gone after the process has terminated.) Signed-off-by: Hanna Reitz Reviewed-by: Daniel P. Berrangé --- softmmu/vl.c | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) diff --git a/softmmu/vl.c b/softmmu/vl.c index f0074845b7..a97af525d1 100644 --- a/softmmu/vl.c +++ b/softmmu/vl.c @@ -1548,11 +1548,18 @@ machine_parse_property_opt(QemuOptsList *opts_list, const char *propname, } static const char *pid_file; -static Notifier qemu_unlink_pidfile_notifier; +struct UnlinkPidfileNotifier { + Notifier notifier; + char *pid_file_realpath; +}; +static struct UnlinkPidfileNotifier qemu_unlink_pidfile_notifier; static void qemu_unlink_pidfile(Notifier *n, void *data) { - unlink(pid_file); + struct UnlinkPidfileNotifier *upn; + + upn = DO_UPCAST(struct UnlinkPidfileNotifier, notifier, n); + unlink(upn->pid_file_realpath); } static const QEMUOption *lookup_opt(int argc, char **argv, @@ -2472,13 +2479,28 @@ static void qemu_maybe_daemonize(const char *pid_file) rcu_disable_atfork(); if (pid_file) { + char *pid_file_realpath = NULL; + if (!qemu_write_pidfile(pid_file, &err)) { error_reportf_err(err, "cannot create PID file: "); exit(1); } - qemu_unlink_pidfile_notifier.notify = qemu_unlink_pidfile; - qemu_add_exit_notifier(&qemu_unlink_pidfile_notifier); + pid_file_realpath = g_malloc0(PATH_MAX); + if (!realpath(pid_file, pid_file_realpath)) { + error_report("cannot resolve PID file path: %s: %s", + pid_file, strerror(errno)); + unlink(pid_file); + exit(1); + } + + qemu_unlink_pidfile_notifier = (struct UnlinkPidfileNotifier) { + .notifier = { + .notify = qemu_unlink_pidfile, + }, + .pid_file_realpath = pid_file_realpath, + }; + qemu_add_exit_notifier(&qemu_unlink_pidfile_notifier.notifier); } }