From patchwork Tue Jul 12 18:08:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hanna Czenczek X-Patchwork-Id: 12915453 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 283AFC433EF for ; Tue, 12 Jul 2022 18:58:19 +0000 (UTC) Received: from localhost ([::1]:52368 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oBL5O-0003mH-1I for qemu-devel@archiver.kernel.org; Tue, 12 Jul 2022 14:58:18 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52522) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oBKJn-00061n-9h for qemu-devel@nongnu.org; Tue, 12 Jul 2022 14:09:07 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:48909) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oBKJl-0006xd-Ns for qemu-devel@nongnu.org; Tue, 12 Jul 2022 14:09:07 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657649345; 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=t6rSVTqCEJRgErg71STTRUlM4jkKu7lQyjXZhF6Dz0Q=; b=Ld/pyIgdTFk70XudHLHEHgKXY5zC8GuQbRO/C1abvg2J6Mcg8P6RWyQyF7CqnPGmuvvmvU tSb0AdFLss7Yg7T2V4WrsII8lRFnFoKBGT9YLvPbdVUyFpVpHU0Gwqwrg8j0mbHhh0uaes dmSN00Cwbx/t5Kn/bT5CpGX2OpYS3y0= 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-656-THgQlf9iNkS-OlF9_tpIoA-1; Tue, 12 Jul 2022 14:08:58 -0400 X-MC-Unique: THgQlf9iNkS-OlF9_tpIoA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E8D44101A54E; Tue, 12 Jul 2022 18:08:57 +0000 (UTC) Received: from localhost (unknown [10.39.193.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A6DC140CFD0A; Tue, 12 Jul 2022 18:08:57 +0000 (UTC) From: Hanna Reitz To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, Hanna Reitz Subject: [PULL 35/35] vl: Unlink absolute PID file path Date: Tue, 12 Jul 2022 20:08:53 +0200 Message-Id: <20220712180853.1364155-3-hreitz@redhat.com> In-Reply-To: <20220712180617.1362407-1-hreitz@redhat.com> References: <20220712180617.1362407-1-hreitz@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 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=ham 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 Message-Id: <20220609122701.17172-4-hreitz@redhat.com> 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 36f46fcdad..aabd82e09a 100644 --- a/softmmu/vl.c +++ b/softmmu/vl.c @@ -1522,11 +1522,18 @@ 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, @@ -2430,13 +2437,28 @@ 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); } }