From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by passt.top (Postfix) with ESMTP id 85CED5A005E for ; Wed, 15 Feb 2023 12:54:30 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1676462069; 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=EAM7xizD5zC99KmZGxnrZsuVLNdN2+k8XTtq9N5NJGY=; b=PfrKJZF8eKfAzerbB3CrXugXcvKzn14YEhWPWHO4TrrMMnmtqogIW8SueiTQUGXQXz0ePw n9EL6HDKhMiNjYFFthgARoKE/rMdMdzPqT/pLvaVWAh05W5pn+WxKv52yFaBcy3d6bB1NA Z7FmX7VJjRld6HSLgFFVFvnNUEsy9zU= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-447-cFBTDJBVP9GVFIAvawoXoA-1; Wed, 15 Feb 2023 06:54:28 -0500 X-MC-Unique: cFBTDJBVP9GVFIAvawoXoA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BC4462806046 for ; Wed, 15 Feb 2023 11:54:27 +0000 (UTC) Received: from maya.cloud.tilaa.com (unknown [10.33.32.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 918E1492B0E; Wed, 15 Feb 2023 11:54:27 +0000 (UTC) Date: Wed, 15 Feb 2023 12:54:24 +0100 From: Stefano Brivio To: Laine Stump Subject: Re: [PATCH v4 1/9] log to stderr until process is daemonized, even if a log file is set Message-ID: <20230215125424.4a6d68d3@elisabeth> In-Reply-To: <20230215082437.110151-2-laine@redhat.com> References: <20230215082437.110151-1-laine@redhat.com> <20230215082437.110151-2-laine@redhat.com> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-ID-Hash: SIDU555NBVEFHBFPXJAGSYNIDY7W4RNR X-Message-ID-Hash: SIDU555NBVEFHBFPXJAGSYNIDY7W4RNR X-MailFrom: sbrivio@redhat.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: passt-dev@passt.top X-Mailman-Version: 3.3.3 Precedence: list List-Id: Development discussion and patches for passt Archived-At: Archived-At: List-Archive: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Wed, 15 Feb 2023 03:24:29 -0500 Laine Stump wrote: > Once a log file (specified on the commandline) is opened, the logging > functions will stop sending error logs to stderr, which is annoying if > passt has been started by another process that wants to collect error > messages from stderr so it can report why passt failed to start. It > would be much nicer if passt continued sending all log messages to > stderr until it daemonizes itself (at which point the process that > started passt can assume that it was started successfully). > > The system log mask is set to LOG_EMERG when the process starts, and > we're already using that to do "special" logging during the period > from process start until the log level requested on the commandline is > processed (setting the log mask to something else). This period > *almost* matches with "the time before the process is daemonized"; if > we just delay setting the log mask a tiny bit, then it will match > exactly, and we can use it to determine if we need to send log > messages to stderr even when a log file has been specified and opened. > > This patch delays the setting of the log mask until immediately before > the call to __daemon(). It also modifies logfn() slightly, so that it > will log to stderr any time log mask is LOG_EMERG, even if a log file > has been opened. > > Signed-off-by: Laine Stump > --- > log.c | 4 ++-- > passt.c | 17 ++++++++++------- > 2 files changed, 12 insertions(+), 9 deletions(-) > > diff --git a/log.c b/log.c > index 468c730..6dc6673 100644 > --- a/log.c > +++ b/log.c > @@ -66,8 +66,8 @@ void name(const char *format, ...) { \ > va_end(args); \ > } \ > \ > - if ((setlogmask(0) & LOG_MASK(LOG_DEBUG) || \ > - setlogmask(0) == LOG_MASK(LOG_EMERG)) && log_file == -1) { \ > + if ((setlogmask(0) & LOG_MASK(LOG_DEBUG) && log_file == -1) || \ > + setlogmask(0) == LOG_MASK(LOG_EMERG)) { \ > va_start(args, format); \ > (void)vfprintf(stderr, format, args); \ > va_end(args); \ Strictly speaking, I think this is correct, but it causes duplicate messages to be printed on interactive terminals, or with -e/--stderr, because in that case we already set LOG_PERROR in our __openlog() wrapper. I had a quick attempt at reworking this whole mess, with a table clearly gathering conditions and logging outcomes, but it's actually not that straightforward. So I'd rather just post a follow-up patch for this, at least for the moment. -- Stefano