From: Dimitris Aragiorgis <dimara@arrikto.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Alex Pyrgiotis <apyrgio@arrikto.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize
Date: Thu, 11 Feb 2016 18:49:19 +0200 [thread overview]
Message-ID: <20160211164919.GC7256@arr> (raw)
In-Reply-To: <56BC7F15.9090603@redhat.com>
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Hi,
* Paolo Bonzini <pbonzini@redhat.com> [2016-02-11 13:31:17 +0100]:
>
>
> On 11/02/2016 13:12, Dimitris Aragiorgis wrote:
> > Besides that, when one executes a daemon, shell redirection is
> > hardly, if ever, used. More so if the daemon already has a logfile
> > option.
> >
> > So, we decided to give it a go and find the least painful way to
> > log the stderr of a QEMU process to a logfile.
> >
> > To our understanding, the logfile (-D option) is used only for
> > messages generated by qemu_log()/qemu_log_mask(). The current
> > situation however is that fprintf(stderr, ...) is used in various
> > places throughout the codebase for logging/debug purposes.
>
> Right, mostly through error_report.
>
> Actually I like your approach (log to -D if daemonize is used). I
> just was not sure of the best way to implement it.
>
Well my apprach was based on the extra option so that the current
behavior does not change and logfiles become too noisy out of the blue.
I have a patch already that:
- modifies do_qemu_set_log() so that if -log-stderr is given to:
+ open the logfile
+ dup stderr to it
+ skip qemu_log_close()
- modifies os_setup_post() to dup stderr to /dev/null only if
qemu_logfile is NULL.
If we do not want this extra option, I guess we are talking about
logging stderr to -D *only* if daemonize is used, right?
> Perhaps when the logfile is opened you can replace the straight fopen with
>
> qemu_logfile = fopen(...);
> if (daemonized) {
> dup2(fileno(qemu_logfile), STDERR_FILENO);
> fclose(qemu_logfile);
> qemu_logfile = stderr;
> }
>
> Then the logfile will never be closed by qemu_log_close, and stderr
> will always be sent to it. Does this look sane?
>
I guess the above snippet will go in do_qemu_set_log(), right?
If true, we have to open the logfile even if the -d option is not given.
Besides that, log.c should become aware of daemonize.
Depending on your answers I'll prepare the corresponding patch.
Thanks,
dimara
> Paolo
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next prev parent reply other threads:[~2016-02-11 16:49 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-16 16:56 [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize Alex Pyrgiotis
2016-02-08 9:29 ` Paolo Bonzini
2016-02-11 12:12 ` Dimitris Aragiorgis
2016-02-11 12:31 ` Paolo Bonzini
2016-02-11 16:49 ` Dimitris Aragiorgis [this message]
2016-02-11 17:56 ` Paolo Bonzini
2016-02-18 11:38 ` [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized Dimitris Aragiorgis
2016-02-18 15:22 ` Paolo Bonzini
2016-02-18 17:12 ` Dimitris Aragiorgis
2016-02-19 17:25 ` Paolo Bonzini
2016-03-01 11:15 ` Gerd Hoffmann
2016-03-01 11:47 ` Daniel P. Berrange
2016-03-01 11:51 ` Paolo Bonzini
2016-03-01 11:58 ` Daniel P. Berrange
2016-03-01 12:03 ` Paolo Bonzini
2016-03-01 13:54 ` Daniel P. Berrange
2016-03-01 11:50 ` Paolo Bonzini
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