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Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize
From: |
Dimitris Aragiorgis |
Subject: |
Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize |
Date: |
Thu, 11 Feb 2016 18:49:19 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Hi,
* Paolo Bonzini <address@hidden> [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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- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Paolo Bonzini, 2016/02/08
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Dimitris Aragiorgis, 2016/02/11
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Paolo Bonzini, 2016/02/11
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize,
Dimitris Aragiorgis <=
- Re: [Qemu-devel] [PATCH] os-posix: Log to logfile in case of daemonize, Paolo Bonzini, 2016/02/11
- [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized, Dimitris Aragiorgis, 2016/02/18
- Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized, Paolo Bonzini, 2016/02/18
- Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized, Dimitris Aragiorgis, 2016/02/18
- Re: [Qemu-devel] [PATCH] log: Redirect stderr to logfile if deamonized, Paolo Bonzini, 2016/02/19