Re: [Qemu-devel] [PATCH 1/1] log: fix hanged connect from virt-manager to libvirt

[Paolo Bonzini <pbonzini@redhat.com>]

On 03/03/2016 15:25, Denis V. Lunev wrote:
>> Actually, the patch in v1 is fine.  My worry after looking at your patch
>> was that I didn't have the dup2(stdout, stderr) case.  However, with my
>> change you can never call qemu_log_close if is_daemonized(), because
>> even the monitor command "logfile" cannot set logfilename to NULL.
>
> IMHO you are wrong.

Possible. :)

> void qemu_set_log_filename(const char *filename)
> {
>     g_free(logfilename);
>     logfilename = g_strdup(filename);
>     qemu_log_close();
>     qemu_set_log(qemu_loglevel);
> }
> 
> static void hmp_logfile(Monitor *mon, const QDict *qdict)
> {
>     qemu_set_log_filename(qdict_get_str(qdict, "filename"));
> }
> 
> This means that we will have qemu_log_close()
> called in ANY case, even daemonized.
> From my point of view stderr will continue to be mapped
> to the old file if we request to stop logging either by
> zero mask or by setting empty filename.

Yes, but filename will never be NULL in hmp_logfile, will it?  It's
declared as 'F' in hmp-commands.hx, not as 'F?'.  If this is changed, I
agree that the dup2 needs to be added.

A different issue is that do_qemu_set_log *exits* instead of printing an
Error if fopen fails. In my opinion, in this case logging should not
even be disabled in this case.  But it can and should be fixed separately.

The code is really ugly, it is old and used to be just a debugging aid.

Paolo