[libcamera-devel] [PATCH] libcamera: keep using syslog logging target also for isolated IPA modules

[Jacopo Mondi]

Hello Matthias

On Mon, Feb 20, 2023 at 10:13:06AM +0100, Matthias Fend wrote:
> Hi Jacopo,
>
> Am 20.02.2023 um 09:50 schrieb Jacopo Mondi:
> > Hello Matthias
> >
> > On Mon, Feb 20, 2023 at 08:43:52AM +0100, Matthias Fend via libcamera-devel wrote:
> > > Currently it is not possible to display debug output from an isolated IPA
> > > module. The standard  descriptors are all closed and any specified log
> > > file is explicitly deactivated for the IPA module. Since libcamera and the
> > > isolated IPA modul are separate processes, they cannot write to the same
> > > file. However, if syslog is used, then this would be possible.
> > >
> > > If syslog is specified as a log file, then this is left as it is for the
> > > isolated IPA module.
> > >
> >
> > I'm certainly missing something, but doesn't logging to syslogd
> > happens through the 'syslog()'[1] function call ?
>
> If LIBCAMERA_LOG_FILE is set to 'syslog', the logging target is set to
> 'LoggingTargetSyslog', which instructs the libcamera logger to use syslog()
> to output log messages. This is already implemented.

Ups, I completely missed that

>
> However, this environment variable is explicitly deleted for an isolated IPA
> module. This change only prevents this behavior if syslog is to be used.
>
> I don't see any other way to see the debug output of such a module - apart
> from adapting the libcamera source code of course.
>

Ok then, this now makes sense to me.

I don't see issues in allowing isolated processes interface to syslog,
but let's wait for other's opinions.

> ~Matthias
>
> >
> > [1] https://linux.die.net/man/3/syslog
> >
> > > Signed-off-by: Matthias Fend <matthias.fend at emfend.at>
> > > ---
> > >   src/libcamera/process.cpp | 4 +++-
> > >   1 file changed, 3 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/src/libcamera/process.cpp b/src/libcamera/process.cpp
> > > index 0e6b4e1d..86a382fb 100644
> > > --- a/src/libcamera/process.cpp
> > > +++ b/src/libcamera/process.cpp
> > > @@ -263,7 +263,9 @@ int Process::start(const std::string &path,
> > >
> > >   		closeAllFdsExcept(fds);
> > >
> > > -		unsetenv("LIBCAMERA_LOG_FILE");
> > > +		const char *file = utils::secure_getenv("LIBCAMERA_LOG_FILE");
> > > +		if (file && strcmp(file, "syslog"))
> > > +			unsetenv("LIBCAMERA_LOG_FILE");

Indentation seems off though

> > >
> > >   		const char **argv = new const char *[args.size() + 2];
> > >   		unsigned int len = args.size();
> > > --
> > > 2.25.1
> > >