Re: [PATCH v2 1/9] log to stderr until process is daemonized, even if a logfile is set

[Stefano Brivio <sbrivio@redhat.com>]

On Wed,  8 Feb 2023 12:48:30 -0500
Laine Stump <laine@redhat.com> wrote:

> Signed-off-by: Laine Stump <laine@redhat.com>
> ---
>  log.c   | 14 +++++++++++++-
>  log.h   |  1 +
>  passt.c |  6 ++++--
>  3 files changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/log.c b/log.c
> index 468c730..0ab0adf 100644
> --- a/log.c
> +++ b/log.c
> @@ -34,6 +34,7 @@ static int	log_sock = -1;		/* Optional socket to system logger */
>  static char	log_ident[BUFSIZ];	/* Identifier string for openlog() */
>  static int	log_mask;		/* Current log priority mask */
>  static int	log_opt;		/* Options for openlog() */
> +static int	log_daemon_mode = false; /* true once process is daemonized */
>  
>  static int	log_file = -1;		/* Optional log file descriptor */
>  static size_t	log_size;		/* Maximum log file size in bytes */
> @@ -67,7 +68,8 @@ void name(const char *format, ...) {					\
>  	}								\
>  									\
>  	if ((setlogmask(0) & LOG_MASK(LOG_DEBUG) ||			\
> -	     setlogmask(0) == LOG_MASK(LOG_EMERG)) && log_file == -1) {	\
> +	     setlogmask(0) == LOG_MASK(LOG_EMERG))			\
> +	     && (log_file == -1 || !log_daemon_mode)) {			\

This is getting a bit complicated.

At the moment, LOG_EMERG is abused with the meaning "we don't know
where/what to log yet", because we didn't process logging options yet.

Would it be an option to extend this abuse a bit further, and use
LOG_EMERG to indicate that passt didn't daemonise yet, instead? You
would just need to move the __setlogmask() calls in main(), and change
the comment about the first one.

I haven't tested this, and we should be a bit careful with this (check
what happens with and without running passt from an interactive
terminal, with and without a log file, etc.).

A possibly cleaner approach could be to decouple this from the log
mask, and have an enum instead, to represent logging "states" or
"modes" -- but I'm not sure we're really going to save much complexity
with it.

By the way, the man page should be updated as well.

-- 
Stefano