Re: [PATCH 2/3] conf: Don't print usage via the logging subsystem

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Jun 05, 2024 at 12:40:41AM +0200, Stefano Brivio wrote:
> On Wed, 29 May 2024 19:04:04 +1000
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
> > The message from usage() when given invalid options, or the -h / --help
> > option is currently printed by many calls to the info() function, also
> > used for runtime logging of informational messages.
> > 
> > That isn't useful: the usage message should always go to the terminal
> > (stdout or stderr), never syslog or a logfile.  It should never be
> > filtered by priority.  Really the only thing using the common logging
> > functions does is give more opportunities for something to go wrong.
> > 
> > Replace all the info() calls with direct fprintf() calls.  This does mean
> > manually adding "\n" to each message.  A little messy, but worth it for the
> > simplicity in other dimensions.
> 
> Yes, definitely less messy than the existing implementation, I just
> wonder:
> 
> > Link: https://bugs.passt.top/show_bug.cgi?id=90
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  conf.c | 318 ++++++++++++++++++++++++++++-----------------------------
> >  1 file changed, 159 insertions(+), 159 deletions(-)
> > 
> > diff --git a/conf.c b/conf.c
> > index f2a92574..31f5b197 100644
> > --- a/conf.c
> > +++ b/conf.c
> > @@ -706,193 +706,194 @@ static unsigned int conf_ip6(unsigned int ifi,
> >  /**
> >   * usage() - Print usage, exit with given status code
> >   * @name:	Executable name
> > + * @f:		Stream to print usage info to
> >   * @status:	Status code for exit()
> >   */
> > -static void usage(const char *name, int status)
> > +static void usage(const char *name, FILE *f, int status)
> >  {
> >  	if (strstr(name, "pasta")) {
> > -		info("Usage: %s [OPTION]... [COMMAND] [ARGS]...", name);
> > -		info("       %s [OPTION]... PID", name);
> > -		info("       %s [OPTION]... --netns [PATH|NAME]", name);
> > -		info("");
> > -		info("Without PID or --netns, run the given command or a");
> > -		info("default shell in a new network and user namespace, and");
> > -		info("connect it via pasta.");
> > +		fprintf(f, "Usage: %s [OPTION]... [COMMAND] [ARGS]...\n", name);
> > +		fprintf(f, "       %s [OPTION]... PID\n", name);
> > +		fprintf(f, "       %s [OPTION]... --netns [PATH|NAME]\n", name);
> > +		fprintf(f, "\n");
> > +		fprintf(f, "Without PID or --netns, run the given command or a\n");
> > +		fprintf(f, "default shell in a new network and user namespace, and\n");
> > +		fprintf(f, "connect it via pasta.\n");
> 
> I haven't checked how it looks like in the end, but in most of this
> function, we use fprintf() without arguments after the format, and we
> need explicit newlines anyway, so, what if we concatenate the whole
> output, say:
> 
> 		fprintf(f,
> 			"Without PID or --netns, run the given command or a\n"
> 			"default shell in a new network and user namespace, and\n"
> 			"connect it via pasta.\n"
> 			);
> 
> ?

Fair point, I've made that change.

> I used separate info() calls (or whatever they were) in the past
> just because of the convenient newlines.
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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