Re: [PATCH 03/11] log: Drop newlines in the middle of the perror()-like messages

[Stefano Brivio <sbrivio@redhat.com>]

On Thu, 25 Jul 2024 13:26:47 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Wed, Jul 24, 2024 at 11:50:09PM +0200, Stefano Brivio wrote:
> > Calling vlogmsg() twice from logmsg_perror() results in this beauty:
> > 
> >   $ ./pasta -i foo
> >   Invalid interface name foo
> >   : No such device
> > 
> > because the first part of the message, corresponding to the first
> > call, doesn't end with a newline, and vlogmsg() adds it.
> > 
> > Given that we can't easily append an argument (error description) to
> > a variadic list, add a 'newline' parameter to all the functions that
> > currently add a newline if missing, and disable that on the first call
> > to vlogmsg() from logmsg_perror(). Not very pretty but I can't think
> > of any solution that's less messy than this.
> > 
> > Signed-off-by: Stefano Brivio <sbrivio@redhat.com>  
> 
> I think my personal inclination would be to rename all the
> lowest-level functions slightly and remove the newline adding logic
> unconditionally.  The create wrappers under the old name which add the
> "\n".  I think that can be done in an easy macro, since the "\n" can
> be constant string appended to the format string.  Just the special
> paths that need to suppress the newline would call the low level "no
> newline" variants.

I gave it a try, but the problem is that the "easy macro" needs to be
conditional, depending on whether the newline is there or not: we don't
want to add a newline in case somebody already added it by mistake (or
habit).

That could probably be done as well with an intermediate function, but
it's getting a bit too complicated (at least for me right now).

> But, I don't actually care that much so
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

-- 
Stefano