Re: [Libguestfs] [PATCH 1/3] launch: add internal helper for socket paths creation

Pino Toscano
Wed, 03 Feb 2016 09:35:07 -0000

On Tuesday 02 February 2016 19:47:12 Richard W.M. Jones
wrote:
> On Tue, Feb 02, 2016 at 03:27:39PM +0100, Pino Toscano wrote:
> > diff --git a/src/launch.c b/src/launch.c
> > index f59818f..ec061e3 100644
> > --- a/src/launch.c
> > +++ b/src/launch.c
> > @@ -418,6 +418,21 @@ guestfs_int_get_cpu_model (int kvm)
> >  #endif
> >  }
> >
> > +/* Create the path for a socket with the selected filename in the
> > + * tmpdir.
> > + */
> > +int
> > +guestfs_int_create_socketname (guestfs_h *g, const char *filename,
> > +                               char (*sockpath)[UNIX_PATH_MAX])
> > +{
> > +  char *path = g->tmpdir;
> > +
> > +  snprintf (*sockpath, UNIX_PATH_MAX-1, "%s/%s", path,
filename);
> > +  (*sockpath)[UNIX_PATH_MAX-1] = '\0';
>
> What's wrong with:
>
>   snprintf (*sockpath, UNIX_PATH_MAX, "%s/%s", path, filename);

If the "$path/$filename" string is longer than UNIX_PATH_MAX, then
*sockpath won't be 0-terminated.  Since the line after that always
puts 0 at the end, we can just save one character.

The truncation of long paths always happens with this patch, and that
is what patch #3 addresses.

--
Pino Toscano