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

[Pino Toscano]

On Wednesday 03 February 2016 10:34:06 Richard W.M. Jones wrote:
> On Wed, Feb 03, 2016 at 10:35:07AM +0100, Pino Toscano wrote:
> > 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.
> 
> That's not true though:
> 
> --------------------------------------------------------- test.c -----
> #include <stdio.h>
> #include <stdlib.h>
> 
> int
> main ()
> {
>   char s[10];
> 
>   snprintf (s, sizeof s, "%s", "0123456789");
>   printf ("s = %s\n", s);
>   return 0;
> }
> ----------------------------------------------------------------------
> 
> $ gcc -Wall test.c -o test
> $ ./test
> s = 012345678

Oh right, snprintf is indeed not strncpy... I stand corrected, thanks.

-- 
Pino Toscano
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