[PATCH 2/2] Ensure strncpy results are null terminated.

[Bryce Harrington]

On Wed, Sep 02, 2015 at 01:53:32PM -0500, Derek Foreman wrote:
> On 28/08/15 03:04 PM, Bryce Harrington wrote:
> > Signed-off-by: Bryce Harrington <bryce at osg.samsung.com>
> > ---
> >  clients/window.c       | 1 +
> >  src/compositor-fbdev.c | 1 +
> >  2 files changed, 2 insertions(+)
> > 
> > diff --git a/clients/window.c b/clients/window.c
> > index 0e73f5b..614b320 100644
> > --- a/clients/window.c
> > +++ b/clients/window.c
> > @@ -5886,6 +5886,7 @@ keysym_modifiers_add(struct wl_array *modifiers_map,
> >  		return;
> >  
> >  	strncpy(p, name, len);
> > +	p[len-1] = '\0';
> 
> In this case, len is defined to be strlen(name) + 1 further up in the
> function, so strncpy will already be 0 padding to that - I think we were
> already ok here?
> 
> However, maybe you want to make this just a strcpy() instead?  We
> already know it's NULL terminated and we just allocated enough space for
> it...
> 
> >  }
> >  
> >  static xkb_mod_index_t
> > diff --git a/src/compositor-fbdev.c b/src/compositor-fbdev.c
> > index a5c7947..b90975c 100644
> > --- a/src/compositor-fbdev.c
> > +++ b/src/compositor-fbdev.c
> > @@ -338,6 +338,7 @@ fbdev_query_screen_info(struct fbdev_output *output, int fd,
> >  	info->buffer_length = fixinfo.smem_len;
> >  	info->line_length = fixinfo.line_length;
> >  	strncpy(info->id, fixinfo.id, sizeof(info->id) / sizeof(*info->id));
> > +	info->id[sizeof(info->id)-1] = '\0';
> 
> This change looks good to me.
> 
> I took the liberty of submitting a patch to remove the odd /
> sizeof(*info->id) bit (strncpy really wants bytes, not "array members" -
> though here the array members are 1 byte in size...)
> 
> Your call if you want to respin yours on top of that or make me do a
> follow up.  :)
> 
> Reviewed-by: Derek Foreman <derekf at osg.samsung.com>
> for this hunk.

Thanks, I updated the patch to just this one-liner, and pushed to trunk.

To ssh://git.freedesktop.org/git/wayland/weston
   c8dcd16..44bbdd0  master -> master

 
> >  
> >  	info->pixel_format = calculate_pixman_format(&varinfo, &fixinfo);
> >  	info->refresh_rate = calculate_refresh_rate(&varinfo);
> >