[PATCH v2 2/3] xwayland: Remove a useless out-of-memory check

[Bryce Harrington]

On Wed, Jul 15, 2015 at 01:09:03PM +0100, Emil Velikov wrote:
> Hello gents,
> 
> On 15 July 2015 at 09:51, Marek Chalupa <mchqwerty at gmail.com> wrote:
> > Reviewed-by: Marek Chalupa <mchqwerty at gmail.com>
> >
> > (http://lists.freedesktop.org/archives/wayland-devel/2015-May/021952.html)
> >
> > On 05/16/2015 07:38 AM, Dima Ryazanov wrote:
> >>
> >> snprintf does not allocate memory, so we can never get an out-of-memory
> >> error.
> >>
> >> (Also, the error handler would free xwl_output after it was already
> >> registered
> >> as an event listener.)
> >>
> >> Signed-off-by: Dima Ryazanov <dima at gmail.com>
> >> ---
> >>   hw/xwayland/xwayland-output.c | 6 +-----
> >>   1 file changed, 1 insertion(+), 5 deletions(-)
> >>
> >> diff --git a/hw/xwayland/xwayland-output.c b/hw/xwayland/xwayland-output.c
> >> index 9baf4eb..41937b8 100644
> >> --- a/hw/xwayland/xwayland-output.c
> >> +++ b/hw/xwayland/xwayland-output.c
> >> @@ -165,11 +165,7 @@ xwl_output_create(struct xwl_screen *xwl_screen,
> >> uint32_t id)
> >>                                             &wl_output_interface, 2);
> >>       wl_output_add_listener(xwl_output->output, &output_listener,
> >> xwl_output);
> >>
> >> -    if (snprintf(name, sizeof name, "XWAYLAND%d", serial++) < 0) {
> >> -        ErrorF("create_output ENOMEM\n");
> >> -        free(xwl_output);
> >> -        return NULL;
> >> -    }
> >> +    snprintf(name, sizeof name, "XWAYLAND%d", serial++);
> >>
> man snprintf does mention
> 
> "      If an output error is encountered, a negative value is returned."
> 
> It does not explicitly state under what conditions. Not sure if we
> should really care here or not but at the very least the error message
> is inaccurate :-)

Well, snprintf errors if the size of the buffer was too small for what
it needs to write to.  That can't happen here because the buffer is
large (256) and the most that's going to be written is an int.

So, the only way this would fail is if the code changed, which would be
a programming error.  In which case maybe an assert() would be more
appropriate?

Bryce