[PATCH weston] weston-launch: use custom error function

[Eric Engestrom]

On Thu, Sep 29, 2016 at 09:26:16PM +0100, Murray Calavera wrote:
> error.h is a gnu extension and not available in other
> popular libcs like musl. This patch provides a replacement.
> 
> Signed-off-by: Murray Calavera <murray.calavera at gmail.com>

How did you test this? For me, `CC=musl-gcc ./autogen.sh` stops on:
  [...]
  checking for library containing pam_open_session... no
  configure: error: weston-launch requires pam

The code looks good though (with one nit-pick), so even if I couldn't
test it, it is:
Reviewed-by: Eric Engestrom <eric.engestrom at imgtec.com>

> ---
>  libweston/weston-launch.c | 20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/libweston/weston-launch.c b/libweston/weston-launch.c
> index 140fde1..84f7d60 100644
> --- a/libweston/weston-launch.c
> +++ b/libweston/weston-launch.c
> @@ -33,7 +33,6 @@
>  #include <poll.h>
>  #include <errno.h>
>  
> -#include <error.h>
>  #include <getopt.h>
>  
>  #include <sys/types.h>
> @@ -112,6 +111,25 @@ struct weston_launch {
>  
>  union cmsg_data { unsigned char b[4]; int fd; };
>  
> +static void
> +error(int status, int errnum, const char *msg, ...)
> +{
> +	va_list args;
> +
> +	fputs("weston-launch: ", stderr);
> +	va_start(args, msg);
> +	vfprintf(stderr, msg, args);
> +	va_end(args);
> +
> +	if (errnum)
> +		fprintf(stderr, ": %s\n", strerror(errnum));
> +	else
> +		fputc('\n', stderr);

Why not `fprintf(stderr, "\n");`?
While fputc() is enough since this is a single char, the use of
a different function here looks... odd.

> +
> +	if (status)
> +		exit(status);
> +}
> +
>  static gid_t *
>  read_groups(void)
>  {
> -- 
> 2.10.0