[PATCH 2/6] libweston: fbdev: support the --seat option, (and XDG_SEAT variable)

[Pekka Paalanen]

On Wed,  6 Sep 2017 08:17:19 -0400
nerdopolis <bluescreen_avenger at verizon.net> wrote:

> ---

Hi,

the commit message is missing a rationale and Signed-off-by.

>  compositor/main.c            | 2 ++
>  libweston/compositor-fbdev.c | 5 ++++-
>  libweston/compositor-fbdev.h | 1 +
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/compositor/main.c b/compositor/main.c
> index 61bda282..f88608cd 100644
> --- a/compositor/main.c
> +++ b/compositor/main.c
> @@ -573,6 +573,7 @@ usage(int error_code)
>  		"Options for fbdev-backend.so:\n\n"
>  		"  --tty=TTY\t\tThe tty to use\n"
>  		"  --device=DEVICE\tThe framebuffer device to use\n"
> +		"  --seat=SEAT\t\tThe seat that weston should run on, instead of the seat defined in XDG_SEAT\n"
>  		"\n");
>  #endif
>  
> @@ -1444,6 +1445,7 @@ load_fbdev_backend(struct weston_compositor *c,
>  	const struct weston_option fbdev_options[] = {
>  		{ WESTON_OPTION_INTEGER, "tty", 0, &config.tty },
>  		{ WESTON_OPTION_STRING, "device", 0, &config.device },
> +		{ WESTON_OPTION_STRING, "seat", 0, &config.seat_id },
>  	};
>  
>  	parse_options(fbdev_options, ARRAY_LENGTH(fbdev_options), argc, argv);
> diff --git a/libweston/compositor-fbdev.c b/libweston/compositor-fbdev.c
> index dabacbb5..b4f0685c 100644
> --- a/libweston/compositor-fbdev.c
> +++ b/libweston/compositor-fbdev.c
> @@ -728,6 +728,8 @@ fbdev_backend_create(struct weston_compositor *compositor,
>  	session_seat=getenv("XDG_SEAT");
>  	if (session_seat)
>  		seat_id=session_seat;
> +	if (param->seat_id)
> +		seat_id = param->seat_id;

This is correct, but there is something else below that is not.

>  
>  	weston_log("initializing fbdev backend\n");
>  
> @@ -751,7 +753,7 @@ fbdev_backend_create(struct weston_compositor *compositor,
>  	wl_signal_add(&compositor->session_signal,
>  		      &backend->session_listener);
>  	compositor->launcher =
> -		weston_launcher_connect(compositor, param->tty, "seat0", false);
> +		weston_launcher_connect(compositor, param->tty, seat_id, false);

Ok.

>  	if (!compositor->launcher) {
>  		weston_log("fatal: fbdev backend should be run "
>  			   "using weston-launch binary or as root\n");
> @@ -797,6 +799,7 @@ config_init_to_defaults(struct weston_fbdev_backend_config *config)
>  	 * udev, rather than passing a device node in as a parameter. */
>  	config->tty = 0; /* default to current tty */
>  	config->device = "/dev/fb0"; /* default frame buffer */
> +	config->seat_id = "seat0"; /* default seat*/

Setting the default here does not work quite right. If seat_id is not
NULL, then fbdev-backend must use seat_id instead of the default or
XDG_SEAT. Otherwise the compositor cannot choose the seat with a
command line option.

The values set in this function will be used when the compositor uses a
version of weston_fbdev_backend_config struct which does not have these
fields.

If the compositor uses a version of weston_fbdev_backend_config that is
up-to-date, in Weston's case always, then these values get ignored.

I think the right action would be to not assign seat_id here at all,
leaving it NULL. Then the only way for it to be non-NULL is when the
compositor passes in a seat name that must be used instead of XDG_SEAT
or the default.

>  }
>  
>  WL_EXPORT int
> diff --git a/libweston/compositor-fbdev.h b/libweston/compositor-fbdev.h
> index 8b7d900e..c4e3305a 100644
> --- a/libweston/compositor-fbdev.h
> +++ b/libweston/compositor-fbdev.h
> @@ -43,6 +43,7 @@ struct weston_fbdev_backend_config {
>  
>  	int tty;
>  	char *device;
> +	char *seat_id;

This is a ABI breaking change to weston_fbdev_backend_config, so you
should bump WESTON_FBDEV_BACKEND_CONFIG_VERSION as well, or put the new
field as the last one instead.

>  
>  	/** Callback used to configure input devices.
>  	 *


Thanks,
pq
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