[PATCH wayland] Revert "client: require WAYLAND_DISPLAY to be set"

[Sjoerd Simons]

On Mon, 2015-08-17 at 16:17 +0300, Pekka Paalanen wrote:
> From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> 
> This reverts commit fb7e13021730d0a5516ecbd3712ea4235e05d24d.

Acked-By: Sjoerd Simons <sjoerd.simons at collabora.co.uk>

> Developers have been trying to reduce the number of by default 
> required
> environment variables, and the mentioned commit is a step backwards 
> in
> that sense. The fundamental assumption is that a user has only one 
> main
> (Wayland) display server where all programs should connect to by
> default, and do so with an a priori known socket name.
> 
> The commit also broke various use cases in the wild, some 
> accidentally
> due to other causes, some intentionally. This revert allows those use
> cases to continue.
> 
> The original problem of running Weston in a window in an existing 
> GNOME
> X11 session and getting applications unintentionally launched into
> Weston can be circumvented by letting Weston use a non-default socket
> name, leaving wayland-0 unused.
> 
> Discussion:
> http://lists.freedesktop.org/archives/wayland-devel/2015
> -August/023927.html
> http://lists.freedesktop.org/archives/wayland-devel/2015
> -August/023937.html
> 
> Cc: Dima Ryazanov <dima at gmail.com>
> Cc: Giulio Camuffo <giuliocamuffo at gmail.com>
> Cc: Daniel Stone <daniel at fooishbar.org>
> Cc: Jasper St. Pierre <jstpierre at mecheye.net>
> Cc: Ryo Munakata <ryomnktml at gmail.com>
> Cc: Ray Strode <halfline at gmail.com>
> Cc: Peter Hutterer <peter.hutterer at who-t.net>
> Cc: Matthias Clasen <mclasen at redhat.com>
> Cc: Sjoerd Simons <sjoerd.simons at collabora.co.uk>
> Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> ---
>  doc/man/wl_display_connect.xml    |  5 +++--
>  doc/publican/sources/Protocol.xml |  8 ++++----
>  src/wayland-client.c              | 10 ++++------
>  3 files changed, 11 insertions(+), 12 deletions(-)
> 
> diff --git a/doc/man/wl_display_connect.xml 
> b/doc/man/wl_display_connect.xml
> index ded3cbd..7e6e05c 100644
> --- a/doc/man/wl_display_connect.xml
> +++ b/doc/man/wl_display_connect.xml
> @@ -57,8 +57,9 @@
>            that was previously opened by a Wayland server. The server 
> socket must
>            be placed in <envar>XDG_RUNTIME_DIR</envar> for this 
> function to
>            find it. The <varname>name</varname> argument specifies 
> the name of
> -          the socket or <constant>NULL</constant> to use the default
> -          (which is the value of <envar>WAYLAND_DISPLAY</envar>). If
> +          the socket or <constant>NULL</constant> to use the default 
> (which is
> +          <constant>"wayland-0"</constant>). The environment 
> variable
> +          <envar>WAYLAND_DISPLAY</envar> replaces the default value. 
> If
>            <envar>WAYLAND_SOCKET</envar> is set, this function 
> behaves like
>            <function>wl_display_connect_to_fd</function> with the 
> file-descriptor
>            number taken from the environment variable.</para>
> diff --git a/doc/publican/sources/Protocol.xml 
> b/doc/publican/sources/Protocol.xml
> index 9464953..477063b 100644
> --- a/doc/publican/sources/Protocol.xml
> +++ b/doc/publican/sources/Protocol.xml
> @@ -60,10 +60,10 @@
>      <title>Wire Format</title>
>      <para>
>        The protocol is sent over a UNIX domain stream socket, where 
> the endpoint
> -      name is determined by the <emphasis>WAYLAND_DISPLAY</emphasis>
> -      environment variable.  Its value will usually be
> -      <systemitem class="service">wayland-0</systemitem>.  The 
> protocol is message-based.
> -      A message sent by a client to the server is called request.  A 
> message
> +      usually is named <systemitem class="service">wayland
> -0</systemitem>
> +      (although it can be changed via 
> <emphasis>WAYLAND_DISPLAY</emphasis>
> +      in the environment).  The protocol is message-based.  A
> +      message sent by a client to the server is called request.  A 
> message
>        from the server to a client is called event.  Every message is
>        structured as 32-bit words, values are represented in the 
> host's
>        byte-order.
> diff --git a/src/wayland-client.c b/src/wayland-client.c
> index ffbca4b..09c594a 100644
> --- a/src/wayland-client.c
> +++ b/src/wayland-client.c
> @@ -764,11 +764,8 @@ connect_to_socket(const char *name)
>  
>  	if (name == NULL)
>  		name = getenv("WAYLAND_DISPLAY");
> -	if (name == NULL) {
> -		wl_log("error: WAYLAND_DISPLAY not set in the 
> environment.\n");
> -		errno = ENOENT;
> -		return -1;
> -	}
> +	if (name == NULL)
> +		name = "wayland-0";
>  
>  	fd = wl_os_socket_cloexec(PF_LOCAL, SOCK_STREAM, 0);
>  	if (fd < 0)
> @@ -872,7 +869,8 @@ wl_display_connect_to_fd(int fd)
>   * \return A \ref wl_display object or \c NULL on failure
>   *
>   * Connect to the Wayland display named \c name. If \c name is \c 
> NULL,
> - * its value will be replaced with the WAYLAND_DISPLAY environment 
> variable.
> + * its value will be replaced with the WAYLAND_DISPLAY environment
> + * variable if it is set, otherwise display "wayland-0" will be 
> used.
>   *
>   * \memberof wl_display
>   */

-- 
Sjoerd Simons <sjoerd.simons at collabora.co.uk>
Collabora Ltd.