[PATCH wayland-protocols v2] Introduce xdg-foreign protocol

Derek Foreman derekf at osg.samsung.com
Fri Aug 5 12:45:50 UTC 2016


On 27/07/16 02:54 AM, Jonas Ådahl wrote:
> xdg-foreign is a protocol meant to enable setting up inter surface
> relationships across clients. Potential use cases are out-of-process
> dialogs, such as file dialogs, meant to be used by sandboxed processes
> that may not have the access it needs to implement such dialogs.
> 
> It works by enabling a client to export a surface, creating a handle
> for the exported surface. The handle, in form of a unique string, may
> be shared in some way with other clients (for example the provider of
> the file dialog) which can then import the exported surface.

Have you considered passing an fd (have the compositor create a pipe)
instead of a string?

Then the shared token is impossible to guess.

Even so, this looks workable and not too hard to implement.

Reviewed-by: Derek Foreman <derekf at osg.samsung.com>

Thanks,
Derek
> Signed-off-by: Jonas Ådahl <jadahl at gmail.com>
> ---
> 
> Changes since v1:
> 
>  - Spelling and grammar fixes
>  - Wording changes (unexport -> revoke)
>  - Fixed the "Warning! .. unstable .." paragraph (was an old version)
>  - Added sandbox client -> unsandboxed file browser dialog example to protocol
>    description
>  - Removed left-over note about restriction of importing a handle only once. It
>    should be possible to import a handle multiple times, but the protocol text
>    had only been updated in one of two places.
> 
> 
> Jonas
> 
> 
> 
>  Makefile.am                                      |   1 +
>  unstable/xdg-foreign/README                      |   4 +
>  unstable/xdg-foreign/xdg-foreign-unstable-v1.xml | 186 +++++++++++++++++++++++
>  3 files changed, 191 insertions(+)
>  create mode 100644 unstable/xdg-foreign/README
>  create mode 100644 unstable/xdg-foreign/xdg-foreign-unstable-v1.xml
> 
> diff --git a/Makefile.am b/Makefile.am
> index 9e2a029..35df201 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -9,6 +9,7 @@ unstable_protocols =								\
>  	unstable/pointer-constraints/pointer-constraints-unstable-v1.xml	\
>  	unstable/tablet/tablet-unstable-v1.xml			                \
>  	unstable/tablet/tablet-unstable-v2.xml			                \
> +	unstable/xdg-foreign/xdg-foreign-unstable-v1.xml			\
>  	$(NULL)
>  
>  stable_protocols =								\
> diff --git a/unstable/xdg-foreign/README b/unstable/xdg-foreign/README
> new file mode 100644
> index 0000000..f5bcb83
> --- /dev/null
> +++ b/unstable/xdg-foreign/README
> @@ -0,0 +1,4 @@
> +xdg foreign protocol
> +
> +Maintainers:
> +Jonas Ådahl <jadahl at gmail.com>
> diff --git a/unstable/xdg-foreign/xdg-foreign-unstable-v1.xml b/unstable/xdg-foreign/xdg-foreign-unstable-v1.xml
> new file mode 100644
> index 0000000..c6f5775
> --- /dev/null
> +++ b/unstable/xdg-foreign/xdg-foreign-unstable-v1.xml
> @@ -0,0 +1,186 @@
> +<?xml version="1.0" encoding="UTF-8"?>
> +<protocol name="xdg_foreign_unstable_v1">
> +
> +  <copyright>
> +    Copyright © 2015-2016 Red Hat Inc.
> +
> +    Permission is hereby granted, free of charge, to any person obtaining a
> +    copy of this software and associated documentation files (the "Software"),
> +    to deal in the Software without restriction, including without limitation
> +    the rights to use, copy, modify, merge, publish, distribute, sublicense,
> +    and/or sell copies of the Software, and to permit persons to whom the
> +    Software is furnished to do so, subject to the following conditions:
> +
> +    The above copyright notice and this permission notice (including the next
> +    paragraph) shall be included in all copies or substantial portions of the
> +    Software.
> +
> +    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> +    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> +    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> +    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> +    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> +    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> +    DEALINGS IN THE SOFTWARE.
> +  </copyright>
> +
> +  <description summary="Protocol for exporting xdg surface handles">
> +    This protocol specifies a way for making it possible to reference a surface
> +    of a different client. With such a reference, a client can, by using the
> +    interfaces provided by this protocol, manipulate the relationship between
> +    its own surfaces and the surface of some other client. For example, stack
> +    some of its own surface above the other clients surface.
> +
> +    In order for a client A to get a reference of a surface of client B, client
> +    B must first export its surface using xdg_exporter.export. Upon doing this,
> +    client B will receive a handle (a unique string) that it may share with
> +    client A in some way (for example D-Bus). After client A has received the
> +    handle from client B, it may use xdg_importer.import to create a reference
> +    to the surface client B just exported. See the corresponding requests for
> +    details.
> +
> +    A possible use case for this is out-of-process dialogs. For example when a
> +    sandboxed client without file system access needs the user to select a file
> +    on the file system, given sandbox environment support, it can export its
> +    surface, passing the exported surface handle to an unsandboxed process that
> +    can show a file browser dialog and stack it above the sandboxed client's
> +    surface.
> +
> +    Warning! The protocol described in this file is experimental and backward
> +    incompatible changes may be made. Backward compatible changes may be added
> +    together with the corresponding interface version bump. Backward
> +    incompatible changes are done by bumping the version number in the protocol
> +    and interface names and resetting the interface version. Once the protocol
> +    is to be declared stable, the 'z' prefix and the version number in the
> +    protocol and interface names are removed and the interface version number is
> +    reset.
> +  </description>
> +
> +  <interface name="zxdg_exporter_v1" version="1">
> +    <description summary="interface for exporting surfaces">
> +      A global interface used for exporting surfaces that can later be imported
> +      using xdg_importer.
> +    </description>
> +
> +    <request name="destroy" type="destructor">
> +      <description summary="destroy the xdg_exporter object">
> +	Notify the compositor that the xdg_exporter object will no longer be
> +	used.
> +      </description>
> +    </request>
> +
> +    <request name="export">
> +      <description summary="export a surface">
> +	The export request exports the passed surface so that it can later be
> +	imported via xdg_importer. When called, a new xdg_exported object will
> +	be created and xdg_exported.handle will be sent immediately. See the
> +	corresponding interface and event for details.
> +
> +	A surface may be exported multiple times, and each exported handle may
> +	be used to create a xdg_imported multiple times. Only xdg_surface
> +	surfaces may be exported.
> +      </description>
> +
> +      <arg name="id" type="new_id" interface="zxdg_exported_v1"
> +	   summary="the new xdg_exported object"/>
> +      <arg name="surface" type="object" interface="wl_surface"
> +	   summary="the surface to export"/>
> +    </request>
> +  </interface>
> +
> +  <interface name="zxdg_importer_v1" version="1">
> +    <description summary="interface for importing surfaces">
> +      A global interface used for importing surfaces exported by xdg_exporter.
> +      With this interface, a client can create a reference to a surface of
> +      another client.
> +    </description>
> +
> +    <request name="destroy" type="destructor">
> +      <description summary="destroy the xdg_importer object">
> +	Notify the compositor that the xdg_importer object will no longer be
> +	used.
> +      </description>
> +    </request>
> +
> +    <request name="import">
> +      <description summary="import a surface">
> +	The import request imports a surface from any client given a handle
> +	retrieved by exporting said surface using xdg_exporter.export. When
> +	called, a new xdg_imported object will be created. This new object
> +	represents the imported surface, and the importing client can
> +	manipulate its relationship using it. See xdg_imported for details.
> +      </description>
> +
> +      <arg name="id" type="new_id" interface="zxdg_imported_v1"
> +	   summary="the new xdg_imported object"/>
> +      <arg name="handle" type="string"
> +	   summary="the exported surface handle"/>
> +    </request>
> +  </interface>
> +
> +  <interface name="zxdg_exported_v1" version="1">
> +    <description summary="an exported surface handle">
> +      A xdg_exported object represents an exported reference to a surface. The
> +      exported surface may be referenced as long as the xdg_exported object not
> +      destroyed. Destroying the xdg_exported invalidates any relationship the
> +      importer may have established using xdg_imported.
> +    </description>
> +
> +    <request name="destroy" type="destructor">
> +      <description summary="unexport the exported surface">
> +	Revoke the previously exported surface. This invalidates any
> +	relationship the importer may have set up using the xdg_imported created
> +	given the handle sent via xdg_exported.handle.
> +      </description>
> +    </request>
> +
> +    <event name="handle">
> +      <description summary="the exported surface handle">
> +	The handle event contains the unique handle of this exported surface
> +	reference. It may be shared with any client, which then can use it to
> +	import the surface by calling xdg_importer.import. A handle may be
> +	used to import the surface multiple times.
> +      </description>
> +
> +      <arg name="handle" type="string" summary="the exported surface handle"/>
> +    </event>
> +  </interface>
> +
> +  <interface name="zxdg_imported_v1" version="1">
> +    <description summary="an imported surface handle">
> +      A xdg_imported object represents an imported reference to surface exported
> +      by some client. A client can use this interface to manipulate
> +      relationships between its own surfaces and the imported surface.
> +    </description>
> +
> +    <request name="destroy" type="destructor">
> +      <description summary="destroy the xdg_imported object">
> +	Notify the compositor that it will no longer use the xdg_imported
> +	object. Any relationship that may have been set up will at this point
> +	be invalidated.
> +      </description>
> +    </request>
> +
> +    <request name="set_parent_of">
> +      <description summary="set as the parent of some surface">
> +	Set the imported surface as the parent of some surface of the client.
> +	The passed surface must be a toplevel xdg_surface. Calling this function
> +	sets up a surface to surface relation with the same stacking and positioning
> +	semantics as xdg_surface.set_parent.
> +      </description>
> +
> +      <arg name="surface" type="object" interface="wl_surface"
> +	   summary="the child surface"/>
> +    </request>
> +
> +    <event name="destroyed">
> +      <description summary="the imported surface handle has been destroyed">
> +	The imported surface handle has been destroyed and any relationship set
> +	up has been invalidated. This may happen for various reasons, for
> +	example if the exported surface or the exported surface handle has been
> +	destroyed, if the handle used for importing was invalid.
> +      </description>
> +    </event>
> +  </interface>
> +
> +</protocol>
> 



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