[PATCH wayland-protocols v2] Introduce xdg-foreign protocol
Jonas Ådahl
jadahl at gmail.com
Fri Aug 5 15:52:15 UTC 2016
On Fri, Aug 05, 2016 at 07:45:50AM -0500, Derek Foreman wrote:
> 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.
As Carsten wrote in the other E-mail, a client can be lazy and generate
a bad string. The client also wouldn't be able to generate a globally
unique string, so to import a handle, the importing client would also
need to associate the string with some kind of client id.
>
> Even so, this looks workable and not too hard to implement.
>
> Reviewed-by: Derek Foreman <derekf at osg.samsung.com>
Thanks!
Jonas
>
> 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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