mirrors/wayland
1
0
Fork 0
mirror of https://gitlab.freedesktop.org/wayland/wayland.git synced 2026-04-16 08:21:35 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

protocol: add wl_display_upgrade global

Browse source 
This global allows the IPC library to upgrade the version of the
wl_display global. To ensure maximum flexibility, there are strict
requirements on the connection state at the time of the upgrade. In
particular, after the compositor has destroyed the wl_display_upgrade
object, the wl_display is the only object in the connection.

Since there are many consumers of wl_display and wl_registry, and the
version of these objects is fixed after the upgrade, care must be taken
not to break any of these consumers. Since no consumer checks the
version of these objects and there is no way to get a wl_registry with a
lower version, incrementing the minor version cannot change the
semantics of existing messages and no new events can be added to
wl_registry. As an exception, new events can be added to wl_display
since those events are handled internally by the IPC library which is
also in charge of upgrading the version.

An additional change that could be made in version 2 of wl_display is
adding a wl_display.delete_server_id request, implementing symmetric
delete_id. A global that wants to make full use of destructor events
could then specify that the global must only be exposed on a wl_registry
whose version (and therefore the version of the wl_display) is at least
2.

Signed-off-by: Julian Orth <ju.orth@gmail.com>
This commit is contained in:
Julian Orth 2026-03-16 17:16:35 +01:00
parent bec2bcddd8
commit 6ab970464b
5 changed files with 218 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

78
src/wayland-client.c
View file

@ -1405,6 +1405,84 @@ wl_display_disconnect(struct wl_display *display)
free(display);
}
struct upgrade_listener {
struct wl_fixes *wl_fixes;
struct wl_display_upgrade *wl_display_upgrade;
uint32_t version;
};
static void upgrade_max_version(void *data,
struct wl_display_upgrade *wl_display_upgrade,
uint32_t version)
{
struct upgrade_listener *listener = data;
listener->version = version;
}
static struct wl_display_upgrade_listener upgrade_upgrade_listener = {
.max_version = upgrade_max_version,
};
static void upgrade_global(void *data, struct wl_registry *wl_registry,
uint32_t name, const char *interface,
uint32_t version)
{
struct upgrade_listener *listener = data;
if (!listener->wl_fixes && strcmp(interface, wl_fixes_interface.name) == 0)
listener->wl_fixes = wl_registry_bind(wl_registry, name, &wl_fixes_interface, 1);
else if (!listener->wl_display_upgrade && strcmp(interface, wl_display_upgrade_interface.name) == 0) {
listener->wl_display_upgrade = wl_registry_bind(wl_registry, name, &wl_display_upgrade_interface, 1);
wl_display_upgrade_add_listener(listener->wl_display_upgrade, &upgrade_upgrade_listener, data);
}
}
static void upgrade_global_remove(void *data, struct wl_registry *wl_registry,
uint32_t name)
{
// nothing
}
static struct wl_registry_listener upgrade_registry_listener = {
.global = upgrade_global,
.global_remove = upgrade_global_remove,
};
#define min(a, b) ((a) < (b) ? (a) : (b))
/** Upgrade the wl_display version.
*
* \param display The display context object
*
* Tries to upgrade the version of the wl_display. After this function returns,
* wl_display_get_version can be used to retrieve the new version of the
* wl_display.
*
* This function should be called immediately after creating the display. It
* must not be called any later than that or multiple times, otherwise a
* protocol error might occur.
*
* \memberof wl_display
*/
WL_EXPORT void
wl_display_upgrade(struct wl_display *display)
{
struct wl_registry *registry = wl_display_get_registry(display);
struct upgrade_listener listener = { };
wl_registry_add_listener(registry, &upgrade_registry_listener, &listener);
wl_display_roundtrip(display);
if (listener.wl_display_upgrade)
wl_display_roundtrip(display);
if (listener.wl_fixes) {
wl_fixes_destroy_registry(listener.wl_fixes, registry);
wl_fixes_destroy(listener.wl_fixes);
}
if (listener.wl_display_upgrade) {
uint32_t version = min(listener.version, (uint32_t)wl_display_interface.version);
wl_display_upgrade_upgrade(listener.wl_display_upgrade, version);
display->proxy.version = version;
}
}
/** Get a display context's file descriptor
*
* \param display The display context object