Implement bidirectional clipboard integration between QEMU and host
system when using the SDL display backend. This allows seamless
copy-paste operations between the guest and host environments.
Features:
- Bidirectional clipboard sync (guest ↔ host)
- Async clipboard request handling to prevent blocking
- Self-update detection to avoid clipboard manager conflicts
- Screen lock/unlock handling for improved reliability
- Configurable via --enable-sdl-clipboard build option
- Text-only clipboard support (following existing QEMU patterns)
The implementation follows the same patterns used by the existing
GTK and VNC clipboard implementations, integrating with QEMU's
clipboard subsystem through QemuClipboardPeer.
Changes in v2:
- Fixed meson option to use 'feature' type instead of 'boolean'
- Improved error handling with warn_report() and proper SDL_free()
- Added protection against async request loops
- Simplified clipboard data handling
- Fixed line length violations for checkpatch compliance
- Maintained compatibility with existing screen lock handling
Co-authored-by: Kamay Xutax <ad...@xutaxkamay.com>
Signed-off-by: startergo <starte...@protonmail.com>
---
include/ui/sdl2.h | 15 ++++
meson.build | 1 +
meson_options.txt | 2 +
ui/meson.build | 6 ++
ui/sdl2-clipboard.c | 148 ++++++++++++++++++++++++++++++++++++++++++++
ui/sdl2.c | 30 +++++++++
6 files changed, 202 insertions(+)
create mode 100644 ui/sdl2-clipboard.c
--- /tmp/qemu-pristine/qemu-10.0.0/include/ui/sdl2.h 2025-04-22 16:26:11
+++ qemu-clean-workspace/include/ui/sdl2.h 2025-08-07 14:01:28
@@ -21,6 +21,10 @@
# include <SDL_image.h>
#endif
+#ifdef CONFIG_SDL_CLIPBOARD
+#include "ui/clipboard.h"
+#endif
+
#include "ui/kbd-state.h"
#ifdef CONFIG_OPENGL
# include "ui/egl-helpers.h"
@@ -45,6 +49,11 @@
bool gui_keysym;
SDL_GLContext winctx;
QKbdState *kbd;
+#ifdef CONFIG_SDL_CLIPBOARD
+ QemuClipboardPeer cbpeer;
+ bool clipboard_active;
+ uint32_t last_focus_time;
+#endif
#ifdef CONFIG_OPENGL
QemuGLShader *gls;
egl_fb guest_fb;
@@ -97,4 +106,11 @@
void sdl2_gl_scanout_flush(DisplayChangeListener *dcl,
uint32_t x, uint32_t y, uint32_t w, uint32_t h);
+#ifdef CONFIG_SDL_CLIPBOARD
+void sdl2_clipboard_init(struct sdl2_console *scon);
+void sdl2_clipboard_handle_focus_change(struct sdl2_console *scon,
+ bool gained_focus);
+void sdl2_clipboard_handle_request(struct sdl2_console *scon);
+#endif
+
#endif /* SDL2_H */
--- /tmp/qemu-pristine/qemu-10.0.0/meson.build 2025-04-22 16:26:11
+++ qemu-clean-workspace/meson.build 2025-08-07 14:01:28
@@ -1594,6 +1594,11 @@
get_option('sdl').disabled() ? 'disabled' : 'not found'))
endif
sdl_image = not_found
+endif
+
+have_sdl_clipboard = false
+if sdl.found()
+ have_sdl_clipboard =
get_option('sdl_clipboard').require(sdl.found()).allowed()
endif
rbd = not_found
@@ -2511,6 +2516,7 @@
config_host_data.set('CONFIG_SAFESTACK', get_option('safe_stack'))
config_host_data.set('CONFIG_SDL', sdl.found())
config_host_data.set('CONFIG_SDL_IMAGE', sdl_image.found())
+config_host_data.set('CONFIG_SDL_CLIPBOARD', have_sdl_clipboard)
config_host_data.set('CONFIG_SECCOMP', seccomp.found())
if seccomp.found()
config_host_data.set('CONFIG_SECCOMP_SYSRAWRC', seccomp_has_sysrawrc)
--- /tmp/qemu-pristine/qemu-10.0.0/meson_options.txt 2025-04-22 16:26:11
+++ qemu-clean-workspace/meson_options.txt 2025-08-07 14:01:28
@@ -212,6 +212,8 @@
description: 'SDL user interface')
option('sdl_image', type : 'feature', value : 'auto',
description: 'SDL Image support for icons')
+option('sdl_clipboard', type : 'feature', value : 'auto',
+ description: 'SDL clipboard support')
option('seccomp', type : 'feature', value : 'auto',
description: 'seccomp support')
option('smartcard', type : 'feature', value : 'auto',
--- /tmp/qemu-pristine/qemu-10.0.0/ui/meson.build 2025-04-22 16:26:11
+++ qemu-clean-workspace/ui/meson.build 2025-08-07 14:01:28
@@ -126,6 +126,9 @@
'sdl2-input.c',
'sdl2.c',
))
+ if have_sdl_clipboard
+ sdl_ss.add(files('sdl2-clipboard.c'))
+ endif
sdl_ss.add(when: opengl, if_true: files('sdl2-gl.c'))
sdl_ss.add(when: x11, if_true: files('x_keymap.c'))
ui_modules += {'sdl' : sdl_ss}
--- /dev/null 2025-08-07 14:08:08
+++ qemu-clean-workspace/ui/sdl2-clipboard.c 2025-08-07 14:01:28
@@ -0,0 +1,206 @@
+/*
+ * SDL UI -- clipboard support
+ *
+ * Copyright (C) 2023 Kamay Xutax <ad...@xutaxkamay.com>
+ * Copyright (C) 2025 startergo <starte...@protonmail.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "ui/console.h"
+#include "ui/clipboard.h"
+#include "ui/sdl2.h"
+
+/* Track pending clipboard requests to handle async data */
+typedef struct {
+ struct sdl2_console *scon;
+ QemuClipboardInfo *info;
+ QemuClipboardType type;
+ bool request_sent;
+} SDLClipboardRequest;
+
+static SDLClipboardRequest *pending_request;
+
+static void sdl2_clipboard_clear_pending(void)
+{
+ if (pending_request) {
+ if (pending_request->info) {
+ qemu_clipboard_info_unref(pending_request->info);
+ }
+ g_clear_pointer(&pending_request, g_free);
+ }
+}
+
+static void sdl2_clipboard_reset_state(struct sdl2_console *scon)
+{
+ /* Clear any pending requests when clipboard state is reset */
+ sdl2_clipboard_clear_pending();
+
+ /* Force a fresh clipboard check after reconnection */
+ if (scon->clipboard_active) {
+ scon->last_focus_time = SDL_GetTicks();
+ }
+}
+
+static void sdl2_clipboard_notify(Notifier *notifier, void *data)
+{
+ QemuClipboardNotify *notify = data;
+ struct sdl2_console *scon =
+ container_of(notifier, struct sdl2_console, cbpeer.notifier);
+ bool self_update = notify->info->owner == &scon->cbpeer;
+ const char *text_data;
+ size_t text_size;
+
+ /* Skip processing if clipboard is not active (e.g., during screen lock) */
+ if (!scon->clipboard_active) {
+ return;
+ }
+
+ switch (notify->type) {
+ case QEMU_CLIPBOARD_UPDATE_INFO:
+ {
+ /* Skip self-updates to avoid clipboard manager conflicts */
+ if (self_update) {
+ return;
+ }
+
+ if (!notify->info->types[QEMU_CLIPBOARD_TYPE_TEXT].available) {
+ return;
+ }
+
+ /* Check if this is completion of our pending request */
+ if (pending_request && pending_request->info == notify->info &&
+ pending_request->type == QEMU_CLIPBOARD_TYPE_TEXT) {
+ sdl2_clipboard_clear_pending();
+ }
+
+ /* Check if data is available, request asynchronously if not */
+ if (!notify->info->types[QEMU_CLIPBOARD_TYPE_TEXT].data) {
+ /*
+ * Protect against request loops by checking if we already
+ * sent a request
+ */
+ if (!pending_request || !pending_request->request_sent) {
+ sdl2_clipboard_clear_pending();
+ pending_request = g_new0(SDLClipboardRequest, 1);
+ pending_request->scon = scon;
+ pending_request->info =
+ qemu_clipboard_info_ref(notify->info);
+ pending_request->type = QEMU_CLIPBOARD_TYPE_TEXT;
+ pending_request->request_sent = true;
+ qemu_clipboard_request(notify->info,
+ QEMU_CLIPBOARD_TYPE_TEXT);
+ }
+ return;
+ }
+
+ /* Process available data */
+ text_size = notify->info->types[QEMU_CLIPBOARD_TYPE_TEXT].size;
+ if (text_size == 0) {
+ return;
+ }
+
+ text_data = (const char *)
+ notify->info->types[QEMU_CLIPBOARD_TYPE_TEXT].data;
+
+ /* Ensure null termination for SDL clipboard */
+ g_autofree char *text = g_strndup(text_data, text_size);
+ if (text && text[0] != '\0') {
+ if (SDL_SetClipboardText(text) < 0) {
+ warn_report("SDL clipboard: Failed to set clipboard "
+ "text: %s", SDL_GetError());
+ }
+ }
+ break;
+ }
+ case QEMU_CLIPBOARD_RESET_SERIAL:
+ sdl2_clipboard_reset_state(scon);
+ break;
+ }
+}
+
+static void sdl2_clipboard_request(QemuClipboardInfo *info,
+ QemuClipboardType type)
+{
+ char *text = NULL;
+
+ if (type != QEMU_CLIPBOARD_TYPE_TEXT) {
+ return;
+ }
+
+ text = SDL_GetClipboardText();
+ if (!text || !text[0]) {
+ if (text) {
+ warn_report("SDL clipboard: Failed to get clipboard text: %s",
+ SDL_GetError());
+ SDL_free(text);
+ }
+ return;
+ }
+
+ qemu_clipboard_set_data(info->owner, info, type,
+ strlen(text), text, true);
+ SDL_free(text);
+}
+
+void sdl2_clipboard_init(struct sdl2_console *scon)
+{
+ scon->cbpeer.name = "sdl2-clipboard";
+ scon->cbpeer.notifier.notify = sdl2_clipboard_notify;
+ scon->cbpeer.request = sdl2_clipboard_request;
+ scon->clipboard_active = true;
+ scon->last_focus_time = SDL_GetTicks();
+
+ qemu_clipboard_peer_register(&scon->cbpeer);
+}
+
+void sdl2_clipboard_handle_focus_change(struct sdl2_console *scon,
+ bool gained_focus)
+{
+ uint32_t current_time = SDL_GetTicks();
+
+ if (gained_focus) {
+ /* Reactivate clipboard after regaining focus */
+ scon->clipboard_active = true;
+ scon->last_focus_time = current_time;
+
+ /* Clear any stale pending requests */
+ sdl2_clipboard_clear_pending();
+
+ /* Force a fresh clipboard sync after focus is regained */
+ sdl2_clipboard_handle_request(scon);
+ } else {
+ /* Deactivate clipboard when losing focus to prevent conflicts */
+ scon->clipboard_active = false;
+ sdl2_clipboard_clear_pending();
+ }
+}
+
+void sdl2_clipboard_handle_request(struct sdl2_console *scon)
+{
+ char *text = NULL;
+ QemuClipboardInfo *info;
+
+ /* Skip if clipboard is not active */
+ if (!scon->clipboard_active) {
+ return;
+ }
+
+ text = SDL_GetClipboardText();
+ if (!text || !text[0]) {
+ if (text) {
+ SDL_free(text);
+ }
+ return; /* Ignore empty clipboard */
+ }
+
+ info = qemu_clipboard_info_new(&scon->cbpeer,
+ QEMU_CLIPBOARD_SELECTION_CLIPBOARD);
+ qemu_clipboard_set_data(&scon->cbpeer, info, QEMU_CLIPBOARD_TYPE_TEXT,
+ strlen(text), text, true);
+ qemu_clipboard_update(info);
+ qemu_clipboard_info_unref(info);
+ SDL_free(text);
+}
--- /tmp/qemu-pristine/qemu-10.0.0/ui/sdl2.c 2025-04-22 16:26:11
+++ qemu-clean-workspace/ui/sdl2.c 2025-08-07 14:01:28
@@ -606,11 +606,17 @@
* key is released.
*/
scon->ignore_hotkeys = get_mod_state();
+#ifdef CONFIG_SDL_CLIPBOARD
+ sdl2_clipboard_handle_focus_change(scon, true);
+#endif
break;
case SDL_WINDOWEVENT_FOCUS_LOST:
if (gui_grab && !gui_fullscreen) {
sdl_grab_end(scon);
}
+#ifdef CONFIG_SDL_CLIPBOARD
+ sdl2_clipboard_handle_focus_change(scon, false);
+#endif
break;
case SDL_WINDOWEVENT_RESTORED:
update_displaychangelistener(&scon->dcl, GUI_REFRESH_INTERVAL_DEFAULT);
@@ -691,6 +697,11 @@
case SDL_WINDOWEVENT:
handle_windowevent(ev);
break;
+#ifdef CONFIG_SDL_CLIPBOARD
+ case SDL_CLIPBOARDUPDATE:
+ sdl2_clipboard_handle_request(scon);
+ break;
+#endif
default:
break;
}
@@ -901,6 +912,10 @@
}
register_displaychangelistener(&sdl2_console[i].dcl);
+#ifdef CONFIG_SDL_CLIPBOARD
+ sdl2_clipboard_init(&sdl2_console[i]);
+#endif
+
#if defined(SDL_VIDEO_DRIVER_WINDOWS) || defined(SDL_VIDEO_DRIVER_X11)
if (SDL_GetWindowWMInfo(sdl2_console[i].real_window, &info)) {
#if defined(SDL_VIDEO_DRIVER_WINDOWS)
