drm: handle monitor hotplugs and fix a few bugs that it revealed (#14)

* handle monitor hotplugs and fix a few bugs that it revealed

* fix cursorFB uaf and other stuf

include/aquamarine/backend/DRM.hpp

@@ -287,7 +287,7 @@ namespace Aquamarine {
         SDRMPageFlip                                   pendingPageFlip;
         bool                                           frameEventScheduled = false;
 
-        drmModeModeInfo                                fallbackModeInfo;
+        Hyprutils::Memory::CSharedPointer<SOutputMode> fallbackMode;
 
         struct {
             bool vrrEnabled = false;

src/backend/Session.cpp

@@ -303,20 +303,28 @@ void Aquamarine::CSession::dispatchUdevEvents() {
         return;
     }
 
+    dev_t              deviceNum = udev_device_get_devnum(device);
+    SP<CSessionDevice> sessionDevice;
+    for (auto& sDev : sessionDevices) {
+        if (sDev->dev == deviceNum) {
+            sessionDevice = sDev;
+            break;
+        }
+    }
+
+    if (!sessionDevice) {
+        udev_device_unref(device);
+        return;
+    }
+
     if (action == std::string{"add"})
         events.addDrmCard.emit(SAddDrmCardEvent{.path = devnode});
-    else if (action == std::string{"change"} || action == std::string{"remove"}) {
+    else if (action == std::string{"change"}) {
-        dev_t deviceNum = udev_device_get_devnum(device);
-
-        for (auto& d : sessionDevices) {
-            if (d->dev != deviceNum)
-                continue;
-
-            if (action == std::string{"change"}) {
         backend->log(AQ_LOG_DEBUG, std::format("udev: DRM device {} changed", sysname ? sysname : "unknown"));
 
         CSessionDevice::SChangeEvent event;
 
+        //
         auto prop = udev_device_get_property_value(device, "HOTPLUG");
         if (prop && prop == std::string{"1"}) {
             event.type = CSessionDevice::AQ_SESSION_EVENT_CHANGE_HOTPLUG;
@@ -332,17 +340,12 @@ void Aquamarine::CSession::dispatchUdevEvents() {
             event.type = CSessionDevice::AQ_SESSION_EVENT_CHANGE_LEASE;
         } else {
             backend->log(AQ_LOG_DEBUG, std::format("udev: DRM device {} change event unrecognized", sysname ? sysname : "unknown"));
-                    break;
         }
 
-                d->events.change.emit(event);
+        sessionDevice->events.change.emit(event);
     } else if (action == std::string{"remove"}) {
         backend->log(AQ_LOG_DEBUG, std::format("udev: DRM device {} removed", sysname ? sysname : "unknown"));
-                d->events.remove.emit();
+        sessionDevice->events.remove.emit();
-            }
-
-            break;
-        }
     }
 
     udev_device_unref(device);

src/backend/drm/DRM.cpp

@@ -238,6 +238,9 @@ std::vector<SP<CDRMBackend>> Aquamarine::CDRMBackend::attempt(SP<CBackend> backe
         }
 
         backends.emplace_back(drmBackend);
+
+        // so that session can handle udev change/remove events for this gpu
+        backend->session->sessionDevices.push_back(gpu);
     }
 
     return backends;
@@ -1024,7 +1027,6 @@ drmModeModeInfo* Aquamarine::SDRMConnector::getCurrentMode() {
     if (crtc->props.mode_id) {
         size_t size = 0;
         return (drmModeModeInfo*)getDRMPropBlob(backend->gpu->fd, crtc->id, crtc->props.mode_id, &size);
-        ;
     }
 
     auto drmCrtc = drmModeGetCrtc(backend->gpu->fd, crtc->id);
@@ -1095,15 +1097,15 @@ void Aquamarine::SDRMConnector::connect(drmModeConnector* connector) {
             continue;
         }
 
-        if (i == 1)
-            fallbackModeInfo = drmMode;
-
         auto aqMode         = makeShared<SOutputMode>();
         aqMode->pixelSize   = {drmMode.hdisplay, drmMode.vdisplay};
         aqMode->refreshRate = calculateRefresh(drmMode);
         aqMode->preferred   = (drmMode.type & DRM_MODE_TYPE_PREFERRED);
         aqMode->modeInfo    = drmMode;
 
+        if (i == 1)
+            fallbackMode = aqMode;
+
         output->modes.emplace_back(aqMode);
 
         if (currentModeInfo && std::memcmp(&drmMode, currentModeInfo, sizeof(drmModeModeInfo))) {
@@ -1120,6 +1122,11 @@ void Aquamarine::SDRMConnector::connect(drmModeConnector* connector) {
                                           aqMode->preferred ? " (preferred)" : ""));
     }
 
+    if (!currentModeInfo) {
+        output->state->setMode(fallbackMode);
+        crtc->refresh = calculateRefresh(fallbackMode->modeInfo.value());
+    }
+
     output->physicalSize = {(double)connector->mmWidth, (double)connector->mmHeight};
 
     backend->backend->log(AQ_LOG_DEBUG, std::format("drm: Physical size {} (mm)", output->physicalSize));
@@ -1181,7 +1188,7 @@ void Aquamarine::SDRMConnector::connect(drmModeConnector* connector) {
         return;
 
     output->swapchain = CSwapchain::create(backend->backend->primaryAllocator, backend->self.lock());
-    backend->backend->events.newOutput.emit(output);
+    backend->backend->events.newOutput.emit(SP<IOutput>(output));
     output->scheduleFrame(IOutput::AQ_SCHEDULE_NEW_CONNECTOR);
 }
 
@@ -1400,7 +1407,7 @@ bool Aquamarine::CDRMOutput::commitState(bool onlyTest) {
         // fail to be created from gbm
         // TODO: add an API to detect this and request drm_dumb linear buffers. Or do something,
         // idk
-        if (data.cursorFB->buffer->dmabuf().modifier == DRM_FORMAT_MOD_INVALID) {
+        if (data.cursorFB->dead || data.cursorFB->buffer->dmabuf().modifier == DRM_FORMAT_MOD_INVALID) {
             TRACE(backend->backend->log(AQ_LOG_TRACE, "drm: Dropping invalid buffer for cursor plane"));
             data.cursorFB = nullptr;
         }