[PATCH 3/4] libcamera: Detect IPC disconnection with poll

[Harvey Yang]

Previously an IPC disconnection will only be detected when there's an
IPC message. This CL fixes the issue with poll event: POLLHUP.

Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
Co-developed-by: Yudhistira Erlandinata <yerlandinata at chromium.org>
Signed-off-by: Yudhistira Erlandinata <yerlandinata at chromium.org>
---
 include/libcamera/base/event_notifier.h      | 1 +
 include/libcamera/internal/ipc_unixsocket.h  | 1 +
 src/libcamera/base/event_dispatcher_poll.cpp | 9 +++++++++
 src/libcamera/base/event_notifier.cpp        | 5 +++++
 src/libcamera/ipc_unixsocket.cpp             | 8 ++++++++
 5 files changed, 24 insertions(+)

diff --git a/include/libcamera/base/event_notifier.h b/include/libcamera/base/event_notifier.h
index 158f2d44b..9ddc1824f 100644
--- a/include/libcamera/base/event_notifier.h
+++ b/include/libcamera/base/event_notifier.h
@@ -35,6 +35,7 @@ public:
 	void setEnabled(bool enable);
 
 	Signal<> activated;
+	Signal<> disconnected;
 
 protected:
 	void message(Message *msg) override;
diff --git a/include/libcamera/internal/ipc_unixsocket.h b/include/libcamera/internal/ipc_unixsocket.h
index a1e326b6b..535be6fbf 100644
--- a/include/libcamera/internal/ipc_unixsocket.h
+++ b/include/libcamera/internal/ipc_unixsocket.h
@@ -51,6 +51,7 @@ private:
 	int recvData(void *buffer, size_t length, int32_t *fds, unsigned int num);
 
 	void dataNotifier();
+	void EventNotifierDisconnected();
 
 	UniqueFD fd_;
 	bool headerReceived_;
diff --git a/src/libcamera/base/event_dispatcher_poll.cpp b/src/libcamera/base/event_dispatcher_poll.cpp
index 52bfb34e2..fdfeeff06 100644
--- a/src/libcamera/base/event_dispatcher_poll.cpp
+++ b/src/libcamera/base/event_dispatcher_poll.cpp
@@ -263,6 +263,15 @@ void EventDispatcherPoll::processNotifiers(const std::vector<struct pollfd> &pol
 			if (!notifier)
 				continue;
 
+			if (pfd.revents & POLLHUP) {
+				LOG(Event, Debug) << "Got signal POLLHUP."
+						  << " Disconnecting IPC";
+
+				notifier->disconnected.emit();
+				unregisterEventNotifier(notifier);
+				continue;
+			}
+
 			/*
 			 * If the file descriptor is invalid, disable the
 			 * notifier immediately.
diff --git a/src/libcamera/base/event_notifier.cpp b/src/libcamera/base/event_notifier.cpp
index 495c281d9..a5a583ac6 100644
--- a/src/libcamera/base/event_notifier.cpp
+++ b/src/libcamera/base/event_notifier.cpp
@@ -131,6 +131,11 @@ void EventNotifier::setEnabled(bool enable)
  * parameter.
  */
 
+/**
+ * \var EventNotifier::disconnected
+ * \brief Signal emitted when the file descriptor is disconnected
+ */
+
 void EventNotifier::message(Message *msg)
 {
 	if (msg->type() == Message::ThreadMoveMessage) {
diff --git a/src/libcamera/ipc_unixsocket.cpp b/src/libcamera/ipc_unixsocket.cpp
index 3d0248857..609549b6f 100644
--- a/src/libcamera/ipc_unixsocket.cpp
+++ b/src/libcamera/ipc_unixsocket.cpp
@@ -133,9 +133,17 @@ int IPCUnixSocket::bind(UniqueFD fd)
 	notifier_ = new EventNotifier(fd_.get(), EventNotifier::Read);
 	notifier_->activated.connect(this, &IPCUnixSocket::dataNotifier);
 
+	notifier_->disconnected.connect(
+		this, &IPCUnixSocket::EventNotifierDisconnected);
+
 	return 0;
 }
 
+void IPCUnixSocket::EventNotifierDisconnected()
+{
+	disconnected.emit();
+}
+
 /**
  * \brief Close the IPC channel
  *
-- 
2.47.0.rc1.288.g06298d1525-goog