libcamera: ipc: unix: Add a IPC mechanism based on Unix sockets

To be able to isolate an IPA component in a separate process an IPC
mechanism is needed to communicate with it. Add an IPC mechanism based
on Unix sockets which allows users to pass both data and file descriptors
to and from the IPA process.

The implementation allows users to send both data and file descriptors
in the same message. This allows users to more easily implement
serialization and deserialization of objects as all elements belonging
to an object can be sent in one message.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/src/libcamera/include/ipc_unixsocket.h b/src/libcamera/include/ipc_unixsocket.h
new file mode 100644
index 00000000..ef166d74
--- /dev/null
+++ b/src/libcamera/include/ipc_unixsocket.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * ipc_unixsocket.h - IPC mechanism based on Unix sockets
+ */
+
+#ifndef __LIBCAMERA_IPC_UNIXSOCKET_H__
+#define __LIBCAMERA_IPC_UNIXSOCKET_H__
+
+#include <cstdint>
+#include <sys/types.h>
+#include <vector>
+
+#include <libcamera/event_notifier.h>
+
+namespace libcamera {
+
+class IPCUnixSocket
+{
+public:
+	struct Payload {
+		std::vector<uint8_t> data;
+		std::vector<int32_t> fds;
+	};
+
+	IPCUnixSocket();
+	~IPCUnixSocket();
+
+	int create();
+	int bind(int fd);
+	void close();
+	bool isBound() const;
+
+	int send(const Payload &payload);
+	int receive(Payload *payload);
+
+	Signal<IPCUnixSocket *> readyRead;
+
+private:
+	struct Header {
+		uint32_t data;
+		uint8_t fds;
+	};
+
+	int sendData(const void *buffer, size_t length, const int32_t *fds, unsigned int num);
+	int recvData(void *buffer, size_t length, int32_t *fds, unsigned int num);
+
+	void dataNotifier(EventNotifier *notifier);
+
+	int fd_;
+	EventNotifier *notifier_;
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_IPC_UNIXSOCKET_H__ */