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diff --git a/src/modules/mavlink/mavlink_ftp.h b/src/modules/mavlink/mavlink_ftp.h
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+++ b/src/modules/mavlink/mavlink_ftp.h
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+/****************************************************************************
+ *
+ *   Copyright (c) 2014 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#pragma once
+
+/**
+ * @file mavlink_ftp.h
+ *
+ * MAVLink remote file server.
+ *
+ * Messages are wrapped in ENCAPSULATED_DATA messages. Every message includes
+ * a session ID and sequence number.
+ *
+ * A limited number of requests (currently 2) may be outstanding at a time.
+ * Additional messages will be discarded.
+ *
+ * Messages consist of a fixed header, followed by a data area.
+ *
+ */
+ 
+#include <dirent.h>
+#include <queue.h>
+
+#include <nuttx/wqueue.h>
+#include <systemlib/err.h>
+
+#include "mavlink_messages.h"
+
+class MavlinkFTP
+{
+public:
+	MavlinkFTP();
+
+	static MavlinkFTP	*getServer();
+
+	// static interface
+	void			handle_message(Mavlink* mavlink,
+					mavlink_message_t *msg);
+
+private:
+
+	static const unsigned	kRequestQueueSize = 2;
+
+	static MavlinkFTP	*_server;
+
+	struct RequestHeader
+	{
+		uint8_t		magic;
+		uint8_t		session;
+		uint8_t		opcode;
+		uint8_t		size;
+		uint32_t	crc32;
+		uint32_t	offset;
+		uint8_t		data[];
+	};
+
+	enum Opcode : uint8_t
+	{
+		kCmdNone,	// ignored, always acked
+		kCmdTerminate,	// releases sessionID, closes file
+		kCmdReset,	// terminates all sessions
+		kCmdList,	// list files in <path> from <offset>
+		kCmdOpen,	// opens <path> for reading, returns <session>
+		kCmdRead,	// reads <size> bytes from <offset> in <session>
+		kCmdCreate,	// creates <path> for writing, returns <session>
+		kCmdWrite,	// appends <size> bytes at <offset> in <session>
+		kCmdRemove,	// remove file (only if created by server?)
+
+		kRspAck,
+		kRspNak
+	};
+
+	enum ErrorCode : uint8_t
+	{
+		kErrNone,
+		kErrNoRequest,
+		kErrNoSession,
+		kErrSequence,
+		kErrNotDir,
+		kErrNotFile,
+		kErrEOF,
+		kErrNotAppend,
+		kErrTooBig,
+		kErrIO,
+		kErrPerm
+	};
+
+    int _findUnusedSession(void);
+    bool _validSession(unsigned index);
+
+    static const unsigned kMaxSession = 2;
+    int	_session_fds[kMaxSession];
+
+	class Request
+	{
+	public:
+		union {
+			dq_entry_t	entry;
+			work_s		work;
+		};
+
+		bool		decode(Mavlink *mavlink, mavlink_message_t *fromMessage) {
+			if (fromMessage->msgid == MAVLINK_MSG_ID_ENCAPSULATED_DATA) {
+				_mavlink = mavlink;
+				mavlink_msg_encapsulated_data_decode(fromMessage, &_message);
+				return true;
+			}
+			return false;
+		}
+
+		void		reply() {
+
+			// XXX the proper way would be an IOCTL / uORB call, rather than exploiting the
+			// flat memory architecture, as we're operating between threads here.
+			mavlink_message_t msg;
+			msg.checksum = 0;
+			unsigned len = mavlink_msg_encapsulated_data_pack_chan(_mavlink->get_system_id(), _mavlink->get_component_id(),
+				_mavlink->get_channel(), &msg, sequence(), rawData());
+
+			_mavlink->lockMessageBufferMutex();
+			bool success = _mavlink->message_buffer_write(&msg, len);
+			_mavlink->unlockMessageBufferMutex();
+
+			if (!success) {
+				warnx("FTP TX ERR");
+			} 
+			// else {
+				// warnx("wrote: sys: %d, comp: %d, chan: %d, len: %d, checksum: %d",
+				// 	_mavlink->get_system_id(),
+				// 	_mavlink->get_component_id(),
+				// 	_mavlink->get_channel(),
+				// 	len,
+				// 	msg.checksum);
+			// }
+		}
+
+		uint8_t		*rawData() { return &_message.data[0]; }
+		RequestHeader 	*header()  { return reinterpret_cast<RequestHeader *>(&_message.data[0]); }
+		uint8_t         *requestData() { return &(header()->data[0]); }
+		unsigned	dataSize() { return header()->size + sizeof(RequestHeader); }
+		uint16_t	sequence() const { return _message.seqnr; }
+		mavlink_channel_t channel() { return _mavlink->get_channel(); }
+
+		char		*dataAsCString();
+
+	private:
+		Mavlink			*_mavlink;
+		mavlink_encapsulated_data_t _message;
+
+	};
+
+	static const uint8_t	kProtocolMagic = 'f';
+	static const char	kDirentFile = 'F';
+	static const char	kDirentDir = 'D';
+	static const char	kDirentUnknown = 'U';
+	static const uint8_t	kMaxDataLength = MAVLINK_MSG_ENCAPSULATED_DATA_FIELD_DATA_LEN - sizeof(RequestHeader);
+
+	/// Request worker; runs on the low-priority work queue to service
+	/// remote requests.
+	///
+	static void		_workerTrampoline(void *arg);
+	void			_worker(Request *req);
+
+	/// Reply to a request (XXX should be a Request method)
+	///
+	void			_reply(Request *req);
+
+	ErrorCode		_workList(Request *req);
+	ErrorCode		_workOpen(Request *req, bool create);
+	ErrorCode		_workRead(Request *req);
+	ErrorCode		_workWrite(Request *req);
+	ErrorCode		_workRemove(Request *req);
+	ErrorCode		_workTerminate(Request *req);
+	ErrorCode		_workReset();
+
+	// work freelist
+	Request			_workBufs[kRequestQueueSize];
+	dq_queue_t		_workFree;
+	sem_t			_lock;
+
+	void			_qLock() { do {} while (sem_wait(&_lock) != 0); }
+	void			_qUnlock() { sem_post(&_lock); }
+
+	void			_qFree(Request *req) {
+		_qLock();
+		dq_addlast(&req->entry, &_workFree);
+		_qUnlock();
+	}
+
+	Request			*_dqFree() {
+		_qLock();
+		auto req = reinterpret_cast<Request *>(dq_remfirst(&_workFree));
+		_qUnlock();
+		return req;
+	}
+    
+};