/*-
 * Copyright (c) 2019 The FreeBSD Foundation
 * All rights reserved.
 *
 * This software was developed by BFF Storage Systems, LLC under sponsorship
 * from the FreeBSD Foundation.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 */

extern "C" {
#include <sys/types.h>

#include <pthread.h>

#include "fuse_kernel.h"
}

#include <gmock/gmock.h>

#define SET_OUT_HEADER_LEN(out, variant) { \
	(out)->header.len = (sizeof((out)->header) + \
			     sizeof((out)->body.variant)); \
}

extern int verbosity;

union fuse_payloads_in {
	/* value is from fuse_kern_chan.c in fusefs-libs */
	uint8_t		bytes[0x21000 - sizeof(struct fuse_in_header)];
	fuse_forget_in	forget;
	fuse_init_in	init;
	char		lookup[0];
	fuse_setattr_in	setattr;
};

struct mockfs_buf_in {
	fuse_in_header		header;
	union fuse_payloads_in	body;
};

union fuse_payloads_out {
	fuse_init_out		init;
	fuse_entry_out		entry;
	fuse_attr_out		attr;
};

struct mockfs_buf_out {
	fuse_out_header		header;
	union fuse_payloads_out	body;
};

/*
 * Fake FUSE filesystem
 *
 * "Mounts" a filesystem to a temporary directory and services requests
 * according to the programmed expectations.
 *
 * Operates directly on the fuse(4) kernel API, not the libfuse(3) user api.
 */
class MockFS {
	public:
	/* thread id of the fuse daemon thread */
	pthread_t m_daemon_id;

	private:
	/* file descriptor of /dev/fuse control device */
	int m_fuse_fd;
	
	/* pid of the test process */
	pid_t m_pid;

	/* 
	 * Thread that's running the mockfs daemon.
	 *
	 * It must run in a separate thread so it doesn't deadlock with the
	 * client test code.
	 */
	pthread_t m_thr;

	/* Initialize a session after mounting */
	void init();

	/* Default request handler */
	void process_default(const mockfs_buf_in*, mockfs_buf_out*);

	/* Entry point for the daemon thread */
	static void* service(void*);

	/* Read, but do not process, a single request from the kernel */
	void read_request(mockfs_buf_in*);

	public:
	/* Create a new mockfs and mount it to a tempdir */
	MockFS();
	virtual ~MockFS();

	/* Process FUSE requests endlessly */
	void loop();

	/* 
	 * Request handler
	 *
	 * This method is expected to provide the response to each FUSE
	 * operation.  Responses must be immediate (so this method can't be used
	 * for testing a daemon with queue depth > 1).  Test cases must define
	 * each response using Googlemock expectations
	 */
	MOCK_METHOD2(process, void(const mockfs_buf_in*, mockfs_buf_out*));

	/* Gracefully unmount */
	void unmount();
};