/* SPDX-License-Identifier: GPL-2.0-or-later
 * Copyright (c) 2025 Red Hat GmbH
 * Author: Stefano Brivio <sbrivio@redhat.com>
 */

#ifndef MIGRATE_H
#define MIGRATE_H

struct migrate_version;

/**
 * struct migrate_meta - Migration metadata
 * @version:		Chosen migration data version, host order
 * @v:			Migration version information
 * @bswap:		Source has opposite endianness
 * @peer_64b:		Source uses 64-bit void *
 * @time_64b:		Source uses 64-bit time_t
 * @flow_size:		Size of union flow in source
 * @flow_sidx_size:	Size of struct flow_sidx in source
 */
struct migrate_meta {
	uint32_t version;
	const struct migrate_version *v;
	bool bswap;
	bool source_64b;
	bool time_64b;
	size_t flow_size;
	size_t flow_sidx_size;
};

/**
 * union migrate_header - Migration header from source
 * @magic:		0xB1BB1D1B0BB1D1B0, host order
 * @version:		Source sends highest known, target aborts if unsupported
 * @voidp_size:		sizeof(void *), network order
 * @time_t_size:	sizeof(time_t), network order
 * @flow_size:		sizeof(union flow), network order
 * @flow_sidx_size:	sizeof(struct flow_sidx_t), network order
 * @unused:		Go figure
 */
union migrate_header {
	struct {
		uint64_t magic;
		uint32_t version;
		uint32_t voidp_size;
		uint32_t time_t_size;
		uint32_t flow_size;
		uint32_t flow_sidx_size;
	};
	uint8_t unused[4096];
} __attribute__((packed));

struct migrate_stage;

/**
 * migrate_cb_t - Callback function to implement one migration stage
 */
typedef int (*migrate_cb_t)(struct ctx *c, struct migrate_meta *m,
			    const struct migrate_stage *stage, int fd);

/**
 * struct migrate_stage - Callbacks and parameters for one stage of migration
 * @name:	Stage name (for debugging)
 * @source:	Callback to implement this stage on the source
 * @target:	Callback to implement this stage on the target
 * @v:		Source version this applies to, host order
 * @sections:	Array of data sections, NULL-terminated
 */
struct migrate_stage {
	const char *name;
	migrate_cb_t source;
	migrate_cb_t target;
	/* FIXME: rollback callbacks? */
	union {
		struct iovec iov;
	};
};

/**
 * struct migrate_version - Stages for a particular protocol version
 * @version:	Version number this implements
 * @stages:	Ordered array of stages
 * @nstages:	Length of @stages
 */
struct migrate_version {
	uint32_t version;
	const struct migrate_stage *stages;
	unsigned nstages;
};

int migrate_source(struct ctx *c, int fd);
int migrate_target(struct ctx *c, int fd);

#endif /* MIGRATE_H */