/* 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

typedef char migrate_magic_t[8];

/**
 * struct migrate_header - Initial header used for all protocol versions
 * @magic:		'{passty}' as a byte array
 * @version:		Version of the protocol used by sender, network order
 * @compat_version:	Lowest compatible protocol version, network order
 */
struct migrate_header {
	migrate_magic_t magic;
	uint32_t version;
	uint32_t compat_version;
};

/**
 * union migrate_header_v1 - Migration header from source
 * @endian:		0x12345678, source host order
 * @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_v1 {
	struct {
		uint32_t endian;
		uint32_t voidp_size;
		uint32_t time_t_size;
		uint32_t flow_size;
		uint32_t flow_sidx_size;
	};
	uint8_t unused[65536];
};

struct migrate_meta;

/**
 * struct migrate_handler - Function to handle a specific data section
 * @fn:			Function pointer taking pointer to context and metadata
 */
struct migrate_handler {
	int (*fn)(struct ctx *c, struct migrate_meta *m);
};

/**
 * struct migrate_version - Handlers and data sections for a protocol version
 * @v:			Source version this applies to, host order
 * @read_header_v:	Read version specific header(s)
 * @pre:		Set of functions to execute in target before data copy
 * @sections:		Array of data sections, NULL-terminated
 * @post:		Set of functions to execute in target after data copy
 */
struct migrate_version {
	uint32_t v;
	int (*read_header_v)(int fd, struct migrate_meta *m);
	struct migrate_handler *pre;
	struct iovec *sections;
	struct migrate_handler *post;
};

/**
 * struct migrate_meta - Migration metadata
 * @version:		Version number, host order
 * @v:			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;
};


void migrate_init(struct ctx *c);
void migrate_close(struct ctx *c);
void migrate_request(struct ctx *c, int fd, bool target);
void migrate_handler(struct ctx *c);

#endif /* MIGRATE_H */