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/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz>
* SPDX-License-Identifier: GPL-3.0-or-later
*/
#include <stdbool.h>
#define MMAPPED_WAS_FIRST 1
struct mmapped {
void *mem;
size_t size;
int fd;
};
/* Initialize/Use file data as mmapped memory.
*
* If write flock can be acquired, the file is resized, zeroed and mmapped,
* header is copied at its beginning and MMAPPED_WAS_FIRST is returned;
* you should finish initialization and call mmapped_init_continue to degrade flock to shared.
* Otherwise, it waits for shared flock, calls mmap, verifies that header is byte-wise identical and returns zero.
* On header mismatch, kr_error(ENOTRECOVERABLE) is returned; on a system error, kr_error(errno) is returned. */
int mmapped_init(struct mmapped *mmapped, const char *mmap_file, size_t size, void *header, size_t header_size);
/* Degrade flock to shared after getting MMAPPED_WAS_FIRST from mmapped_init.
*
* Returns zero on success and kr_error(errno) on system error. */
int mmapped_init_continue(struct mmapped *mmapped);
/* Free mmapped memory and, unless the underlying file is used by other processes, truncate it to zero size. */
void mmapped_deinit(struct mmapped *mmapped);
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