// SPDX-License-Identifier: GPL-2.0-or-later

/* some parts copied from QEMU include/qemu/iov.h */

#ifndef IOVEC_H
#define IOVEC_H

#include <unistd.h>
#include <string.h>

size_t iov_from_buf_full(const struct iovec *iov, unsigned int iov_cnt,
			 size_t offset, const void *buf, size_t bytes);
size_t iov_to_buf_full(const struct iovec *iov, const unsigned int iov_cnt,
		       size_t offset, void *buf, size_t bytes);

static inline size_t iov_from_buf(const struct iovec *iov,
				  unsigned int iov_cnt, size_t offset,
				  const void *buf, size_t bytes)
{
	if (__builtin_constant_p(bytes) && iov_cnt &&
		offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
		memcpy((char *)iov[0].iov_base + offset, buf, bytes);
		return bytes;
	} else {
		return iov_from_buf_full(iov, iov_cnt, offset, buf, bytes);
	}
}

static inline size_t iov_to_buf(const struct iovec *iov,
				const unsigned int iov_cnt, size_t offset,
				void *buf, size_t bytes)
{
	if (__builtin_constant_p(bytes) && iov_cnt &&
		offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
		memcpy(buf, (char *)iov[0].iov_base + offset, bytes);
		return bytes;
	} else {
		return iov_to_buf_full(iov, iov_cnt, offset, buf, bytes);
	}
}

size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
		  const struct iovec *iov, unsigned int iov_cnt,
		  size_t offset, size_t bytes);
#endif