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/*-------------------------------------------------------------------------
*
* pg_iovec.h
* Header for vectored I/O functions, to use in place of <sys/uio.h>.
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/port/pg_iovec.h
*
*-------------------------------------------------------------------------
*/
#ifndef PG_IOVEC_H
#define PG_IOVEC_H
#include <limits.h>
#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif
/* If <sys/uio.h> is missing, define our own POSIX-compatible iovec struct. */
#ifndef HAVE_SYS_UIO_H
struct iovec
{
void *iov_base;
size_t iov_len;
};
#endif
/*
* If <limits.h> didn't define IOV_MAX, define our own. POSIX requires at
* least 16.
*/
#ifndef IOV_MAX
#define IOV_MAX 16
#endif
/* Define a reasonable maximum that is safe to use on the stack. */
#define PG_IOV_MAX Min(IOV_MAX, 32)
#if HAVE_DECL_PREADV
#define pg_preadv preadv
#else
extern ssize_t pg_preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset);
#endif
#if HAVE_DECL_PWRITEV
#define pg_pwritev pwritev
#else
extern ssize_t pg_pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset);
#endif
#endif /* PG_IOVEC_H */
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