56 lines
1.3 KiB
C
56 lines
1.3 KiB
C
/*-------------------------------------------------------------------------
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*
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* pg_iovec.h
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* Header for vectored I/O functions, to use in place of <sys/uio.h>.
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*
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* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/port/pg_iovec.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef PG_IOVEC_H
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#define PG_IOVEC_H
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#ifndef WIN32
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#include <limits.h>
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#include <sys/uio.h>
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#else
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/* POSIX requires at least 16 as a maximum iovcnt. */
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#define IOV_MAX 16
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/* Define our own POSIX-compatible iovec struct. */
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struct iovec
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{
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void *iov_base;
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size_t iov_len;
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};
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#endif
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/* Define a reasonable maximum that is safe to use on the stack. */
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#define PG_IOV_MAX Min(IOV_MAX, 32)
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/*
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* Note that pg_preadv and pg_pwritev have a pg_ prefix as a warning that the
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* Windows implementations have the side-effect of changing the file position.
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*/
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#if HAVE_DECL_PREADV
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#define pg_preadv preadv
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#else
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extern ssize_t pg_preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset);
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#endif
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#if HAVE_DECL_PWRITEV
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#define pg_pwritev pwritev
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#else
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extern ssize_t pg_pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset);
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#endif
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#endif /* PG_IOVEC_H */
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