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+.\" Copyright (C) 2021 Stefan Roesch <shr@fb.com>
+.\"
+.\" SPDX-License-Identifier: LGPL-2.0-or-later
+.\"
+.TH io_uring_prep_read 3 "November 15, 2021" "liburing-2.1" "liburing Manual"
+.SH NAME
+io_uring_prep_read \- prepare I/O read request
+.SH SYNOPSIS
+.nf
+.B #include <liburing.h>
+.PP
+.BI "void io_uring_prep_read(struct io_uring_sqe *" sqe ","
+.BI "                        int " fd ","
+.BI "                        void *" buf ","
+.BI "                        unsigned " nbytes ","
+.BI "                        __u64 " offset ");"
+.fi
+.SH DESCRIPTION
+.PP
+The
+.BR io_uring_prep_read (3)
+prepares an IO read request. The submission queue entry
+.I sqe
+is setup to use the file descriptor
+.I fd
+to start reading
+.I nbytes
+into the buffer
+.I buf
+at the specified
+.IR offset .
+
+On files that support seeking, if the offset is set to
+.BR -1 ,
+the read operation commences at the file offset, and the file offset is
+incremented by the number of bytes read. See
+.BR read (2)
+for more details. Note that for an async API, reading and updating the
+current file offset may result in unpredictable behavior, unless access
+to the file is serialized. It is not encouraged to use this feature, if it's
+possible to provide the desired IO offset from the application or library.
+
+On files that are not capable of seeking, the offset is ignored.
+
+After the read has been prepared it can be submitted with one of the submit
+functions.
+
+.SH RETURN VALUE
+None
+.SH ERRORS
+The CQE
+.I res
+field will contain the result of the operation. See the related man page for
+details on possible values. Note that where synchronous system calls will return
+.B -1
+on failure and set
+.I errno
+to the actual error value, io_uring never uses
+.IR errno .
+Instead it returns the negated
+.I errno
+directly in the CQE
+.I res
+field.
+.SH SEE ALSO
+.BR io_uring_get_sqe (3),
+.BR io_uring_prep_readv (3),
+.BR io_uring_prep_readv2 (3),
+.BR io_uring_submit (3)