98 lines
2.9 KiB
Groff
98 lines
2.9 KiB
Groff
.\" Copyright (C) 2022 Jens Axboe <axboe@kernel.dk>
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.\"
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.\" SPDX-License-Identifier: LGPL-2.0-or-later
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.\"
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.TH io_uring_prep_socket 3 "May 27, 2022" "liburing-2.2" "liburing Manual"
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.SH NAME
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io_uring_prep_socket \- prepare a socket creation request
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.SH SYNOPSIS
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.nf
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.B #include <sys/socket.h>
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.B #include <liburing.h>
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.PP
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.BI "void io_uring_prep_socket(struct io_uring_sqe *" sqe ","
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.BI " int " domain ","
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.BI " int " type ","
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.BI " int " protocol ","
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.BI " unsigned int " flags ");"
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.PP
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.BI "void io_uring_prep_socket_direct(struct io_uring_sqe *" sqe ","
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.BI " int " domain ","
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.BI " int " type ","
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.BI " int " protocol ","
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.BI " unsigned int " file_index ","
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.BI " unsigned int " flags ");"
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.fi
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.SH DESCRIPTION
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.PP
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The
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.BR io_uring_prep_socket (3)
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function prepares a socket creation request. The submission queue entry
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.I sqe
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is setup to use the communication domain defined by
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.I domain
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and use the communication type defined by
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.I type
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and the protocol set by
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.IR protocol .
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The
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.I flags
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argument are currently unused.
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The
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.BR io_uring_prep_socket_direct (3)
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works just like
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.BR io_uring_prep_socket (3),
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except it maps the socket to a direct descriptor rather than return a normal
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file descriptor. The
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.I file_index
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argument should be set to the slot that should be used for this socket, or
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.B IORING_FILE_INDEX_ALLOC
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if io_uring should allocate a free one.
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If the direct variant is used, the application must first have registered
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a file table using
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.BR io_uring_register_files (3)
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of the appropriate size. Once registered, a direct socket request may use any
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entry in that table, as long as it is within the size of the registered table.
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If a specified entry already contains a file, the file will first be removed
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from the table and closed. It's consistent with the behavior of updating an
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existing file with
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.BR io_uring_register_files_update (3).
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For a direct descriptor socket request, the
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.I file_index
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argument can be set to
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.BR IORING_FILE_INDEX_ALLOC ,
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In this case a free entry in io_uring file table will
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be used automatically and the file index will be returned as CQE
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.IR res .
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.B -ENFILE
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is otherwise returned if there is no free entries in the io_uring file table.
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These functions prepare an async
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.BR socket (2)
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request. See that man page for details.
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.SH RETURN VALUE
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None
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.SH ERRORS
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The CQE
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.I res
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field will contain the result of the operation. See the related man page for
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details on possible values. Note that where synchronous system calls will return
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.B -1
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on failure and set
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.I errno
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to the actual error value, io_uring never uses
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.IR errno .
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Instead it returns the negated
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.I errno
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directly in the CQE
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.I res
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field.
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.SH SEE ALSO
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.BR io_uring_get_sqe (3),
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.BR io_uring_submit (3),
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.BR socket (2)
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