mirror of https://github.com/mkerrisk/man-pages
241 lines
5.7 KiB
Groff
241 lines
5.7 KiB
Groff
.\" Copyright (C) 2010, Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
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.\" This is free documentation; you can redistribute it and/or
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.\" modify it under the terms of the GNU General Public License as
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.\" published by the Free Software Foundation; either version 2 of
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.\" the License, or (at your option) any later version.
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.\"
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.\" The GNU General Public License's references to "object code"
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.\" and "executables" are to be interpreted as the output of any
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.\" document formatting or typesetting system, including
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.\" intermediate and printed output.
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.\"
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.\" This manual is distributed in the hope that it will be useful,
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.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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.\" GNU General Public License for more details.
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.\"
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.\" You should have received a copy of the GNU General Public
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.\" License along with this manual; if not, see
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.\" <http://www.gnu.org/licenses/>.
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.\" %%%LICENSE_END
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.\"
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.TH LIO_LISTIO 3 2016-10-08 "" "Linux Programmer's Manual"
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.SH NAME
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lio_listio \- initiate a list of I/O requests
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.SH SYNOPSIS
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.nf
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.B "#include <aio.h>"
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.PP
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.BI "int lio_listio(int " mode ", struct aiocb *const " aiocb_list [],
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.BI " int " nitems ", struct sigevent *" sevp );
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.PP
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Link with \fI\-lrt\fP.
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.fi
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.SH DESCRIPTION
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The
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.BR lio_listio ()
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function initiates the list of I/O operations described by the array
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.IR aiocb_list .
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.PP
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The
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.I mode
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operation has one of the following values:
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.TP 12
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.B LIO_WAIT
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The call blocks until all operations are complete.
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The
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.I sevp
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argument is ignored.
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.TP
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.B LIO_NOWAIT
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The I/O operations are queued for processing and the call returns immediately.
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When all of the I/O operations complete, asynchronous notification occurs,
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as specified by the
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.IR sevp
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argument; see
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.BR sigevent (7)
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for details.
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If
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.IR sevp
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is NULL, no asynchronous notification occurs.
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.PP
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The
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.I aiocb_list
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argument is an array of pointers to
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.I aiocb
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structures that describe I/O operations.
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These operations are executed in an unspecified order.
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The
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.I nitems
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argument specifies the size of the array
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.IR aiocb_list .
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null pointers in
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.I aiocb_list
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are ignored.
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.PP
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In each control block in
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.IR aiocb_list ,
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the
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.I aio_lio_opcode
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field specifies the I/O operation to be initiated, as follows:
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.TP 10
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.BR LIO_READ
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Initiate a read operation.
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The operation is queued as for a call to
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.BR aio_read (3)
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specifying this control block.
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.TP
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.BR LIO_WRITE
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Initiate a write operation.
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The operation is queued as for a call to
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.BR aio_write (3)
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specifying this control block.
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.TP
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.BR LIO_NOP
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Ignore this control block.
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.PP
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The remaining fields in each control block have the same meanings as for
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.BR aio_read (3)
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and
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.BR aio_write (3).
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The
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.I aio_sigevent
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fields of each control block can be used to specify notifications
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for the individual I/O operations (see
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.BR sigevent (7)).
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.SH RETURN VALUE
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If
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.I mode
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is
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.BR LIO_NOWAIT ,
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.BR lio_listio ()
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returns 0 if all I/O operations are successfully queued.
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Otherwise, \-1 is returned, and
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.I errno
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is set to indicate the error.
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.PP
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If
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.I mode
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is
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.BR LIO_WAIT ,
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.BR lio_listio ()
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returns 0 when all of the I/O operations have completed successfully.
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Otherwise, \-1 is returned, and
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.I errno
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is set to indicate the error.
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.PP
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The return status from
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.BR lio_listio ()
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provides information only about the call itself,
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not about the individual I/O operations.
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One or more of the I/O operations may fail,
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but this does not prevent other operations completing.
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The status of individual I/O operations in
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.IR aiocb_list
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can be determined using
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.BR aio_error (3).
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When an operation has completed,
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its return status can be obtained using
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.BR aio_return (3).
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Individual I/O operations can fail for the reasons described in
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.BR aio_read (3)
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and
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.BR aio_write (3).
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.SH ERRORS
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The
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.BR lio_listio ()
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function may fail for the following reasons:
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.TP
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.B EAGAIN
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Out of resources.
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.TP
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.B EAGAIN
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.\" Doesn't happen in glibc(?)
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The number of I/O operations specified by
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.I nitems
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would cause the limit
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.BR AIO_MAX
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to be exceeded.
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.TP
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.B EINTR
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.I mode
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was
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.BR LIO_WAIT
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and a signal
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was caught before all I/O operations completed; see
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.BR signal (7).
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(This may even be one of the signals used for
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asynchronous I/O completion notification.)
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.TP
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.B EINVAL
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.I mode
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is invalid, or
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.\" Doesn't happen in glibc(?)
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.I nitems
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exceeds the limit
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.BR AIO_LISTIO_MAX .
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.TP
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.B EIO
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One of more of the operations specified by
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.IR aiocb_list
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failed.
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.\" e.g., ioa_reqprio or aio_lio_opcode was invalid
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The application can check the status of each operation using
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.BR aio_return (3).
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.PP
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If
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.BR lio_listio ()
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fails with the error
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.BR EAGAIN ,
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.BR EINTR ,
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or
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.BR EIO ,
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then some of the operations in
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.IR aiocb_list
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may have been initiated.
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If
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.BR lio_listio ()
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fails for any other reason,
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then none of the I/O operations has been initiated.
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.SH VERSIONS
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The
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.BR lio_listio ()
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function is available since glibc 2.1.
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lb lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR lio_listio ()
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T} Thread safety MT-Safe
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.TE
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.sp 1
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.SH CONFORMING TO
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POSIX.1-2001, POSIX.1-2008.
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.SH NOTES
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It is a good idea to zero out the control blocks before use.
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The control blocks must not be changed while the I/O operations
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are in progress.
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The buffer areas being read into or written from
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.\" or the control block of the operation
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must not be accessed during the operations or undefined results may occur.
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The memory areas involved must remain valid.
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.PP
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Simultaneous I/O operations specifying the same
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.I aiocb
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structure produce undefined results.
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.SH SEE ALSO
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.BR aio_cancel (3),
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.BR aio_error (3),
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.BR aio_fsync (3),
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.BR aio_return (3),
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.BR aio_suspend (3),
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.BR aio_write (3),
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.BR aio (7)
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