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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>lio_listio</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_000_007_362"> </a>NAME</h4><blockquote>lio_listio - list directed I/O(<b>REALTIME</b>)</blockquote><h4><a name = "tag_000_007_363"> </a>SYNOPSIS</h4><blockquote><pre><code>#include <<a href="aio.h.html">aio.h</a>>int lio_listio(int <i>mode</i>, struct aiocb * const <i>list</i>[], int <i>nent</i>, struct sigevent *<i>sig</i>);</code></pre></blockquote><h4><a name = "tag_000_007_364"> </a>DESCRIPTION</h4><blockquote>The<i>lio_listio()</i>function allows the calling process to initiatea list of I/O requests with a single function call.<p>The<i>mode</i>argument takes one of the values LIO_WAIT or LIO_NOWAIT declared in<i><a href="aio.h.html"><aio.h></a></i>and determines whether the function returnswhen the I/O operations have been completed,or as soon as the operations have been queued.If the<i>mode</i>argument is LIO_WAIT,the function waits until all I/O is complete and the<i>sig</i>argument is ignored.<p>If the<i>mode</i>argument is LIO_NOWAIT,the function returns immediately,andasynchronous notificationoccurs, according to the<i>sig</i>argument, when all the I/O operations complete.If<i>sig</i>is NULL, then no asynchronous notification occurs.If<i>sig</i>is not NULL, asynchronous notification occurs as specified in<xref href=siggendel><a href="sigaction.html#tag_000_008_581_001">Signal Generation and Delivery</a></xref>when all the requests in<i>list</i>have completed.<p>The I/O requests enumerated by<i>list</i>are submitted in an unspecified order.<p>The<i>list</i>argument is an array of pointers to<b>aiocb</b>structures.The array contains<i>nent</i>elements.The array may contain NULL elements,which are ignored.<p>The<i>aio_lio_opcode</i>field of each<b>aiocb</b>structure specifies the operation to be performed.The supported operations areLIO_READ, LIO_WRITE and LIO_NOP;these symbols are defined in<i><a href="aio.h.html"><aio.h></a></i>.The LIO_NOP operation causes the list entry to be ignored.If the<i>aio_lio_opcode</i>element is equal to LIO_READ,then an I/O operation is submitted as if by a call to<i><a href="aio_read.html">aio_read()</a></i>with the<i>aiocbp</i>equal to the address of the<b>aiocb</b>structure.If the<i>aio_lio_opcode</i>element is equal to LIO_WRITE,then an I/O operation is submitted as if by a call to<i><a href="aio_write.html">aio_write()</a></i>with the<i>aiocbp</i>equal to the address of the<b>aiocb</b>structure.<p>The<i>aio_fildes</i>member specifies the file descriptor on which the operationis to be performed.<p>The<i>aio_buf</i>member specifies the address of the buffer to or fromwhich the data is to be transferred.<p>The<i>aio_nbytes</i>member specifies the number of bytes of data to be transferred.<p>The members of the<i>aiocb</i>structure further describe the I/O operation to be performed,in a manner identical to that of the corresponding<b>aiocb</b>structure when used by the<i><a href="aio_read.html">aio_read()</a></i>and<i><a href="aio_write.html">aio_write()</a></i>functions.<p>The<i>nent</i>argument specifies how many elements are members of the list,that is, the length of the array.<p>The behaviour of this function is alteredaccording to the definitions ofsynchronised I/O data integrity completion andsynchronised I/O file integrity completion.if synchronised I/O is enabled on the file associated with<i>aio_fildes</i>.<p>For regular files, no data transfer will occur past the offset maximumestablished in the open file description associated with<i>aiocbp->aio_fildes</i>.</blockquote><h4><a name = "tag_000_007_365"> </a>RETURN VALUE</h4><blockquote>If the<i>mode</i>argument has the value LIO_NOWAIT,the<i>lio_listio()</i>function returns the value zeroif the I/O operations are successfully queued;otherwise, the function returns the value -1 and sets<i>errno</i>to indicate the error.<p>If the<i>mode</i>argument has the value LIO_WAIT,the<i>lio_listio()</i>function returns the value zerowhen all the indicated I/O has completed successfully.Otherwise,<i>lio_listio()</i>returns a value of -1 and sets<i>errno</i>to indicate the error.<p>In either case, the return value only indicatesthe success or failure of the<i>lio_listio()</i>call itself, not thestatus of the individual I/O requests.In some cases one or more of the I/O requests contained in the list may fail.Failure of an individual request does not prevent completion of any otherindividual request.To determine the outcome of each I/O request,the application examines the error status associated with each<b>aiocb</b>control block.The error statuses so returnedare identical to those returned as the result of an<i><a href="aio_read.html">aio_read()</a></i>or<i><a href="aio_write.html">aio_write()</a></i>function.</blockquote><h4><a name = "tag_000_007_366"> </a>ERRORS</h4><blockquote>The <i>lio_listio()</i>function will fail if:<dl compact><dt>[EAGAIN]<dd>The resources necessary to queueall the I/O requests were not available.The application may checkthe error status for each<b>aiocb</b>to determine the individual request(s) that failed.<dt>[EAGAIN]<dd>The number of entries indicated by<i>nent</i>would cause the systemwide limit AIO_MAX to be exceeded.<dt>[EINVAL]<dd>The<i>mode</i>argument is not a proper value,or the value of<i>nent</i>was greater than AIO_LISTIO_MAX.<dt>[EINTR]<dd>A signal was deliveredwhile waiting for all I/O requests to complete during aLIO_WAIT operation.Note that, since each I/O operation invoked by<i>lio_listio()</i>may possibly provoke a signal when it completes,this error return may be caused by the completion of one (or more) of thevery I/O operations being awaited.Outstanding I/O requests are not canceled,and the application examines each list elementto determine whether the request was initiated, canceled, or completed.<dt>[EIO]<dd>One or more of the individual I/O operations failed.The application may check the error status for each<b>aiocb</b>structure to determine the individual request(s) that failed.<dt>[ENOSYS]<dd>The<i>lio_listio()</i>function is not supported by this implementation.</dl><p>In addition to the errors returned by the<i>lio_listio()</i>function, if the<i>lio_listio()</i>function succeeds or fails with errors of[EAGAIN], [EINTR], or [EIO],then some of the I/O specified by the list may have been initiated.If the<i>lio_listio()</i>function fails with an error code other than [EAGAIN], [EINTR], or [EIO],no operations from the list have been initiated.The I/O operation indicated by each list element can encounter errorsspecific to the individual read or write function being performed.In this event, the error status for each<b>aiocb</b>control block contains the associated error code.The error codes that can be set are the same as would be set by a<i><a href="read.html">read()</a></i>or<i><a href="write.html">write()</a></i>function, with the following additional error codes possible:<dl compact><dt>[EAGAIN]<dd>The requested I/O operation was not queued due to resource limitations.<dt>[ECANCELED]<dd>The requested I/O was canceled before the I/O completed due to an explicit<i><a href="aio_cancel.html">aio_cancel()</a></i>request.<dt>[EFBIG]<dd>The <i>aiocbp->aio_lio_opcode</i>is LIO_WRITE, the file is a regular file,<i>aiocbp->aio_nbytes</i>is greater than 0, and the <i>aiocbp->aio_offset</i>is greater than or equal to the offset maximum in the open filedescription associated with <i>aiocbp->aio_fildes</i>.<dt>[EINPROGRESS]<dd>The requested I/O is in progress.<dt>[EOVERFLOW]<dd>The <i>aiocbp->aio_lio_opcode</i>is LIO_READ, the file is a regular file,<i>aiocbp->aio_nbytes</i>is greater than 0, and the<i>aiocbp->aio_offset</i>is before the end-of-file and is greater than or equal to the offsetmaximum in the open file description associated with<i>aiocbp->aio_fildes</i>.</dl></blockquote><h4><a name = "tag_000_007_367"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_368"> </a>APPLICATION USAGE</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_369"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_000_007_370"> </a>SEE ALSO</h4><blockquote><i><a href="aio_read.html">aio_read()</a></i>,<i><a href="aio_write.html">aio_write()</a></i>,<i><a href="aio_error.html">aio_error()</a></i>,<i><a href="aio_return.html">aio_return()</a></i>,<i><a href="aio_cancel.html">aio_cancel()</a></i>,<i><a href="read.html">read()</a></i>,<i><a href="lseek.html">lseek()</a></i>,<i><a href="close.html">close()</a></i>,<i><a href="_exit.html">_exit()</a></i>,<i><a href="exec.html">exec</a></i>,<i><a href="fork.html">fork()</a></i>.</blockquote><h4>DERIVATION</h4><blockquote>Derived from the POSIX Realtime Extension (1003.1b-1993/1003.1i-1995)</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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