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LIO_LISTIO(3P) POSIX Programmer's Manual LIO_LISTIO(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
lio_listio — list directed I/O
#include <aio.h>
int lio_listio(int mode, struct aiocb *restrict const list[restrict],
int nent, struct sigevent *restrict sig);
The lio_listio() function shall initiate a list of I/O requests with
a single function call.
The mode argument takes one of the values LIO_WAIT or LIO_NOWAIT
declared in <aio.h> and determines whether the function returns when
the I/O operations have been completed, or as soon as the operations
have been queued. If the mode argument is LIO_WAIT, the function
shall wait until all I/O is complete and the sig argument shall be
ignored.
If the mode argument is LIO_NOWAIT, the function shall return
immediately, and asynchronous notification shall occur, according to
the sig argument, when all the I/O operations complete. If sig is
NULL, then no asynchronous notification shall occur. If sig is not
NULL, asynchronous notification occurs as specified in Section 2.4.1,
Signal Generation and Delivery when all the requests in list have
completed.
The I/O requests enumerated by list are submitted in an unspecified
order.
The list argument is an array of pointers to aiocb structures. The
array contains nent elements. The array may contain NULL elements,
which shall be ignored.
If the buffer pointed to by list or the aiocb structures pointed to
by the elements of the array list become illegal addresses before all
asynchronous I/O completed and, if necessary, the notification is
sent, then the behavior is undefined. If the buffers pointed to by
the aio_buf member of the aiocb structure pointed to by the elements
of the array list become illegal addresses prior to the asynchronous
I/O associated with that aiocb structure being completed, the
behavior is undefined.
The aio_lio_opcode field of each aiocb structure specifies the
operation to be performed. The supported operations are LIO_READ,
LIO_WRITE, and LIO_NOP; these symbols are defined in <aio.h>. The
LIO_NOP operation causes the list entry to be ignored. If the
aio_lio_opcode element is equal to LIO_READ, then an I/O operation is
submitted as if by a call to aio_read() with the aiocbp equal to the
address of the aiocb structure. If the aio_lio_opcode element is
equal to LIO_WRITE, then an I/O operation is submitted as if by a
call to aio_write() with the aiocbp equal to the address of the aiocb
structure.
The aio_fildes member specifies the file descriptor on which the
operation is to be performed.
The aio_buf member specifies the address of the buffer to or from
which the data is transferred.
The aio_nbytes member specifies the number of bytes of data to be
transferred.
The members of the aiocb structure further describe the I/O operation
to be performed, in a manner identical to that of the corresponding
aiocb structure when used by the aio_read() and aio_write()
functions.
The nent argument specifies how many elements are members of the
list; that is, the length of the array.
The behavior of this function is altered according to the definitions
of synchronized I/O data integrity completion and synchronized I/O
file integrity completion if synchronized I/O is enabled on the file
associated with aio_fildes.
For regular files, no data transfer shall occur past the offset
maximum established in the open file description associated with
aiocbp->aio_fildes.
If sig->sigev_notify is SIGEV_THREAD and sig->sigev_notify_attributes
is a non-null pointer and the block pointed to by this pointer
becomes an illegal address prior to all asynchronous I/O being
completed, then the behavior is undefined.
If the mode argument has the value LIO_NOWAIT, the lio_listio()
function shall return the value zero if the I/O operations are
successfully queued; otherwise, the function shall return the value
−1 and set errno to indicate the error.
If the mode argument has the value LIO_WAIT, the lio_listio()
function shall return the value zero when all the indicated I/O has
completed successfully. Otherwise, lio_listio() shall return a value
of −1 and set errno to indicate the error.
In either case, the return value only indicates the success or
failure of the lio_listio() call itself, not the status 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 other individual request.
To determine the outcome of each I/O request, the application shall
examine the error status associated with each aiocb control block.
The error statuses so returned are identical to those returned as the
result of an aio_read() or aio_write() function.
The lio_listio() function shall fail if:
EAGAIN The resources necessary to queue all the I/O requests were not
available. The application may check the error status for each
aiocb to determine the individual request(s) that failed.
EAGAIN The number of entries indicated by nent would cause the
system-wide limit {AIO_MAX} to be exceeded.
EINVAL The mode argument is not a proper value, or the value of nent
was greater than {AIO_LISTIO_MAX}.
EINTR A signal was delivered while waiting for all I/O requests to
complete during an LIO_WAIT operation. Note that, since each
I/O operation invoked by lio_listio() may possibly provoke a
signal when it completes, this error return may be caused by
the completion of one (or more) of the very I/O operations
being awaited. Outstanding I/O requests are not canceled, and
the application shall examine each list element to determine
whether the request was initiated, canceled, or completed.
EIO One or more of the individual I/O operations failed. The
application may check the error status for each aiocb
structure to determine the individual request(s) that failed.
In addition to the errors returned by the lio_listio() function, if
the lio_listio() 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 lio_listio() function fails with an error
code other than [EAGAIN], [EINTR], or [EIO], no operations from the
list shall have been initiated. The I/O operation indicated by each
list element can encounter errors specific to the individual read or
write function being performed. In this event, the error status for
each aiocb control block contains the associated error code. The
error codes that can be set are the same as would be set by a read()
or write() function, with the following additional error codes
possible:
EAGAIN The requested I/O operation was not queued due to resource
limitations.
ECANCELED
The requested I/O was canceled before the I/O completed due to
an explicit aio_cancel() request.
EFBIG The aiocbp->aio_lio_opcode is LIO_WRITE, the file is a regular
file, aiocbp->aio_nbytes is greater than 0, and the
aiocbp->aio_offset is greater than or equal to the offset
maximum in the open file description associated with
aiocbp->aio_fildes.
EINPROGRESS
The requested I/O is in progress.
EOVERFLOW
The aiocbp->aio_lio_opcode is LIO_READ, the file is a regular
file, aiocbp->aio_nbytes is greater than 0, and the
aiocbp->aio_offset is before the end-of-file and is greater
than or equal to the offset maximum in the open file
description associated with aiocbp->aio_fildes.
The following sections are informative.
None.
None.
Although it may appear that there are inconsistencies in the
specified circumstances for error codes, the [EIO] error condition
applies when any circumstance relating to an individual operation
makes that operation fail. This might be due to a badly formulated
request (for example, the aio_lio_opcode field is invalid, and
aio_error() returns [EINVAL]) or might arise from application
behavior (for example, the file descriptor is closed before the
operation is initiated, and aio_error() returns [EBADF]).
The limitation on the set of error codes returned when operations
from the list shall have been initiated enables applications to know
when operations have been started and whether aio_error() is valid
for a specific operation.
None.
aio_read(3p), aio_write(3p), aio_error(3p), aio_return(3p),
aio_cancel(3p), close(3p), exec(1p), exit(3p), fork(3p), lseek(3p),
read(3p)
The Base Definitions volume of POSIX.1‐2008, aio.h(0p)
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 LIO_LISTIO(3P)
Pages that refer to this page: aio.h(0p), aio_error(3p), aio_read(3p), aio_return(3p), aio_suspend(3p), aio_write(3p)