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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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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.1‐2017, aio.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. 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.opengroup.org/unix/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 2017 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)
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HTML rendering created 2023-12-22 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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