lio_listio (3)
Leading comments
Copyright (C) 2010, Michael Kerrisk <mtk.manpages@gmail.com> %%%LICENSE_START(GPLv2+_DOC_FULL) This is free documentation; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. The GNU General Public License's references to "object code" and "executables" are to be interpreted as the output of any document formatting or typesetting system...
NAME
lio_listio - initiate a list of I/O requestsSYNOPSIS
#include <aio.h> int lio_listio(int mode, struct aiocb *const aiocb_list[], int nitems, struct sigevent *sevp); Link with -lrt.
DESCRIPTION
The lio_listio() function initiates the list of I/O operations described by the array aiocb_list.The mode operation has one of the following values:
- LIO_WAIT
- The call blocks until all operations are complete. The sevp argument is ignored.
- LIO_NOWAIT
- The I/O operations are queued for processing and the call returns immediately. When all of the I/O operations complete, asynchronous notification occurs, as specified by the sevp argument; see sigevent(7) for details. If sevp is NULL, no asynchronous notification occurs.
The
aiocb_list
argument is an array of pointers to
aiocb
structures that describe I/O operations.
These operations are executed in an unspecified order.
The
nitems
argument specifies the size of the array
aiocb_list.
null pointers in
aiocb_list
are ignored.
In each control block in
aiocb_list,
the
aio_lio_opcode
field specifies the I/O operation to be initiated, as follows:
- LIO_READ
- Initiate a read operation. The operation is queued as for a call to aio_read(3) specifying this control block.
- LIO_WRITE
- Initiate a write operation. The operation is queued as for a call to aio_write(3) specifying this control block.
- LIO_NOP
- Ignore this control block.
The remaining fields in each control block have the same meanings as for aio_read(3) and aio_write(3). The aio_sigevent fields of each control block can be used to specify notifications for the individual I/O operations (see sigevent(7)).
RETURN VALUE
If mode is LIO_NOWAIT, lio_listio() returns 0 if all I/O operations are successfully queued. Otherwise, -1 is returned, and errno is set to indicate the error.If mode is LIO_WAIT, lio_listio() returns 0 when all of the I/O operations have completed successfully. Otherwise, -1 is returned, and errno is set to indicate the error.
The return status from lio_listio() provides information only about the call itself, not about the individual I/O operations. One or more of the I/O operations may fail, but this does not prevent other operations completing. The status of individual I/O operations in aiocb_list can be determined using aio_error(3). When an operation has completed, its return status can be obtained using aio_return(3). Individual I/O operations can fail for the reasons described in aio_read(3) and aio_write(3).
ERRORS
The lio_listio() function may fail for the following reasons:- EAGAIN
- Out of resources.
- EAGAIN
- The number of I/O operations specified by nitems would cause the limit AIO_MAX to be exceeded.
- EINVAL
- mode is invalid, or nitems exceeds the limit AIO_LISTIO_MAX.
- EINTR
- mode was LIO_WAIT and a signal was caught before all I/O operations completed. (This may even be one of the signals used for asynchronous I/O completion notification.)
- EIO
- One of more of the operations specified by aiocb_list failed. The application can check the status of each operation using aio_return(3).
If lio_listio() fails with the error EAGAIN, EINTR, or EIO, then some of the operations in aiocb_list may have been initiated. If lio_listio() fails for any other reason, then none of the I/O operations has been initiated.
VERSIONS
The lio_listio() function is available since glibc 2.1.ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).| Interface | Attribute | Value |
| lio_listio() | Thread safety | MT-Safe |
CONFORMING TO
POSIX.1-2001, POSIX.1-2008.NOTES
It is a good idea to zero out the control blocks before use. The control blocks must not be changed while the I/O operations are in progress. The buffer areas being read into or written from must not be accessed during the operations or undefined results may occur. The memory areas involved must remain valid.Simultaneous I/O operations specifying the same aiocb structure produce undefined results.