aio_read - asynchronous read
int aio_read(struct aiocb *aiocbp);
Link with -lrt
() function queues the I/O request described by the buffer
pointed to by aiocbp
. This function is the asynchronous analog of
. The arguments of the call
read(fd, buf, count)
correspond (in order) to the fields aio_fildes
of the structure pointed to by aiocbp
for a description of the aiocb
The data is read starting at the absolute position aiocbp->aio_offset
regardless of the file offset. After the call, the value of the file offset is
The "asynchronous" means that this call returns as soon as the request
has been enqueued; the read may or may not have completed when the call
returns. One tests for completion using aio_error(3)
. The return status
of a completed I/O operation can be obtained by aio_return(3)
Asynchronous notification of I/O completion can be obtained by setting
appropriately; see sigevent(7)
is defined, and this file supports it, then the
asynchronous operation is submitted at a priority equal to that of the calling
process minus aiocbp->aio_reqprio
The field aiocbp->aio_lio_opcode
No data is read from a regular file beyond its maximum offset.
On success, 0 is returned. On error, the request is not enqueued, -1 is
returned, and errno
is set appropriately. If an error is detected only
later, it will be reported via aio_return(3)
(returns status -1) and
(error status—whatever one would have gotten in
, such as EBADF
- Out of resources.
- aio_fildes is not a valid file descriptor open for
- One or more of aio_offset, aio_reqprio, or
aio_nbytes are invalid.
- aio_read() is not implemented.
- The file is a regular file, we start reading before
end-of-file and want at least one byte, but the starting position is past
the maximum offset for this file.
() function is available since glibc 2.1.
For an explanation of the terms used in this section, see attributes(7)
It is a good idea to zero out the control block before use. The control block
must not be changed while the read operation is in progress. The buffer area
being read into must not be accessed during the operation or undefined results
may occur. The memory areas involved must remain valid.
Simultaneous I/O operations specifying the same aiocb
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