int aio_read(struct aiocb *aiocbp);
Link with -lrt.
The aio_read() function queues the I/O request described by the buffer
pointed to by aiocbp. This function is the asynchronous analog of
read(2). The arguments of the call
read(fd, buf, count)
correspond (in order) to the fields aio_fildes, aio_buf, and aio_nbytes
of the structure pointed to by aiocbp. (See aio(7) for a description
of the aiocb structure.)
The data is read starting at the absolute file offset aiocbp->aio_off-
set, regardless of the current file offset. After the call, the value
of the current file offset is unspecified.
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 sta-
tus of a completed I/O operation can be obtained by aio_return(3).
Asynchronous notification of I/O completion can be obtained by setting
aiocbp->aio_sigevent appropriately; see sigevent(7) for details.
If _POSIX_PRIORITIZED_IO 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 is ignored.
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 aio_error(3) (error status--whatever one would have gotten in
errno, such as EBADF).
EAGAIN Out of resources.
EBADF aio_fildes is not a valid file descriptor open for reading.
EINVAL One or more of aio_offset, aio_reqprio, or aio_nbytes are
ENOSYS aio_read() is not implemented.
|Interface | Attribute | Value |
|aio_read() | Thread safety | MT-Safe |
It is a good idea to zero out the control block before use. The con-
trol block must not be changed while the read operation is in progress.
The buffer area being read into must not be accessed during the opera-
tion or undefined results may occur. The memory areas involved must
Simultaneous I/O operations specifying the same aiocb structure produce
aio_cancel(3), aio_error(3), aio_fsync(3), aio_return(3), aio_sus-
pend(3), aio_write(3), lio_listio(3), aio(7)
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