|AIO_READ(2)||System Calls Manual||AIO_READ(2)|
asynchronous read from a file (REALTIME)
Standard C Library (libc, -lc)
system call allows the calling process to read
aiocbp->aio_nbytes from the descriptor
aiocbp->aio_fildes, beginning at the offset
aiocbp->aio_offset, into the buffer pointed to by
aiocbp->aio_buf. The call returns immediately after
the read request has been enqueued to the descriptor; the read may or may
not have completed at the time the call returns.
If _POSIX_PRIORITIZED_IO is defined, and the descriptor supports it, then the enqueued operation is submitted at a priority equal to that of the calling process minus aiocbp->aio_reqprio.
aiocbp->aio_lio_opcode argument is ignored by the
If the request could not be enqueued (generally due to invalid arguments), then the call returns without having enqueued the request.
If the request is successfully enqueued, the value of aiocbp->aio_offset can be modified during the request as context, so this value must not be referenced after the request is enqueued.
The Asynchronous I/O Control Block structure pointed to by aiocbp and the buffer that the aiocbp->aio_buf member of that structure references must remain valid until the operation has completed. For this reason, use of auto (stack) variables for these objects is discouraged.
The asynchronous I/O control buffer
aiocbp should be zeroed before the
call to avoid passing bogus context information to the kernel.
Modifications of the Asynchronous I/O Control Block structure or the buffer contents after the request has been enqueued, but before the request has completed, are not allowed.
If the file offset in aiocbp->aio_offset is past the offset maximum for aiocbp->aio_fildes, no I/O will occur.
aio_read() function returns the
value 0 if successful; otherwise the value -1 is returned and
the global variable errno is set to indicate the
aio_read() system call will fail
aio_read() system call is not supported.
The following conditions may be synchronously detected when the
aio_read() system call is made, or asynchronously,
at any time thereafter. If they are detected at call time,
aio_read() returns -1 and sets
errno appropriately. Otherwise, the
aio_return() system call must be called. It will
aio_error() must then be called to
determine the actual value that would have been returned in
If the request is successfully enqueued, but subsequently
cancelled or an error occurs, the value returned by the
aio_return() system call is per the
read(2) system call, and the value
returned by the
aio_error() system call is either
one of the error returns from the read(2)
system call, or one of:
aio_read() system call is expected to
conform to the IEEE Std 1003.1
aio_read() system call first appeared
in FreeBSD 3.0.
This manual page was written by Terry Lambert ⟨email@example.com⟩.
Invalid information in aiocbp->_aiocb_private may confuse the kernel.
|November 17, 1998||macOS 14.1|