Standard C Library Functions aio_read(3C)
NAME
aio_read - asynchronous read from a file
SYNOPSIS
#include
int aio_read(struct aiocb *aiocbp);
DESCRIPTION
The aio_read() function allows the calling process to read
aiocbp->aio_nbytes from the file associated with aiocbp-
>aio_fildes into the buffer pointed to by aiocbp->aio_buf.
The function call returns when the read request has been initiated or queued to the file or device (even when the data cannot be delivered immediately). If_POSIX_PRIORITIZED_IO is defined and prioritized I/O is sup-
ported for this file, then the asynchronous operation is submitted at a priority equal to the scheduling priority ofthe process minus aiocbp->aio_reqprio. The aiocbp value may
be used as an argument to aio_error(3C) and aio_return(3C)
in order to determine the error status and return status, respectively, of the asynchronous operation while it is proceeding. If an error condition is encountered during queuing, the function call returns without having initiated or queued the request. The requested operation takes placeat the absolute position in the file as given by aio_offset,
as if lseek(2) were called immediately prior to the opera-
tion with an offset equal to aio_offset and a whence equal
to SEEK_SET. After a successful call to enqueue an asynchro-
nous I/O operation, the value of the file offset for the file is unspecified.
The aiocbp->aio_sigevent structure defines what asynchronous
notification is to occur when the asynchronous operation completes, as specified in signal.h(3HEAD).The aiocbp->aio_lio_opcode field is ignored by aio_read().
The aiocbp argument points to an aiocb structure. If thebuffer pointed to by aiocbp->aio_buf or the control block
pointed to by aiocbp becomes an illegal address prior toasynchronous I/O completion, then the behavior is undefined. Simultaneous asynchronous operations using the same aiocbp produce undefined results.
SunOS 5.11 Last change: 5 Feb 2008 1
Standard C Library Functions aio_read(3C)
If _POSIX_SYNCHRONIZED_IO is defined and synchronized I/O is
enabled on the file associated with aiocbp->aio_fildes, the
behavior of this function is according to the definitions ofsynchronized I/O data integrity completion and synchronized
I/O file integrity completion. For any system action that changes the process memory space
while an asynchronous I/O is outstanding to the address range being changed, the result of that action is undefined. For regular files, no data transfer will occur past the offset maximum established in the open file description
associated with aiocbp->aio_fildes.
RETURN VALUES
The aio_read() function returns 0 to the calling process if
the I/O operation is successfully queued; otherwise, the
function returns -1 and sets errno to indicate the error.
ERRORS
The aio_read() function will fail if:
EAGAIN The requested asynchronous I/O operation was not queued due to system resource limitations.
Each of the following conditions may be detected synchro-
nously at the time of the call to aio_read(), or asynchro-
nously. If any of the conditions below are detected synchro-
nously, the aio_read() function returns -1 and sets errno to
the corresponding value. If any of the conditions below aredetected asynchronously, the return status of the asynchro-
nous operation is set to -1, and the error status of the
asynchronous operation will be set to the corresponding value.EBADF The aiocbp->aio_fildes argument is not a valid
file descriptor open for reading.EINVAL The file offset value implied by aiocbp-
>aio_offset would be invalid, aiocbp->aio_reqprio
is not a valid value, or aiocbp->aio_nbytes is an
invalid value.In the case that the aio_read() successfully queues the I/O
operation but the operation is subsequently canceled orSunOS 5.11 Last change: 5 Feb 2008 2
Standard C Library Functions aio_read(3C)
encounters an error, the return status of the asynchronous operation is one of the values normally returned by the read(2) function call. In addition, the error status of theasynchronous operation will be set to one of the error sta-
tuses normally set by the read() function call, or one of the following values:EBADF The aiocbp->aio_fildes argument is not a valid
file descriptor open for reading.ECANCELED The requested I/O was canceled before the I/O
completed due to an explicit aio_cancel(3C)
request.EINVAL The file offset value implied by aiocbp-
>aio_offset would be invalid.
The following condition may be detected synchronously or asynchronously:EOVERFLOW The file is a regular file, aiobcp->aio_nbytes
is greater than 0 and the starting offset inaiobcp->aio_offset is before the end-of-file
and is at or beyond the offset maximum in theopen file description associated with aiocbp-
>aio_fildes.
USAGE
For portability, the application should set aiocb-
>aio_reqprio to 0.
The aio_read() function has a transitional interface for
64-bit file offsets. See lf64(5).
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:SunOS 5.11 Last change: 5 Feb 2008 3
Standard C Library Functions aio_read(3C)
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
SEE ALSO
close(2), exec(2), exit(2), fork(2), lseek(2), read(2),write(2), aio_cancel(3C), aio_return(3C), aio.h(3HEAD),
lio_listio(3C), siginfo.h(3HEAD), signal.h(3HEAD), attri-
butes(5), lf64(5), standards(5)SunOS 5.11 Last change: 5 Feb 2008 4