AIOWRITE(3) AIOWRITE(3)
NAME
aio_write, aio_write64 - asynchronous I/O write
C SYNOPSIS
#include <aio.h>
int aiowrite(aiocbt *aiocbp);
int aiowrite64(aiocb64t *aiocbp);
DESCRIPTION
The aiowrite() function allows the calling process to write aiocbp-
>aionbytes from the file associated with aiocbp->aiofildes into the
buffer pointed to by aiocbp->aiobuf (see write(2)). The function call
returns when the write request has been initiated or, at a minimum,
queued for the file or device.
The aiocb->aiosigevent defines how the calling process will be notified
upon I/O completion.
If sigevnotify is SIGEVNONE, then no notification will be posted to the
calling application.
If sigevnotify is SIGEVSIGNAL, then the signal specified in sigevsigno
will be sent to the calling process. If SASIGINFO is set for the signal
(see sigaction(2)) and the signal is in the range of SIGRTMIN and
SIGRTMAX then the signal will be queued to the process and the value in
sigevvalue will be the sivalue in the generated signal.
If sigevnotify is SIGEVCALLBACK then the function sigevfunc will be
called with sigevvalue as the argument. Only one callback will be called
at a time, however programs should be careful to note that a callback may
be run in parallel with the calling process.
If sigevnotify is SIGEVTHREAD then the function sigevnotifyfunction
will be called by a new thread (see pthreads(5)) with sigevvalue as the
argument. This thread is created when the event arrives with the
attributes specified in sigevnotifyattributes except that it is
automatically detached. The calling process should ensure there are
sufficient resources to create the thread.
All aiowrite() calls must supply a complete aiocb->aiosigevent
structure.
The aiocbp->aiolioopcode field is ignored by aiowrite().
Prioritized I/O is not currently supported among asynchronous file
operations. aiocbp->aioreqprio must be set to 0, otherwise the call
will fail.
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The I/O requests submitted in an unspecified order unless the file was
opened with the OAPPEND in which case the write operations will happen
in the order that they were submitted.
After a call to aiowrite the aiocbp may be used as an argument to
aioerror() and aioreturn() 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 queueing, the
function call returns without having initiated or queued the request.
After a successful call to enqueue an asynchronous I/O operation, the
value of the file offset for the file is undefined.
If the buffer pointed to by aiocbp->aiobuf or the control block pointed
to by aiocbp changes or becomes an illegal address prior to asynchronous
I/O completion then the behavior is undefined. Simultaneous asynchronous
operations using the same aiocbp produce undefined results.
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 asynchronous I/O is undefined.
The aiowrite64() function is identical to aiowrite() except that it
takes an aiocb64t * (see <aio.h>). This structure allows for the
specification of a file offset greater than 2 Gigabytes.
SEE ALSO
aio_read(3), lio_listio(3), aio_error(3), aio_return(3), aio_hold(3),
aio_cancel(3), aio_sgi_init(3), aio_fsync(3), write(2), lseek(2),
close(2), _exit(2), exec(2), fork(2), pthreads(5), sysconf(3C).
DIAGNOSTICS
The aiowrite() returns the value 0 to the calling process if the I/O
operation is successfully queued; otherwise, the function shall return
the value -1 and shall set errno to indicate the error.
[EAGAIN] The requested asynchronous I/O operation was not queued
due to system resource limitations. Often this is due to
exceeding the maximum number of asynchronous I/O
operations for the system. The maximum can be checked with
a call to sysconf() with an argument of SCAIOMAX.
Each of the following conditions may be detected synchronously at the
time of the call to aiowrite() , or asynchronously. If any of the
conditions below are detected synchronously at the time of the call, the
aiowrite() function shall return -1 and set errno to the corresponding
value. If any of the conditions below are detected asynchronously, the
return status of the asynchronous operation shall be set to -1 and the
error status of the asynchronous operation shall be set to the
corresponding value.
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[EBADF] The aiocbp->aiofildes argument is not a valid file
descriptor open for writing.
[EINVAL] The file offset value implied by aiocbp->aiooffset would
be invalid, aiocbp->aioreqprio is not a valid value, or
aiocbp->aionbytes is an invalid value.
In the case that the aiowrite() successfully queues the I/O operation,
the return status of the asynchronous operation shall be one of the
values normally returned by the write(2) function call. If the operation
is successfully queued, but is subsequently canceled or encounters an
error, the error status for the asynchronous operation shall contain one
of the values normally set by the write(2) function call, or one of the
following:
[EBADF] The aiocbp->aiofildes argument is not a valid file
descriptor open for writing.
[EINVAL] The file offset value implied by aiocbp->aiooffset would
be invalid.
[ECANCELED] The requested I/O was canceled before the I/O completed
due to an explicit aiocancel(3) request.
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