aio_return - Return the status of an asynchronous I/O operation (P1003.1b)
ssize_t aio_return (struct
The aio_return function returns the number of bytes read or written by the corresponding asynchronous I/O function. The return status for an asynchronous I/O operation is the value that would be returned by the corresponding synchronous read, write, or fsync function call. The aio_error function returns the error status for an asynchronous I/O operation.
The aio_error function returns the error status associated with the specified aiocbp. If the aio_error function returns anything but EINPROGRESS, the asynchronous I/O operation is complete. Once the operation is complete, a call to the aio_return function will show if the operation is successful.
Once you call the aio_return function, the aiocb structure is marked for reuse, thus destroying your ability to reuse the structure for that particular asynchronous I/O request. To avoid losing data, use the aio_error function to poll for completion before you call the aio_return function. Then use the aio_return function to retrieve the number of bytes read or written during the asynchronous I/O operation.
If you do not call the aio_return function, the structure is not marked for reuse. In this situation, the number of asynchronous I/O operations available for use in your application is reduced by one for every completed asynchronous I/O operation that does not return data through a call to the aio_return function.
If the asynchronous I/O operation has completed, then the return value is any of the return values normally associated with a synchronous read, write, or fsync function (the number of bytes transferred or -1). If the asynchronous I/O operation has not yet completed, the results of aio_return are undefined. On an unsuccessful call, the value of -1 is returned and errno is set to indicate the error.
The aio_return function fails under the following conditions:
Functions: close(2), exec(2), _exit(2), fork(2), lseek(2), read(2), write(2), aio_cancel(3), aio_error(3), aio_group_completion_np(3), aio_read(3), aio_results_np(3), aio_suspend(3), aio_write(3), lio_listio(3). delim off