aio_cancel

Date:: 10-20-2011

NAME

aio_cancel - Cancels an asynchronous I/O request

SYNOPSIS

#include <aio.h>

int aio_cancel(int fildes, aiocb_t *aiocbp);

DESCRIPTION

The aio_cancel function attempts to cancel one or more asynchronous I/O requests currently outstanding against file descriptor fildes. The aiocb argument points to the asynchronous I/O control block for a particular request to be canceled. If aiocbp is NULL, then all outstanding cancelable asynchronous I/O requests against fildes are canceled.

Normal signal delivery will not occur for asynchronous I/O operations that are successfully canceled. If there are requests that cannot be canceled, then the normal asynchronous completion process will take place for those requests when they are completed.

For requested operations that have been successfully canceled, the associated error status is set to ECANCELED and the return status is -1. For requested operations that are not successfully canceled, the aiocbp is not modified by aio_cancel.

If aiocbp is not NULL, and if fildes does not have the same value as the file descriptor with which the asynchronous operation was initiated, unspecified results occur.

RETURN VALUES

The aio_cancel function returns the value AIO_CANCELED to the calling process if the requested operation(s) were canceled. The value AIO_NOTCANCELED is returned if at least one of the requested operation(s) cannot be canceled because it is in progress. In this case, the state of any other operations referenced in the call to aio_cancel is not indicated by the return value of aio_cancel The application may determine the state of affairs for these operations by using aio_error function. The value AIO_ALLDONE is returned if all of the operations have already completed. Otherwise, the function returns -1, and sets errno to indicate the error.

MESSAGES

If the following error condition occurs, the aio_cancel function returns -1 and sets errno to the corresponding value.

EBADF: The fildes argument is not a valid file descriptor.