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aio_return.2 (2010 09)

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aio_return(2) aio_return(2)
NAME
aio_return() - return status of an asynchronous I/O operation
SYNOPSIS
#include <aio.h>
ssize_t aio_return(struct aiocb *aiocbp);
DESCRIPTION
The aio_return() function returns the return status associated with the
aiocb structure referenced
by the aiocbp argument. The return value for an asynchronous I/O operation is the value that would be
set by the corresponding
read(), write(),orfsync() operation. If the operation has been queued
but not completed,
aio_return() returns -1 and errno
is set to EINPROGRESS. A successful
aio_return() call frees all kernel resources associated with the calls
aiocb referenced by aiocbp .
To use this function, link in the realtime library by specifying
-lrt on the compiler or linker command
line.
RETURN VALUE
If the
aiocb is invalid or if no asynchronous I/O operation is enqueued for the
aiocb,
aio_returns()
returns -1 and errno is set to indicate the error. Otherwise, aio_return()
returns the error status of the referenced aiocb. See aio_read (2), read (2), aio_write (2), write (2),
aio_fsync (2), fsync(2) and lio_listio (2) for relevant error values.
ERRORS
If
aio_return() detects one of the following error conditions, errno is set to the indicated value:
[EINVAL] The aiocbp is not a valid address within the process virtual address space.
[EINVAL] There was no asynchronous I/O operation enqueued for the referenced
aiocb.
EXAMPLE
The following code sequence illustrates using
aio_return() to retrieve the error status of an
aio_read() operation and free the aiocb for future re-use.
#include <fcntl.h>
#include <errno.h>
#include <aio.h>
char buf[4096];
int retval; ssize_t nbytes;
struct aiocb myaiocb;
bzero( &myaiocb, sizeof (struct aiocb));
myaiocb.aio_fildes = open( "/dev/null", O_RDONLY);
myaiocb.aio_offset = 0;
myaiocb.aio_buf = (void *) buf;
myaiocb.aio_nbytes = sizeof (buf);
myaiocb.aio_sigevent.sigev_notify = SIGEV_NONE;
retval = aio_read( &myaiocb );
if (retval) perror("aio_read:");
/* continue processing */
...
/* wait for completion */
while ( (retval = aio_error( &myaiocb) ) == EINPROGRESS) ;
/* free the aiocb */
nbytes = aio_return( &myaiocb);
SEE ALSO
aio_cancel(2), aio_error(2), aio_fsync(2), aio_read(2), aio_suspend(2), aio_write(2), fsync(2), lio_listio(2),
read(2), write(2), aio(5).
STANDARDS CONFORMANCE
aio_return(): POSIX Realtime Extensions, IEEE Std 1003.1b
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1

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