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#include <aio.h>
ssize_t aio_return(struct aiocb * aiocbp);
int aio_error(const struct aiocb * aiocbp);
struct aiocb {
int aio_fildes; /* file descriptor */
volatile void *aio_buf; /* buffer location */
size_t aio_nbytes; /* length of transfer */
off_t aio_offset; /* file offset */
int aio_reqprio; /* request priority offset */
struct sigevent aio_sigevent; /* signal number and offset */
int aio_lio_opcode; /* listio operation */
};
struct sigevent {
int sigev_notify; /* notification mode */
int sigev_signo; /* signal number */
union sigval sigev_value; /* signal value */
};
union sigval {
int sival_int; /* integer value */
void *sival_ptr; /* pointer value */
};
aio_error() returns the error status of the asynchronous I/O request associated with the aiocb structure pointed to by aiocbp.
aio_return() should be called only once to retrieve the valid return status of a given asynchronous operation, after aio_error() has returned a value other than EINPROGRESS.
If the asynchronous I/O operation has completed successfully, aio_error() returns 0. If the operation has not yet completed, then EINPROGRESS is returned. If the asynchronous I/O operation has completed unsuccessfully, then the error status, as described for read(2) , write(2) , and fsync(3C) is returned.
If unsuccessful, aio_return() or aio_error() return -1, and set errno to indicate the error condition.
#include <aio.h>
#include <errno.h>
#include <signal.h>
struct aiocb my_aiocb;
struct sigaction my_sigaction;
void my_aio_handler(int, siginfo_t *, void *);
...
my_sigaction.sa_flags = SA_SIGINFO;
my_sigaction.sa_sigaction = my_aio_handler;
sigsetempty(&my_sigaction.sa_mask);
(void) sigaction(SIGRTMIN, &my_sigaction, NULL);
...
my_aiocb.aio_sigevent.sigev_notify = SIGEV_SIGNAL;
my_aiocb.aio_sigevent.sigev_signo = SIGRTMIN;
my_aiocb.aio_sigevent.sigev_value.sival_ptr = &myaiocb;
...
(void) aio_read(&my_aiocb);
...
void
my_aio_handler(int signo, siginfo_t *siginfo, void *context) {
int my_errno;
struct aiocb *my_aiocbp;
my_aiocbp = siginfo.si_value.sival_ptr;
if ((my_errno = aio_error(my_aiocb)) != EINPROGRESS) {
int my_status = aio_return(my_aiocb);
if (my_status >= 0) {/* start another operation */
...
} else {
/* handle I/O error */
...
}
}
}