プログラムのソース¶

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <aio.h>
#include <signal.h>
#define BUF_SIZE 20     /* Size of buffers for read operations */
#define errExit(msg) do { perror(msg); exit(EXIT_FAILURE); } while (0)
#define errMsg(msg)  do { perror(msg); } while (0)
struct ioRequest {      /* Application-defined structure for tracking


                           I/O requests */


    int           reqNum;


    int           status;


    struct aiocb *aiocbp;
};
static volatile sig_atomic_t gotSIGQUIT = 0;


                        /* On delivery of SIGQUIT, we attempt to


                           cancel all outstanding I/O requests */
static void             /* Handler for SIGQUIT */
quitHandler(int sig)
{


    gotSIGQUIT = 1;
}
#define IO_SIGNAL SIGUSR1   /* Signal used to notify I/O completion */
static void                 /* Handler for I/O completion signal */
aioSigHandler(int sig, siginfo_t *si, void *ucontext)
{


    write(STDOUT_FILENO, "I/O completion signal received\n", 31);


    /* The corresponding ioRequest structure would be available as


           struct ioRequest *ioReq = si->si_value.sival_ptr;


       and the file descriptor would then be available via


           ioReq->aiocbp->aio_fildes */
}
int
main(int argc, char *argv[])
{


    struct ioRequest *ioList;


    struct aiocb *aiocbList;


    struct sigaction sa;


    int s, j;


    int numReqs;        /* Total number of queued I/O requests */


    int openReqs;       /* Number of I/O requests still in progress */


    if (argc < 2) {


        fprintf(stderr, "Usage: %s <pathname> <pathname>...\n",


                argv[0]);


        exit(EXIT_FAILURE);


    }


    numReqs = argc - 1;


    /* Allocate our arrays */


    ioList = calloc(numReqs, sizeof(struct ioRequest));


    if (ioList == NULL)


        errExit("calloc");


    aiocbList = calloc(numReqs, sizeof(struct aiocb));


    if (aiocbList == NULL)


        errExit("calloc");


    /* Establish handlers for SIGQUIT and the I/O completion signal */


    sa.sa_flags = SA_RESTART;


    sigemptyset(&sa.sa_mask);


    sa.sa_handler = quitHandler;


    if (sigaction(SIGQUIT, &sa, NULL) == -1)


        errExit("sigaction");


    sa.sa_flags = SA_RESTART | SA_SIGINFO;


    sa.sa_sigaction = aioSigHandler;


    if (sigaction(IO_SIGNAL, &sa, NULL) == -1)


        errExit("sigaction");


    /* Open each file specified on the command line, and queue


       a read request on the resulting file descriptor */


    for (j = 0; j < numReqs; j++) {


        ioList[j].reqNum = j;


        ioList[j].status = EINPROGRESS;


        ioList[j].aiocbp = &aiocbList[j];


        ioList[j].aiocbp->aio_fildes = open(argv[j + 1], O_RDONLY);


        if (ioList[j].aiocbp->aio_fildes == -1)


            errExit("open");


        printf("opened %s on descriptor %d\n", argv[j + 1],


                ioList[j].aiocbp->aio_fildes);


        ioList[j].aiocbp->aio_buf = malloc(BUF_SIZE);


        if (ioList[j].aiocbp->aio_buf == NULL)


            errExit("malloc");


        ioList[j].aiocbp->aio_nbytes = BUF_SIZE;


        ioList[j].aiocbp->aio_reqprio = 0;


        ioList[j].aiocbp->aio_offset = 0;


        ioList[j].aiocbp->aio_sigevent.sigev_notify = SIGEV_SIGNAL;


        ioList[j].aiocbp->aio_sigevent.sigev_signo = IO_SIGNAL;


        ioList[j].aiocbp->aio_sigevent.sigev_value.sival_ptr =


                                &ioList[j];


        s = aio_read(ioList[j].aiocbp);


        if (s == -1)


            errExit("aio_read");


    }


    openReqs = numReqs;


    /* Loop, monitoring status of I/O requests */


    while (openReqs > 0) {


        sleep(3);       /* Delay between each monitoring step */


        if (gotSIGQUIT) {


            /* On receipt of SIGQUIT, attempt to cancel each of the


               outstanding I/O requests, and display status returned


               from the cancellation requests */


            printf("got SIGQUIT; canceling I/O requests: \n");


            for (j = 0; j < numReqs; j++) {


                if (ioList[j].status == EINPROGRESS) {


                    printf("    Request %d on descriptor %d:", j,


                            ioList[j].aiocbp->aio_fildes);


                    s = aio_cancel(ioList[j].aiocbp->aio_fildes,


                            ioList[j].aiocbp);


                    if (s == AIO_CANCELED)


                        printf("I/O canceled\n");


                    else if (s == AIO_NOTCANCELED)


                            printf("I/O not canceled\n");


                    else if (s == AIO_ALLDONE)


                        printf("I/O all done\n");


                    else


                        errMsg("aio_cancel");


                }


            }


            gotSIGQUIT = 0;


        }


        /* Check the status of each I/O request that is still


           in progress */


        printf("aio_error():\n");


        for (j = 0; j < numReqs; j++) {


            if (ioList[j].status == EINPROGRESS) {


                printf("    for request %d (descriptor %d): ",


                        j, ioList[j].aiocbp->aio_fildes);


                ioList[j].status = aio_error(ioList[j].aiocbp);


                switch (ioList[j].status) {


                case 0:


                    printf("I/O succeeded\n");


                    break;


                case EINPROGRESS:


                    printf("In progress\n");


                    break;


                case ECANCELED:


                    printf("Canceled\n");


                    break;


                default:


                    errMsg("aio_error");


                    break;


                }


                if (ioList[j].status != EINPROGRESS)


                    openReqs--;


            }


        }


    }


    printf("All I/O requests completed\n");


    /* Check status return of all I/O requests */


    printf("aio_return():\n");


    for (j = 0; j < numReqs; j++) {


        ssize_t s;


        s = aio_return(ioList[j].aiocbp);


        printf("    for request %d (descriptor %d): %zd\n",


                j, ioList[j].aiocbp->aio_fildes, s);


    }


    exit(EXIT_SUCCESS);
}