strlist.c

unix环境高级编程的源代码

#include    <sys/conf.h>
#include    <sys/types.h>
#include    <fcntl.h>
#include    <stropts.h>
#include    "ourhdr.h"

int
main(int argc, char *argv[])
{
    int                    fd, i, nmods;
    struct str_list        list;

    if (argc != 2)
        err_quit("usage: a.out <pathname>");

    if ( (fd = open(argv[1], O_RDONLY)) < 0)
        err_sys("can't open %s", argv[1]);
    if (isastream(fd) == 0)
        err_quit("%s is not a stream", argv[1]);

            /* fetch number of modules */
    if ( (nmods = ioctl(fd, I_LIST, (void *) 0)) < 0)
        err_sys("I_LIST error for nmods");
    printf("#modules = %d\n", nmods);

            /* allocate storage for all the module names */
    list.sl_modlist = calloc(nmods, sizeof(struct str_mlist));
    if (list.sl_modlist == NULL)
        err_sys("calloc error");
    list.sl_nmods = nmods;

            /* and fetch the module names */
    if (ioctl(fd, I_LIST, &list) < 0)
        err_sys("I_LIST error for list");

            /* print the module names */
    for (i = 1; i <= nmods; i++)
        printf("  %s: %s\n", (i == nmods) ? "driver" : "module",
                                list.sl_modlist++);
    exit(0);
}