strlist.c

该代码为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);
}