linux-kernel-module-cheat/userland/anonymous_inode.c

/* https://github.com/cirosantilli/linux-kernel-module-cheat#anonymous-inode */

#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h> /* sleep */

#include "../include/anonymous_inode.h"

int main(int argc, char **argv)
{
	char buf[1024];
	int fd_ioctl, fd_ioctl_anon, ret;
	size_t i, nreads;

	if (argc < 2) {
		puts("Usage: ./prog <ioctl-file> [<nreads>]");
		return EXIT_FAILURE;
	} else if (argc > 2) {
		nreads = strtol(argv[2], NULL, 10);
	} else {
		nreads = 3;
	}
	fd_ioctl = open(argv[1], O_RDONLY);
	if (fd_ioctl == -1) {
		perror("open");
		return EXIT_FAILURE;
	}
	ret = ioctl(fd_ioctl, LKMC_ANONYMOUS_INODE_GET_FD, &fd_ioctl_anon);
	if (ret == -1) {
		perror("ioctl");
		return EXIT_FAILURE;
	}
	for (i = 0; i < nreads; ++i) {
		ret = read(fd_ioctl_anon, buf, sizeof(buf));
		printf("%.*s\n", ret, buf);
	}
	close(fd_ioctl_anon);
	close(fd_ioctl);
	return EXIT_SUCCESS;
}