#include <sys/sendfile.h>
#include <sys/socket.h>
#include <linux/if_alg.h>
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
int main(void)
{
	int opfd;
	int tfmfd;
	struct sockaddr_alg sa = {
		.salg_family = AF_ALG,
		.salg_type = "hash",
		.salg_name = "sha1"
	};
	char *buf2;
	char buf[20];
	int i;
	struct stat st;
	ssize_t size;

	tfmfd = socket(AF_ALG, SOCK_SEQPACKET, 0);

	bind(tfmfd, (struct sockaddr *)&sa, sizeof(sa));

	opfd = accept(tfmfd, NULL, 0);

        int t = open("/bin/true", O_RDONLY);
        fstat(t, &st);

        size = sendfile(opfd, t, NULL, st.st_size);
        if (size != st.st_size)
                exit(1);                
	read(opfd, &buf, 20);

	for (i = 0; i < 20; i++) {
		printf("%02x", (unsigned char)buf[i]);
	}
	printf("\n");

        lseek(t, 0, SEEK_SET);
        buf2 = malloc(st.st_size + 1);
        read(t, buf2, st.st_size);
        write(opfd, buf2, st.st_size);
	read(opfd, &buf, 20);

	for (i = 0; i < 20; i++) {
		printf("%02x", (unsigned char)buf[i]);
	}
	printf("\n");

	close(opfd);
	close(tfmfd);

	return 0;
}