#define _LARGEFILE_SOURCE
#define _LARGEFILE64_SOURCE
#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>
#include <linux/fs.h>
#include <sys/ioctl.h>

#ifndef O_DIRECT
#define O_DIRECT         040000 /* direct disk access hint */
#endif
const char *progname;
#define NBLK 10
#define NTRL 100

#define BLKSZ 1024

int displaywidth;
char *what;

static void usage(void)
{
	fprintf(stderr, "Usage: %s blockdevice\n", progname);
	exit(1);
}

char b[NBLK][BLKSZ];

struct {
	off64_t where;
	int which;
} trials[NTRL];

static uint64_t
rnd(uint64_t limit)
{
	double r = (unsigned long)random();
	r *= limit;
	r /= RAND_MAX;
	return (uint64_t)r;
}


static void
do_randomise(void)
{
	int i;
	int j;

	for (i = 0; i < NBLK; i++) {
		for (j = 0; j < BLKSZ; j++)
			b[i][j] = random();
	}
}

static void
setup_display(void)
{
	int cols = 80;
	struct winsize w;

	if (ioctl(0, TIOCGWINSZ, &w) == 0)
		cols = w.ws_col;

	what = malloc(cols + 1);
	memset(what, ' ', cols);
	what[cols] = 0;
	displaywidth = cols;
}

static void
update_display(int i, off64_t sz)
{
	int x = trials[i].where * displaywidth / sz;
	switch (what[x]) {
	case ' ':
		what[x] = '.';
		break;
	case '.':
		what[x] = '-';
		break;
	case '-':
		what[x] = '_';
		break;
	case '_':
		what[x] = '+';
		break;
	case '+':
		what[x] = '=';
		break;
	case '=':
		what[x] = 'o';
		break;
	case 'o':
		what[x] = 'a';
		break;
	case 'a':
		what[x] = 'x';
		break;
	case 'x':
		what[x] = '%';
		break;
	default:
		what[x] = '#';
		break;
	}

	printf("\r%s", what);
	fflush(stdout);
}


static void
endit(void)
{
	printf("\n");
	exit(0);
}

static void
do_writes(int fd, off64_t sz)
{
	int i;
	int n;

	for (i = 0; i < NTRL; i++) {
		trials[i].where =  rnd(sz) & ~511ULL;
		trials[i].which = random() % NBLK;

		update_display(i, sz);

		if (lseek64(fd, trials[i].where, SEEK_SET) == -1) {
			fprintf(stderr, "\nFailed to seek to %llu for writing: %s\n", 
				trials[i].where,
				strerror(errno));
			endit();
		}
		if ((n = write(fd, b[trials[i].which], BLKSZ)) != BLKSZ) {
			fprintf(stderr, "\nFailed to write %d bytes at %llu:%s \n",
				BLKSZ - (n == -1 ? 0 : n),
				trials[i].where,
				strerror(errno));
			endit();
		}
	}
}

static void 
do_reads(int fd)
{
	int i;
	char buf[BLKSZ];

	for (i = 0; i < NTRL; i++) {
		if (lseek64(fd, trials[i].where, SEEK_SET) == -1) {
			fprintf(stderr, "\nFailed to seek to %llu for reading: %s\n", 
				trials[i].where,
				strerror(errno));
			endit();
		}
		if (read(fd, buf, BLKSZ) != BLKSZ) {
			fprintf(stderr, "\nFailed to read BLKSZ bytes at %llu\n: %s",
				trials[i].where,
				strerror(errno));
			endit();
		}
		if (memcmp(buf, b[trials[i].which], BLKSZ)) {
			fprintf(stderr, "\nBlock read from %llu not the same as was written\n",
				trials[i].where);
			endit();
		}
	}
}


int
main(int ac, char *av[])
{
	int fd;
	off64_t sz;
	int i;

	progname = av[0];
	if (av[1] == NULL)
		usage();

	srandom(10);
	setup_display();

	if ((fd = open(av[1], O_RDWR|O_LARGEFILE)) == -1) {
		perror(av[1]);
		return 1;
	}

	sz = lseek64(fd, 0, SEEK_END);
	
	for (i = 0; i < 1000; i++) {
		do_randomise();
		do_writes(fd, sz);
		do_reads(fd);
	}
	endit();
	return 0;
}