#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>
#include <unistd.h>

#include "main.h"
#include "disk.h"
#include "config.h"

struct ext2_super_block superblock;
struct ext2_group_desc *group_desc_block;

int read_super(int fd)
{
	if (read(fd, &superblock, sizeof(superblock)) != sizeof(superblock))
		return 0;
	if (superblock.s_magic != EXT2_SUPER_MAGIC || superblock.s_blocks_count == 0 || superblock.s_blocks_per_group == 0 || superblock.s_inodes_per_group == 0)
		return 0;
	if (superblock.s_mtime < SUPER_MTIME_MIN || superblock.s_mtime > SUPER_MTIME_MAX || superblock.s_creator_os != SUPER_CREATOR_OS)
		return 0;
	return 1;
}

static off_t _find_super(int fd, long block, unsigned long bs)
{
	unsigned long bsiz;
	off_t off;

	for (bsiz = (unsigned long) EXT2_MIN_BLOCK_SIZE;
			bsiz <= (unsigned long) EXT2_MAX_BLOCK_SIZE;
			bsiz *= 2) {
		if (bs<0 || bs==bsiz) {
		if (block >= 0)
			off = block * bs;
		else
			off = 1024;

		lseek(fd, off, SEEK_SET);
		if (read(fd, &superblock, sizeof(superblock)) == sizeof(superblock)) {
			if ((nr_blocks = superblock.s_blocks_count) <= 0)
				return 0;
			bsiz = fs_size / nr_blocks;
			if (superblock.s_magic == EXT2_SUPER_MAGIC && bsiz == bs) {
				blocksize = bs;
				return (off);
			}
				else if (superblock.s_magic == EXT2_SUPER_MAGIC
						&& bsiz > 1024-2) {
					blocksize = bs;	/* ZZZ hack */
				return (off);
			} else {
					fprintf(stderr, "M=0x%04x BS=%d",
					superblock.s_magic,
							superblock.s_log_block_size);
					fprintf(stderr, " (%lu = %llu / %lu)\n",
							bsiz, fs_size, nr_blocks);
			}
		} else
			fprintf(stderr, "Internal error 16378:2352\n");

		return (0);
	}
	}
	return 0;
}

int find_super(int fd, long block, unsigned long bs)
{
	off_t off;
	if ((off = _find_super(fd, block, bs)) == 0)
		return (0);
	nr_inodes = superblock.s_inodes_count;
	off += blocksize;
	groups = (int) ( (superblock.s_blocks_count + superblock.s_blocks_per_group - 1) / superblock.s_blocks_per_group); inodes_per_group = superblock.s_inodes_per_group;
	blocks_per_inodetable = ((inodes_per_group * sizeof(struct ext2_inode)) + blocksize - 1) / blocksize;
	if ( (group_desc_block = malloc(sizeof(struct ext2_group_desc) * groups)) == NULL) {
		fprintf(stderr, "Out of memory: Can't alocate group header\n");
		exit(-1);
	}
	lseek(fd, off, SEEK_SET);
	if (read (fd, group_desc_block, sizeof(struct ext2_group_desc) * groups) != sizeof(struct ext2_group_desc) * groups) {
		fprintf(stderr, "Can't read group header\n");
		exit(-1);
	}
	return (1);
}