/*
fat.c (09.11.10)
File Allocation Table creation code.
Copyright (C) 2009, 2010 Andrew Nayenko
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see .
*/
#include
#include
#include
#include "mkexfat.h"
#include "cbm.h"
#include "uct.h"
#include "rootdir.h"
off_t fat_alignment(void)
{
return (off_t) le32_to_cpu(sb.fat_sector_start) * SECTOR_SIZE(sb);
}
off_t fat_size(void)
{
return (off_t) le32_to_cpu(sb.fat_sector_count) * SECTOR_SIZE(sb);
}
static cluster_t fat_write_entry(cluster_t cluster, cluster_t value, int fd)
{
le32_t fat_entry = cpu_to_le32(value);
if (write(fd, &fat_entry, sizeof(fat_entry)) == -1)
return 0;
return cluster + 1;
}
static cluster_t fat_write_entries(cluster_t cluster, uint64_t length, int fd)
{
cluster_t end = cluster + DIV_ROUND_UP(length, CLUSTER_SIZE(sb));
while (cluster < end - 1)
{
cluster = fat_write_entry(cluster, cluster + 1, fd);
if (cluster == 0)
return 0;
}
return fat_write_entry(cluster, EXFAT_CLUSTER_END, fd);
}
int fat_write(off_t base, int fd)
{
cluster_t c = 0;
if (base != le32_to_cpu(sb.fat_sector_start) * SECTOR_SIZE(sb))
exfat_bug("unexpected FAT location: %"PRIu64" (expected %u)",
base, le32_to_cpu(sb.fat_sector_start) * SECTOR_SIZE(sb));
if (!(c = fat_write_entry(c, 0xfffffff8, fd))) /* media type */
return errno;
if (!(c = fat_write_entry(c, 0xffffffff, fd))) /* some weird constant */
return errno;
if (!(c = fat_write_entries(c, cbm_size(), fd)))
return errno;
if (!(c = fat_write_entries(c, uct_size(), fd)))
return errno;
if (!(c = fat_write_entries(c, rootdir_size(), fd)))
return errno;
return 0;
}