static int vbr_write(struct exfat_dev* dev)
{
struct exfat_super_block sb;
uint32_t checksum;
le32_t* sector = malloc(get_sector_size());
size_t i;
if (sector == NULL)
{
exfat_error("failed to allocate sector-sized block of memory");
return 1;
}
init_sb(&sb);
if (exfat_write(dev, &sb, sizeof(struct exfat_super_block)) < 0)
{
free(sector);
exfat_error("failed to write super block sector");
return 1;
}
checksum = exfat_vbr_start_checksum(&sb, sizeof(struct exfat_super_block));
memset(sector, 0, get_sector_size());
sector[get_sector_size() / sizeof(sector[0]) - 1] =
cpu_to_le32(0xaa550000);
for (i = 0; i < 8; i++)
{
if (exfat_write(dev, sector, get_sector_size()) < 0)
{
free(sector);
exfat_error("failed to write a sector with boot signature");
return 1;
}
checksum = exfat_vbr_add_checksum(sector, get_sector_size(), checksum);
}
memset(sector, 0, get_sector_size());
for (i = 0; i < 2; i++)
{
if (exfat_write(dev, sector, get_sector_size()) < 0)
{
free(sector);
exfat_error("failed to write an empty sector");
return 1;
}
checksum = exfat_vbr_add_checksum(sector, get_sector_size(), checksum);
}
for (i = 0; i < get_sector_size() / sizeof(sector[0]); i++)
sector[i] = cpu_to_le32(checksum);
if (exfat_write(dev, sector, get_sector_size()) < 0)
{
free(sector);
exfat_error("failed to write checksum sector");
return 1;
}
free(sector);
return 0;
}
static bool verify_vbr_checksum(struct exfat_dev* dev, void* sector,
fbx_off_t sector_size)
{
uint32_t vbr_checksum;
int i;
if (exfat_pread(dev, sector, sector_size, 0) < 0)
{
exfat_error("failed to read boot sector");
return false;
}
vbr_checksum = exfat_vbr_start_checksum(sector, sector_size);
for (i = 1; i < 11; i++)
{
if (exfat_pread(dev, sector, sector_size, i * sector_size) < 0)
{
exfat_error("failed to read VBR sector");
return false;
}
vbr_checksum = exfat_vbr_add_checksum(sector, sector_size,
vbr_checksum);
}
if (exfat_pread(dev, sector, sector_size, i * sector_size) < 0)
{
exfat_error("failed to read VBR checksum sector");
return false;
}
for (i = 0; i < sector_size / sizeof(vbr_checksum); i++)
if (le32_to_cpu(((const le32_t*) sector)[i]) != vbr_checksum)
{
exfat_error("invalid VBR checksum 0x%x (expected 0x%x)",
le32_to_cpu(((const le32_t*) sector)[i]), vbr_checksum);
return false;
}
return true;
}