/// <summary>
/// Constructor for FatFileSystem in specified readOnly mode
/// </summary>
/// <param name="device">the <see cref="IBlockDevice"/> holding the file system</param>
/// <param name="readOnly"></param>
/// <param name="ignoreFatDifferences"></param>
/// <exception cref="IOException">IOException on read error</exception>
private FatFileSystem(IBlockDevice device, bool readOnly,
bool ignoreFatDifferences) : base(readOnly)
{
bs = BootSector.Read(device);
if (bs.GetNrFats() <= 0)
{
throw new IOException(
"boot sector says there are no FATs");
}
filesOffset = FatUtils.GetFilesOffset(bs);
fatType = bs.GetFatType();
fat = Fat.Read(bs, 0);
if (!ignoreFatDifferences)
{
for (var i = 1; i < bs.GetNrFats(); i++)
{
var tmpFat = Fat.Read(bs, i);
if (!fat.Equals(tmpFat))
{
throw new IOException("FAT " + i + " differs from FAT 0");
}
}
}
if (fatType == FatType.BaseFat32)
{
var f32Bs = (Fat32BootSector)bs;
var rootDirFile = new ClusterChain(fat,
f32Bs.GetRootDirFirstCluster(), IsReadOnly());
rootDirStore = ClusterChainDirectory.ReadRoot(rootDirFile);
fsiSector = FsInfoSector.Read(f32Bs);
if (fsiSector.GetFreeClusterCount() != fat.GetFreeClusterCount())
{
throw new IOException("free cluster count mismatch - fat: " +
fat.GetFreeClusterCount() + " - fsinfo: " +
fsiSector.GetFreeClusterCount());
}
}
else
{
rootDirStore =
Fat16RootDirectory.Read((Fat16BootSector)bs, readOnly);
fsiSector = null;
}
rootDir = new FatLfnDirectory(rootDirStore, fat, IsReadOnly());
}
public ClusterChain(Fat fat, long startCluster, bool readOnly) : base(readOnly)
{
this.fat = fat;
if (startCluster != 0)
{
this.fat.TestCluster(startCluster);
if (this.fat.IsFreeCluster(startCluster))
{
throw new ArgumentException(
"cluster " + startCluster + " is free");
}
}
device = fat.GetDevice();
dataOffset = FatUtils.GetFilesOffset(fat.GetBootSector());
this.startCluster = startCluster;
clusterSize = fat.GetBootSector().GetBytesPerCluster();
}
/**
* Returns the size of the data-containing portion of the file system.
*
* @return the number of bytes usable for storing user data
*/
private long GetDataSize()
{
return((GetSectorCount() * GetBytesPerSector()) -
FatUtils.GetFilesOffset(this));
}
