/// <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());
}
/// <summary>
/// Reads a <see cref="Fat"/> as specified by a <see cref="BootSector"/>.
/// </summary>
/// <param name="bs">the boot sector specifying the <see cref="Fat"/> layout</param>
/// <param name="fatNr">the number of the <see cref="Fat"/> to read</param>
/// <returns>the <see cref="Fat"/> that was read</returns>
/// <exception cref="IOException">IOException on read error</exception>
/// <exception cref="ArgumentException">ArgumentException if fatNr is greater than
/// <see cref="BootSector.GetNrFats"/></exception>
public static Fat Read(BootSector bs, int fatNr)
{
if (fatNr > bs.GetNrFats())
{
throw new ArgumentException(
"boot sector says there are only " + bs.GetNrFats() +
" FATs when reading FAT #" + fatNr);
}
var fatOffset = FatUtils.GetFatOffset(bs, fatNr);
var result = new Fat(bs, fatOffset);
result.Read();
return(result);
}