| public GetString ( uint offset, uint length ) : string | ||
| offset | uint | The offset. |
| length | uint | The length. |
| return | string | |
/// <summary>
/// Reads the boot sector.
/// </summary>
/// <returns></returns>
protected bool ReadBootSector()
{
valid = false;
if (blockSize != 512) // only going to work with 512 sector sizes (for now)
return false;
BinaryFormat bootSector = new BinaryFormat(partition.ReadBlock(0, 1));
if (bootSector.GetUShort(BootSector.BootSectorSignature) != 0xAA55)
return false;
byte extendedBootSignature = bootSector.GetByte(BootSector.ExtendedBootSignature);
byte extendedBootSignature32 = bootSector.GetByte(BootSector.FAT32_ExtendedBootSignature);
if ((extendedBootSignature != 0x29) && (extendedBootSignature != 0x28) && (extendedBootSignature32 != 0x29))
return false;
volumeLabel = bootSector.GetString(BootSector.VolumeLabel, 8).ToString().TrimEnd();
bytesPerSector = bootSector.GetUShort(BootSector.BytesPerSector);
sectorsPerCluster = bootSector.GetByte(BootSector.SectorsPerCluster);
reservedSectors = bootSector.GetByte(BootSector.ReservedSectors);
nbrFats = bootSector.GetByte(BootSector.FatAllocationTables);
rootEntries = bootSector.GetUShort(BootSector.MaxRootDirEntries);
rootCluster32 = bootSector.GetUInt(BootSector.FAT32_ClusterNumberOfRoot);
uint sectorsPerFat16 = bootSector.GetUShort(BootSector.SectorsPerFAT);
uint sectorsPerFat32 = bootSector.GetUInt(BootSector.FAT32_SectorPerFAT);
uint totalSectors16 = bootSector.GetUShort(BootSector.TotalSectors16);
uint totalSectors32 = bootSector.GetUInt(BootSector.TotalSectors32);
uint sectorsPerFat = (sectorsPerFat16 != 0) ? sectorsPerFat16 : sectorsPerFat32;
uint fatSectors = 0;
try
{
fatSectors = nbrFats * sectorsPerFat;
clusterSizeInBytes = sectorsPerCluster * blockSize;
rootDirSectors = (((rootEntries * 32) + (bytesPerSector - 1)) / bytesPerSector);
firstDataSector = reservedSectors + (nbrFats * sectorsPerFat) + rootDirSectors;
totalSectors = (totalSectors16 != 0) ? totalSectors16 : totalSectors32;
dataSectors = totalSectors - (reservedSectors + (nbrFats * sectorsPerFat) + rootDirSectors);
totalClusters = dataSectors / sectorsPerCluster;
entriesPerSector = (bytesPerSector / 32);
firstRootDirectorySector = reservedSectors + fatSectors;
dataAreaStart = firstRootDirectorySector + rootDirSectors;
}
catch
{
return false;
}
// Some basic checks
if ((nbrFats == 0) || (nbrFats > 2) || (totalSectors == 0) || (sectorsPerFat == 0))
return false;
if (totalClusters < 4085)
fatType = FatType.FAT12;
else if (totalClusters < 65525)
fatType = FatType.FAT16;
else
fatType = FatType.FAT32;
if (fatType == FatType.FAT12)
{
reservedClusterMark = 0xFF0;
endOfClusterMark = 0x0FF8;
badClusterMark = 0x0FF7;
fatMask = 0xFFFFFFFF;
fatEntries = sectorsPerFat * 3 * blockSize / 2;
}
else if (fatType == FatType.FAT16)
{
reservedClusterMark = 0xFFF0;
endOfClusterMark = 0xFFF8;
badClusterMark = 0xFFF7;
fatMask = 0xFFFFFFFF;
fatEntries = sectorsPerFat * blockSize / 2;
}
else
{ // if (type == FatType.FAT32) {
reservedClusterMark = 0xFFF0;
endOfClusterMark = 0x0FFFFFF8;
badClusterMark = 0x0FFFFFF7;
fatMask = 0x0FFFFFFF;
fatEntries = sectorsPerFat * blockSize / 4;
}
// More basic checks
if ((fatType == FatType.FAT32) && (rootCluster32 == 0))
return false;
valid = true;
serialNbr = bootSector.GetBytes(fatType != FatType.FAT32 ? BootSector.IDSerialNumber : BootSector.FAT32_IDSerialNumber, 4);
return true;
}