public FileAllocationTable(FatType type, Stream stream, ushort firstFatSector, uint fatSize, byte numFats, byte activeFat)
{
_stream = stream;
_firstFatSector = firstFatSector;
_numFats = numFats;
_stream.Position = (firstFatSector + (fatSize * activeFat)) * Utilities.SectorSize;
_buffer = new FatBuffer(type, Utilities.ReadFully(_stream, (int)(fatSize * Utilities.SectorSize)));
}
/// <summary>
/// Creates a formatted hard disk partition in a stream.
/// </summary>
/// <param name="stream">The stream to write the new file system to</param>
/// <param name="label">The volume label for the partition (or null)</param>
/// <param name="diskGeometry">The geometry of the disk containing the partition</param>
/// <param name="firstSector">The starting sector number of this partition (hide's sectors in other partitions)</param>
/// <param name="sectorCount">The number of sectors in this partition</param>
/// <param name="reservedSectors">The number of reserved sectors at the start of the partition</param>
/// <returns>An object that provides access to the newly created partition file system</returns>
public static FatFileSystem FormatPartition(
Stream stream,
string label,
Geometry diskGeometry,
int firstSector,
int sectorCount,
short reservedSectors)
{
long pos = stream.Position;
long ticks = DateTime.UtcNow.Ticks;
uint volId = (uint)((ticks & 0xFFFF) | (ticks >> 32));
byte sectorsPerCluster;
FatType fatType;
ushort maxRootEntries;
/*
* Write the BIOS Parameter Block (BPB) - a single sector
*/
byte[] bpb = new byte[512];
if (sectorCount <= 8400)
{
throw new ArgumentException("Requested size is too small for a partition");
}
else if (sectorCount < 1024 * 1024)
{
fatType = FatType.Fat16;
maxRootEntries = 512;
if (sectorCount <= 32680)
{
sectorsPerCluster = 2;
}
else if (sectorCount <= 262144)
{
sectorsPerCluster = 4;
}
else if (sectorCount <= 524288)
{
sectorsPerCluster = 8;
}
else
{
sectorsPerCluster = 16;
}
if (reservedSectors < 1)
{
reservedSectors = 1;
}
}
else
{
fatType = FatType.Fat32;
maxRootEntries = 0;
if (sectorCount <= 532480)
{
sectorsPerCluster = 1;
}
else if (sectorCount <= 16777216)
{
sectorsPerCluster = 8;
}
else if (sectorCount <= 33554432)
{
sectorsPerCluster = 16;
}
else if (sectorCount <= 67108864)
{
sectorsPerCluster = 32;
}
else
{
sectorsPerCluster = 64;
}
if (reservedSectors < 32)
{
reservedSectors = 32;
}
}
WriteBPB(bpb, (uint)sectorCount, fatType, maxRootEntries, (uint)firstSector, (ushort)reservedSectors, sectorsPerCluster, diskGeometry, false, volId, label);
stream.Write(bpb, 0, bpb.Length);
/*
* Skip the reserved sectors
*/
stream.Position = pos + (((ushort)reservedSectors) * Utilities.SectorSize);
/*
* Write both FAT copies
*/
byte[] fat = new byte[CalcFatSize((uint)sectorCount, fatType, sectorsPerCluster) * Utilities.SectorSize];
FatBuffer fatBuffer = new FatBuffer(fatType, fat);
fatBuffer.SetNext(0, 0xFFFFFFF8);
fatBuffer.SetEndOfChain(1);
if (fatType >= FatType.Fat32)
{
// Mark cluster 2 as End-of-chain (i.e. root directory
// is a single cluster in length)
fatBuffer.SetEndOfChain(2);
}
stream.Write(fat, 0, fat.Length);
stream.Write(fat, 0, fat.Length);
/*
* Write the (empty) root directory
*/
uint rootDirSectors;
if (fatType < FatType.Fat32)
{
rootDirSectors = (uint)(((maxRootEntries * 32) + Utilities.SectorSize - 1) / Utilities.SectorSize);
}
else
{
rootDirSectors = sectorsPerCluster;
}
byte[] rootDir = new byte[rootDirSectors * Utilities.SectorSize];
stream.Write(rootDir, 0, rootDir.Length);
/*
* Make sure the stream is at least as large as the partition requires.
*/
if (stream.Length < pos + (sectorCount * Utilities.SectorSize))
{
stream.SetLength(pos + (sectorCount * Utilities.SectorSize));
}
/*
* Give the caller access to the new file system
*/
stream.Position = pos;
return new FatFileSystem(stream);
}
/// <summary>
/// Creates a formatted floppy disk image in a stream.
/// </summary>
/// <param name="stream">The stream to write the blank image to</param>
/// <param name="type">The type of floppy to create</param>
/// <param name="label">The volume label for the floppy (or null)</param>
/// <returns>An object that provides access to the newly created floppy disk image</returns>
public static FatFileSystem FormatFloppy(Stream stream, FloppyDiskType type, string label)
{
long pos = stream.Position;
long ticks = DateTime.UtcNow.Ticks;
uint volId = (uint)((ticks & 0xFFFF) | (ticks >> 32));
// Write the BIOS Parameter Block (BPB) - a single sector
byte[] bpb = new byte[512];
uint sectors;
if (type == FloppyDiskType.DoubleDensity)
{
sectors = 1440;
WriteBPB(bpb, sectors, FatType.Fat12, 224, 0, 1, 1, new Geometry(80, 2, 9), true, volId, label);
}
else if (type == FloppyDiskType.HighDensity)
{
sectors = 2880;
WriteBPB(bpb, sectors, FatType.Fat12, 224, 0, 1, 1, new Geometry(80, 2, 18), true, volId, label);
}
else if (type == FloppyDiskType.Extended)
{
sectors = 5760;
WriteBPB(bpb, sectors, FatType.Fat12, 224, 0, 1, 1, new Geometry(80, 2, 36), true, volId, label);
}
else
{
throw new ArgumentException("Unrecognised Floppy Disk type", "type");
}
stream.Write(bpb, 0, bpb.Length);
// Write both FAT copies
uint fatSize = CalcFatSize(sectors, FatType.Fat12, 1);
byte[] fat = new byte[fatSize * Utilities.SectorSize];
FatBuffer fatBuffer = new FatBuffer(FatType.Fat12, fat);
fatBuffer.SetNext(0, 0xFFFFFFF0);
fatBuffer.SetEndOfChain(1);
stream.Write(fat, 0, fat.Length);
stream.Write(fat, 0, fat.Length);
// Write the (empty) root directory
uint rootDirSectors = ((224 * 32) + Utilities.SectorSize - 1) / Utilities.SectorSize;
byte[] rootDir = new byte[rootDirSectors * Utilities.SectorSize];
stream.Write(rootDir, 0, rootDir.Length);
// Write a single byte at the end of the disk to ensure the stream is at least as big
// as needed for this disk image.
stream.Position = pos + (sectors * Utilities.SectorSize) - 1;
stream.WriteByte(0);
// Give the caller access to the new file system
stream.Position = pos;
return new FatFileSystem(stream);
}