/// <summary>
/// Reads the master boot block.
/// </summary>
/// <returns></returns>
public bool Read()
{
valid = false;
MasterBootBlock mbr = new MasterBootBlock(diskDevice);
if (!mbr.Valid)
return false;
if ((mbr.Partitions[0].PartitionType != PartitionType.GPT) ||
(mbr.Partitions[1].PartitionType != PartitionType.Empty) ||
(mbr.Partitions[2].PartitionType != PartitionType.Empty) ||
(mbr.Partitions[3].PartitionType != PartitionType.Empty) ||
(!mbr.Partitions[0].Bootable) || (mbr.Partitions[0].StartLBA != 1))
return false;
BinaryFormat gpt = new BinaryFormat(diskDevice.ReadBlock(1, 1));
if ((gpt.GetByte(0) != 45) && (gpt.GetByte(1) != 46) && (gpt.GetByte(2) != 49) && (gpt.GetByte(3) != 20) &&
(gpt.GetByte(4) != 50) && (gpt.GetByte(5) != 41) && (gpt.GetByte(6) != 52) && (gpt.GetByte(7) != 54))
return false;
if ((gpt.GetUInt(GPT.Revision) != GPTConstant.SupportedRevision) ||
(gpt.GetUInt(GPT.HeaderSize) != GPTConstant.HeaderSize) ||
(gpt.GetUInt(GPT.Reserved) != 0) ||
(gpt.GetUInt(GPT.PartitionStartingLBA) != 2)
)
return false;
valid = true;
return valid;
}
/// <summary>
/// Gets the size of the file.
/// </summary>
/// <param name="directoryBlock">The directory block.</param>
/// <param name="index">The index.</param>
/// <returns></returns>
public uint GetFileSize(uint directoryBlock, uint index)
{
BinaryFormat directory = new BinaryFormat(partition.ReadBlock(directoryBlock, 1));
return directory.GetUInt((index * Entry.EntrySize) + Entry.FileSize);
}
/// <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;
}
/// <summary>
/// Gets the cluster entry value.
/// </summary>
/// <param name="cluster">The cluster.</param>
/// <returns></returns>
protected uint GetClusterEntryValue(uint cluster)
{
uint fatoffset = 0;
if (fatType == FatType.FAT12)
fatoffset = (cluster + (cluster / 2));
else if (fatType == FatType.FAT16)
fatoffset = cluster * 2;
else //if (type == FatType.FAT32)
fatoffset = cluster * 4;
uint sector = reservedSectors + (fatoffset / bytesPerSector);
uint sectorOffset = fatoffset % bytesPerSector;
uint nbrSectors = 1;
if ((fatType == FatType.FAT12) && (sectorOffset == bytesPerSector - 1))
nbrSectors = 2;
BinaryFormat fat = new BinaryFormat(partition.ReadBlock(sector, nbrSectors));
uint clusterValue;
if (fatType == FatType.FAT12)
{
clusterValue = fat.GetUShort(sectorOffset);
if (cluster % 2 == 1)
clusterValue = clusterValue >> 4;
else
clusterValue = clusterValue & 0x0FFF;
}
else if (fatType == FatType.FAT16)
clusterValue = fat.GetUShort(sectorOffset);
else //if (type == FatType.FAT32)
clusterValue = fat.GetUInt(sectorOffset) & 0x0FFFFFFF;
return clusterValue;
}
public static void PatchSyslinux_3_72(PartitionDevice partitionDevice, FatFileSystem fat)
{
// Locate ldlinux.sys file for patching
string filename = "ldlinux.sys";
string name = (Path.GetFileNameWithoutExtension(filename) + Path.GetExtension(filename).PadRight(4).Substring(0, 4)).ToUpper();
var location = fat.FindEntry(new Mosa.FileSystem.FAT.Find.WithName(name), 0);
if (location.IsValid)
{
// Read boot sector
var bootSector = new BinaryFormat(partitionDevice.ReadBlock(0, 1));
// Set the first sector location of the file
bootSector.SetUInt(0x1F8, fat.GetSectorByCluster(location.FirstCluster));
// Change jump address
bootSector.SetUInt(0x01, 0x58);
// Write back patched boot sector
partitionDevice.WriteBlock(0, 1, bootSector.Data);
// Get the file size & number of sectors used
uint fileSize = fat.GetFileSize(location.DirectorySector, location.DirectorySectorIndex);
uint sectorCount = (fileSize + 511) >> 9;
uint[] sectors = new uint[65];
uint nsec = 0;
// Create list of the first 65 sectors of the file
for (uint cluster = location.FirstCluster; ((cluster != 0) & (nsec <= 64)); cluster = fat.GetNextCluster(cluster))
{
uint sec = fat.GetSectorByCluster(cluster);
for (uint s = 0; s < fat.SectorsPerCluster; s++)
sectors[nsec++] = sec + s;
}
// Read the first cluster of the file
var firstCluster = new BinaryFormat(fat.ReadCluster(location.FirstCluster));
uint patchArea = 0;
// Search for 0x3EB202FE (magic)
for (patchArea = 0; (firstCluster.GetUInt(patchArea) != 0x3EB202FE) && (patchArea < fat.ClusterSizeInBytes); patchArea += 4) ;
patchArea = patchArea + 8;
if (patchArea < fat.ClusterSizeInBytes)
{
// Set up the totals
firstCluster.SetUShort(patchArea, (ushort)(fileSize >> 2));
firstCluster.SetUShort(patchArea + 2, (ushort)(sectorCount - 1));
// Clear sector entries
firstCluster.Fill(patchArea + 8, 0, 64 * 4);
// Set sector entries
for (nsec = 0; nsec < 64; nsec++)
firstCluster.SetUInt(patchArea + 8 + (nsec * 4), sectors[nsec + 1]);
// Clear out checksum
firstCluster.SetUInt(patchArea + 4, 0);
// Write back the updated cluster
fat.WriteCluster(location.FirstCluster, firstCluster.Data);
// Re-Calculate checksum by opening the file
var file = new FatFileStream(fat, location);
uint csum = 0x3EB202FE;
for (uint index = 0; index < (file.Length >> 2); index++)
{
uint value = (uint)file.ReadByte() | ((uint)file.ReadByte() << 8) | ((uint)file.ReadByte() << 16) | ((uint)file.ReadByte() << 24);
csum -= value;
}
// Set the checksum
firstCluster.SetUInt(patchArea + 4, csum);
// Write patched cluster back to disk
fat.WriteCluster(location.FirstCluster, firstCluster.Data);
}
}
}
/// <summary>
/// Opens the specified drive NBR.
/// </summary>
/// <param name="drive">The drive NBR.</param>
/// <returns></returns>
public bool Open(uint drive)
{
if (drive > MaximunDriveCount)
return false;
if (!driveInfo[drive].Present)
return false;
if (drive == 0)
DeviceHeadPort.Write8(0xA0);
else
if (drive == 1)
DeviceHeadPort.Write8(0xB0);
else
return false;
CommandPort.Write8(IDECommands.IdentifyDrive);
if (!WaitForRegisterReady())
return false;
var info = new BinaryFormat(new byte[512]);
for (uint index = 0; index < 256; index++)
info.SetUShort(index * 2, DataPort.Read16());
driveInfo[drive].MaxLBA = info.GetUInt(IdentifyDrive.MaxLBA28);
return true;
}
/// <summary>
/// Reads the master boot block.
/// </summary>
/// <returns></returns>
public bool Read()
{
valid = false;
if (diskDevice.BlockSize != 512) return false; // only going to work with 512 sector sizes
if (diskDevice.TotalBlocks < 3) return false;
BinaryFormat masterboot = new BinaryFormat(diskDevice.ReadBlock(0, 1));
if (masterboot.GetUShort(MBR.MBRSignature) != MBRConstant.MBRSignature)
return false;
valid = true;
diskSignature = masterboot.GetUInt(MBR.DiskSignature);
for (uint index = 0; index < MaxMBRPartitions; index++) {
uint offset = MBR.FirstPartition + (index * MBRConstant.PartitionSize);
GenericPartition partition = new GenericPartition(index);
partition.Bootable = masterboot.GetByte(offset + PartitionRecord.Status) == MBRConstant.Bootable;
partition.PartitionType = masterboot.GetByte(offset + PartitionRecord.PartitionType);
partition.StartLBA = masterboot.GetUInt(offset + PartitionRecord.LBA);
partition.TotalBlocks = masterboot.GetUInt(offset + PartitionRecord.Sectors);
Partitions[index] = partition;
}
//TODO: Extended Partitions
code = new byte[MBRConstant.CodeAreaSize];
for (uint index = 0; index < MBRConstant.CodeAreaSize; index++)
code[index] = masterboot.GetByte(index);
return valid;
}
