/// <summary>
/// Loads a DOS MZ executable file from disk.
/// </summary>
/// <param name="fileName">Name of the file to open.</param>
public MZFile(string fileName)
{
if (fileName == null)
{
throw new ArgumentNullException("fileName");
}
using (FileStream stream = new FileStream(fileName,
FileMode.Open, FileAccess.Read, FileShare.Read))
using (BinaryReader reader = new BinaryReader(stream))
{
// Read file header.
header = new MZHeader();
header.Signature = reader.ReadUInt16();
header.LastPageSize = reader.ReadUInt16();
header.PageCount = reader.ReadUInt16();
header.RelocCount = reader.ReadUInt16();
header.HeaderSize = reader.ReadUInt16();
header.MinAlloc = reader.ReadUInt16();
header.MaxAlloc = reader.ReadUInt16();
header.InitialSS = reader.ReadUInt16();
header.InitialSP = reader.ReadUInt16();
header.Checksum = reader.ReadUInt16();
header.InitialIP = reader.ReadUInt16();
header.InitialCS = reader.ReadUInt16();
header.RelocOff = reader.ReadUInt16();
header.Overlay = reader.ReadUInt16();
// Verify signature. Both 'MZ' and 'ZM' are allowed.
if (!(header.Signature == 0x5A4D || header.Signature == 0x4D5A))
{
throw new InvalidDataException("Signature mismatch.");
}
// Calculate the stated size of the executable.
if (header.PageCount <= 0)
{
throw new InvalidDataException("The PageCount field must be positive.");
}
int fileSize = header.PageCount * 512 -
(header.LastPageSize > 0 ? 512 - header.LastPageSize : 0);
// Make sure the stated file size is within the actual file size.
if (fileSize > stream.Length)
{
throw new InvalidDataException("The stated file size is larger than the actual file size.");
}
// Validate the header size.
int headerSize = header.HeaderSize * 16;
if (headerSize < 28 || headerSize > fileSize)
{
throw new InvalidDataException("The stated header size is invalid.");
}
// Make sure the relocation table is within the header.
if (header.RelocOff < 28 ||
header.RelocOff + header.RelocCount * 4 > headerSize)
{
throw new InvalidDataException("The relocation table location is invalid.");
}
// Load relocation table.
relocationTable = new FarPointer[header.RelocCount];
stream.Seek(header.RelocOff, SeekOrigin.Begin);
for (int i = 0; i < header.RelocCount; i++)
{
UInt16 off = reader.ReadUInt16();
UInt16 seg = reader.ReadUInt16();
relocationTable[i] = new FarPointer(seg, off);
}
// Load the whole image into memory.
int imageSize = fileSize - headerSize;
stream.Seek(headerSize, SeekOrigin.Begin);
image = new byte[imageSize];
stream.Read(image, 0, image.Length);
}
}
/// <summary>
/// Loads a DOS MZ executable file from disk.
/// </summary>
/// <param name="fileName">Name of the file to open.</param>
public MZFile(string fileName)
{
if (fileName == null)
throw new ArgumentNullException("fileName");
using (FileStream stream = new FileStream(fileName,
FileMode.Open, FileAccess.Read, FileShare.Read))
using (BinaryReader reader = new BinaryReader(stream))
{
// Read file header.
header = new MZHeader();
header.Signature = reader.ReadUInt16();
header.LastPageSize = reader.ReadUInt16();
header.PageCount = reader.ReadUInt16();
header.RelocCount = reader.ReadUInt16();
header.HeaderSize = reader.ReadUInt16();
header.MinAlloc = reader.ReadUInt16();
header.MaxAlloc = reader.ReadUInt16();
header.InitialSS = reader.ReadUInt16();
header.InitialSP = reader.ReadUInt16();
header.Checksum = reader.ReadUInt16();
header.InitialIP = reader.ReadUInt16();
header.InitialCS = reader.ReadUInt16();
header.RelocOff = reader.ReadUInt16();
header.Overlay = reader.ReadUInt16();
// Verify signature. Both 'MZ' and 'ZM' are allowed.
if (!(header.Signature == 0x5A4D || header.Signature == 0x4D5A))
throw new InvalidDataException("Signature mismatch.");
// Calculate the stated size of the executable.
if (header.PageCount <= 0)
throw new InvalidDataException("The PageCount field must be positive.");
int fileSize = header.PageCount * 512 -
(header.LastPageSize > 0 ? 512 - header.LastPageSize : 0);
// Make sure the stated file size is within the actual file size.
if (fileSize > stream.Length)
throw new InvalidDataException("The stated file size is larger than the actual file size.");
// Validate the header size.
int headerSize = header.HeaderSize * 16;
if (headerSize < 28 || headerSize > fileSize)
throw new InvalidDataException("The stated header size is invalid.");
// Make sure the relocation table is within the header.
if (header.RelocOff < 28 ||
header.RelocOff + header.RelocCount * 4 > headerSize)
{
throw new InvalidDataException("The relocation table location is invalid.");
}
// Load relocation table.
relocationTable = new FarPointer[header.RelocCount];
stream.Seek(header.RelocOff, SeekOrigin.Begin);
for (int i = 0; i < header.RelocCount; i++)
{
UInt16 off = reader.ReadUInt16();
UInt16 seg = reader.ReadUInt16();
relocationTable[i] = new FarPointer(seg, off);
}
// Load the whole image into memory.
int imageSize = fileSize - headerSize;
stream.Seek(headerSize, SeekOrigin.Begin);
image = new byte[imageSize];
stream.Read(image, 0, image.Length);
}
}