erik/openDecal
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fix DecalDat to work with real AC DAT files

Browse source 
The DAT file reader had several bugs inherited from the old C++ reference
code, which targeted an older format version. Verified and fixed against
real client_portal.dat and client_cell_1.dat files:

- Fix header offset: BTree root is at 0x160, not 0x148 (file size field)
- Fix BTree entry size: 24 bytes (flags+id+offset+size+timestamp), not 12
- Fix sector-chain node reading: BTree nodes span multiple sectors via
  linked-list headers; must assemble node data across sector boundaries
- Fix DatStreamImpl.Read() BSTR handling: use Buffer.BlockCopy to match
  C++ SysAllocStringByteLen instead of Marshal.PtrToStringAnsi
- Fix DatStreamImpl.ReadBinary() pointer lifetime: inline fixed block to
  keep destination buffer pinned during Marshal.Copy
- Document LoadFilters() dependency on parameterized COM properties in
  IDecalCore.Configuration that need IDispatch to call correctly

Add smoke test project (13/13 tests pass against real DAT files).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
erik 2026-02-08 23:12:04 +01:00
parent c0d1135431
commit f0b6fedc9b
5 changed files with 356 additions and 56 deletions
Download patch file Download diff file Expand all files Collapse all files

33
Managed/Decal.DecalDat/DatStreamImpl.cs
View file

@ -38,8 +38,14 @@ namespace Decal.DecalDat
var buf = new byte[Bytes];
_file.Read(buf, 0, Bytes);
// Copy to unmanaged buffer starting at ref Buffer
Marshal.Copy(buf, 0, GetBufferPtr(ref Buffer), Bytes);
// Pin the destination buffer for the duration of the copy
unsafe
{
fixed (byte* p = &Buffer)
{
Marshal.Copy(buf, 0, new IntPtr(p), Bytes);
}
}
}
public string Read(int Bytes)
@ -49,22 +55,13 @@ namespace Decal.DecalDat
var buf = new byte[Bytes];
int read = _file.Read(buf, 0, Bytes);
// Return as binary BSTR (same as SysAllocStringByteLen in C++)
unsafe
{
fixed (byte* p = buf)
{
return Marshal.PtrToStringAnsi(new IntPtr(p), read);
}
}
}
private static unsafe IntPtr GetBufferPtr(ref byte buffer)
{
fixed (byte* p = &buffer)
{
return new IntPtr(p);
}
// Match C++ SysAllocStringByteLen: pack raw bytes into WCHAR pairs.
// When the CLR marshals this string to BSTR, the raw bytes are preserved
// byte-for-byte (each char = 2 raw bytes, little-endian).
int charCount = (read + 1) / 2;
var chars = new char[charCount];
Buffer.BlockCopy(buf, 0, chars, 0, read);
return new string(chars, 0, charCount);
}
}
}