DCDv1 unpack

temp.c

#include <Windows.h>
#include <msdelta.h>

#pragma comment(lib, "msdelta.lib")

BOOL load_file(LPCTSTR FileName, LPDWORD BytesRead, LPVOID *AllocatedBuffer)
{
	HANDLE			f;
	LARGE_INTEGER	fsz;
	LPVOID			buffer = NULL;
	BOOL			result = FALSE;

	f = CreateFile(FileName, GENERIC_READ | SYNCHRONIZE,
		FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);

	while (f != INVALID_HANDLE_VALUE) {
		fsz.QuadPart = 0;
		if (!GetFileSizeEx(f, &fsz))
			break;

		if (fsz.QuadPart > 2147483648ll)
			break;

		buffer = VirtualAlloc(NULL, fsz.LowPart,
			MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
		if (buffer == NULL)
			break;

		if (!ReadFile(f, buffer, fsz.LowPart, BytesRead, NULL))
		{
			VirtualFree(buffer, 0, MEM_RELEASE);
			buffer = NULL;
			break;
		}

		result = TRUE;
		break;
	}

	if (f != INVALID_HANDLE_VALUE)
		CloseHandle(f);

	*AllocatedBuffer = buffer;
	return result;
}

BOOL save_file(LPCTSTR FileName, DWORD FileSize, LPVOID Buffer)
{
	HANDLE			f;
	DWORD			bytesIO;
	BOOL			result = FALSE;

	f = CreateFile(FileName, GENERIC_WRITE | SYNCHRONIZE,
		FILE_SHARE_READ, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

	if (f != INVALID_HANDLE_VALUE)
	{
		result = WriteFile(f, Buffer, FileSize, &bytesIO, NULL);
		CloseHandle(f);
	}

	return result;
}

void main()
{
	DELTA_HEADER_INFO   dhi;
	unsigned char		*bsrc = NULL, *bdelta = NULL;
	DWORD				filesize_src = 0, filesize_delta = 0;
	DELTA_INPUT			isrc, idelta, ioutput;
	BOOL				result;

	load_file(
		TEXT("C:\\TEMP\\PA30\\format.com.src"),
		&filesize_src,
		&bsrc);

	load_file(
		TEXT("C:\\TEMP\\PA30\\format.com.delta"),
		&filesize_delta,
		&bdelta);

	isrc.Editable = TRUE;
	isrc.lpStart = bsrc;
	isrc.uSize = filesize_src;

	idelta.Editable = FALSE;
	idelta.lpStart = bdelta+0x0c;
	idelta.uSize = filesize_delta-0x0c;

	result = GetDeltaInfoB(idelta, &dhi);

	result = ApplyDeltaB(DELTA_DEFAULT_FLAGS_RAW, isrc, idelta, &ioutput);
	
	save_file(TEXT("C:\\TEMP\\PA30\\format.com.target"), ioutput.uSize, ioutput.lpcStart);

	ExitProcess(0);
}