PBYTE CDetourDis::AdjustTarget()

in src/disasm.cpp [496:574]

• 72 lines of code
• 14 McCabe index (conditional complexity)

PBYTE CDetourDis::AdjustTarget(PBYTE pbDst, PBYTE pbSrc, UINT cbOp,
                               UINT cbTargetOffset, UINT cbTargetSize)
{
    PBYTE pbTarget = NULL;
#if 1 // fault injection to test test code
#if defined(DETOURS_X64)
    typedef LONGLONG T;
#else
    typedef LONG T;
#endif
    T nOldOffset;
    T nNewOffset;
    PVOID pvTargetAddr = &pbDst[cbTargetOffset];

    switch (cbTargetSize) {
      case 1:
        nOldOffset = *(signed char*&)pvTargetAddr;
        break;
      case 2:
        nOldOffset = *(UNALIGNED SHORT*&)pvTargetAddr;
        break;
      case 4:
        nOldOffset = *(UNALIGNED LONG*&)pvTargetAddr;
        break;
#if defined(DETOURS_X64)
      case 8:
        nOldOffset = *(UNALIGNED LONGLONG*&)pvTargetAddr;
        break;
#endif
      default:
        ASSERT(!"cbTargetSize is invalid.");
        nOldOffset = 0;
        break;
    }

    pbTarget = pbSrc + cbOp + nOldOffset;
    nNewOffset = nOldOffset - (T)(pbDst - pbSrc);

    switch (cbTargetSize) {
      case 1:
        *(CHAR*&)pvTargetAddr = (CHAR)nNewOffset;
        if (nNewOffset < SCHAR_MIN || nNewOffset > SCHAR_MAX) {
            *m_plExtra = sizeof(ULONG) - 1;
        }
        break;
      case 2:
        *(UNALIGNED SHORT*&)pvTargetAddr = (SHORT)nNewOffset;
        if (nNewOffset < SHRT_MIN || nNewOffset > SHRT_MAX) {
            *m_plExtra = sizeof(ULONG) - 2;
        }
        break;
      case 4:
        *(UNALIGNED LONG*&)pvTargetAddr = (LONG)nNewOffset;
        if (nNewOffset < LONG_MIN || nNewOffset > LONG_MAX) {
            *m_plExtra = sizeof(ULONG) - 4;
        }
        break;
#if defined(DETOURS_X64)
      case 8:
        *(UNALIGNED LONGLONG*&)pvTargetAddr = nNewOffset;
        break;
#endif
    }
#ifdef DETOURS_X64
    // When we are only computing size, source and dest can be
    // far apart, distance not encodable in 32bits. Ok.
    // At least still check the lower 32bits.

    if (pbDst >= m_rbScratchDst && pbDst < (sizeof(m_rbScratchDst) + m_rbScratchDst)) {
        ASSERT((((size_t)pbDst + cbOp + nNewOffset) & 0xFFFFFFFF) == (((size_t)pbTarget) & 0xFFFFFFFF));
    }
    else
#endif
    {
        ASSERT(pbDst + cbOp + nNewOffset == pbTarget);
    }
#endif
    return pbTarget;
}