PBYTE CDetourDis::CopyBytes()

in src/disasm.cpp [361:440]

• 70 lines of code
• 19 McCabe index (conditional complexity)

PBYTE CDetourDis::CopyBytes(REFCOPYENTRY pEntry, PBYTE pbDst, PBYTE pbSrc)
{
    UINT nBytesFixed;

    if (m_bVex || m_bEvex)
    {
        ASSERT(pEntry->nFlagBits == 0);
        ASSERT(pEntry->nFixedSize == pEntry->nFixedSize16);
    }

    UINT const nModOffset = pEntry->nModOffset;
    UINT const nFlagBits = pEntry->nFlagBits;
    UINT const nFixedSize = pEntry->nFixedSize;
    UINT const nFixedSize16 = pEntry->nFixedSize16;

    if (nFlagBits & ADDRESS) {
        nBytesFixed = m_bAddressOverride ? nFixedSize16 : nFixedSize;
    }
#ifdef DETOURS_X64
    // REX.W trumps 66
    else if (m_bRaxOverride) {
        nBytesFixed = nFixedSize + ((nFlagBits & RAX) ? 4 : 0);
    }
#endif
    else {
        nBytesFixed = m_bOperandOverride ? nFixedSize16 : nFixedSize;
    }

    UINT nBytes = nBytesFixed;
    UINT nRelOffset = pEntry->nRelOffset;
    UINT cbTarget = nBytes - nRelOffset;
    if (nModOffset > 0) {
        ASSERT(nRelOffset == 0);
        BYTE const bModRm = pbSrc[nModOffset];
        BYTE const bFlags = s_rbModRm[bModRm];

        nBytes += bFlags & NOTSIB;

        if (bFlags & SIB) {
            BYTE const bSib = pbSrc[nModOffset + 1];

            if ((bSib & 0x07) == 0x05) {
                if ((bModRm & 0xc0) == 0x00) {
                    nBytes += 4;
                }
                else if ((bModRm & 0xc0) == 0x40) {
                    nBytes += 1;
                }
                else if ((bModRm & 0xc0) == 0x80) {
                    nBytes += 4;
                }
            }
            cbTarget = nBytes - nRelOffset;
        }
#ifdef DETOURS_X64
        else if (bFlags & RIP) {
            nRelOffset = nModOffset + 1;
            cbTarget = 4;
        }
#endif
    }
    CopyMemory(pbDst, pbSrc, nBytes);

    if (nRelOffset) {
        *m_ppbTarget = AdjustTarget(pbDst, pbSrc, nBytes, nRelOffset, cbTarget);
#ifdef DETOURS_X64
        if (pEntry->nRelOffset == 0) {
            // This is a data target, not a code target, so we shouldn't return it.
            *m_ppbTarget = NULL;
        }
#endif
    }
    if (nFlagBits & NOENLARGE) {
        *m_plExtra = -*m_plExtra;
    }
    if (nFlagBits & DYNAMIC) {
        *m_ppbTarget = (PBYTE)DETOUR_INSTRUCTION_TARGET_DYNAMIC;
    }
    return pbSrc + nBytes;
}