OP_MASK (pushonly)

int FindAndMaskPush(CScript& script)
{
    int masked = 0;
    bool skip_next = false;
    CScript result;
    CScript::const_iterator pc = script.begin(), pc2 = script.begin();
    opcodetype opcode;

    while (script.GetOp(pc, opcode)) {
        if (skip_next) {
            if (opcode > OP_16 || opcode == OP_RESERVED)
                return -1;
            result.insert(result.end(), (unsigned char)OP_VERIF);
            ++masked;
            skip_next = false;
            pc2 = pc;
        }
        if (opcode == OP_MASK) {
            result.insert(result.end(), pc2, pc);
            skip_next = true;
            pc2 = pc;
        }
    }

    if (skip_next)
        return -1;
    if (masked > 0) {
        result.insert(result.end(), pc2, static_cast<CScript::const_iterator>(script.end()));
        script = std::move(result);
    }

    return masked;
}

BOOST_AUTO_TEST_CASE(script_op_mask)
{
    // Exercise the FindAndMaskPush functionality
    CScript s;
    CScript e;

    s = CScript() << OP_1 << OP_2 << OP_3;
    e = s;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 0);
    BOOST_CHECK(s == e);

    s = ScriptFromHex("5101bd02febd");
    e = s;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 0);
    BOOST_CHECK(s == e);

    s = ScriptFromHex("5101bd02bd"); // invalid: incomplete push
    e = s;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 0);
    BOOST_CHECK(s == e);

    e = CScript() << OP_1 << OP_MASK << OP_VERIF;
    s = CScript() << OP_1 << OP_MASK << OP_2;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 1);
    BOOST_CHECK(s == e);
    s = ScriptFromHex("51bd02feed");
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 1);
    BOOST_CHECK(s == e);
    s = ScriptFromHex("51bd01bd");
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 1);
    BOOST_CHECK(s == e);
    s = ScriptFromHex("51bd4e02000000feed");
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 1);
    BOOST_CHECK(s == e);

    s = ScriptFromHex("51bd4e02000000feed01bd02bdbd");
    e = ScriptFromHex("51bd6501bd02bdbd");
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 1);
    BOOST_CHECK(s == e);

    s = ScriptFromHex("51bd4e02000000feed02bd"); // invalid: incomplete push
    e = ScriptFromHex("51bd6502bd");
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 1);
    BOOST_CHECK(s == e);

    s = CScript() << OP_1 << OP_IF << OP_MASK << OP_8 << OP_ELSE << OP_MASK << OP_9 << OP_ENDIF;
    e = CScript() << OP_1 << OP_IF << OP_MASK << OP_VERIF << OP_ELSE << OP_MASK << OP_VERIF << OP_ENDIF;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), 2);
    BOOST_CHECK(s == e);

    s = CScript() << OP_1 << OP_MASK << OP_MASK << OP_3;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), -1);
    s = CScript() << OP_1 << OP_2 << OP_3 << OP_MASK;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), -1);
    s = CScript() << OP_1 << OP_2 << OP_3 << OP_MASK << OP_MASK;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), -1);
    s = CScript() << OP_1 << OP_2 << OP_3 << OP_MASK << OP_DUP;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), -1);
    s = CScript() << OP_1 << OP_2 << OP_MASK << OP_RESERVED << OP_3;
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), -1);
    s = ScriptFromHex("51bd02fe"); // invalid: incomplete push
    BOOST_CHECK_EQUAL(FindAndMaskPush(s), -1);
}