Function ExecuteWitnessScript

src/script/interpreter.cpp:1842–1880

template class GenericTransactionSignatureChecker<CMutableTransaction>;

static bool ExecuteWitnessScript(const std::span<const valtype>& stack_span, const CScript& exec_script, script_verify_flags flags, SigVersion sigversion, const BaseSignatureChecker& checker, ScriptExecutionData& execdata, ScriptError* serror)
{
    std::vector<valtype> stack{stack_span.begin(), stack_span.end()};

    if (sigversion == SigVersion::TAPSCRIPT) {
        // OP_SUCCESSx processing overrides everything, including stack element size limits
        CScript::const_iterator pc = exec_script.begin();
        while (pc < exec_script.end()) {
            opcodetype opcode;
            if (!exec_script.GetOp(pc, opcode)) {
                // Note how this condition would not be reached if an unknown OP_SUCCESSx was found
                return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
            }
            // New opcodes will be listed here. May use a different sigversion to modify existing opcodes.
            if (IsOpSuccess(opcode)) {
                if (flags & SCRIPT_VERIFY_DISCOURAGE_OP_SUCCESS) {
                    return set_error(serror, SCRIPT_ERR_DISCOURAGE_OP_SUCCESS);
                }
                return set_success(serror);
            }
        }

        // Tapscript enforces initial stack size limits (altstack is empty here)
        if (stack.size() > MAX_STACK_SIZE) return set_error(serror, SCRIPT_ERR_STACK_SIZE);
    }

    // Disallow stack item size > MAX_SCRIPT_ELEMENT_SIZE in witness stack
    for (const valtype& elem : stack) {
        if (elem.size() > MAX_SCRIPT_ELEMENT_SIZE) return set_error(serror, SCRIPT_ERR_PUSH_SIZE);
    }

    // Run the script interpreter.
    if (!EvalScript(stack, exec_script, flags, checker, sigversion, execdata, serror)) return false;

    // Scripts inside witness implicitly require cleanstack behaviour
    if (stack.size() != 1) return set_error(serror, SCRIPT_ERR_CLEANSTACK);
    if (!CastToBool(stack.back())) return set_error(serror, SCRIPT_ERR_EVAL_FALSE);
    return true;
}

uint256 ComputeTapleafHash(uint8_t leaf_version, std::span<const unsigned char> script)
{