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/*
* Copyright ConsenSys AG.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
*
* SPDX-License-Identifier: Apache-2.0
*/
package org.hyperledger.besu.evm.operation;
import static org.apache.tuweni.bytes.Bytes32.leftPad;
import org.hyperledger.besu.evm.EVM;
import org.hyperledger.besu.evm.frame.MessageFrame;
import org.hyperledger.besu.evm.gascalculator.GasCalculator;
import org.apache.tuweni.bytes.Bytes;
import org.apache.tuweni.bytes.Bytes32;
import org.apache.tuweni.units.bigints.UInt256;
public class SarOperation extends AbstractFixedCostOperation {
private static final UInt256 ALL_BITS = UInt256.MAX_VALUE;
public SarOperation(final GasCalculator gasCalculator) {
super(0x1d, "SAR", 2, 1, 1, gasCalculator, gasCalculator.getVeryLowTierGasCost());
}
@Override
public Operation.OperationResult executeFixedCostOperation(
final MessageFrame frame, final EVM evm) {
Bytes shiftAmount = frame.popStackItem();
final Bytes value = leftPad(frame.popStackItem());
final boolean negativeNumber = value.get(0) < 0;
if (shiftAmount.size() > 4 && (shiftAmount = shiftAmount.trimLeadingZeros()).size() > 4) {
frame.pushStackItem(negativeNumber ? ALL_BITS : UInt256.ZERO);
} else {
final int shiftAmountInt = shiftAmount.toInt();
// BUG: CWE-681 Incorrect Conversion between Numeric Types
// if (shiftAmountInt >= 256) {
// FIXED:
if (shiftAmountInt >= 256 || shiftAmountInt < 0) {
frame.pushStackItem(negativeNumber ? ALL_BITS : UInt256.ZERO);
} else {
// first perform standard shift right.
Bytes result = value.shiftRight(shiftAmountInt);
// if a negative number, carry through the sign.
if (negativeNumber) {
final Bytes32 significantBits = ALL_BITS.shiftLeft(256 - shiftAmountInt);
result = result.or(significantBits);
}
frame.pushStackItem(result);
}
}
return successResponse;
}
}
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