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Ported from DependencyTrack/dependency-track#2400 Note: Evaluation of SPDX expressions is not implemented for CEL policies. This will be done separately in DependencyTrack/hyades#872. Co-authored-by: Hendrik Borchardt <[email protected]> Signed-off-by: nscuro <[email protected]>
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src/main/java/org/dependencytrack/parser/spdx/expression/SpdxExpressionParser.java
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/* | ||
* This file is part of Dependency-Track. | ||
* | ||
* 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 | ||
* Copyright (c) Steve Springett. All Rights Reserved. | ||
*/ | ||
package org.dependencytrack.parser.spdx.expression; | ||
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import java.util.ArrayDeque; | ||
import java.util.Iterator; | ||
import java.util.List; | ||
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import org.dependencytrack.parser.spdx.expression.model.SpdxOperator; | ||
import org.dependencytrack.parser.spdx.expression.model.SpdxExpression; | ||
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/** | ||
* This class parses SPDX expressions according to | ||
* https://spdx.github.io/spdx-spec/v2-draft/SPDX-license-expressions/ into a tree of | ||
* SpdxExpressions and SpdxExpressionOperations | ||
* | ||
* @author hborchardt | ||
* @since 4.8.0 | ||
*/ | ||
public class SpdxExpressionParser { | ||
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/** | ||
* Reads in a SPDX expression and returns a parsed tree of SpdxExpressionOperators and license | ||
* ids. | ||
* | ||
* @param spdxExpression | ||
* spdx expression string | ||
* @return parsed SpdxExpression tree, or SpdxExpression.INVALID if an error has occurred during | ||
* parsing | ||
*/ | ||
public SpdxExpression parse(final String spdxExpression) { | ||
// operators are surrounded by spaces or brackets. Let's make our life easier and surround brackets by spaces. | ||
var _spdxExpression = spdxExpression.replace("(", " ( ").replace(")", " ) ").split(" "); | ||
if (_spdxExpression.length == 1) { | ||
return new SpdxExpression(spdxExpression); | ||
} | ||
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// Shunting yard algorithm to convert SPDX expression to reverse polish notation | ||
// specify list of infix operators | ||
List<String> infixOperators = List.of(SpdxOperator.OR.getToken(), SpdxOperator.AND.getToken(), | ||
SpdxOperator.WITH.getToken()); | ||
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ArrayDeque<String> operatorStack = new ArrayDeque<>(); | ||
ArrayDeque<String> outputQueue = new ArrayDeque<>(); | ||
Iterator<String> it = List.of(_spdxExpression).iterator(); | ||
while(it.hasNext()) { | ||
var token = it.next(); | ||
if (token.length() == 0) { | ||
continue; | ||
} | ||
if (infixOperators.contains(token)) { | ||
int opPrecedence = SpdxOperator.valueOf(token).getPrecedence(); | ||
for (String o2; (o2 = operatorStack.peek()) != null && !o2.equals("(") | ||
&& SpdxOperator.valueOf(o2).getPrecedence() > opPrecedence;) { | ||
outputQueue.push(operatorStack.pop()); | ||
} | ||
; | ||
operatorStack.push(token); | ||
} else if (token.equals("(")) { | ||
operatorStack.push(token); | ||
} else if (token.equals(")")) { | ||
for (String o2; (o2 = operatorStack.peek()) == null || !o2.equals("(");) { | ||
if (o2 == null) { | ||
// Mismatched parentheses | ||
return SpdxExpression.INVALID; | ||
} | ||
outputQueue.push(operatorStack.pop()); | ||
} | ||
; | ||
String leftParens = operatorStack.pop(); | ||
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if (!"(".equals(leftParens)) { | ||
// Mismatched parentheses | ||
return SpdxExpression.INVALID; | ||
} | ||
// no function tokens implemented | ||
} else { | ||
outputQueue.push(token); | ||
} | ||
} | ||
for (String o2; (o2 = operatorStack.peek()) != null;) { | ||
if ("(".equals(o2)) { | ||
// Mismatched parentheses | ||
return SpdxExpression.INVALID; | ||
} | ||
outputQueue.push(operatorStack.pop()); | ||
} | ||
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// convert RPN stack into tree | ||
// this is easy because all infix operators have two arguments | ||
ArrayDeque<SpdxExpression> expressions = new ArrayDeque<>(); | ||
SpdxExpression expr = null; | ||
while (!outputQueue.isEmpty()) { | ||
var token = outputQueue.pollLast(); | ||
if (infixOperators.contains(token)) { | ||
var rhs = expressions.pop(); | ||
var lhs = expressions.pop(); | ||
expr = new SpdxExpression(SpdxOperator.valueOf(token), List.of(lhs, rhs)); | ||
} else { | ||
if (token.endsWith("+")) { | ||
// trailing `+` is not a whitespace-delimited operator - process it separately | ||
expr = new SpdxExpression(SpdxOperator.PLUS, | ||
List.of(new SpdxExpression(token.substring(0, token.length() - 1)))); | ||
} else { | ||
expr = new SpdxExpression(token); | ||
} | ||
} | ||
expressions.push(expr); | ||
} | ||
return expr; | ||
} | ||
} |
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src/main/java/org/dependencytrack/parser/spdx/expression/model/SpdxExpression.java
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/* | ||
* This file is part of Dependency-Track. | ||
* | ||
* 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 | ||
* Copyright (c) Steve Springett. All Rights Reserved. | ||
*/ | ||
package org.dependencytrack.parser.spdx.expression.model; | ||
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import java.util.List; | ||
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/** | ||
* A node of an SPDX expression tree. If it is a leaf node, it contains a spdxLicenseId. If it is an | ||
* inner node, containss an operation. | ||
* | ||
* @author hborchardt | ||
* @since 4.8.0 | ||
*/ | ||
public class SpdxExpression { | ||
public static final SpdxExpression INVALID = new SpdxExpression(null); | ||
public SpdxExpression(String spdxLicenseId) { | ||
this.spdxLicenseId = spdxLicenseId; | ||
} | ||
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public SpdxExpression(SpdxOperator operator, List<SpdxExpression> arguments) { | ||
this.operation = new SpdxExpressionOperation(operator, arguments); | ||
} | ||
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private SpdxExpressionOperation operation; | ||
private String spdxLicenseId; | ||
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public SpdxExpressionOperation getOperation() { | ||
return operation; | ||
} | ||
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public void setOperation(SpdxExpressionOperation operation) { | ||
this.operation = operation; | ||
} | ||
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public String getSpdxLicenseId() { | ||
return spdxLicenseId; | ||
} | ||
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public void setSpdxLicenseId(String spdxLicenseId) { | ||
this.spdxLicenseId = spdxLicenseId; | ||
} | ||
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@Override | ||
public String toString() { | ||
if (this == INVALID) { | ||
return "INVALID"; | ||
} | ||
if (spdxLicenseId != null) { | ||
return spdxLicenseId; | ||
} | ||
return operation.toString(); | ||
} | ||
} |
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