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StaticFinalBufferCheck.java
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StaticFinalBufferCheck.java
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/*
* Copyright 2021 The Netty Project
*
* The Netty Project licenses this file to you 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.
*/
package io.netty.build.checkstyle;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.FileContents;
import com.puppycrawl.tools.checkstyle.api.FullIdent;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import java.util.regex.Pattern;
/**
* This check verifies that static final buffers are unreleasable and read-only.
*
* It aims to prevent corruption bugs like khttps://github.com/netty/netty/issues/11792
* from happening in the future.
*/
public class StaticFinalBufferCheck extends AbstractCheck {
// Pattern is single line because variable definition is flattened and trimmed before the match.
private static final Pattern pattern = Pattern.compile(
"(Unpooled\\s*\\.)?unreleasableBuffer\\(.*?\\)\\s*\\.asReadOnly\\(\\)");
@Override
public int[] getRequiredTokens() {
return new int[]{TokenTypes.VARIABLE_DEF};
}
@Override
public int[] getDefaultTokens() {
return getRequiredTokens();
}
@Override
public int[] getAcceptableTokens() {
return getRequiredTokens();
}
@Override
public void visitToken(DetailAST ast) {
DetailAST modifiersAST = ast.findFirstToken(TokenTypes.MODIFIERS);
boolean isStatic = modifiersAST.findFirstToken(TokenTypes.LITERAL_STATIC) != null;
boolean isFinal = modifiersAST.findFirstToken(TokenTypes.FINAL) != null;
FullIdent typeIdent = FullIdent.createFullIdentBelow(ast.findFirstToken(TokenTypes.TYPE));
if (!isStatic || !isFinal || !typeIdent.getText().endsWith("Buf")) {
return;
}
DetailAST assignAST = ast.findFirstToken(TokenTypes.ASSIGN);
DetailAST semiAST = ast.findFirstToken(TokenTypes.SEMI);
if (assignAST == null || semiAST == null) {
log(ast.getLineNo(), "Missing assignment for static final buffer");
return;
}
FileContents fc = getFileContents();
StringBuilder sb = new StringBuilder();
for (int i = assignAST.getLineNo(); i <= semiAST.getLineNo(); i++) {
// getLineNo returns 1-based line number, getLine expects 0-based.
sb.append(fc.getLine(i - 1).trim());
}
if (!pattern.matcher(sb.toString()).find()) {
log(ast.getLineNo(), "static final buffer assignment should match pattern " + pattern);
}
}
}