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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.hosted.node.admin.task.util.file;
import com.yahoo.vespa.hosted.node.admin.component.TaskContext;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.LinkedList;
import java.util.List;
import java.util.function.Consumer;
import java.util.function.Supplier;
import java.util.logging.Logger;
import static com.yahoo.vespa.hosted.node.admin.task.util.file.IOExceptionUtil.ifExists;
import static com.yahoo.yolean.Exceptions.uncheck;
/**
* An editor meant to edit small line-based files like /etc/fstab.
*
* @author hakonhall
*/
public class Editor {
private static final Logger logger = Logger.getLogger(Editor.class.getName());
private static final Charset ENCODING = StandardCharsets.UTF_8;
private static final int MAX_LENGTH = 500;
private final Supplier<List<String>> supplier;
private final Consumer<List<String>> consumer;
private final String name;
private final LineEditor editor;
private int diffSize = 0;
/**
* Read the file which must be encoded in UTF-8, use the LineEditor to edit it,
* and any modifications were done write it back and return true.
*/
public Editor(Path path, LineEditor editor) {
this(path.toString(),
() -> ifExists(() -> Files.readAllLines(path, ENCODING)).orElseGet(List::of),
(newLines) -> uncheck(() -> Files.write(path, newLines, ENCODING)),
editor);
}
/**
* @param name The name of what is being edited - used in logging
* @param supplier Supplies the editor with a list of lines to edit
* @param consumer Consumes the lines to presist if any changes is detected
* @param editor The line operations to execute on the lines supplied
*/
public Editor(String name,
Supplier<List<String>> supplier,
Consumer<List<String>> consumer,
LineEditor editor) {
this.supplier = supplier;
this.consumer = consumer;
this.name = name;
this.editor = editor;
}
public boolean edit(Consumer<String> logConsumer) {
List<String> lines = supplier.get();
List<String> newLines = new LinkedList<>();
StringBuilder diff = new StringBuilder();
boolean modified = false;
for (String line : lines) {
LineEdit edit = editor.edit(line);
if (!edit.prependLines().isEmpty()) {
modified = true;
maybeAdd(diff, edit.prependLines());
newLines.addAll(edit.prependLines());
}
switch (edit.getType()) {
case REPLACE -> {
modified = true;
maybeRemove(diff, line);
}
case NONE -> newLines.add(line);
default -> throw new IllegalArgumentException("Unknown EditType " + edit.getType());
}
if (!edit.appendLines().isEmpty()) {
modified = true;
maybeAdd(diff, edit.appendLines());
newLines.addAll(edit.appendLines());
}
}
List<String> linesToAppend = editor.onComplete();
if (!linesToAppend.isEmpty()) {
modified = true;
newLines.addAll(linesToAppend);
maybeAdd(diff, linesToAppend);
}
if (!modified) {
return false;
}
String diffDescription = diffTooLarge() ? ": Diff too large (" + diffSize + ")" : ":\n" + diff;
logConsumer.accept("Patching file " + name + diffDescription);
consumer.accept(newLines);
return true;
}
public boolean converge(TaskContext context) {
return this.edit(line -> context.recordSystemModification(logger, line));
}
private void maybeAdd(StringBuilder diff, List<String> lines) {
for (String line : lines) {
// 2 for '+' and '\n'
diffSize += 2 + line.length();
if (!diffTooLarge()) {
diff.append('+').append(line).append('\n');
}
}
}
private void maybeRemove(StringBuilder diff, String line) {
// 2 for '-' and '\n'
diffSize += 2 + line.length();
if (!diffTooLarge()) {
diff.append('-').append(line).append('\n');
}
}
private boolean diffTooLarge() {
return diffSize > MAX_LENGTH;
}
}
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