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/*
* Copyright (C) 2015 The Android Open Source Project
*
* 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.
*/
package libcore.tzdata.update;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.zip.CRC32;
/**
* Utility methods for files operations.
*/
public final class FileUtils {
private FileUtils() {
}
/**
* Creates a new {@link java.io.File} from the {@code parentDir} and {@code name}, but only if
* the resulting file would exist beneath {@code parentDir}. Useful if {@code name} could
* contain "/../" or symlinks. The returned object has a canonicalized path.
*
* @throws java.io.IOException if the file would not exist beneath {@code parentDir}
*/
public static File createSubFile(File parentDir, String name) throws IOException {
// The subFile must exist beneath parentDir. If name contains "/../" this may not be the
// case so we check.
File subFile = new File(parentDir, name).getCanonicalFile();
if (!subFile.getPath().startsWith(parentDir.getCanonicalPath())) {
throw new IOException(name + " must exist beneath " + parentDir +
". Canonicalized subpath: " + subFile);
}
return subFile;
}
/**
* Makes sure a directory exists. If it doesn't exist, it is created. Parent directories are
* also created as needed. If {@code makeWorldReadable} is {@code true} the directory's default
* permissions will be set. Even when {@code makeWorldReadable} is {@code true}, only
* directories explicitly created will have their permissions set; existing directories are
* untouched.
*
* @throws IOException if the directory or one of its parents did not already exist and could
* not be created
*/
public static void ensureDirectoriesExist(File dir, boolean makeWorldReadable)
throws IOException {
LinkedList<File> dirs = new LinkedList<>();
File currentDir = dir;
do {
dirs.addFirst(currentDir);
currentDir = currentDir.getParentFile();
} while (currentDir != null);
for (File dirToCheck : dirs) {
if (!dirToCheck.exists()) {
if (!dirToCheck.mkdir()) {
throw new IOException("Unable to create directory: " + dir);
}
if (makeWorldReadable) {
makeDirectoryWorldAccessible(dirToCheck);
}
} else if (!dirToCheck.isDirectory()) {
throw new IOException(dirToCheck + " exists but is not a directory");
}
}
}
public static void makeDirectoryWorldAccessible(File directory) throws IOException {
if (!directory.isDirectory()) {
throw new IOException(directory + " must be a directory");
}
makeWorldReadable(directory);
if (!directory.setExecutable(true, false /* ownerOnly */)) {
throw new IOException("Unable to make " + directory + " world-executable");
}
}
public static void makeWorldReadable(File file) throws IOException {
if (!file.setReadable(true, false /* ownerOnly */)) {
throw new IOException("Unable to make " + file + " world-readable");
}
}
/**
* Calculates the checksum from the contents of a file.
*/
public static long calculateChecksum(File file) throws IOException {
final int BUFFER_SIZE = 8196;
CRC32 crc32 = new CRC32();
try (FileInputStream fis = new FileInputStream(file)) {
byte[] buffer = new byte[BUFFER_SIZE];
int count;
while ((count = fis.read(buffer)) != -1) {
crc32.update(buffer, 0, count);
}
}
return crc32.getValue();
}
public static void rename(File from, File to) throws IOException {
ensureFileDoesNotExist(to);
if (!from.renameTo(to)) {
throw new IOException("Unable to rename " + from + " to " + to);
}
}
public static void ensureFileDoesNotExist(File file) throws IOException {
if (file.exists()) {
if (!file.isFile()) {
throw new IOException(file + " is not a file");
}
doDelete(file);
}
}
public static void doDelete(File file) throws IOException {
if (!file.delete()) {
throw new IOException("Unable to delete: " + file);
}
}
public static boolean isSymlink(File file) throws IOException {
String baseName = file.getName();
String canonicalPathExceptBaseName =
new File(file.getParentFile().getCanonicalFile(), baseName).getPath();
return !file.getCanonicalPath().equals(canonicalPathExceptBaseName);
}
public static void deleteRecursive(File toDelete) throws IOException {
if (toDelete.isDirectory()) {
for (File file : toDelete.listFiles()) {
if (file.isDirectory() && !FileUtils.isSymlink(file)) {
// The isSymlink() check is important so that we don't delete files in other
// directories: only the symlink itself.
deleteRecursive(file);
} else {
// Delete symlinks to directories or files.
FileUtils.doDelete(file);
}
}
String[] remainingFiles = toDelete.list();
if (remainingFiles.length != 0) {
throw new IOException("Unable to delete files: " + Arrays
.toString(remainingFiles));
}
}
FileUtils.doDelete(toDelete);
}
public static boolean filesExist(File rootDir, String... fileNames) throws IOException {
for (String fileName : fileNames) {
File file = new File(rootDir, fileName);
if (!file.exists()) {
return false;
}
}
return true;
}
/**
* Read all lines from a UTF-8 encoded file, returning them as a list of strings.
*/
public static List<String> readLines(File file) throws IOException {
FileInputStream in = new FileInputStream(file);
try (BufferedReader fileReader = new BufferedReader(
new InputStreamReader(in, StandardCharsets.UTF_8));
) {
List<String> lines = new ArrayList<>();
String line;
while ((line = fileReader.readLine()) != null) {
lines.add(line);
}
return lines;
}
}
}
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