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/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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 org.apache.hadoop.util;
import java.io.File;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.FsPermission;
/**
* Class that provides utility functions for checking disk problem
*/
@InterfaceAudience.Private
@InterfaceStability.Unstable
public class DiskChecker {
public static class DiskErrorException extends IOException {
public DiskErrorException(String msg) {
super(msg);
}
public DiskErrorException(String msg, Throwable cause) {
super(msg, cause);
}
}
public static class DiskOutOfSpaceException extends IOException {
public DiskOutOfSpaceException(String msg) {
super(msg);
}
}
/**
* The semantics of mkdirsWithExistsCheck method is different from the mkdirs
* method provided in the Sun's java.io.File class in the following way:
* While creating the non-existent parent directories, this method checks for
* the existence of those directories if the mkdir fails at any point (since
* that directory might have just been created by some other process).
* If both mkdir() and the exists() check fails for any seemingly
* non-existent directory, then we signal an error; Sun's mkdir would signal
* an error (return false) if a directory it is attempting to create already
* exists or the mkdir fails.
* @param dir
* @return true on success, false on failure
*/
public static boolean mkdirsWithExistsCheck(File dir) {
if (dir.mkdir() || dir.exists()) {
return true;
}
File canonDir = null;
try {
canonDir = dir.getCanonicalFile();
} catch (IOException e) {
return false;
}
String parent = canonDir.getParent();
return (parent != null) &&
(mkdirsWithExistsCheck(new File(parent)) &&
(canonDir.mkdir() || canonDir.exists()));
}
/**
* Recurse down a directory tree, checking all child directories.
* @param dir
* @throws DiskErrorException
*/
public static void checkDirs(File dir) throws DiskErrorException {
checkDir(dir);
for (File child : dir.listFiles()) {
if (child.isDirectory()) {
checkDirs(child);
}
}
}
/**
* Create the directory if it doesn't exist and check that dir is readable,
* writable and executable
*
* @param dir
* @throws DiskErrorException
*/
public static void checkDir(File dir) throws DiskErrorException {
if (!mkdirsWithExistsCheck(dir)) {
throw new DiskErrorException("Cannot create directory: "
+ dir.toString());
}
checkDirAccess(dir);
}
/**
* Create the directory or check permissions if it already exists.
*
* The semantics of mkdirsWithExistsAndPermissionCheck method is different
* from the mkdirs method provided in the Sun's java.io.File class in the
* following way:
* While creating the non-existent parent directories, this method checks for
* the existence of those directories if the mkdir fails at any point (since
* that directory might have just been created by some other process).
* If both mkdir() and the exists() check fails for any seemingly
* non-existent directory, then we signal an error; Sun's mkdir would signal
* an error (return false) if a directory it is attempting to create already
* exists or the mkdir fails.
*
* @param localFS local filesystem
* @param dir directory to be created or checked
* @param expected expected permission
* @throws IOException
*/
public static void mkdirsWithExistsAndPermissionCheck(
LocalFileSystem localFS, Path dir, FsPermission expected)
throws IOException {
File directory = localFS.pathToFile(dir);
boolean created = false;
if (!directory.exists())
created = mkdirsWithExistsCheck(directory);
if (created || !localFS.getFileStatus(dir).getPermission().equals(expected))
localFS.setPermission(dir, expected);
}
/**
* Create the local directory if necessary, check permissions and also ensure
* it can be read from and written into.
*
* @param localFS local filesystem
* @param dir directory
* @param expected permission
* @throws DiskErrorException
* @throws IOException
*/
public static void checkDir(LocalFileSystem localFS, Path dir,
FsPermission expected)
throws DiskErrorException, IOException {
mkdirsWithExistsAndPermissionCheck(localFS, dir, expected);
checkDirAccess(localFS.pathToFile(dir));
}
/**
* Checks that the given file is a directory and that the current running
* process can read, write, and execute it.
*
* @param dir File to check
* @throws DiskErrorException if dir is not a directory, not readable, not
* writable, or not executable
*/
private static void checkDirAccess(File dir) throws DiskErrorException {
if (!dir.isDirectory()) {
throw new DiskErrorException("Not a directory: "
+ dir.toString());
}
checkAccessByFileMethods(dir);
}
/**
* Checks that the current running process can read, write, and execute the
* given directory by using methods of the File object.
*
* @param dir File to check
* @throws DiskErrorException if dir is not readable, not writable, or not
* executable
*/
private static void checkAccessByFileMethods(File dir)
throws DiskErrorException {
if (!FileUtil.canRead(dir)) {
throw new DiskErrorException("Directory is not readable: "
+ dir.toString());
}
if (!FileUtil.canWrite(dir)) {
throw new DiskErrorException("Directory is not writable: "
+ dir.toString());
}
if (!FileUtil.canExecute(dir)) {
throw new DiskErrorException("Directory is not executable: "
+ dir.toString());
}
}
}
