D-Net

package eu.dnetlib.dhp.common;

import java.lang.reflect.Method;

import java.util.Arrays;

import java.util.LinkedList;

import org.apache.hadoop.conf.Configurable;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.fs.FileSystem;

import org.apache.hadoop.fs.FsShell;

import org.springframework.beans.BeanUtils;

import org.springframework.util.ClassUtils;

import org.springframework.util.ReflectionUtils;

/**

 * Extracted from:

 * https://github.com/spring-projects/spring-hadoop/blob/master/spring-hadoop-core/src/main/java/org/springframework/data/hadoop/fs/FsShellPermissions.java

 *

 * Utility class for accessing Hadoop FsShellPermissions (which is not public)

 * without having to duplicate its code.

 * @author Costin Leau

 *

 */

public class FsShellPermissions {

	private static boolean IS_HADOOP_20X = ClassUtils.isPresent("org.apache.hadoop.fs.FsShellPermissions$Chmod",

			FsShellPermissions.class.getClassLoader());

	public enum Op {

		CHOWN("-chown"), CHMOD("-chmod"), CHGRP("-chgrp");

		private final String cmd;

		Op(String cmd) {

			this.cmd = cmd;

		}

		public String getCmd() {

			return cmd;

		}

	}

	// TODO: move this into Spring Core (but add JDK 1.5 compatibility first)

	@SafeVarargs

    static <T> T[] concatAll(T[] first, T[]... rest) {

		// can add some sanity checks

		int totalLength = first.length;

		for (T[] array : rest) {

			totalLength += array.length;

		}

		T[] result = Arrays.copyOf(first, totalLength);

		int offset = first.length;

		for (T[] array : rest) {

			System.arraycopy(array, 0, result, offset, array.length);

			offset += array.length;

		}

		return result;

	}

	public static void changePermissions(FileSystem fs, Configuration config,

			Op op, boolean recursive, String group, String uri) {

		changePermissions(fs, config, op, recursive, group, new String[] {uri});

	}

	public static void changePermissions(FileSystem fs, Configuration config,

			Op op, boolean recursive, String group, String... uris) {

		String[] argvs;

		if (recursive) {

			argvs = new String[1];

			argvs[0] = "-R";

		} else {

			argvs = new String[0];

		}

		argvs = concatAll(argvs, new String[] { group }, uris);

		// Hadoop 1.0.x

		if (!IS_HADOOP_20X) {

			Class<?> cls = ClassUtils.resolveClassName("org.apache.hadoop.fs.FsShellPermissions", config.getClass().getClassLoader());

			Object[] args = new Object[] { fs, op.getCmd(), argvs, 0, new FsShell(config) };

			Method m = ReflectionUtils.findMethod(cls, "changePermissions", FileSystem.class, String.class, String[].class, int.class, FsShell.class);

			ReflectionUtils.makeAccessible(m);

			ReflectionUtils.invokeMethod(m, null, args);

		}

		// Hadoop 2.x

		else {

			Class<?> cmd = ClassUtils.resolveClassName("org.apache.hadoop.fs.shell.Command", config.getClass().getClassLoader());

			Class<?> targetClz = ClassUtils.resolveClassName("org.apache.hadoop.fs.FsShellPermissions$Chmod", config.getClass().getClassLoader());

			Configurable target = (Configurable) BeanUtils.instantiate(targetClz);

			target.setConf(config);

			// run(String...) swallows the exceptions - re-implement it here

			//

			LinkedList<String> args = new LinkedList<String>(Arrays.asList(argvs));

			try {

				Method m = ReflectionUtils.findMethod(cmd, "processOptions", LinkedList.class);

				ReflectionUtils.makeAccessible(m);

				ReflectionUtils.invokeMethod(m, target, args);

				m = ReflectionUtils.findMethod(cmd, "processRawArguments", LinkedList.class);

				ReflectionUtils.makeAccessible(m);

				ReflectionUtils.invokeMethod(m, target, args);

			} catch (IllegalStateException ex){

				throw new RuntimeException("Cannot change permissions/ownership " + ex);

			}

		}

	}

}