/**
* 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.hcatalog.templeton;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.Semaphore;
import org.apache.commons.exec.CommandLine;
import org.apache.commons.exec.DefaultExecutor;
import org.apache.commons.exec.ExecuteException;
import org.apache.commons.exec.ExecuteWatchdog;
import org.apache.commons.exec.PumpStreamHandler;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Execute a local program. This is a singleton service that will
* execute programs as non-privileged users on the local box. See
* ExecService.run and ExecService.runUnlimited for details.
*/
public class ExecServiceImpl implements ExecService {
private static final Log LOG = LogFactory.getLog(ExecServiceImpl.class);
private static AppConfig appConf = Main.getAppConfigInstance();
private static volatile ExecServiceImpl theSingleton;
/**
* Retrieve the singleton.
*/
public static synchronized ExecServiceImpl getInstance() {
if (theSingleton == null) {
theSingleton = new ExecServiceImpl();
}
return theSingleton;
}
private Semaphore avail;
private ExecServiceImpl() {
avail = new Semaphore(appConf.getInt(AppConfig.EXEC_MAX_PROCS_NAME, 16));
}
/**
* Run the program synchronously as the given user. We rate limit
* the number of processes that can simultaneously created for
* this instance.
*
* @param program The program to run
* @param args Arguments to pass to the program
* @param env Any extra environment variables to set
* @return The result of the run.
*/
public ExecBean run(String program, List<String> args,
Map<String, String> env)
throws NotAuthorizedException, BusyException, ExecuteException, IOException {
boolean aquired = false;
try {
aquired = avail.tryAcquire();
if (aquired) {
return runUnlimited(program, args, env);
} else {
throw new BusyException();
}
} finally {
if (aquired) {
avail.release();
}
}
}
/**
* Run the program synchronously as the given user. Warning:
* CommandLine will trim the argument strings.
*
* @param program The program to run.
* @param args Arguments to pass to the program
* @param env Any extra environment variables to set
* @return The result of the run.
*/
public ExecBean runUnlimited(String program, List<String> args,
Map<String, String> env)
throws NotAuthorizedException, ExecuteException, IOException {
try {
return auxRun(program, args, env);
} catch (IOException e) {
File cwd = new java.io.File(".");
if (cwd.canRead() && cwd.canWrite())
throw e;
else
throw new IOException("Invalid permissions on Templeton directory: "
+ cwd.getCanonicalPath());
}
}
private ExecBean auxRun(String program, List<String> args, Map<String, String> env)
throws NotAuthorizedException, ExecuteException, IOException {
DefaultExecutor executor = new DefaultExecutor();
executor.setExitValues(null);
// Setup stdout and stderr
int nbytes = appConf.getInt(AppConfig.EXEC_MAX_BYTES_NAME, -1);
ByteArrayOutputStream outStream = new MaxByteArrayOutputStream(nbytes);
ByteArrayOutputStream errStream = new MaxByteArrayOutputStream(nbytes);
executor.setStreamHandler(new PumpStreamHandler(outStream, errStream));
// Only run for N milliseconds
int timeout = appConf.getInt(AppConfig.EXEC_TIMEOUT_NAME, 0);
ExecuteWatchdog watchdog = new ExecuteWatchdog(timeout);
executor.setWatchdog(watchdog);
CommandLine cmd = makeCommandLine(program, args);
LOG.info("Running: " + cmd);
ExecBean res = new ExecBean();
res.exitcode = executor.execute(cmd, execEnv(env));
String enc = appConf.get(AppConfig.EXEC_ENCODING_NAME);
res.stdout = outStream.toString(enc);
res.stderr = errStream.toString(enc);
return res;
}
private CommandLine makeCommandLine(String program,
List<String> args)
throws NotAuthorizedException, IOException {
String path = validateProgram(program);
CommandLine cmd = new CommandLine(path);
if (args != null)
for (String arg : args)
cmd.addArgument(arg, false);
return cmd;
}
/**
* Build the environment used for all exec calls.
*
* @return The environment variables.
*/
public Map<String, String> execEnv(Map<String, String> env) {
HashMap<String, String> res = new HashMap<String, String>();
for (String key : appConf.getStrings(AppConfig.EXEC_ENVS_NAME)) {
String val = System.getenv(key);
if (val != null) {
res.put(key, val);
}
}
if (env != null)
res.putAll(env);
for (Map.Entry<String, String> envs : res.entrySet()) {
LOG.info("Env " + envs.getKey() + "=" + envs.getValue());
}
return res;
}
/**
* Given a program name, lookup the fully qualified path. Throws
* an exception if the program is missing or not authorized.
*
* @param path The path of the program.
* @return The path of the validated program.
*/
public String validateProgram(String path)
throws NotAuthorizedException, IOException {
File f = new File(path);
if (f.canExecute()) {
return f.getCanonicalPath();
} else {
throw new NotAuthorizedException("Unable to access program: " + path);
}
}
}