+ support for su and whoami command (#10)

Author: Vity01

README.md

@@ -37,7 +37,7 @@ There are 3 possible usecases:
 - It's working on both Windows/Linux Hadoop 2.6.0
 
 #### Download
-- [Download binary](https://github.com/avast/hdfs-shell/releases/download/v1.0.5/hdfs-shell-1.0.5.zip)
+- [Download binary](https://github.com/avast/hdfs-shell/releases/download/v1.0.6/hdfs-shell-1.0.6.zip)
 
 #### Configuring launch script(s) for your environment
 HDFS-Shell is a standard Java application. For its launch you need to define 2 things on your classpath:
@@ -70,6 +70,8 @@ Pre-defined launch scripts are located in the zip file. You can modify it locall
 For our purposes we also integrated following commands:
 - ```set showResultCodeON```  and ```set showResultCodeOFF``` - if it's enabled, it will write command result code after its completion
 - ```cd```, ```pwd```
+- ```su <username>``` - ***experimental*** -  changes current active user - it won't probably work on secured HDFS (KERBEROS)
+- ```whoami``` - prints effective username
 - ```edit 'my file'``` - see the config below
 
 

src/main/java/com/avast/server/hdfsshell/commands/ContextCommands.java

@@ -4,6 +4,7 @@
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.security.UserGroupInformation;
 import org.springframework.shell.core.CommandMarker;
 import org.springframework.shell.core.annotation.CliAvailabilityIndicator;
 import org.springframework.shell.core.annotation.CliCommand;
@@ -12,14 +13,15 @@
 import org.springframework.util.StringUtils;
 
 import java.io.IOException;
+import java.util.Arrays;
 
 @SuppressWarnings("SameParameterValue")
 @Component
 public class ContextCommands implements CommandMarker {
 
-    private volatile String currentDir;
-    private volatile Configuration configuration;
-    private volatile String homeDir;
+    private String currentDir;
+    private Configuration configuration;
+    private String homeDir;
 
     private boolean showResultCode = false;
     private boolean failOnError;
@@ -69,6 +71,36 @@ public String cd(@CliOption(key = {""}, help = "cd [<path>]") String newDir) {
         return "";
     }
 
+    @CliCommand(value = "su", help = "Changes current active user [*experimental*]")
+    public synchronized String su(@CliOption(key = {""}, help = "su [<username>]") String newUser) throws IOException {
+        if (StringUtils.isEmpty(newUser)) {
+            return "No username is defined! ";
+        }
+//        else {
+//            newUser = BashUtils.parseArguments(newUser)[0];
+//        }
+        final FileSystem fs = getFileSystem();
+        final Path usersDir = new Path("/user");
+        if (fs.exists(usersDir)) {
+            final String finalNewUser = newUser;
+            final boolean foundUser = Arrays.stream(fs.listStatus(usersDir)).
+                    filter(FileStatus::isDirectory).
+                    anyMatch(fileStatus -> fileStatus.getPath().getName().equals(finalNewUser));
+            if (!foundUser) {
+                return "User " + newUser + " does not exist!";
+            }
+        }
+        System.setProperty("HADOOP_USER_NAME", newUser);
+        UserGroupInformation.loginUserFromSubject(null);
+        currentDir = null;
+        return "";
+    }
+
+    @CliCommand(value = "whoami", help = "Print effective username")
+    public synchronized String whoami() throws IOException {
+        return UserGroupInformation.getCurrentUser().getUserName();
+    }
+
     public synchronized String getCurrentDir() {
         if (currentDir == null) {
             try {

src/main/java/com/avast/server/hdfsshell/commands/EditCommands.java

@@ -44,7 +44,7 @@ public EditCommands(HadoopDfsCommands hadoopDfsCommands, ContextCommands context
 
     @SuppressWarnings("ResultOfMethodCallIgnored")
     @CliCommand(value = "edit", help = "Get file to local file system, edit and put it back to HDFS")
-    public String set(@CliOption(key = {"_raw_"}, help = "File to edit") String path) throws IOException {
+    public String set(@CliOption(key = {""}, help = "File to edit") String path) throws IOException {
         if (StringUtils.isEmpty(path)) {
             return "You have to define path param";
         }
@@ -79,7 +79,7 @@ public String set(@CliOption(key = {"_raw_"}, help = "File to edit") String path
         return "";
     }
 
-    private Path getFilePathForEdit(@CliOption(key = {"_raw_"}, help = "File to edit") String path) {
+    private Path getFilePathForEdit(@CliOption(key = {""}, help = "File to edit") String path) {
         Path p;
         if (!path.startsWith("/")) {
             p = new Path(contextCommands.getCurrentDir(), path);