HADOOP-9483. winutils support for readlink command. Contributed by Arpit Agarwal.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1478592 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -542,6 +542,9 @@ Trunk (Unreleased)
 
     HADOOP-9043. Disallow in winutils creating symlinks with forwards slashes.
     (Chris Nauroth and Arpit Agarwal via suresh)
+
+    HADOOP-9483. winutils support for readlink command.
+    (Arpit Agarwal via suresh)
     
 Release 2.0.5-beta - UNRELEASED
 

hadoop-common-project/hadoop-common/src/main/winutils/include/winutils.h

@@ -104,6 +104,9 @@ void TaskUsage();
 int Symlink(__in int argc, __in_ecount(argc) wchar_t *argv[]);
 void SymlinkUsage();
 
+int Readlink(__in int argc, __in_ecount(argc) wchar_t *argv[]);
+void ReadlinkUsage();
+
 int SystemInfo();
 void SystemInfoUsage();
 

hadoop-common-project/hadoop-common/src/main/winutils/main.c

@@ -55,6 +55,10 @@ int wmain(__in int argc, __in_ecount(argc) wchar_t* argv[])
   {
     return Symlink(argc - 1, argv + 1);
   }
+  else if (wcscmp(L"readlink", cmd) == 0)
+  {
+    return Readlink(argc - 1, argv + 1);
+  }
   else if (wcscmp(L"task", cmd) == 0)
   {
     return Task(argc - 1, argv + 1);
@@ -105,6 +109,10 @@ The available commands and their usages are:\n\n", program);
   SymlinkUsage();
   fwprintf(stdout, L"\n\n");
 
+  fwprintf(stdout, L"%-10s%s\n\n", L"readlink", L"Print the target of a symbolic link.");
+  ReadlinkUsage();
+  fwprintf(stdout, L"\n\n");
+
   fwprintf(stdout, L"%-15s%s\n\n", L"systeminfo", L"System information.");
   SystemInfoUsage();
   fwprintf(stdout, L"\n\n");

hadoop-common-project/hadoop-common/src/main/winutils/winutils.vcxproj

@@ -160,6 +160,7 @@
     </Link>
   </ItemDefinitionGroup>
   <ItemGroup>
+    <ClCompile Include="readlink.c" />
     <ClCompile Include="symlink.c" />
     <ClCompile Include="systeminfo.c" />
     <ClCompile Include="chmod.c" />
@@ -178,4 +179,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project>
+</Project>

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestWinUtils.java

@@ -33,6 +33,8 @@ import org.apache.hadoop.fs.FileUtil;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
+import static org.junit.Assume.*;
+import static org.hamcrest.CoreMatchers.*;
 
 /**
  * Test cases for helper Windows winutils.exe utility.
@@ -359,4 +361,85 @@ public class TestWinUtils {
         "Expected: Failed to create symlink with forward slashes in target");
     }
   }
+
+  @Test (timeout = 30000)
+  public void testReadLink() throws IOException {
+    // Create TEST_DIR\dir1\file1.txt
+    //
+    File dir1 = new File(TEST_DIR, "dir1");
+    assertTrue(dir1.mkdirs());
+
+    File file1 = new File(dir1, "file1.txt");
+    assertTrue(file1.createNewFile());
+
+    File dirLink = new File(TEST_DIR, "dlink");
+    File fileLink = new File(TEST_DIR, "flink");
+
+    // Next create a directory symlink to dir1 and a file
+    // symlink to file1.txt.
+    //
+    Shell.execCommand(
+        Shell.WINUTILS, "symlink", dirLink.toString(), dir1.toString());
+    Shell.execCommand(
+        Shell.WINUTILS, "symlink", fileLink.toString(), file1.toString());
+
+    // Read back the two links and ensure we get what we expected.
+    //
+    String readLinkOutput = Shell.execCommand(Shell.WINUTILS,
+        "readlink",
+        dirLink.toString());
+    assertThat(readLinkOutput, equalTo(dir1.toString()));
+
+    readLinkOutput = Shell.execCommand(Shell.WINUTILS,
+        "readlink",
+        fileLink.toString());
+    assertThat(readLinkOutput, equalTo(file1.toString()));
+
+    // Try a few invalid inputs and verify we get an ExitCodeException for each.
+    //
+    try {
+      // No link name specified.
+      //
+      Shell.execCommand(Shell.WINUTILS, "readlink", "");
+      fail("Failed to get Shell.ExitCodeException when reading bad symlink");
+    } catch (Shell.ExitCodeException ece) {
+      assertThat(ece.getExitCode(), is(1));
+    }
+
+    try {
+      // Bad link name.
+      //
+      Shell.execCommand(Shell.WINUTILS, "readlink", "ThereIsNoSuchLink");
+      fail("Failed to get Shell.ExitCodeException when reading bad symlink");
+    } catch (Shell.ExitCodeException ece) {
+      assertThat(ece.getExitCode(), is(1));
+    }
+
+    try {
+      // Non-symlink directory target.
+      //
+      Shell.execCommand(Shell.WINUTILS, "readlink", dir1.toString());
+      fail("Failed to get Shell.ExitCodeException when reading bad symlink");
+    } catch (Shell.ExitCodeException ece) {
+      assertThat(ece.getExitCode(), is(1));
+    }
+
+    try {
+      // Non-symlink file target.
+      //
+      Shell.execCommand(Shell.WINUTILS, "readlink", file1.toString());
+      fail("Failed to get Shell.ExitCodeException when reading bad symlink");
+    } catch (Shell.ExitCodeException ece) {
+      assertThat(ece.getExitCode(), is(1));
+    }
+
+    try {
+      // Too many parameters.
+      //
+      Shell.execCommand(Shell.WINUTILS, "readlink", "a", "b");
+      fail("Failed to get Shell.ExitCodeException with bad parameters");
+    } catch (Shell.ExitCodeException ece) {
+      assertThat(ece.getExitCode(), is(1));
+    }
+  }
 }