[SPARK-4075][SPARK-4434] Fix the URI validation logic for Application Jar name.

This PR adds a regression test for SPARK-4434.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #3326 from sarutak/add-triple-slash-testcase and squashes the following commits:

82bc9cc [Kousuke Saruta] Fixed wrong grammar in comment
9149027 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into add-triple-slash-testcase
c1c80ca [Kousuke Saruta] Fixed style
4f30210 [Kousuke Saruta] Modified comments
9e09da2 [Kousuke Saruta] Fixed URI validation for jar file
d4b99ef [Kousuke Saruta] [SPARK-4075] [Deploy] Jar url validation is not enough for Jar file
ac79906 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into add-triple-slash-testcase
6d4f47e [Kousuke Saruta] Added a test case as a regression check for SPARK-4434

core/src/main/scala/org/apache/spark/deploy/ClientArguments.scala

@@ -17,6 +17,8 @@
 
 package org.apache.spark.deploy
 
+import java.net.{URI, URISyntaxException}
+
 import scala.collection.mutable.ListBuffer
 
 import org.apache.log4j.Level
@@ -73,7 +75,8 @@ private[spark] class ClientArguments(args: Array[String]) {
 
       if (!ClientArguments.isValidJarUrl(_jarUrl)) {
         println(s"Jar url '${_jarUrl}' is not in valid format.")
-        println(s"Must be a jar file path in URL format (e.g. hdfs://XX.jar, file://XX.jar)")
+        println(s"Must be a jar file path in URL format " +
+          "(e.g. hdfs://host:port/XX.jar, file:///XX.jar)")
         printUsageAndExit(-1)
       }
 
@@ -114,5 +117,12 @@ private[spark] class ClientArguments(args: Array[String]) {
 }
 
 object ClientArguments {
-  def isValidJarUrl(s: String): Boolean = s.matches("(.+):(.+)jar")
+  def isValidJarUrl(s: String): Boolean = {
+    try {
+      val uri = new URI(s)
+      uri.getScheme != null && uri.getPath != null && uri.getPath.endsWith(".jar")
+    } catch {
+      case _: URISyntaxException => false
+    }
+  }
 }

core/src/test/scala/org/apache/spark/deploy/ClientSuite.scala

@@ -23,12 +23,27 @@ import org.scalatest.Matchers
 class ClientSuite extends FunSuite with Matchers {
   test("correctly validates driver jar URL's") {
     ClientArguments.isValidJarUrl("http://someHost:8080/foo.jar") should be (true)
-    ClientArguments.isValidJarUrl("file://some/path/to/a/jarFile.jar") should be (true)
+
+    // file scheme with authority and path is valid.
+    ClientArguments.isValidJarUrl("file://somehost/path/to/a/jarFile.jar") should be (true)
+
+    // file scheme without path is not valid.
+    // In this case, jarFile.jar is recognized as authority.
+    ClientArguments.isValidJarUrl("file://jarFile.jar") should be (false)
+
+    // file scheme without authority but with triple slash is valid.
+    ClientArguments.isValidJarUrl("file:///some/path/to/a/jarFile.jar") should be (true)
     ClientArguments.isValidJarUrl("hdfs://someHost:1234/foo.jar") should be (true)
 
     ClientArguments.isValidJarUrl("hdfs://someHost:1234/foo") should be (false)
     ClientArguments.isValidJarUrl("/missing/a/protocol/jarfile.jar") should be (false)
     ClientArguments.isValidJarUrl("not-even-a-path.jar") should be (false)
+
+    // This URI doesn't have authority and path.
+    ClientArguments.isValidJarUrl("hdfs:someHost:1234/jarfile.jar") should be (false)
+
+    // Invalid syntax.
+    ClientArguments.isValidJarUrl("hdfs:") should be (false)
   }
 
 }