Rework Unix spark-class to handle argument with newlines.

Author: Marcelo Vanzin

bin/spark-class

@@ -67,11 +67,12 @@ fi
 
 SPARK_LAUNCHER_CP="${SPARK_LAUNCHER_CP}${LAUNCHER_DIR}/${LAUNCHER_JARS}"
 
-# The launcher library will print one argument per line of its output. The next line sets
-# the new line char as the only delimiter used when parsing that output into an array.
-IFS="
-"
-CMD=($($RUNNER -cp $SPARK_LAUNCHER_CP org.apache.spark.launcher.Main "$@"))
+# The launcher library will print arguments separated by a NULL character. Read that in a while
+# loop, populating an array that will be used to exec the final command.
+CMD=()
+while IFS= read -d '' -r ARG; do
+  CMD+=("$ARG")
+done < <($RUNNER -cp "$SPARK_LAUNCHER_CP" org.apache.spark.launcher.Main "$@")
 
 if [ "${CMD[0]}" = "usage" ]; then
   "${CMD[@]}"

launcher/src/main/java/org/apache/spark/launcher/AbstractLauncher.java

@@ -427,7 +427,7 @@ private List<String> prepareForWindows(
       List<String> cmd,
       String libPath,
       Map<String, String> env) {
-    StringBuilder cmdline = new StringBuilder("cmd /c \"");
+    StringBuilder cmdline = new StringBuilder("\"");
     if (libPath != null) {
       cmdline.append("set PATH=%PATH%;").append(libPath).append(" &&");
     }
@@ -445,7 +445,7 @@ private List<String> prepareForWindows(
       cmdline.append(quoteForBatchScript(arg));
     }
     cmdline.append("\"");
-    return Arrays.asList(cmdline.toString());
+    return Arrays.asList("cmd", "/c", cmdline.toString());
   }
 
   /**

launcher/src/main/java/org/apache/spark/launcher/Main.java

@@ -36,9 +36,12 @@ public class Main extends LauncherCommon {
    *   <li>"spark-class": if another class is provided, an internal Spark class is run.</li>
    * </ul>
    *
-   * The ultimate command will not be run in the same process. Instead, the command to be executed
-   * will be printed to stdout. On Unix systems, this will be one argument per line. On Windows
-   * systems, this will be a single line containing the command to be executed.
+   * This class works in tandem with the "bin/spark-class" script on Unix-like systems, and
+   * "bin/spark-class2.cmd" batch script on Windows to execute the final command.
+   * <p/>
+   * On Unix-like systems, the output is a list of command arguments, separated by the NULL
+   * character. On Windows, the output is single command line suitable for direct execution
+   * form the script.
    */
   public static void main(String[] argsArray) throws Exception {
     checkArgument(argsArray.length > 0, "Not enough arguments: missing class name.");
@@ -66,8 +69,14 @@ public static void main(String[] argsArray) throws Exception {
       System.err.println("========================================");
     }
 
-    for (String c : cmd) {
-      System.out.println(c);
+    if (isWindows()) {
+      String cmdLine = join(" ", cmd);
+      System.out.println(cmdLine);
+    } else {
+      for (String c : cmd) {
+        System.out.print(c);
+        System.out.print('\0');
+      }
     }
   }