AllLinesParser: Enable draining of stdout (#8670)

Author: rp-

utils/src/main/java/com/cloud/utils/script/OutputInterpreter.java

@@ -137,6 +137,11 @@ public String interpret(BufferedReader reader) throws IOException {
         public String getLines() {
             return allLines;
         }
+
+        @Override
+        public boolean drain() {
+            return true;
+        }
     }
 
     public static class LineByLineOutputLogger extends OutputInterpreter {

utils/src/test/java/com/cloud/utils/ScriptTest.java

@@ -111,6 +111,20 @@ public String interpret(BufferedReader reader) throws IOException {
         Assert.assertNotNull(value);
     }
 
+    @Test
+    public void executeWithOutputInterpreterAllLinesParserLargeOutput() {
+        Assume.assumeTrue(SystemUtils.IS_OS_LINUX);
+        OutputInterpreter.AllLinesParser parser = new OutputInterpreter.AllLinesParser();
+        Script script = new Script("seq");
+        script.add("-f");
+        script.add("my text to test cloudstack %g");
+        script.add("4096"); // AllLinesParser doesn't work with that amount of data
+        String value = script.execute(parser);
+        // it is a stack trace in this case as string
+        Assert.assertNull(value);
+        Assert.assertEquals(129965, parser.getLines().length());
+    }
+
     @Test
     public void runSimpleBashScriptNotExisting() {
         Assume.assumeTrue(SystemUtils.IS_OS_LINUX);