fix evaluation of mediaconch output

The mediaconch process returns code 0 for valid and
invalid files. Therefore, the text output produced
by the process must be parsed to determined the
validation result.

java/org/slub/rosetta/dps/repository/plugin/SLUBMatroskaFFV1FormatValidationPlugin.java

@@ -167,23 +167,9 @@ public class SLUBMatroskaFFV1FormatValidationPlugin implements FormatValidationP
             
             // wait for the output reader thread to terminate
             procOutputReaderThread.join();
-
-            if (p.exitValue() == 0) {
-                isvalid = true;
-                iswellformed = true;
-            } else { // something wrong
-                isvalid = false;
-                iswellformed = false;
-            }
-
-            for (String line : procOutputLineList) {
-                if (line.contains("pass!")) {
-                    break;
-                }
-                System.out.println("MEDIACONCH line: " + line);
-                validationLog.add(line);
-                log.info( line );
-            }            
+            
+            boolean fileIsValid = evaluateAndLogMediaconchOutput(p.exitValue(), procOutputLineList, filePath); 
+            setValid(fileIsValid);
         } catch (IOException e) {
             log.error("(actual) mediaconch not available, path=" + this.mediaconch_binary_path + ", " , e.getMessage());
             System.out.println("ERROR: (actual) mediaconch not available, path=" + this.mediaconch_binary_path + ", " + e.getMessage());
@@ -201,14 +187,35 @@ public class SLUBMatroskaFFV1FormatValidationPlugin implements FormatValidationP
         iswellformed = value;
     }
 
-    private void extractErrorsFromReader(BufferedReader reader) throws IOException {
-        while (true) {
-            String line = reader.readLine();
-            if (line == null) break;
-            System.out.println("MEDIACONCH line: " + line);
-            validationLog.add(line);
-            log.info(line);
+    
+    private boolean evaluateMediaconchOutput(int processExitValue, List<String> procOutputLineList, String filePath) {
+    	if (processExitValue != 0) {
+    		log.info("the mediaconch process returned a non-zero exit code (" +processExitValue+ ") -> file '"+filePath+"' is considered invalid");
+    		
+    		return false;
+    	}
+    	
+    	if (procOutputLineList == null || procOutputLineList.isEmpty()) {
+    		log.info("the mediaconch process returned an empty validation result -> file '"+filePath+"' is considered invalid");
+    		
+    		return false;    		
+    	}
+    	
+    	// the result is in the first line
+    	return procOutputLineList.get(0).startsWith("pass! "+ filePath);
+    }
+    
+    private boolean evaluateAndLogMediaconchOutput(int processExitValue, List<String> procOutputLineList, String filePath) {
+    	boolean result = evaluateMediaconchOutput(processExitValue, procOutputLineList, filePath);
+    	
+        if (!result) {
+        	validationLog.add("mediaconch exit code for file " + filePath + " is "+processExitValue);
+            for (String line : procOutputLineList) {
+                validationLog.add("MEDIACONCH line: " + line);
+            }
         }
+        
+        return result;
     }
 
     @Override