delete ctags temp files at the end of indexing (#3188)

fixes #3183

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/index/Indexer.java

@@ -18,7 +18,7 @@
  */
 
 /*
- * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
  * Portions Copyright 2011 Jens Elkner.
  * Portions Copyright (c) 2017-2020, Chris Fraire <cfraire@me.com>.
  */
@@ -1089,6 +1089,8 @@ public void run() {
                     " for executor to finish", exp);
         }
         elapsed.report(LOGGER, "Done indexing data of all repositories");
+
+        CtagsUtil.deleteTempFiles();
     }
 
     public void refreshSearcherManagers(RuntimeEnvironment env, List<String> projects, String host) {

opengrok-indexer/src/main/java/org/opengrok/indexer/util/CtagsUtil.java

@@ -18,7 +18,7 @@
  */
 
 /*
- * Copyright (c) 2006, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
  * Portions Copyright (c) 2019, Chris Fraire <cfraire@me.com>.
  */
 
@@ -29,10 +29,13 @@
 import org.opengrok.indexer.configuration.RuntimeEnvironment;
 import org.opengrok.indexer.logger.LoggerFactory;
 
+import java.io.File;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 public class CtagsUtil {
 
@@ -86,6 +89,39 @@ public static List<String> getLanguages(String ctagsBinary) {
         return result;
     }
 
+    /**
+     * Deletes Ctags temporary files left over after terminating Ctags processes
+     * in case of timeout, @see Ctags#doCtags.
+     */
+    public static void deleteTempFiles() {
+        String[] dirs = {System.getProperty("java.io.tmpdir"),
+                System.getenv("TMPDIR"), System.getenv("TMP")};
+
+        for (String dir : dirs) {
+            deleteTempFiles(dir);
+        }
+    }
+
+    private static void deleteTempFiles(String directoryName) {
+        final Pattern pattern = Pattern.compile("tags\\.\\S{6}"); // ctags uses this pattern to call mkstemp()
+
+        if (directoryName == null) {
+            return;
+        }
+
+        File dir = new File(directoryName);
+        File[] files = dir.listFiles((dir1, name) -> {
+            Matcher matcher = pattern.matcher(name);
+            return matcher.find();
+        });
+
+        for (File file : files) {
+            if (file.isFile() && !file.delete()) {
+                LOGGER.log(Level.WARNING, "cannot delete file {0}", file);
+            }
+        }
+    }
+
     /**
      * Creates a new instance, and attempts to configure it from the
      * environment.