Added a specific process manager for FreeBSD (#137)

jodconverter-local/src/main/java/org/jodconverter/office/LocalOfficeUtils.java

@@ -38,6 +38,7 @@
 
 import org.jodconverter.document.DocumentFamily;
 import org.jodconverter.office.utils.Lo;
+import org.jodconverter.process.FreeBSDProcessManager;
 import org.jodconverter.process.MacProcessManager;
 import org.jodconverter.process.ProcessManager;
 import org.jodconverter.process.PureJavaProcessManager;
@@ -148,6 +149,8 @@ public static ProcessManager findBestProcessManager() {
 
     if (SystemUtils.IS_OS_MAC) {
       return MacProcessManager.getDefault();
+    } else if (SystemUtils.IS_OS_FREE_BSD) {
+      return FreeBSDProcessManager.getDefault();
     } else if (SystemUtils.IS_OS_UNIX) {
       return UnixProcessManager.getDefault();
     } else if (SystemUtils.IS_OS_WINDOWS) {

jodconverter-local/src/main/java/org/jodconverter/process/FreeBSDProcessManager.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2004 - 2012 Mirko Nasato and contributors
+ *           2016 - 2018 Simon Braconnier and contributors
+ *
+ * This file is part of JODConverter - Java OpenDocument Converter.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jodconverter.process;
+
+public class FreeBSDProcessManager extends UnixProcessManager {
+
+  // This class is required in order to create the default FreeBSDProcessManager
+  // only on demand, as explained by the Initialization-on-demand holder idiom:
+  // https://www.wikiwand.com/en/Initialization-on-demand_holder_idiom
+  private static class DefaultHolder {
+    // NOSONAR
+    /* default */ static final FreeBSDProcessManager INSTANCE = new FreeBSDProcessManager();
+  }
+
+  /**
+   * Gets the default instance of {@code FreeBSDProcessManager}.
+   *
+   * @return The default {@code FreeBSDProcessManager} instance.
+   */
+  public static FreeBSDProcessManager getDefault() {
+    return DefaultHolder.INSTANCE;
+  }
+
+  @Override
+  protected String[] getRunningProcessesCommand(final String process) {
+
+    return new String[] {
+      "/bin/sh",
+      "-c",
+      "/bin/ps -e -o pid,args | /usr/bin/grep " + process + " | /usr/bin/grep -v grep"
+    };
+  }
+}