added RSYNC4J_HOME environment variable support on Windows for custom…

… location of binaries and keys

README.md

@@ -11,7 +11,7 @@ Add the following artifact to your dependencies of your `pom.xml`:
     <dependency>
       <groupId>com.github.fracpete</groupId>
       <artifactId>rsync4j</artifactId>
-      <version>3.1.2-5</version>
+      <version>3.1.2-6</version>
     </dependency>
 ```
 
@@ -338,11 +338,18 @@ Will get automatically get converted to:
 /cygdrive/c/some/path/blah.txt
 ```
 
+### Custom location
+
+It is possible to use another location than `%USERPROFILE%\rsync4j`. You only
+have to set up the `RSYNC4J_HOME` environment variable to point to the top-level
+directory (doesn't have to exist) where you want to house the binaries and keys. 
+
+
 ## FAQ
 
 * **Q** I'm trying to sync, but it just sits there and does nothing!
 * **A** Since *rsync4j* is not interactive, you will have to connect to the 
-  remote host at least once before to add the host the `known_hosts` file.
+  remote host at least once before to add the host to the `known_hosts` file.
 * **Q** How do I use a specific public key pair?
 * **A** You can let `ssh` know what identity file to use using rsync's `--rsh` 
   option and ssh's `-i` option, e.g.: `rsync --rsh="ssh -i /some/where/id_rsa" ...`

src/main/java/com/github/fracpete/rsync4j/Binaries.java

@@ -13,9 +13,9 @@
  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-/**
+/*
  * Binaries.java
- * Copyright (C) 2017 University of Waikato, Hamilton, New Zealand
+ * Copyright (C) 2017-2018 University of Waikato, Hamilton, New Zealand
  */
 
 package com.github.fracpete.rsync4j;
@@ -46,6 +46,9 @@ public class Binaries {
   /** the sub-directory for the windows binaries. */
   public final static String WINDOWS_DIR = "windows-x86_64/";
 
+  /** the windows environment variable for the rsyncj4 home directory. */
+  public final static String WINDOWS_HOME_DIR = "RSYNC4J_HOME";
+
   /** for storing any previously extract binary. */
   protected static Boolean binariesExtracted;
 
@@ -128,6 +131,30 @@ protected static String copyResourceTo(String inDir, String name, String outDir)
     return result;
   }
 
+  /**
+   * Returns the home directory to use for rsync4j.
+   * On Windows, use the {@link #WINDOWS_HOME_DIR} environment variable
+   * to point it to a custom location.
+   *
+   * @return		the directory
+   */
+  protected static String homeDir() {
+    String	result;
+    File	dir;
+
+    result = System.getProperty("user.home") + File.separator + "rsync4j";
+
+    if (SystemUtils.IS_OS_WINDOWS) {
+      if (System.getenv(WINDOWS_HOME_DIR) != null) {
+        dir = new File(System.getenv(WINDOWS_HOME_DIR));
+        if (!dir.exists() || dir.isDirectory())
+          result = dir.getAbsolutePath();
+      }
+    }
+
+    return result;
+  }
+
   /**
    * Extracts the binaries to the tmp directory.
    *
@@ -152,7 +179,7 @@ protected static void extractBinaries() throws Exception {
 	throw new IllegalStateException("ssh not installed (" + sshBinary + ")?");
     }
     else if (SystemUtils.IS_OS_WINDOWS) {
-      homeDir = System.getProperty("user.home") + File.separator + "rsync4j";
+      homeDir = homeDir();
       binDir  = homeDir + File.separator + "bin";
       sshDir  = homeDir + File.separator + "home" + File.separator + System.getProperty("user.name") + File.separator + ".ssh";
       if (!new File(binDir + File.separator + "rsync.exe").exists()) {