add option to skip app cache when backing up

fixes jensstein#64

src/main/java/dk/jens/backup/ShellCommands.java

@@ -96,16 +96,17 @@ public int doBackup(Context context, File backupSubDir, String label, String pac
         // -L because fat (which will often be used to store the backup files)
         // doesn't support symlinks
         String followSymlinks = prefs.getBoolean("followSymlinks", true) ? "L" : "";
+        String skipCache = prefs.getBoolean("skipCache", false) ? " --exclude cache" : "";
         switch(backupMode)
         {
             case AppInfo.MODE_APK:
                 commands.add("cp " + packageApk + " " + backupSubDirPath);
                 break;
             case AppInfo.MODE_DATA:
-                commands.add("cp -R" + followSymlinks + " " + packageData + " " + backupSubDirPath);
+                commands.add("rsync -r" + followSymlinks + skipCache + " " + packageData + " " + backupSubDirPath);
                 break;
             default: // defaults to MODE_BOTH
-                commands.add("cp -R" + followSymlinks + " " + packageData + " " + backupSubDirPath);
+                commands.add("rsync -r" + followSymlinks + skipCache + " " + packageData + " " + backupSubDirPath);
                 commands.add("cp " + packageApk + " " + backupSubDirPath);
                 break;
         }
@@ -133,7 +134,7 @@ public int doBackup(Context context, File backupSubDir, String label, String pac
                     TextUtils.join(", ", commands)), e);
                 writeErrorLog(label, e.toString());
             }, this);
-        if(errors.size() == 1 ) {
+        if(errors.size() == 2 ) { // 2, because rsync adds another line when there is an error
             String line = errors.get(0);
             // ignore error if it is about /lib while followSymlinks
             // is false or if it is about /lock in the data of firefox

src/main/res/values/strings.xml

@@ -111,7 +111,7 @@
     <string name="prefs_rememberFiltering">remember sort and filter</string>
     <string name="prefs_summaryRememberFiltering">saves the chosen sorting and filtering method. only those marked by a checkbox in the menu is considered.</string>
     <string name="prefs_followSymlinks">follow symbolic links</string>
-    <string name="prefs_summaryFollowSymlinks">always follow symbolic links when copying (cp -L)</string>
+    <string name="prefs_summaryFollowSymlinks">always follow symbolic links when copying (rsync -L)</string>
     <string name="prefs_enableSpecialBackups">enable special backups</string>
     <string name="prefs_backupExternalFiles">handle external data</string>
     <string name="prefs_summaryBackupExternalFiles">backs up and restores data that is placed on the external storage (e.g. /sdcard/Android/data/)</string>
@@ -163,4 +163,6 @@
     <string name="error_updating_schedule_mode">Error updating %1$s of schedule %2$d</string>
     <string name="permission_not_granted">Permission to access external storage is required</string>
     <string name="restart_dialog">Application seems to need to be restarted</string>
+    <string name="prefs_skipCache">skip application cache</string>
+    <string name="prefs_summaryskipCache">skip backing up the cache for apps</string>
 </resources>

src/main/res/xml/preferences.xml

@@ -42,6 +42,12 @@
         android:summary="@string/prefs_summaryFollowSymlinks"
         android:defaultValue="true"
         />
+    <CheckBoxPreference
+        android:key="skipCache"
+        android:title="@string/prefs_skipCache"
+        android:summary="@string/prefs_summaryskipCache"
+        android:defaultValue="false"
+        />
     <CheckBoxPreference
         android:key="backupExternalFiles"
         android:title="@string/prefs_backupExternalFiles"