Device names could contain characters not allowed for a dir name, fixed.

src/main/java/org/kde/kdeconnect/Helpers/FilesHelper.java

@@ -15,4 +15,42 @@ public class FilesHelper {
         return mime;
     }
 
+    //Following code from http://activemq.apache.org/maven/5.7.0/kahadb/apidocs/src-html/org/apache/kahadb/util/IOHelper.html
+    /**
+     * Converts any string into a string that is safe to use as a file name.
+     * The result will only include ascii characters and numbers, and the "-","_", and "." characters.
+     *
+     * @param name
+     * @param dirSeparators
+     * @param maxFileLength
+     * @return the resulting string
+     */
+    public static String toFileSystemSafeName(String name, boolean dirSeparators, int maxFileLength) {
+        int size = name.length();
+        StringBuffer rc = new StringBuffer(size * 2);
+        for (int i = 0; i < size; i++) {
+            char c = name.charAt(i);
+            boolean valid = c >= 'a' && c <= 'z';
+            valid = valid || (c >= 'A' && c <= 'Z');
+            valid = valid || (c >= '0' && c <= '9');
+            valid = valid || (c == '_') || (c == '-') || (c == '.');
+            valid = valid || (dirSeparators && ( (c == '/') || (c == '\\')));
+
+            if (valid) {
+                rc.append(c);
+            }
+        }
+        String result = rc.toString();
+        if (result.length() > maxFileLength) {
+            result = result.substring(result.length()-maxFileLength,result.length());
+        }
+        return result;
+    }
+    public static String toFileSystemSafeName(String name, boolean dirSeparators) {
+        return toFileSystemSafeName(name, dirSeparators, 255);
+    }
+    public static String toFileSystemSafeName(String name) {
+        return toFileSystemSafeName(name, true, 255);
+    }
+
 }

src/main/java/org/kde/kdeconnect/Plugins/SharePlugin/SharePlugin.java

@@ -86,10 +86,11 @@ public class SharePlugin extends Plugin {
                 final int fileLength = np.getPayloadSize();
                 final String filename = np.getString("filename", new Long(System.currentTimeMillis()).toString());
 
+                String deviceDir = FilesHelper.toFileSystemSafeName(device.getName());
                 //Get the external storage and append "/kdeconnect/DEVICE_NAME/"
                 String destinationDir = Environment.getExternalStorageDirectory().getPath();
                 destinationDir = new File(destinationDir, "kdeconnect").getPath();
-                destinationDir = new File(destinationDir, device.getName()).getPath();
+                destinationDir = new File(destinationDir, deviceDir).getPath();
 
                 //Create directories if needed
                 new File(destinationDir).mkdirs();