Added support for downloading files with unicode characters

Currently only certain ASCII characters are allowed in a filename, all
other characters are replaced with an underscore. This gives bad
usability for foreign languages (e.g. japanese). This fix replaces the
current regexp with a method which replaces only those characters unsafe
to be used on VFAT filesystems (should work on most other
filesystems as well).

Change-Id: I114d47b4b35f28490e6b12493138355532fda499
Signed-off-by: Eddie Ringle <eddie.ringle@gmail.com>

1 files changed, 52 insertions, 2 deletions

diff --git a/src/com/android/providers/downloads/Helpers.java b/src/com/android/providers/downloads/Helpers.java
index 06669fd7..2b88512e 100644
--- a/src/com/android/providers/downloads/Helpers.java
+++ b/src/com/android/providers/downloads/Helpers.java
@@ -324,8 +324,9 @@ public class Helpers {
             filename = Constants.DEFAULT_DL_FILENAME;
         }
 
-        filename = filename.replaceAll("[^a-zA-Z0-9\\.\\-_]+", "_");
-
+        // The VFAT file system is assumed as target for downloads.
+        // Replace invalid characters according to the specifications of VFAT.
+        filename = replaceInvalidVfatCharacters(filename);
 
         return filename;
     }
@@ -779,4 +780,53 @@ public class Helpers {
         resolver.delete(Downloads.Impl.ALL_DOWNLOADS_CONTENT_URI, Downloads.Impl._ID + " = ? ",
                 new String[]{String.valueOf(id)});
     }
+
+    /*
+     * Replace invalid filename characters according to
+     * specifications of the VFAT.
+     * @note Package-private due to testing.
+     */
+    private static String replaceInvalidVfatCharacters(String filename) {
+        final char START_CTRLCODE = 0x00;
+        final char END_CTRLCODE = 0x1f;
+        final char QUOTEDBL = 0x22;
+        final char ASTERISK = 0x2A;
+        final char SLASH = 0x2F;
+        final char COLON = 0x3A;
+        final char LESS = 0x3C;
+        final char GREATER = 0x3E;
+        final char QUESTION = 0x3F;
+        final char BACKSLASH = 0x5C;
+        final char BAR = 0x7C;
+        final char DEL = 0x7F;
+        final char UNDERSCORE = 0x5F;
+
+        StringBuffer sb = new StringBuffer();
+        char ch;
+        boolean isRepetition = false;
+        for (int i = 0; i < filename.length(); i++) {
+            ch = filename.charAt(i);
+            if ((START_CTRLCODE <= ch &&
+                ch <= END_CTRLCODE) ||
+                ch == QUOTEDBL ||
+                ch == ASTERISK ||
+                ch == SLASH ||
+                ch == COLON ||
+                ch == LESS ||
+                ch == GREATER ||
+                ch == QUESTION ||
+                ch == BACKSLASH ||
+                ch == BAR ||
+                ch == DEL){
+                if (!isRepetition) {
+                    sb.append(UNDERSCORE);
+                    isRepetition = true;
+                }
+            } else {
+                sb.append(ch);
+                isRepetition = false;
+            }
+        }
+        return sb.toString();
+    }
 }