Issue when opening a DOCX file through a third party app using IOCipher and ContentProvider

问题

I'm building a secure android application that runs with IOCipher and SQLCipher. My app is storing PDF, DOC, DOCX, XLS, XLSX files that are intended to be openned by a third party application. Currently I can open all these type of files but DOCX. When I open a docx file that is stored in IOCipher using this method:

    File file = new File(path);
    Uri contentUri = Uri.parse(VFSContentProvider.FILES_URI + file.getName());

    Intent intent = new Intent();
    intent.setAction(Intent.ACTION_VIEW);
    intent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    intent.setData(contentUri);

Microsoft Word prompt me with that error message :

Can't open file "myFile.docx.docx".

This happen For all my docx file, it seems to append the mime type twice at the end of the file when it's returned by the content provider...

Here is my IOCipher Content Provider:

public class VFSContentProvider extends ContentProvider {
    public static final String TAG = "VFSContentProvider";
    public static final Uri FILES_URI = Uri
            .parse("content://com.plante.android.cobalt.VFSContentProvider/");
    private MimeTypeMap mimeTypeMap;

    @Override
    public boolean onCreate() {
        mimeTypeMap = MimeTypeMap.getSingleton();
        return true;
    }

    @Override
    public String getType(Uri uri) {
        String fileExtension = MimeTypeMap.getFileExtensionFromUrl(uri.toString());
        return mimeTypeMap.getMimeTypeFromExtension(fileExtension);
    }

    @Override
    public ParcelFileDescriptor openFile(Uri uri, String mode)
            throws FileNotFoundException {
        ParcelFileDescriptor[] pipe = null;
        InputStream in = null;

        try {
            pipe = ParcelFileDescriptor.createPipe();
            String path = uri.getPath();
            Log.i(TAG, "streaming " + path);
            // BufferedInputStream could help, AutoCloseOutputStream conflicts
            in = new FileInputStream(new File(path));
            new PipeFeederThread(in, new AutoCloseOutputStream(pipe[1])).start();
        } catch (IOException e) {
            Log.e(TAG, "Error opening pipe", e);
            throw new FileNotFoundException("Could not open pipe for: "
                    + uri.toString());
        }

        return (pipe[0]);
    }

    @Override
    public Cursor query(Uri url, String[] projection, String selection,
                        String[] selectionArgs, String sort) {
        // throw new RuntimeException("Operation not supported");
        return null;
    }

    @Override
    public Uri insert(Uri uri, ContentValues initialValues) {
        throw new RuntimeException("Operation not supported");
    }

    @Override
    public int update(Uri uri, ContentValues values, String where,
                      String[] whereArgs) {
        throw new RuntimeException("Operation not supported");
    }

    @Override
    public int delete(Uri uri, String where, String[] whereArgs) {
        throw new RuntimeException("Operation not supported");
    }

    static class PipeFeederThread extends Thread {
        InputStream in;
        OutputStream out;

        PipeFeederThread(InputStream in, OutputStream out) {
            this.in = in;
            this.out = out;
        }

        @Override
        public void run() {
            byte[] buf = new byte[8192];
            int len;

            try {
                while ((len = in.read(buf)) > 0) {
                    out.write(buf, 0, len);
                }

                in.close();
                out.flush();
                out.close();
            } catch (IOException e) {
                Log.e(TAG, "File transfer failed:", e);
            }
        }
    }

Here is the log file:

03-16 13:38:20.714 800-1325/? I/ActivityManager: START u0 {act=android.intent.action.VIEW dat=content://com.plante.android.cobalt.VFSContentProvider/0c8dbc0e1671e127ed9fcb2786b218d379f12888Finance_Corporate_BCP_Checklist_2014_MH20150115.docx flg=0x13000003 cmp=com.microsoft.office.word/com.microsoft.office.apphost.LaunchActivity} from uid 10182 on display 0

来源：https://stackoverflow.com/questions/36038999/issue-when-opening-a-docx-file-through-a-third-party-app-using-iocipher-and-cont