Permission denied when opening a file on desktop with fopen

Question

I'm trying the following code, but it returns EACCESS (permission denied). I really don't know why. I even tried to run VS in Administrator mode, without success. It always works well.. maybe because it is windows universal app?

auto err = _wfopen_s(&f, L"C:/Users/Lukas/Desktop/Audio.mp3", L"rb");
if (err > 0)
    return;

fseek(f, SEEK_END, 0);
unsigned int size = ftell(f);
fseek(f, SEEK_SET, 0);

char *data = new char[size];
fread(data, 1, size, f);

fclose(f);

Answer 1

This is expected for a Universal Windows app. Windows Runtime apps run in a sandbox and do not have access to arbitrary parts of the file system. They can directly access (e.g. via fopen, etc.)only their appx package (read only) and app data (read write) directories. All other locations are available only with user permission through the StorageFile and StorageFolder broker objects.

To access your MP3 on the desktop you'll need to have the user select it with a file picker (or equivalent) to get a StorageFile with appropriate permissions, which can then be cached for later use with the AccessCache classes. Alternatively, put the MP3 in the music library and the app can declare the music library capability and get a StorageFile via the KnownFolders.MusicLibrary folder.

I go into more detail in my blog entry at http://blogs.msdn.com/b/wsdevsol/archive/2012/12/05/stray-from-the-path-stick-to-the-storagefile.aspx