On Fri, 2013-11-15 at 11:08 -0800, John Stultz wrote:
On 11/15/2013 09:55 AM, Jon Medhurst (Tixy) wrote:
So, hacking getFatVolumeId to return a value other than -1 means the system works and files on 'external' sdcard are seen and usable by apps.
I guess the issue is that the file system is 'fuse' not 'vfat' and the fuse filesystem doesn't implement VFAT_IOCTL_GET_VOLUME_ID.
So it would seem logical that the config is wrong somehow the the non-emulated external media shouldn't be using fuse. However, the description at http://source.android.com/devices/tech/storage/index.html says:
Starting in Android 4.4, the owner, group and modes of files on external storage devices are now synthesized based on directory structure. [...] These synthesized permissions are accomplished by wrapping raw storage devices in a FUSE daemon.???
So I've just been barely following along here, but that quoted paragraph is a little frightening. Instead of using a filesystem with actual granular permissions, they've added a permissions meta-layer over FAT via fuse? Eww.
As far as the rest of the issue goes, it sounds like you've managed to work it out. But if it ends up being a problem with either of the GET_VOLUME_ID ioctls, let me know.
By the way, this sort of hiccup (and its workaround) is something we probably should be documenting and publicizing.
My 'work around' was to hard code the FileUtils.getFatVolumeID function on Android to return 0x12345678 for the volume ID, which is not something that I would want to commit to the Linaro tree. Not very good if there is more than one media partition, or if it isn't mounted yet (which comments in the code seem to anticipate) and I don't know where else that function might get used.
The only reason I tried the hack was to see if there were other issues with getting storage devices to actually work.
I'm still assuming we must have something configured wrong, unless KitKat is just simply broken and I'm the first person to notice.
I'll try an come up with a cleaner hack next week if I find time to understand all the uses of that function...