The document discusses OBB (Opaque Binary Blob) files in Android, which allow expansion files to be stored externally on the device storage and mounted into the Android application sandbox as needed. It covers how to use the StorageManager and OnObbStateChangeListener APIs to mount OBB files, and details the OBB file format which stores metadata like the package name and signature. Examples are given of using the SDK tools and command line obbtool to manage OBB files on external storage like the SD card.

1. android.os.storage
YAMAZAKI Makoto (@zaki50)

2. Who am I?
• YAMAZAKI Makoto(twitter: @zaki50)
• market: (FeliCa push middleware)
• http://sites.google.com/site/94katsu/

3. storage API

4. storage API...?
•
• SD
• OBB?
•

5. Disk Image!

6. • (vfat)
• /
•
•

7. • (ro mount
)
•

8. StorageManager

9. OnObbStateChangeListener

10. (mount)

11. (ObbInfo)

12. mount

13. OBB
• Android SDK(r8)
• AOSP
(gingerbread or master branch)
• vfat OBB

14. obbtool
gingerbread sdk

15. OBB
signature version 4 footer (1)
package version 4 (?)
(vfat) flag 4
OBB
salt 8 salt
package name size 4
package name
signature version package
footer size 4
OBB OBB
name
footer marker 4 (0x01059983)

16. OBB
Mac
Linux loopback mount Windows ...

17. • zip
• SD CARD
• StorageManager(OBB)

18. • SDK tool
• SD CARD OBB
• OBB NFS

19. • API Reference
• http://developer.android.com/reference/
• AOSP
• frameworks/base/libs/util/ObbFile.cpp
• development/samples/Obb
• OBB
• http://zaki.tdiary.net/20101224.html