External Storage
case-insensitive
without linux
attributes.
e.g
fat,fat32,or other
|
Primary
External
All APIs prior to KITKAT reference
here for external
storage.
Examples:
Removable
card inside of phone
e.g
/mnt/sdcard/<>
e.g /SDCARD/<>
Internal
memory,
2nd partition
e.g
/storage/sdcard0/<>
e.g
/sdcard/
e.g /mnt/sdcard0/<>
e.g
/mnt/emmc/<>
Internal
memory pretending to be
sdcard (emulated)
e.g
/storage/emulated/0/<> |
PE Private Storage
<>/Android/data/<PACKAGE_NAME>
e.g
/mnt/sdcard/Android/data/<PACKAGE_NAME>
- no sandboxing
restrictions.
- treated as
'private' but available publicly due to
media being
external.
- cleared upon
app-uninstall.
-
getExternalStorageDirectory
()
(deprecated
since API 29 Android
Q)
-
Context.getExternalFilesDir(null)
Before
KITKAT:
- No
permissions needed for read
access.
-
WRITE_EXTERNAL_STORAGE needed for write
access, even if app is
owner.
After KITKAT:
- Owner app
gets full access without needing
permissions.
After Android-11:
- Sandboxed as private for owner app
with full access.
- Not available publicly. Even SAF
cannot access it.
|
PE Shared Storage
- no sandboxing
restrictions.
- not cleared
upon app-uninstall.
- Environment.
getExternalStoragePublicDirectory(type)
e.g
/mnt/sdcard/Movies
(deprecated
since API 29 Android Q)
- Context.getExternalFilesDir(type)
/mnt/sdcard/Android/data/
<PACKAGE_NAME>/Movies
Before
KITKAT:
- No
permissions needed for read
access.
-
WRITE_EXTERNAL_STORAGE needed for write
access.
After
KITKAT:
-
READ_EXTERNAL_STORAGE needed for read
access.
-
WRITE_EXTERNAL_STORAGE grants
read,write on same
volume.
After Android-11:
- Access restricted to SAF or
MediaStore for all apps, even the owner
app.
|
|
Secondary
External
(new sandbox restrictions
being enforced here since KITKAT)
Examples:
Removable card inside of
phone.
e.g /storage/external_SD/<>
e.g /mnt/external_SD/<>
Removable card on outside
slot of phone.
e.g
/extsd/<>
e.g
/extSdcard/<>
e.g
/storage/1234-ABCD/<>
|
SE Private Storage
<>/Android/data/<PACKAGE_NAME>
e.g
/extsd/Android/data/<PACKAGE_NAME>
- app is
sandboxed here.
- cleared upon
app-uninstall
-
Context.getExternalFilesDirs()
- as additional
item.
Before
KITKAT:
-
WRITE_EXTERNAL_STORAGE needed for
write.
After KITKAT:
- Owner app
gets full access without needing
permissions.
|
SE Shared Storage
-
READ_EXTERNAL_STORAGE needed for read
access after KITKAT.
-
WRITE_EXTERNAL_STORAGE does NOT
grant sdcard_rw membership on this
volume.
In
KitKat:
SAF API needed to r/w
outside
application-specific directories on
secondary storage for specific
directories.
In
Lollipop:
SAF API extension removes the
restriction to app-specific directories
with
ACTION_OPEN_DOCUMENT_TREE.
After Android-11:
- Access restricted to SAF or
MediaStore for all apps, even the owner
app.
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