Effective in 2026, to align with our trunk stable development model and ensure platform stability for the ecosystem, we will publish source code to AOSP in Q2 and Q4. For building and contributing to AOSP, we recommend utilizing android-latest-release instead of aosp-main. The android-latest-release manifest branch will always reference the most recent release pushed to AOSP. For more information, see Changes to AOSP.

OverlayFsUtils

public class OverlayFsUtils
extends TestWatcher

java.lang.Object
↳	org.junit.rules.TestWatcher
	↳	com.android.sts.common.OverlayFsUtils

TestWatcher that enables writing to read-only partitions and reboots device when done.

Summary

Fields
`static final Pattern`	`PERM_PATTERN`

Public constructors
`OverlayFsUtils(BaseHostJUnit4Test test)`

Public methods
`boolean`	`anyOverlayFsMounted()`
`void`	`finished(Description d)`
`void`	`makeWritable(String dir, int megabytes)` Mounts an OverlayFS dir over the top most common dir in the list.

Fields

PERM_PATTERN

static final Pattern PERM_PATTERN

Public constructors

OverlayFsUtils

public OverlayFsUtils (BaseHostJUnit4Test test)

Parameters
`test`	`BaseHostJUnit4Test`

Public methods

anyOverlayFsMounted

public boolean anyOverlayFsMounted ()

Returns
`boolean`

Throws
`DeviceNotAvailableException`

finished

public void finished (Description d)

Parameters
`d`	`Description`

makeWritable

public void makeWritable (String dir, 
                int megabytes)

Mounts an OverlayFS dir over the top most common dir in the list.

The directory should be writable after this returns successfully. To cleanup, reboot the device as unfortunately unmounting overlayfs is complicated.

Parameters
`dir`	`String`: The directory to make writable. Directories with single quotes are not supported.
`megabytes`	`int`

Throws
`DeviceNotAvailableException`
`IOException`
`IllegalStateException`