Merge "StorageManager: Properly convert FAT volume identifiers." (d9c361be) · Commits · e / os / android_frameworks_base

core/api/test-current.txt

+5 −0

Original line number	Diff line number	Diff line
		@@ -1548,6 +1548,11 @@ package android.os.storage {
		field @NonNull public static final android.os.Parcelable.Creator<android.os.storage.CrateInfo> CREATOR;
		}

		public class StorageManager {
		method @NonNull public static java.util.UUID convert(@NonNull String);
		method @NonNull public static String convert(@NonNull java.util.UUID);
		}

		public final class StorageVolume implements android.os.Parcelable {
		method public String getPath();
		}

core/java/android/os/storage/StorageManager.java

+41 −2

Original line number	Diff line number	Diff line
		@@ -43,6 +43,7 @@ import android.annotation.SdkConstant;
		import android.annotation.SuppressLint;
		import android.annotation.SystemApi;
		import android.annotation.SystemService;
		import android.annotation.TestApi;
		import android.annotation.WorkerThread;
		import android.app.Activity;
		import android.app.ActivityThread;
		@@ -115,6 +116,7 @@ import java.util.Arrays;
		import java.util.Collections;
		import java.util.Iterator;
		import java.util.List;
		import java.util.Locale;
		import java.util.Objects;
		import java.util.UUID;
		import java.util.concurrent.CompletableFuture;
		@@ -166,6 +168,9 @@ public class StorageManager {
		/** {@hide} */
		public static final String UUID_SYSTEM = "system";

		// NOTE: See comments around #convert for more details.
		private static final String FAT_UUID_PREFIX = "fafafafa-fafa-5afa-8afa-fafa";

		// NOTE: UUID constants below are namespaced
		// uuid -v5 ad99aa3d-308e-4191-a200-ebcab371c0ad default
		// uuid -v5 ad99aa3d-308e-4191-a200-ebcab371c0ad primary_physical
		@@ -2620,21 +2625,44 @@ public class StorageManager {
		return isCacheBehavior(path, XATTR_CACHE_TOMBSTONE);
		}

		/**
		* Returns true if {@code uuid} is a FAT volume identifier. FAT Volume identifiers
		* are 32 randomly generated bits that are represented in string form as AAAA-AAAA.
		*/
		private static boolean isFatVolumeIdentifier(String uuid) {
		return uuid.length() == 9 && uuid.charAt(4) == '-';
		}

		/** {@hide} */
		public static UUID convert(String uuid) {
		@TestApi
		public static @NonNull UUID convert(@NonNull String uuid) {
		if (Objects.equals(uuid, UUID_PRIVATE_INTERNAL)) {
		return UUID_DEFAULT;
		} else if (Objects.equals(uuid, UUID_PRIMARY_PHYSICAL)) {
		return UUID_PRIMARY_PHYSICAL_;
		} else if (Objects.equals(uuid, UUID_SYSTEM)) {
		return UUID_SYSTEM_;
		} else if (isFatVolumeIdentifier(uuid)) {
		// FAT volume identifiers are not UUIDs but we need to coerce them into
		// UUIDs in order to satisfy apis that take java.util.UUID arguments.
		//
		// We coerce a 32 bit fat volume identifier of the form XXXX-YYYY into
		// a UUID of form "fafafafa-fafa-5afa-8afa-fafaXXXXYYYY". This is an
		// RFC-422 UUID with Version 5, which is a namespaced UUID. The UUIDs we
		// coerce into are not true namespace UUIDs; although FAT storage volume
		// identifiers are unique names within a fixed namespace, this UUID is not
		// based on an SHA-1 hash of the name. We avoid the SHA-1 hash because
		// (a) we need this transform to be reversible (b) it's pointless to generate
		// a 128 bit hash from a 32 bit value.
		return UUID.fromString(FAT_UUID_PREFIX + uuid.replace("-", ""));
		} else {
		return UUID.fromString(uuid);
		}
		}

		/** {@hide} */
		public static String convert(UUID storageUuid) {
		@TestApi
		public static @NonNull String convert(@NonNull UUID storageUuid) {
		if (UUID_DEFAULT.equals(storageUuid)) {
		return UUID_PRIVATE_INTERNAL;
		} else if (UUID_PRIMARY_PHYSICAL_.equals(storageUuid)) {
		@@ -2642,6 +2670,17 @@ public class StorageManager {
		} else if (UUID_SYSTEM_.equals(storageUuid)) {
		return UUID_SYSTEM;
		} else {
		String uuidString = storageUuid.toString();
		// This prefix match will exclude fsUuids from private volumes because
		// (a) linux fsUuids are generally Version 4 (random) UUIDs so the prefix
		// will contain 4xxx instead of 5xxx and (b) we've already matched against
		// known namespace (Version 5) UUIDs above.
		if (uuidString.startsWith(FAT_UUID_PREFIX)) {
		String fatStr = uuidString.substring(FAT_UUID_PREFIX.length())
		.toUpperCase(Locale.US);
		return fatStr.substring(0, 4) + "-" + fatStr.substring(4);
		}

		return storageUuid.toString();
		}
		}