Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.os; import android.annotation.AppIdInt; import android.annotation.SystemApi; import android.annotation.TestApi; import android.annotation.UnsupportedAppUsage; import android.annotation.UserIdInt; import java.io.PrintWriter; /** * Representation of a user on the device. */ public final class UserHandle implements Parcelable { // NOTE: keep logic in sync with system/core/libcutils/multiuser.c /** * @hide Range of uids allocated for a user. */ @UnsupportedAppUsage public static final int PER_USER_RANGE = 100000; /** @hide A user id to indicate all users on the device */ @UnsupportedAppUsage public static final @UserIdInt int USER_ALL = -1; /** @hide A user handle to indicate all users on the device */ @SystemApi @TestApi public static final UserHandle ALL = new UserHandle(USER_ALL); /** @hide A user id to indicate the currently active user */ @UnsupportedAppUsage public static final @UserIdInt int USER_CURRENT = -2; /** @hide A user handle to indicate the current user of the device */ @SystemApi @TestApi public static final UserHandle CURRENT = new UserHandle(USER_CURRENT); /** @hide A user id to indicate that we would like to send to the current * user, but if this is calling from a user process then we will send it * to the caller's user instead of failing with a security exception */ @UnsupportedAppUsage public static final @UserIdInt int USER_CURRENT_OR_SELF = -3; /** @hide A user handle to indicate that we would like to send to the current * user, but if this is calling from a user process then we will send it * to the caller's user instead of failing with a security exception */ @UnsupportedAppUsage public static final UserHandle CURRENT_OR_SELF = new UserHandle(USER_CURRENT_OR_SELF); /** @hide An undefined user id */ @UnsupportedAppUsage public static final @UserIdInt int USER_NULL = -10000; /** * @hide A user id constant to indicate the "owner" user of the device * @deprecated Consider using either {@link UserHandle#USER_SYSTEM} constant or * check the target user's flag {@link android.content.pm.UserInfo#isAdmin}. */ @UnsupportedAppUsage @Deprecated public static final @UserIdInt int USER_OWNER = 0; /** * @hide A user handle to indicate the primary/owner user of the device * @deprecated Consider using either {@link UserHandle#SYSTEM} constant or * check the target user's flag {@link android.content.pm.UserInfo#isAdmin}. */ @UnsupportedAppUsage @Deprecated public static final UserHandle OWNER = new UserHandle(USER_OWNER); /** @hide A user id constant to indicate the "system" user of the device */ @UnsupportedAppUsage public static final @UserIdInt int USER_SYSTEM = 0; /** @hide A user serial constant to indicate the "system" user of the device */ @UnsupportedAppUsage public static final int USER_SERIAL_SYSTEM = 0; /** @hide A user handle to indicate the "system" user of the device */ @SystemApi @TestApi public static final UserHandle SYSTEM = new UserHandle(USER_SYSTEM); /** * @hide Enable multi-user related side effects. Set this to false if * there are problems with single user use-cases. */ @UnsupportedAppUsage public static final boolean MU_ENABLED = true; /** @hide */ @UnsupportedAppUsage public static final int ERR_GID = -1; /** @hide */ @UnsupportedAppUsage public static final int AID_ROOT = android.os.Process.ROOT_UID; /** @hide */ @UnsupportedAppUsage public static final int AID_APP_START = android.os.Process.FIRST_APPLICATION_UID; /** @hide */ @UnsupportedAppUsage public static final int AID_APP_END = android.os.Process.LAST_APPLICATION_UID; /** @hide */ @UnsupportedAppUsage public static final int AID_SHARED_GID_START = android.os.Process.FIRST_SHARED_APPLICATION_GID; /** @hide */ @UnsupportedAppUsage public static final int AID_CACHE_GID_START = android.os.Process.FIRST_APPLICATION_CACHE_GID; @UnsupportedAppUsage final int mHandle; /** * Checks to see if the user id is the same for the two uids, i.e., they belong to the same * user. * @hide */ public static boolean isSameUser(int uid1, int uid2) { return getUserId(uid1) == getUserId(uid2); } /** * Checks to see if both uids are referring to the same app id, ignoring the user id part of the * uids. * @param uid1 uid to compare * @param uid2 other uid to compare * @return whether the appId is the same for both uids * @hide */ @UnsupportedAppUsage public static boolean isSameApp(int uid1, int uid2) { return getAppId(uid1) == getAppId(uid2); } /** * Whether a UID is an "isolated" UID. * @hide */ @UnsupportedAppUsage public static boolean isIsolated(int uid) { if (uid > 0) { final int appId = getAppId(uid); return appId >= Process.FIRST_ISOLATED_UID && appId <= Process.LAST_ISOLATED_UID; } else { return false; } } /** * Whether a UID belongs to a regular app. *Note* "Not a regular app" does not mean * "it's system", because of isolated UIDs. Use {@link #isCore} for that. * @hide */ @UnsupportedAppUsage public static boolean isApp(int uid) { if (uid > 0) { final int appId = getAppId(uid); return appId >= Process.FIRST_APPLICATION_UID && appId <= Process.LAST_APPLICATION_UID; } else { return false; } } /** * Whether a UID belongs to a system core component or not. * @hide */ public static boolean isCore(int uid) { if (uid >= 0) { final int appId = getAppId(uid); return appId < Process.FIRST_APPLICATION_UID; } else { return false; } } /** * Returns the user for a given uid. * @param uid A uid for an application running in a particular user. * @return A {@link UserHandle} for that user. */ public static UserHandle getUserHandleForUid(int uid) { return of(getUserId(uid)); } /** * Returns the user id for a given uid. * @hide */ @UnsupportedAppUsage public static @UserIdInt int getUserId(int uid) { if (MU_ENABLED) { return uid / PER_USER_RANGE; } else { return UserHandle.USER_SYSTEM; } } /** @hide */ @UnsupportedAppUsage public static @UserIdInt int getCallingUserId() { return getUserId(Binder.getCallingUid()); } /** @hide */ public static @AppIdInt int getCallingAppId() { return getAppId(Binder.getCallingUid()); } /** @hide */ @SystemApi public static UserHandle of(@UserIdInt int userId) { return userId == USER_SYSTEM ? SYSTEM : new UserHandle(userId); } /** * Returns the uid that is composed from the userId and the appId. * @hide */ @UnsupportedAppUsage public static int getUid(@UserIdInt int userId, @AppIdInt int appId) { if (MU_ENABLED) { return userId * PER_USER_RANGE + (appId % PER_USER_RANGE); } else { return appId; } } /** * Returns the app id (or base uid) for a given uid, stripping out the user id from it. * @hide */ @TestApi @SystemApi public static @AppIdInt int getAppId(int uid) { return uid % PER_USER_RANGE; } /** * Returns the gid shared between all apps with this userId. * @hide */ public static int getUserGid(@UserIdInt int userId) { return getUid(userId, Process.SHARED_USER_GID); } /** @hide */ public static int getSharedAppGid(int uid) { return getSharedAppGid(getUserId(uid), getAppId(uid)); } /** @hide */ public static int getSharedAppGid(int userId, int appId) { if (appId >= AID_APP_START && appId <= AID_APP_END) { return (appId - AID_APP_START) + AID_SHARED_GID_START; } else if (appId >= AID_ROOT && appId <= AID_APP_START) { return appId; } else { return -1; } } /** * Returns the app id for a given shared app gid. Returns -1 if the ID is invalid. * @hide */ @UnsupportedAppUsage public static @AppIdInt int getAppIdFromSharedAppGid(int gid) { final int appId = getAppId(gid) + Process.FIRST_APPLICATION_UID - Process.FIRST_SHARED_APPLICATION_GID; if (appId < 0 || appId >= Process.FIRST_SHARED_APPLICATION_GID) { return -1; } return appId; } /** @hide */ public static int getCacheAppGid(int uid) { return getCacheAppGid(getUserId(uid), getAppId(uid)); } /** @hide */ public static int getCacheAppGid(int userId, int appId) { if (appId >= AID_APP_START && appId <= AID_APP_END) { return getUid(userId, (appId - AID_APP_START) + AID_CACHE_GID_START); } else { return -1; } } /** * Generate a text representation of the uid, breaking out its individual * components -- user, app, isolated, etc. * @hide */ public static void formatUid(StringBuilder sb, int uid) { if (uid < Process.FIRST_APPLICATION_UID) { sb.append(uid); } else { sb.append('u'); sb.append(getUserId(uid)); final int appId = getAppId(uid); if (appId >= Process.FIRST_ISOLATED_UID && appId <= Process.LAST_ISOLATED_UID) { sb.append('i'); sb.append(appId - Process.FIRST_ISOLATED_UID); } else if (appId >= Process.FIRST_APPLICATION_UID) { sb.append('a'); sb.append(appId - Process.FIRST_APPLICATION_UID); } else { sb.append('s'); sb.append(appId); } } } /** * Generate a text representation of the uid, breaking out its individual * components -- user, app, isolated, etc. * @hide */ public static String formatUid(int uid) { StringBuilder sb = new StringBuilder(); formatUid(sb, uid); return sb.toString(); } /** * Generate a text representation of the uid, breaking out its individual * components -- user, app, isolated, etc. * @hide */ public static void formatUid(PrintWriter pw, int uid) { if (uid < Process.FIRST_APPLICATION_UID) { pw.print(uid); } else { pw.print('u'); pw.print(getUserId(uid)); final int appId = getAppId(uid); if (appId >= Process.FIRST_ISOLATED_UID && appId <= Process.LAST_ISOLATED_UID) { pw.print('i'); pw.print(appId - Process.FIRST_ISOLATED_UID); } else if (appId >= Process.FIRST_APPLICATION_UID) { pw.print('a'); pw.print(appId - Process.FIRST_APPLICATION_UID); } else { pw.print('s'); pw.print(appId); } } } /** @hide */ public static @UserIdInt int parseUserArg(String arg) { int userId; if ("all".equals(arg)) { userId = UserHandle.USER_ALL; } else if ("current".equals(arg) || "cur".equals(arg)) { userId = UserHandle.USER_CURRENT; } else { try { userId = Integer.parseInt(arg); } catch (NumberFormatException e) { throw new IllegalArgumentException("Bad user number: " + arg); } } return userId; } /** * Returns the user id of the current process * @return user id of the current process * @hide */ @SystemApi public static @UserIdInt int myUserId() { return getUserId(Process.myUid()); } /** * Returns true if this UserHandle refers to the owner user; false otherwise. * @return true if this UserHandle refers to the owner user; false otherwise. * @hide * @deprecated please use {@link #isSystem()} or check for * {@link android.content.pm.UserInfo#isPrimary()} * {@link android.content.pm.UserInfo#isAdmin()} based on your particular use case. */ @Deprecated @SystemApi public boolean isOwner() { return this.equals(OWNER); } /** * @return true if this UserHandle refers to the system user; false otherwise. * @hide */ @SystemApi public boolean isSystem() { return this.equals(SYSTEM); } /** @hide */ @UnsupportedAppUsage public UserHandle(int h) { mHandle = h; } /** * Returns the userId stored in this UserHandle. * @hide */ @SystemApi @TestApi public @UserIdInt int getIdentifier() { return mHandle; } @Override public String toString() { return "UserHandle{" + mHandle + "}"; } @Override public boolean equals(Object obj) { try { if (obj != null) { UserHandle other = (UserHandle) obj; return mHandle == other.mHandle; } } catch (ClassCastException e) { } return false; } @Override public int hashCode() { return mHandle; } public int describeContents() { return 0; } public void writeToParcel(Parcel out, int flags) { out.writeInt(mHandle); } /** * Write a UserHandle to a Parcel, handling null pointers. Must be * read with {@link #readFromParcel(Parcel)}. * * @param h The UserHandle to be written. * @param out The Parcel in which the UserHandle will be placed. * * @see #readFromParcel(Parcel) */ public static void writeToParcel(UserHandle h, Parcel out) { if (h != null) { h.writeToParcel(out, 0); } else { out.writeInt(USER_NULL); } } /** * Read a UserHandle from a Parcel that was previously written * with {@link #writeToParcel(UserHandle, Parcel)}, returning either * a null or new object as appropriate. * * @param in The Parcel from which to read the UserHandle * @return Returns a new UserHandle matching the previously written * object, or null if a null had been written. * * @see #writeToParcel(UserHandle, Parcel) */ public static UserHandle readFromParcel(Parcel in) { int h = in.readInt(); return h != USER_NULL ? new UserHandle(h) : null; } public static final Parcelable.Creator<UserHandle> CREATOR = new Parcelable.Creator<UserHandle>() { public UserHandle createFromParcel(Parcel in) { return new UserHandle(in); } public UserHandle[] newArray(int size) { return new UserHandle[size]; } }; /** * Instantiate a new UserHandle from the data in a Parcel that was * previously written with {@link #writeToParcel(Parcel, int)}. Note that you * must not use this with data written by * {@link #writeToParcel(UserHandle, Parcel)} since it is not possible * to handle a null UserHandle here. * * @param in The Parcel containing the previously written UserHandle, * positioned at the location in the buffer where it was written. */ public UserHandle(Parcel in) { mHandle = in.readInt(); } }