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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.os;
     18 
     19 import android.app.admin.DevicePolicyManager;
     20 import android.content.Context;
     21 import android.os.storage.StorageManager;
     22 import android.os.storage.StorageVolume;
     23 import android.text.TextUtils;
     24 import android.util.Log;
     25 
     26 import java.io.File;
     27 
     28 /**
     29  * Provides access to environment variables.
     30  */
     31 public class Environment {
     32     private static final String TAG = "Environment";
     33 
     34     private static final String ENV_EXTERNAL_STORAGE = "EXTERNAL_STORAGE";
     35     private static final String ENV_ANDROID_ROOT = "ANDROID_ROOT";
     36     private static final String ENV_ANDROID_DATA = "ANDROID_DATA";
     37     private static final String ENV_ANDROID_EXPAND = "ANDROID_EXPAND";
     38     private static final String ENV_ANDROID_STORAGE = "ANDROID_STORAGE";
     39     private static final String ENV_DOWNLOAD_CACHE = "DOWNLOAD_CACHE";
     40     private static final String ENV_OEM_ROOT = "OEM_ROOT";
     41     private static final String ENV_ODM_ROOT = "ODM_ROOT";
     42     private static final String ENV_VENDOR_ROOT = "VENDOR_ROOT";
     43 
     44     /** {@hide} */
     45     public static final String DIR_ANDROID = "Android";
     46     private static final String DIR_DATA = "data";
     47     private static final String DIR_MEDIA = "media";
     48     private static final String DIR_OBB = "obb";
     49     private static final String DIR_FILES = "files";
     50     private static final String DIR_CACHE = "cache";
     51 
     52     /** {@hide} */
     53     @Deprecated
     54     public static final String DIRECTORY_ANDROID = DIR_ANDROID;
     55 
     56     private static final File DIR_ANDROID_ROOT = getDirectory(ENV_ANDROID_ROOT, "/system");
     57     private static final File DIR_ANDROID_DATA = getDirectory(ENV_ANDROID_DATA, "/data");
     58     private static final File DIR_ANDROID_EXPAND = getDirectory(ENV_ANDROID_EXPAND, "/mnt/expand");
     59     private static final File DIR_ANDROID_STORAGE = getDirectory(ENV_ANDROID_STORAGE, "/storage");
     60     private static final File DIR_DOWNLOAD_CACHE = getDirectory(ENV_DOWNLOAD_CACHE, "/cache");
     61     private static final File DIR_OEM_ROOT = getDirectory(ENV_OEM_ROOT, "/oem");
     62     private static final File DIR_ODM_ROOT = getDirectory(ENV_ODM_ROOT, "/odm");
     63     private static final File DIR_VENDOR_ROOT = getDirectory(ENV_VENDOR_ROOT, "/vendor");
     64 
     65     private static UserEnvironment sCurrentUser;
     66     private static boolean sUserRequired;
     67 
     68     static {
     69         initForCurrentUser();
     70     }
     71 
     72     /** {@hide} */
     73     public static void initForCurrentUser() {
     74         final int userId = UserHandle.myUserId();
     75         sCurrentUser = new UserEnvironment(userId);
     76     }
     77 
     78     /** {@hide} */
     79     public static class UserEnvironment {
     80         private final int mUserId;
     81 
     82         public UserEnvironment(int userId) {
     83             mUserId = userId;
     84         }
     85 
     86         public File[] getExternalDirs() {
     87             final StorageVolume[] volumes = StorageManager.getVolumeList(mUserId,
     88                     StorageManager.FLAG_FOR_WRITE);
     89             final File[] files = new File[volumes.length];
     90             for (int i = 0; i < volumes.length; i++) {
     91                 files[i] = volumes[i].getPathFile();
     92             }
     93             return files;
     94         }
     95 
     96         @Deprecated
     97         public File getExternalStorageDirectory() {
     98             return getExternalDirs()[0];
     99         }
    100 
    101         @Deprecated
    102         public File getExternalStoragePublicDirectory(String type) {
    103             return buildExternalStoragePublicDirs(type)[0];
    104         }
    105 
    106         public File[] buildExternalStoragePublicDirs(String type) {
    107             return buildPaths(getExternalDirs(), type);
    108         }
    109 
    110         public File[] buildExternalStorageAndroidDataDirs() {
    111             return buildPaths(getExternalDirs(), DIR_ANDROID, DIR_DATA);
    112         }
    113 
    114         public File[] buildExternalStorageAndroidObbDirs() {
    115             return buildPaths(getExternalDirs(), DIR_ANDROID, DIR_OBB);
    116         }
    117 
    118         public File[] buildExternalStorageAppDataDirs(String packageName) {
    119             return buildPaths(getExternalDirs(), DIR_ANDROID, DIR_DATA, packageName);
    120         }
    121 
    122         public File[] buildExternalStorageAppMediaDirs(String packageName) {
    123             return buildPaths(getExternalDirs(), DIR_ANDROID, DIR_MEDIA, packageName);
    124         }
    125 
    126         public File[] buildExternalStorageAppObbDirs(String packageName) {
    127             return buildPaths(getExternalDirs(), DIR_ANDROID, DIR_OBB, packageName);
    128         }
    129 
    130         public File[] buildExternalStorageAppFilesDirs(String packageName) {
    131             return buildPaths(getExternalDirs(), DIR_ANDROID, DIR_DATA, packageName, DIR_FILES);
    132         }
    133 
    134         public File[] buildExternalStorageAppCacheDirs(String packageName) {
    135             return buildPaths(getExternalDirs(), DIR_ANDROID, DIR_DATA, packageName, DIR_CACHE);
    136         }
    137     }
    138 
    139     /**
    140      * Return root of the "system" partition holding the core Android OS.
    141      * Always present and mounted read-only.
    142      */
    143     public static File getRootDirectory() {
    144         return DIR_ANDROID_ROOT;
    145     }
    146 
    147     /** {@hide} */
    148     public static File getStorageDirectory() {
    149         return DIR_ANDROID_STORAGE;
    150     }
    151 
    152     /**
    153      * Return root directory of the "oem" partition holding OEM customizations,
    154      * if any. If present, the partition is mounted read-only.
    155      *
    156      * @hide
    157      */
    158     public static File getOemDirectory() {
    159         return DIR_OEM_ROOT;
    160     }
    161 
    162     /**
    163      * Return root directory of the "odm" partition holding ODM customizations,
    164      * if any. If present, the partition is mounted read-only.
    165      *
    166      * @hide
    167      */
    168     public static File getOdmDirectory() {
    169         return DIR_ODM_ROOT;
    170     }
    171 
    172     /**
    173      * Return root directory of the "vendor" partition that holds vendor-provided
    174      * software that should persist across simple reflashing of the "system" partition.
    175      * @hide
    176      */
    177     public static File getVendorDirectory() {
    178         return DIR_VENDOR_ROOT;
    179     }
    180 
    181     /**
    182      * Return the system directory for a user. This is for use by system
    183      * services to store files relating to the user. This directory will be
    184      * automatically deleted when the user is removed.
    185      *
    186      * @deprecated This directory is valid and still exists, but callers should
    187      *             <em>strongly</em> consider switching to
    188      *             {@link #getDataSystemCeDirectory(int)} which is protected
    189      *             with user credentials or
    190      *             {@link #getDataSystemDeDirectory(int)} which supports fast
    191      *             user wipe.
    192      * @hide
    193      */
    194     @Deprecated
    195     public static File getUserSystemDirectory(int userId) {
    196         return new File(new File(getDataSystemDirectory(), "users"), Integer.toString(userId));
    197     }
    198 
    199     /**
    200      * Returns the config directory for a user. This is for use by system
    201      * services to store files relating to the user which should be readable by
    202      * any app running as that user.
    203      *
    204      * @deprecated This directory is valid and still exists, but callers should
    205      *             <em>strongly</em> consider switching to
    206      *             {@link #getDataMiscCeDirectory(int)} which is protected with
    207      *             user credentials or {@link #getDataMiscDeDirectory(int)}
    208      *             which supports fast user wipe.
    209      * @hide
    210      */
    211     @Deprecated
    212     public static File getUserConfigDirectory(int userId) {
    213         return new File(new File(new File(
    214                 getDataDirectory(), "misc"), "user"), Integer.toString(userId));
    215     }
    216 
    217     /**
    218      * Return the user data directory.
    219      */
    220     public static File getDataDirectory() {
    221         return DIR_ANDROID_DATA;
    222     }
    223 
    224     /** {@hide} */
    225     public static File getDataDirectory(String volumeUuid) {
    226         if (TextUtils.isEmpty(volumeUuid)) {
    227             return DIR_ANDROID_DATA;
    228         } else {
    229             return new File("/mnt/expand/" + volumeUuid);
    230         }
    231     }
    232 
    233     /** {@hide} */
    234     public static File getExpandDirectory() {
    235         return DIR_ANDROID_EXPAND;
    236     }
    237 
    238     /** {@hide} */
    239     public static File getDataSystemDirectory() {
    240         return new File(getDataDirectory(), "system");
    241     }
    242 
    243     /**
    244      * Returns the base directory for per-user system directory, device encrypted.
    245      * {@hide}
    246      */
    247     public static File getDataSystemDeDirectory() {
    248         return buildPath(getDataDirectory(), "system_de");
    249     }
    250 
    251     /**
    252      * Returns the base directory for per-user system directory, credential encrypted.
    253      * {@hide}
    254      */
    255     public static File getDataSystemCeDirectory() {
    256         return buildPath(getDataDirectory(), "system_ce");
    257     }
    258 
    259     /** {@hide} */
    260     public static File getDataSystemCeDirectory(int userId) {
    261         return buildPath(getDataDirectory(), "system_ce", String.valueOf(userId));
    262     }
    263 
    264     /** {@hide} */
    265     public static File getDataSystemDeDirectory(int userId) {
    266         return buildPath(getDataDirectory(), "system_de", String.valueOf(userId));
    267     }
    268 
    269     /** {@hide} */
    270     public static File getDataMiscDirectory() {
    271         return new File(getDataDirectory(), "misc");
    272     }
    273 
    274     /** {@hide} */
    275     public static File getDataMiscCeDirectory(int userId) {
    276         return buildPath(getDataDirectory(), "misc_ce", String.valueOf(userId));
    277     }
    278 
    279     /** {@hide} */
    280     public static File getDataMiscDeDirectory(int userId) {
    281         return buildPath(getDataDirectory(), "misc_de", String.valueOf(userId));
    282     }
    283 
    284     private static File getDataProfilesDeDirectory(int userId) {
    285         return buildPath(getDataDirectory(), "misc", "profiles", "cur", String.valueOf(userId));
    286     }
    287 
    288     /** {@hide} */
    289     public static File getReferenceProfile(String packageName) {
    290         return buildPath(getDataDirectory(), "misc", "profiles", "ref", packageName);
    291     }
    292 
    293     /** {@hide} */
    294     public static File getDataProfilesDePackageDirectory(int userId, String packageName) {
    295         return buildPath(getDataProfilesDeDirectory(userId), packageName);
    296     }
    297 
    298     /** {@hide} */
    299     public static File getDataProfilesDeForeignDexDirectory(int userId) {
    300         return buildPath(getDataProfilesDeDirectory(userId), "foreign-dex");
    301     }
    302 
    303     /** {@hide} */
    304     public static File getDataAppDirectory(String volumeUuid) {
    305         return new File(getDataDirectory(volumeUuid), "app");
    306     }
    307 
    308     /** {@hide} */
    309     public static File getDataAppEphemeralDirectory(String volumeUuid) {
    310         return new File(getDataDirectory(volumeUuid), "app-ephemeral");
    311     }
    312 
    313     /** {@hide} */
    314     public static File getDataUserCeDirectory(String volumeUuid) {
    315         return new File(getDataDirectory(volumeUuid), "user");
    316     }
    317 
    318     /** {@hide} */
    319     public static File getDataUserCeDirectory(String volumeUuid, int userId) {
    320         return new File(getDataUserCeDirectory(volumeUuid), String.valueOf(userId));
    321     }
    322 
    323     /** {@hide} */
    324     public static File getDataUserCePackageDirectory(String volumeUuid, int userId,
    325             String packageName) {
    326         // TODO: keep consistent with installd
    327         return new File(getDataUserCeDirectory(volumeUuid, userId), packageName);
    328     }
    329 
    330     /** {@hide} */
    331     public static File getDataUserDeDirectory(String volumeUuid) {
    332         return new File(getDataDirectory(volumeUuid), "user_de");
    333     }
    334 
    335     /** {@hide} */
    336     public static File getDataUserDeDirectory(String volumeUuid, int userId) {
    337         return new File(getDataUserDeDirectory(volumeUuid), String.valueOf(userId));
    338     }
    339 
    340     /** {@hide} */
    341     public static File getDataUserDePackageDirectory(String volumeUuid, int userId,
    342             String packageName) {
    343         // TODO: keep consistent with installd
    344         return new File(getDataUserDeDirectory(volumeUuid, userId), packageName);
    345     }
    346 
    347     /**
    348      * Return preloads directory.
    349      * <p>This directory may contain pre-loaded content such as
    350      * {@link #getDataPreloadsDemoDirectory() demo videos} and
    351      * {@link #getDataPreloadsAppsDirectory() APK files} .
    352      * {@hide}
    353      */
    354     public static File getDataPreloadsDirectory() {
    355         return new File(getDataDirectory(), "preloads");
    356     }
    357 
    358     /**
    359      * @see #getDataPreloadsDirectory()
    360      * {@hide}
    361      */
    362     public static File getDataPreloadsDemoDirectory() {
    363         return new File(getDataPreloadsDirectory(), "demo");
    364     }
    365 
    366     /**
    367      * @see #getDataPreloadsDirectory()
    368      * {@hide}
    369      */
    370     public static File getDataPreloadsAppsDirectory() {
    371         return new File(getDataPreloadsDirectory(), "apps");
    372     }
    373 
    374     /**
    375      * @see #getDataPreloadsDirectory()
    376      * {@hide}
    377      */
    378     public static File getDataPreloadsMediaDirectory() {
    379         return new File(getDataPreloadsDirectory(), "media");
    380     }
    381 
    382     /**
    383      * Return the primary shared/external storage directory. This directory may
    384      * not currently be accessible if it has been mounted by the user on their
    385      * computer, has been removed from the device, or some other problem has
    386      * happened. You can determine its current state with
    387      * {@link #getExternalStorageState()}.
    388      * <p>
    389      * <em>Note: don't be confused by the word "external" here. This directory
    390      * can better be thought as media/shared storage. It is a filesystem that
    391      * can hold a relatively large amount of data and that is shared across all
    392      * applications (does not enforce permissions). Traditionally this is an SD
    393      * card, but it may also be implemented as built-in storage in a device that
    394      * is distinct from the protected internal storage and can be mounted as a
    395      * filesystem on a computer.</em>
    396      * <p>
    397      * On devices with multiple users (as described by {@link UserManager}),
    398      * each user has their own isolated shared storage. Applications only have
    399      * access to the shared storage for the user they're running as.
    400      * <p>
    401      * In devices with multiple shared/external storage directories, this
    402      * directory represents the primary storage that the user will interact
    403      * with. Access to secondary storage is available through
    404      * {@link Context#getExternalFilesDirs(String)},
    405      * {@link Context#getExternalCacheDirs()}, and
    406      * {@link Context#getExternalMediaDirs()}.
    407      * <p>
    408      * Applications should not directly use this top-level directory, in order
    409      * to avoid polluting the user's root namespace. Any files that are private
    410      * to the application should be placed in a directory returned by
    411      * {@link android.content.Context#getExternalFilesDir
    412      * Context.getExternalFilesDir}, which the system will take care of deleting
    413      * if the application is uninstalled. Other shared files should be placed in
    414      * one of the directories returned by
    415      * {@link #getExternalStoragePublicDirectory}.
    416      * <p>
    417      * Writing to this path requires the
    418      * {@link android.Manifest.permission#WRITE_EXTERNAL_STORAGE} permission,
    419      * and starting in {@link android.os.Build.VERSION_CODES#KITKAT}, read access requires the
    420      * {@link android.Manifest.permission#READ_EXTERNAL_STORAGE} permission,
    421      * which is automatically granted if you hold the write permission.
    422      * <p>
    423      * Starting in {@link android.os.Build.VERSION_CODES#KITKAT}, if your
    424      * application only needs to store internal data, consider using
    425      * {@link Context#getExternalFilesDir(String)},
    426      * {@link Context#getExternalCacheDir()}, or
    427      * {@link Context#getExternalMediaDirs()}, which require no permissions to
    428      * read or write.
    429      * <p>
    430      * This path may change between platform versions, so applications should
    431      * only persist relative paths.
    432      * <p>
    433      * Here is an example of typical code to monitor the state of external
    434      * storage:
    435      * <p>
    436      * {@sample development/samples/ApiDemos/src/com/example/android/apis/content/ExternalStorage.java
    437      * monitor_storage}
    438      *
    439      * @see #getExternalStorageState()
    440      * @see #isExternalStorageRemovable()
    441      */
    442     public static File getExternalStorageDirectory() {
    443         throwIfUserRequired();
    444         return sCurrentUser.getExternalDirs()[0];
    445     }
    446 
    447     /** {@hide} */
    448     public static File getLegacyExternalStorageDirectory() {
    449         return new File(System.getenv(ENV_EXTERNAL_STORAGE));
    450     }
    451 
    452     /** {@hide} */
    453     public static File getLegacyExternalStorageObbDirectory() {
    454         return buildPath(getLegacyExternalStorageDirectory(), DIR_ANDROID, DIR_OBB);
    455     }
    456 
    457     /**
    458      * Standard directory in which to place any audio files that should be
    459      * in the regular list of music for the user.
    460      * This may be combined with
    461      * {@link #DIRECTORY_PODCASTS}, {@link #DIRECTORY_NOTIFICATIONS},
    462      * {@link #DIRECTORY_ALARMS}, and {@link #DIRECTORY_RINGTONES} as a series
    463      * of directories to categories a particular audio file as more than one
    464      * type.
    465      */
    466     public static String DIRECTORY_MUSIC = "Music";
    467 
    468     /**
    469      * Standard directory in which to place any audio files that should be
    470      * in the list of podcasts that the user can select (not as regular
    471      * music).
    472      * This may be combined with {@link #DIRECTORY_MUSIC},
    473      * {@link #DIRECTORY_NOTIFICATIONS},
    474      * {@link #DIRECTORY_ALARMS}, and {@link #DIRECTORY_RINGTONES} as a series
    475      * of directories to categories a particular audio file as more than one
    476      * type.
    477      */
    478     public static String DIRECTORY_PODCASTS = "Podcasts";
    479 
    480     /**
    481      * Standard directory in which to place any audio files that should be
    482      * in the list of ringtones that the user can select (not as regular
    483      * music).
    484      * This may be combined with {@link #DIRECTORY_MUSIC},
    485      * {@link #DIRECTORY_PODCASTS}, {@link #DIRECTORY_NOTIFICATIONS}, and
    486      * {@link #DIRECTORY_ALARMS} as a series
    487      * of directories to categories a particular audio file as more than one
    488      * type.
    489      */
    490     public static String DIRECTORY_RINGTONES = "Ringtones";
    491 
    492     /**
    493      * Standard directory in which to place any audio files that should be
    494      * in the list of alarms that the user can select (not as regular
    495      * music).
    496      * This may be combined with {@link #DIRECTORY_MUSIC},
    497      * {@link #DIRECTORY_PODCASTS}, {@link #DIRECTORY_NOTIFICATIONS},
    498      * and {@link #DIRECTORY_RINGTONES} as a series
    499      * of directories to categories a particular audio file as more than one
    500      * type.
    501      */
    502     public static String DIRECTORY_ALARMS = "Alarms";
    503 
    504     /**
    505      * Standard directory in which to place any audio files that should be
    506      * in the list of notifications that the user can select (not as regular
    507      * music).
    508      * This may be combined with {@link #DIRECTORY_MUSIC},
    509      * {@link #DIRECTORY_PODCASTS},
    510      * {@link #DIRECTORY_ALARMS}, and {@link #DIRECTORY_RINGTONES} as a series
    511      * of directories to categories a particular audio file as more than one
    512      * type.
    513      */
    514     public static String DIRECTORY_NOTIFICATIONS = "Notifications";
    515 
    516     /**
    517      * Standard directory in which to place pictures that are available to
    518      * the user.  Note that this is primarily a convention for the top-level
    519      * public directory, as the media scanner will find and collect pictures
    520      * in any directory.
    521      */
    522     public static String DIRECTORY_PICTURES = "Pictures";
    523 
    524     /**
    525      * Standard directory in which to place movies that are available to
    526      * the user.  Note that this is primarily a convention for the top-level
    527      * public directory, as the media scanner will find and collect movies
    528      * in any directory.
    529      */
    530     public static String DIRECTORY_MOVIES = "Movies";
    531 
    532     /**
    533      * Standard directory in which to place files that have been downloaded by
    534      * the user.  Note that this is primarily a convention for the top-level
    535      * public directory, you are free to download files anywhere in your own
    536      * private directories.  Also note that though the constant here is
    537      * named DIRECTORY_DOWNLOADS (plural), the actual file name is non-plural for
    538      * backwards compatibility reasons.
    539      */
    540     public static String DIRECTORY_DOWNLOADS = "Download";
    541 
    542     /**
    543      * The traditional location for pictures and videos when mounting the
    544      * device as a camera.  Note that this is primarily a convention for the
    545      * top-level public directory, as this convention makes no sense elsewhere.
    546      */
    547     public static String DIRECTORY_DCIM = "DCIM";
    548 
    549     /**
    550      * Standard directory in which to place documents that have been created by
    551      * the user.
    552      */
    553     public static String DIRECTORY_DOCUMENTS = "Documents";
    554 
    555     /**
    556      * List of standard storage directories.
    557      * <p>
    558      * Each of its values have its own constant:
    559      * <ul>
    560      *   <li>{@link #DIRECTORY_MUSIC}
    561      *   <li>{@link #DIRECTORY_PODCASTS}
    562      *   <li>{@link #DIRECTORY_ALARMS}
    563      *   <li>{@link #DIRECTORY_RINGTONES}
    564      *   <li>{@link #DIRECTORY_NOTIFICATIONS}
    565      *   <li>{@link #DIRECTORY_PICTURES}
    566      *   <li>{@link #DIRECTORY_MOVIES}
    567      *   <li>{@link #DIRECTORY_DOWNLOADS}
    568      *   <li>{@link #DIRECTORY_DCIM}
    569      *   <li>{@link #DIRECTORY_DOCUMENTS}
    570      * </ul>
    571      * @hide
    572      */
    573     public static final String[] STANDARD_DIRECTORIES = {
    574             DIRECTORY_MUSIC,
    575             DIRECTORY_PODCASTS,
    576             DIRECTORY_RINGTONES,
    577             DIRECTORY_ALARMS,
    578             DIRECTORY_NOTIFICATIONS,
    579             DIRECTORY_PICTURES,
    580             DIRECTORY_MOVIES,
    581             DIRECTORY_DOWNLOADS,
    582             DIRECTORY_DCIM,
    583             DIRECTORY_DOCUMENTS
    584     };
    585 
    586     /**
    587      * @hide
    588      */
    589     public static boolean isStandardDirectory(String dir) {
    590         for (String valid : STANDARD_DIRECTORIES) {
    591             if (valid.equals(dir)) {
    592                 return true;
    593             }
    594         }
    595         return false;
    596     }
    597 
    598     /**
    599      * Get a top-level shared/external storage directory for placing files of a
    600      * particular type. This is where the user will typically place and manage
    601      * their own files, so you should be careful about what you put here to
    602      * ensure you don't erase their files or get in the way of their own
    603      * organization.
    604      * <p>
    605      * On devices with multiple users (as described by {@link UserManager}),
    606      * each user has their own isolated shared storage. Applications only have
    607      * access to the shared storage for the user they're running as.
    608      * </p>
    609      * <p>
    610      * Here is an example of typical code to manipulate a picture on the public
    611      * shared storage:
    612      * </p>
    613      * {@sample development/samples/ApiDemos/src/com/example/android/apis/content/ExternalStorage.java
    614      * public_picture}
    615      *
    616      * @param type The type of storage directory to return. Should be one of
    617      *            {@link #DIRECTORY_MUSIC}, {@link #DIRECTORY_PODCASTS},
    618      *            {@link #DIRECTORY_RINGTONES}, {@link #DIRECTORY_ALARMS},
    619      *            {@link #DIRECTORY_NOTIFICATIONS}, {@link #DIRECTORY_PICTURES},
    620      *            {@link #DIRECTORY_MOVIES}, {@link #DIRECTORY_DOWNLOADS},
    621      *            {@link #DIRECTORY_DCIM}, or {@link #DIRECTORY_DOCUMENTS}. May not be null.
    622      * @return Returns the File path for the directory. Note that this directory
    623      *         may not yet exist, so you must make sure it exists before using
    624      *         it such as with {@link File#mkdirs File.mkdirs()}.
    625      */
    626     public static File getExternalStoragePublicDirectory(String type) {
    627         throwIfUserRequired();
    628         return sCurrentUser.buildExternalStoragePublicDirs(type)[0];
    629     }
    630 
    631     /**
    632      * Returns the path for android-specific data on the SD card.
    633      * @hide
    634      */
    635     public static File[] buildExternalStorageAndroidDataDirs() {
    636         throwIfUserRequired();
    637         return sCurrentUser.buildExternalStorageAndroidDataDirs();
    638     }
    639 
    640     /**
    641      * Generates the raw path to an application's data
    642      * @hide
    643      */
    644     public static File[] buildExternalStorageAppDataDirs(String packageName) {
    645         throwIfUserRequired();
    646         return sCurrentUser.buildExternalStorageAppDataDirs(packageName);
    647     }
    648 
    649     /**
    650      * Generates the raw path to an application's media
    651      * @hide
    652      */
    653     public static File[] buildExternalStorageAppMediaDirs(String packageName) {
    654         throwIfUserRequired();
    655         return sCurrentUser.buildExternalStorageAppMediaDirs(packageName);
    656     }
    657 
    658     /**
    659      * Generates the raw path to an application's OBB files
    660      * @hide
    661      */
    662     public static File[] buildExternalStorageAppObbDirs(String packageName) {
    663         throwIfUserRequired();
    664         return sCurrentUser.buildExternalStorageAppObbDirs(packageName);
    665     }
    666 
    667     /**
    668      * Generates the path to an application's files.
    669      * @hide
    670      */
    671     public static File[] buildExternalStorageAppFilesDirs(String packageName) {
    672         throwIfUserRequired();
    673         return sCurrentUser.buildExternalStorageAppFilesDirs(packageName);
    674     }
    675 
    676     /**
    677      * Generates the path to an application's cache.
    678      * @hide
    679      */
    680     public static File[] buildExternalStorageAppCacheDirs(String packageName) {
    681         throwIfUserRequired();
    682         return sCurrentUser.buildExternalStorageAppCacheDirs(packageName);
    683     }
    684 
    685     /**
    686      * Return the download/cache content directory.
    687      */
    688     public static File getDownloadCacheDirectory() {
    689         return DIR_DOWNLOAD_CACHE;
    690     }
    691 
    692     /**
    693      * Unknown storage state, such as when a path isn't backed by known storage
    694      * media.
    695      *
    696      * @see #getExternalStorageState(File)
    697      */
    698     public static final String MEDIA_UNKNOWN = "unknown";
    699 
    700     /**
    701      * Storage state if the media is not present.
    702      *
    703      * @see #getExternalStorageState(File)
    704      */
    705     public static final String MEDIA_REMOVED = "removed";
    706 
    707     /**
    708      * Storage state if the media is present but not mounted.
    709      *
    710      * @see #getExternalStorageState(File)
    711      */
    712     public static final String MEDIA_UNMOUNTED = "unmounted";
    713 
    714     /**
    715      * Storage state if the media is present and being disk-checked.
    716      *
    717      * @see #getExternalStorageState(File)
    718      */
    719     public static final String MEDIA_CHECKING = "checking";
    720 
    721     /**
    722      * Storage state if the media is present but is blank or is using an
    723      * unsupported filesystem.
    724      *
    725      * @see #getExternalStorageState(File)
    726      */
    727     public static final String MEDIA_NOFS = "nofs";
    728 
    729     /**
    730      * Storage state if the media is present and mounted at its mount point with
    731      * read/write access.
    732      *
    733      * @see #getExternalStorageState(File)
    734      */
    735     public static final String MEDIA_MOUNTED = "mounted";
    736 
    737     /**
    738      * Storage state if the media is present and mounted at its mount point with
    739      * read-only access.
    740      *
    741      * @see #getExternalStorageState(File)
    742      */
    743     public static final String MEDIA_MOUNTED_READ_ONLY = "mounted_ro";
    744 
    745     /**
    746      * Storage state if the media is present not mounted, and shared via USB
    747      * mass storage.
    748      *
    749      * @see #getExternalStorageState(File)
    750      */
    751     public static final String MEDIA_SHARED = "shared";
    752 
    753     /**
    754      * Storage state if the media was removed before it was unmounted.
    755      *
    756      * @see #getExternalStorageState(File)
    757      */
    758     public static final String MEDIA_BAD_REMOVAL = "bad_removal";
    759 
    760     /**
    761      * Storage state if the media is present but cannot be mounted. Typically
    762      * this happens if the file system on the media is corrupted.
    763      *
    764      * @see #getExternalStorageState(File)
    765      */
    766     public static final String MEDIA_UNMOUNTABLE = "unmountable";
    767 
    768     /**
    769      * Storage state if the media is in the process of being ejected.
    770      *
    771      * @see #getExternalStorageState(File)
    772      */
    773     public static final String MEDIA_EJECTING = "ejecting";
    774 
    775     /**
    776      * Returns the current state of the primary shared/external storage media.
    777      *
    778      * @see #getExternalStorageDirectory()
    779      * @return one of {@link #MEDIA_UNKNOWN}, {@link #MEDIA_REMOVED},
    780      *         {@link #MEDIA_UNMOUNTED}, {@link #MEDIA_CHECKING},
    781      *         {@link #MEDIA_NOFS}, {@link #MEDIA_MOUNTED},
    782      *         {@link #MEDIA_MOUNTED_READ_ONLY}, {@link #MEDIA_SHARED},
    783      *         {@link #MEDIA_BAD_REMOVAL}, or {@link #MEDIA_UNMOUNTABLE}.
    784      */
    785     public static String getExternalStorageState() {
    786         final File externalDir = sCurrentUser.getExternalDirs()[0];
    787         return getExternalStorageState(externalDir);
    788     }
    789 
    790     /**
    791      * @deprecated use {@link #getExternalStorageState(File)}
    792      */
    793     @Deprecated
    794     public static String getStorageState(File path) {
    795         return getExternalStorageState(path);
    796     }
    797 
    798     /**
    799      * Returns the current state of the shared/external storage media at the
    800      * given path.
    801      *
    802      * @return one of {@link #MEDIA_UNKNOWN}, {@link #MEDIA_REMOVED},
    803      *         {@link #MEDIA_UNMOUNTED}, {@link #MEDIA_CHECKING},
    804      *         {@link #MEDIA_NOFS}, {@link #MEDIA_MOUNTED},
    805      *         {@link #MEDIA_MOUNTED_READ_ONLY}, {@link #MEDIA_SHARED},
    806      *         {@link #MEDIA_BAD_REMOVAL}, or {@link #MEDIA_UNMOUNTABLE}.
    807      */
    808     public static String getExternalStorageState(File path) {
    809         final StorageVolume volume = StorageManager.getStorageVolume(path, UserHandle.myUserId());
    810         if (volume != null) {
    811             return volume.getState();
    812         } else {
    813             return MEDIA_UNKNOWN;
    814         }
    815     }
    816 
    817     /**
    818      * Returns whether the primary shared/external storage media is physically
    819      * removable.
    820      *
    821      * @return true if the storage device can be removed (such as an SD card),
    822      *         or false if the storage device is built in and cannot be
    823      *         physically removed.
    824      */
    825     public static boolean isExternalStorageRemovable() {
    826         if (isStorageDisabled()) return false;
    827         final File externalDir = sCurrentUser.getExternalDirs()[0];
    828         return isExternalStorageRemovable(externalDir);
    829     }
    830 
    831     /**
    832      * Returns whether the shared/external storage media at the given path is
    833      * physically removable.
    834      *
    835      * @return true if the storage device can be removed (such as an SD card),
    836      *         or false if the storage device is built in and cannot be
    837      *         physically removed.
    838      * @throws IllegalArgumentException if the path is not a valid storage
    839      *             device.
    840      */
    841     public static boolean isExternalStorageRemovable(File path) {
    842         final StorageVolume volume = StorageManager.getStorageVolume(path, UserHandle.myUserId());
    843         if (volume != null) {
    844             return volume.isRemovable();
    845         } else {
    846             throw new IllegalArgumentException("Failed to find storage device at " + path);
    847         }
    848     }
    849 
    850     /**
    851      * Returns whether the primary shared/external storage media is emulated.
    852      * <p>
    853      * The contents of emulated storage devices are backed by a private user
    854      * data partition, which means there is little benefit to apps storing data
    855      * here instead of the private directories returned by
    856      * {@link Context#getFilesDir()}, etc.
    857      * <p>
    858      * This returns true when emulated storage is backed by either internal
    859      * storage or an adopted storage device.
    860      *
    861      * @see DevicePolicyManager#setStorageEncryption(android.content.ComponentName,
    862      *      boolean)
    863      */
    864     public static boolean isExternalStorageEmulated() {
    865         if (isStorageDisabled()) return false;
    866         final File externalDir = sCurrentUser.getExternalDirs()[0];
    867         return isExternalStorageEmulated(externalDir);
    868     }
    869 
    870     /**
    871      * Returns whether the shared/external storage media at the given path is
    872      * emulated.
    873      * <p>
    874      * The contents of emulated storage devices are backed by a private user
    875      * data partition, which means there is little benefit to apps storing data
    876      * here instead of the private directories returned by
    877      * {@link Context#getFilesDir()}, etc.
    878      * <p>
    879      * This returns true when emulated storage is backed by either internal
    880      * storage or an adopted storage device.
    881      *
    882      * @throws IllegalArgumentException if the path is not a valid storage
    883      *             device.
    884      */
    885     public static boolean isExternalStorageEmulated(File path) {
    886         final StorageVolume volume = StorageManager.getStorageVolume(path, UserHandle.myUserId());
    887         if (volume != null) {
    888             return volume.isEmulated();
    889         } else {
    890             throw new IllegalArgumentException("Failed to find storage device at " + path);
    891         }
    892     }
    893 
    894     static File getDirectory(String variableName, String defaultPath) {
    895         String path = System.getenv(variableName);
    896         return path == null ? new File(defaultPath) : new File(path);
    897     }
    898 
    899     /** {@hide} */
    900     public static void setUserRequired(boolean userRequired) {
    901         sUserRequired = userRequired;
    902     }
    903 
    904     private static void throwIfUserRequired() {
    905         if (sUserRequired) {
    906             Log.wtf(TAG, "Path requests must specify a user by using UserEnvironment",
    907                     new Throwable());
    908         }
    909     }
    910 
    911     /**
    912      * Append path segments to each given base path, returning result.
    913      *
    914      * @hide
    915      */
    916     public static File[] buildPaths(File[] base, String... segments) {
    917         File[] result = new File[base.length];
    918         for (int i = 0; i < base.length; i++) {
    919             result[i] = buildPath(base[i], segments);
    920         }
    921         return result;
    922     }
    923 
    924     /**
    925      * Append path segments to given base path, returning result.
    926      *
    927      * @hide
    928      */
    929     public static File buildPath(File base, String... segments) {
    930         File cur = base;
    931         for (String segment : segments) {
    932             if (cur == null) {
    933                 cur = new File(segment);
    934             } else {
    935                 cur = new File(cur, segment);
    936             }
    937         }
    938         return cur;
    939     }
    940 
    941     private static boolean isStorageDisabled() {
    942         return SystemProperties.getBoolean("config.disable_storage", false);
    943     }
    944 
    945     /**
    946      * If the given path exists on emulated external storage, return the
    947      * translated backing path hosted on internal storage. This bypasses any
    948      * emulation later, improving performance. This is <em>only</em> suitable
    949      * for read-only access.
    950      * <p>
    951      * Returns original path if given path doesn't meet these criteria. Callers
    952      * must hold {@link android.Manifest.permission#WRITE_MEDIA_STORAGE}
    953      * permission.
    954      *
    955      * @hide
    956      */
    957     public static File maybeTranslateEmulatedPathToInternal(File path) {
    958         return StorageManager.maybeTranslateEmulatedPathToInternal(path);
    959     }
    960 }
    961