Utility methods useful for working with files.

Part of getting DocumentsUI ready for building against public API.

Test: builds
Bug: 110959821
Change-Id: I7cc0acd5ac3bcc89790cb49f34291ae523e44019

1 files changed, 192 insertions, 64 deletions

diff --git a/core/java/android/os/FileUtils.java b/core/java/android/os/FileUtils.java
index 88d6e847b644..9fccd1ec7b43 100644
--- a/core/java/android/os/FileUtils.java
+++ b/core/java/android/os/FileUtils.java
@@ -53,32 +53,35 @@ import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.Comparator;
 import java.util.Objects;
+import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.regex.Pattern;
 import java.util.zip.CRC32;
 import java.util.zip.CheckedInputStream;
 
 /**
- * Tools for managing files.  Not for public consumption.
- * @hide
+ * Utility methods useful for working with files.
  */
 public class FileUtils {
     private static final String TAG = "FileUtils";
 
-    public static final int S_IRWXU = 00700;
-    public static final int S_IRUSR = 00400;
-    public static final int S_IWUSR = 00200;
-    public static final int S_IXUSR = 00100;
+    /** {@hide} */ public static final int S_IRWXU = 00700;
+    /** {@hide} */ public static final int S_IRUSR = 00400;
+    /** {@hide} */ public static final int S_IWUSR = 00200;
+    /** {@hide} */ public static final int S_IXUSR = 00100;
 
-    public static final int S_IRWXG = 00070;
-    public static final int S_IRGRP = 00040;
-    public static final int S_IWGRP = 00020;
-    public static final int S_IXGRP = 00010;
+    /** {@hide} */ public static final int S_IRWXG = 00070;
+    /** {@hide} */ public static final int S_IRGRP = 00040;
+    /** {@hide} */ public static final int S_IWGRP = 00020;
+    /** {@hide} */ public static final int S_IXGRP = 00010;
 
-    public static final int S_IRWXO = 00007;
-    public static final int S_IROTH = 00004;
-    public static final int S_IWOTH = 00002;
-    public static final int S_IXOTH = 00001;
+    /** {@hide} */ public static final int S_IRWXO = 00007;
+    /** {@hide} */ public static final int S_IROTH = 00004;
+    /** {@hide} */ public static final int S_IWOTH = 00002;
+    /** {@hide} */ public static final int S_IXOTH = 00001;
+
+    private FileUtils() {
+    }
 
     /** Regular expression for safe filenames: no spaces or metacharacters.
       *
@@ -94,6 +97,9 @@ public class FileUtils {
 
     private static final long COPY_CHECKPOINT_BYTES = 524288;
 
+    /**
+     * Listener that is called periodically as progress is made.
+     */
     public interface ProgressListener {
         public void onProgress(long progress);
     }
@@ -105,6 +111,7 @@ public class FileUtils {
      * @param uid to apply through {@code chown}, or -1 to leave unchanged
      * @param gid to apply through {@code chown}, or -1 to leave unchanged
      * @return 0 on success, otherwise errno.
+     * @hide
      */
     public static int setPermissions(File path, int mode, int uid, int gid) {
         return setPermissions(path.getAbsolutePath(), mode, uid, gid);
@@ -117,6 +124,7 @@ public class FileUtils {
      * @param uid to apply through {@code chown}, or -1 to leave unchanged
      * @param gid to apply through {@code chown}, or -1 to leave unchanged
      * @return 0 on success, otherwise errno.
+     * @hide
      */
     public static int setPermissions(String path, int mode, int uid, int gid) {
         try {
@@ -145,6 +153,7 @@ public class FileUtils {
      * @param uid to apply through {@code chown}, or -1 to leave unchanged
      * @param gid to apply through {@code chown}, or -1 to leave unchanged
      * @return 0 on success, otherwise errno.
+     * @hide
      */
     public static int setPermissions(FileDescriptor fd, int mode, int uid, int gid) {
         try {
@@ -166,7 +175,14 @@ public class FileUtils {
         return 0;
     }
 
-    public static void copyPermissions(File from, File to) throws IOException {
+    /**
+     * Copy the owner UID, owner GID, and mode bits from one file to another.
+     *
+     * @param from File where attributes should be copied from.
+     * @param to File where attributes should be copied to.
+     * @hide
+     */
+    public static void copyPermissions(@NonNull File from, @NonNull File to) throws IOException {
         try {
             final StructStat stat = Os.stat(from.getAbsolutePath());
             Os.chmod(to.getAbsolutePath(), stat.st_mode);
@@ -177,8 +193,10 @@ public class FileUtils {
     }
 
     /**
-     * Return owning UID of given path, otherwise -1.
+     * @deprecated use {@link Os#stat(String)} instead.
+     * @hide
      */
+    @Deprecated
     public static int getUid(String path) {
         try {
             return Os.stat(path).st_uid;
@@ -190,6 +208,8 @@ public class FileUtils {
     /**
      * Perform an fsync on the given FileOutputStream.  The stream at this
      * point must be flushed but not yet closed.
+     *
+     * @hide
      */
     public static boolean sync(FileOutputStream stream) {
         try {
@@ -204,6 +224,7 @@ public class FileUtils {
 
     /**
      * @deprecated use {@link #copy(File, File)} instead.
+     * @hide
      */
     @Deprecated
     public static boolean copyFile(File srcFile, File destFile) {
@@ -217,6 +238,7 @@ public class FileUtils {
 
     /**
      * @deprecated use {@link #copy(File, File)} instead.
+     * @hide
      */
     @Deprecated
     public static void copyFileOrThrow(File srcFile, File destFile) throws IOException {
@@ -227,6 +249,7 @@ public class FileUtils {
 
     /**
      * @deprecated use {@link #copy(InputStream, OutputStream)} instead.
+     * @hide
      */
     @Deprecated
     public static boolean copyToFile(InputStream inputStream, File destFile) {
@@ -240,6 +263,7 @@ public class FileUtils {
 
     /**
      * @deprecated use {@link #copy(InputStream, OutputStream)} instead.
+     * @hide
      */
     @Deprecated
     public static void copyToFileOrThrow(InputStream in, File destFile) throws IOException {
@@ -265,7 +289,7 @@ public class FileUtils {
      * @return number of bytes copied.
      */
     public static long copy(@NonNull File from, @NonNull File to) throws IOException {
-        return copy(from, to, null, null);
+        return copy(from, to, null, null, null);
     }
 
     /**
@@ -274,16 +298,17 @@ public class FileUtils {
      * Attempts to use several optimization strategies to copy the data in the
      * kernel before falling back to a userspace copy as a last resort.
      *
-     * @param listener to be periodically notified as the copy progresses.
      * @param signal to signal if the copy should be cancelled early.
+     * @param executor that listener events should be delivered via.
+     * @param listener to be periodically notified as the copy progresses.
      * @return number of bytes copied.
      */
     public static long copy(@NonNull File from, @NonNull File to,
-            @Nullable ProgressListener listener, @Nullable CancellationSignal signal)
-            throws IOException {
+            @Nullable CancellationSignal signal, @Nullable Executor executor,
+            @Nullable ProgressListener listener) throws IOException {
         try (FileInputStream in = new FileInputStream(from);
                 FileOutputStream out = new FileOutputStream(to)) {
-            return copy(in, out, listener, signal);
+            return copy(in, out, signal, executor, listener);
         }
     }
 
@@ -296,7 +321,7 @@ public class FileUtils {
      * @return number of bytes copied.
      */
     public static long copy(@NonNull InputStream in, @NonNull OutputStream out) throws IOException {
-        return copy(in, out, null, null);
+        return copy(in, out, null, null, null);
     }
 
     /**
@@ -305,22 +330,23 @@ public class FileUtils {
      * Attempts to use several optimization strategies to copy the data in the
      * kernel before falling back to a userspace copy as a last resort.
      *
-     * @param listener to be periodically notified as the copy progresses.
      * @param signal to signal if the copy should be cancelled early.
+     * @param executor that listener events should be delivered via.
+     * @param listener to be periodically notified as the copy progresses.
      * @return number of bytes copied.
      */
     public static long copy(@NonNull InputStream in, @NonNull OutputStream out,
-            @Nullable ProgressListener listener, @Nullable CancellationSignal signal)
-            throws IOException {
+            @Nullable CancellationSignal signal, @Nullable Executor executor,
+            @Nullable ProgressListener listener) throws IOException {
         if (ENABLE_COPY_OPTIMIZATIONS) {
             if (in instanceof FileInputStream && out instanceof FileOutputStream) {
                 return copy(((FileInputStream) in).getFD(), ((FileOutputStream) out).getFD(),
-                        listener, signal);
+                        signal, executor, listener);
             }
         }
 
         // Worse case fallback to userspace
-        return copyInternalUserspace(in, out, listener, signal);
+        return copyInternalUserspace(in, out, signal, executor, listener);
     }
 
     /**
@@ -333,7 +359,7 @@ public class FileUtils {
      */
     public static long copy(@NonNull FileDescriptor in, @NonNull FileDescriptor out)
             throws IOException {
-        return copy(in, out, null, null);
+        return copy(in, out, null, null, null);
     }
 
     /**
@@ -342,14 +368,15 @@ public class FileUtils {
      * Attempts to use several optimization strategies to copy the data in the
      * kernel before falling back to a userspace copy as a last resort.
      *
-     * @param listener to be periodically notified as the copy progresses.
      * @param signal to signal if the copy should be cancelled early.
+     * @param executor that listener events should be delivered via.
+     * @param listener to be periodically notified as the copy progresses.
      * @return number of bytes copied.
      */
     public static long copy(@NonNull FileDescriptor in, @NonNull FileDescriptor out,
-            @Nullable ProgressListener listener, @Nullable CancellationSignal signal)
-            throws IOException {
-        return copy(in, out, listener, signal, Long.MAX_VALUE);
+            @Nullable CancellationSignal signal, @Nullable Executor executor,
+            @Nullable ProgressListener listener) throws IOException {
+        return copy(in, out, Long.MAX_VALUE, signal, executor, listener);
     }
 
     /**
@@ -358,22 +385,24 @@ public class FileUtils {
      * Attempts to use several optimization strategies to copy the data in the
      * kernel before falling back to a userspace copy as a last resort.
      *
-     * @param listener to be periodically notified as the copy progresses.
-     * @param signal to signal if the copy should be cancelled early.
      * @param count the number of bytes to copy.
+     * @param signal to signal if the copy should be cancelled early.
+     * @param executor that listener events should be delivered via.
+     * @param listener to be periodically notified as the copy progresses.
      * @return number of bytes copied.
+     * @hide
      */
-    public static long copy(@NonNull FileDescriptor in, @NonNull FileDescriptor out,
-            @Nullable ProgressListener listener, @Nullable CancellationSignal signal, long count)
-            throws IOException {
+    public static long copy(@NonNull FileDescriptor in, @NonNull FileDescriptor out, long count,
+            @Nullable CancellationSignal signal, @Nullable Executor executor,
+            @Nullable ProgressListener listener) throws IOException {
         if (ENABLE_COPY_OPTIMIZATIONS) {
             try {
                 final StructStat st_in = Os.fstat(in);
                 final StructStat st_out = Os.fstat(out);
                 if (S_ISREG(st_in.st_mode) && S_ISREG(st_out.st_mode)) {
-                    return copyInternalSendfile(in, out, listener, signal, count);
+                    return copyInternalSendfile(in, out, count, signal, executor, listener);
                 } else if (S_ISFIFO(st_in.st_mode) || S_ISFIFO(st_out.st_mode)) {
-                    return copyInternalSplice(in, out, listener, signal, count);
+                    return copyInternalSplice(in, out, count, signal, executor, listener);
                 }
             } catch (ErrnoException e) {
                 throw e.rethrowAsIOException();
@@ -381,15 +410,17 @@ public class FileUtils {
         }
 
         // Worse case fallback to userspace
-        return copyInternalUserspace(in, out, listener, signal, count);
+        return copyInternalUserspace(in, out, count, signal, executor, listener);
     }
 
     /**
      * Requires one of input or output to be a pipe.
+     *
+     * @hide
      */
     @VisibleForTesting
-    public static long copyInternalSplice(FileDescriptor in, FileDescriptor out,
-            ProgressListener listener, CancellationSignal signal, long count)
+    public static long copyInternalSplice(FileDescriptor in, FileDescriptor out, long count,
+            CancellationSignal signal, Executor executor, ProgressListener listener)
             throws ErrnoException {
         long progress = 0;
         long checkpoint = 0;
@@ -405,24 +436,32 @@ public class FileUtils {
                 if (signal != null) {
                     signal.throwIfCanceled();
                 }
-                if (listener != null) {
-                    listener.onProgress(progress);
+                if (executor != null && listener != null) {
+                    final long progressSnapshot = progress;
+                    executor.execute(() -> {
+                        listener.onProgress(progressSnapshot);
+                    });
                 }
                 checkpoint = 0;
             }
         }
-        if (listener != null) {
-            listener.onProgress(progress);
+        if (executor != null && listener != null) {
+            final long progressSnapshot = progress;
+            executor.execute(() -> {
+                listener.onProgress(progressSnapshot);
+            });
         }
         return progress;
     }
 
     /**
      * Requires both input and output to be a regular file.
+     *
+     * @hide
      */
     @VisibleForTesting
-    public static long copyInternalSendfile(FileDescriptor in, FileDescriptor out,
-            ProgressListener listener, CancellationSignal signal, long count)
+    public static long copyInternalSendfile(FileDescriptor in, FileDescriptor out, long count,
+            CancellationSignal signal, Executor executor, ProgressListener listener)
             throws ErrnoException {
         long progress = 0;
         long checkpoint = 0;
@@ -437,33 +476,52 @@ public class FileUtils {
                 if (signal != null) {
                     signal.throwIfCanceled();
                 }
-                if (listener != null) {
-                    listener.onProgress(progress);
+                if (executor != null && listener != null) {
+                    final long progressSnapshot = progress;
+                    executor.execute(() -> {
+                        listener.onProgress(progressSnapshot);
+                    });
                 }
                 checkpoint = 0;
             }
         }
-        if (listener != null) {
-            listener.onProgress(progress);
+        if (executor != null && listener != null) {
+            final long progressSnapshot = progress;
+            executor.execute(() -> {
+                listener.onProgress(progressSnapshot);
+            });
         }
         return progress;
     }
 
+    /** {@hide} */
+    @Deprecated
     @VisibleForTesting
     public static long copyInternalUserspace(FileDescriptor in, FileDescriptor out,
-            ProgressListener listener, CancellationSignal signal, long count) throws IOException {
+            ProgressListener listener, CancellationSignal signal, long count)
+            throws IOException {
+        return copyInternalUserspace(in, out, count, signal, Runnable::run, listener);
+    }
+
+    /** {@hide} */
+    @VisibleForTesting
+    public static long copyInternalUserspace(FileDescriptor in, FileDescriptor out, long count,
+            CancellationSignal signal, Executor executor, ProgressListener listener)
+            throws IOException {
         if (count != Long.MAX_VALUE) {
             return copyInternalUserspace(new SizedInputStream(new FileInputStream(in), count),
-                    new FileOutputStream(out), listener, signal);
+                    new FileOutputStream(out), signal, executor, listener);
         } else {
             return copyInternalUserspace(new FileInputStream(in),
-                    new FileOutputStream(out), listener, signal);
+                    new FileOutputStream(out), signal, executor, listener);
         }
     }
 
+    /** {@hide} */
     @VisibleForTesting
     public static long copyInternalUserspace(InputStream in, OutputStream out,
-            ProgressListener listener, CancellationSignal signal) throws IOException {
+            CancellationSignal signal, Executor executor, ProgressListener listener)
+            throws IOException {
         long progress = 0;
         long checkpoint = 0;
         byte[] buffer = new byte[8192];
@@ -479,14 +537,20 @@ public class FileUtils {
                 if (signal != null) {
                     signal.throwIfCanceled();
                 }
-                if (listener != null) {
-                    listener.onProgress(progress);
+                if (executor != null && listener != null) {
+                    final long progressSnapshot = progress;
+                    executor.execute(() -> {
+                        listener.onProgress(progressSnapshot);
+                    });
                 }
                 checkpoint = 0;
             }
         }
-        if (listener != null) {
-            listener.onProgress(progress);
+        if (executor != null && listener != null) {
+            final long progressSnapshot = progress;
+            executor.execute(() -> {
+                listener.onProgress(progressSnapshot);
+            });
         }
         return progress;
     }
@@ -494,6 +558,7 @@ public class FileUtils {
     /**
      * Check if a filename is "safe" (no metacharacters or spaces).
      * @param file  The file to check
+     * @hide
      */
     public static boolean isFilenameSafe(File file) {
         // Note, we check whether it matches what's known to be safe,
@@ -509,6 +574,7 @@ public class FileUtils {
      * @param ellipsis to add of the file was truncated (can be null)
      * @return the contents of the file, possibly truncated
      * @throws IOException if something goes wrong reading the file
+     * @hide
      */
     public static String readTextFile(File file, int max, String ellipsis) throws IOException {
         InputStream input = new FileInputStream(file);
@@ -563,13 +629,16 @@ public class FileUtils {
         }
     }
 
+    /** {@hide} */
     public static void stringToFile(File file, String string) throws IOException {
         stringToFile(file.getAbsolutePath(), string);
     }
 
-    /*
+    /**
      * Writes the bytes given in {@code content} to the file whose absolute path
      * is {@code filename}.
+     *
+     * @hide
      */
     public static void bytesToFile(String filename, byte[] content) throws IOException {
         if (filename.startsWith("/proc/")) {
@@ -592,18 +661,23 @@ public class FileUtils {
      * @param filename
      * @param string
      * @throws IOException
+     * @hide
      */
     public static void stringToFile(String filename, String string) throws IOException {
         bytesToFile(filename, string.getBytes(StandardCharsets.UTF_8));
     }
 
     /**
-     * Computes the checksum of a file using the CRC32 checksum routine.
-     * The value of the checksum is returned.
+     * Computes the checksum of a file using the CRC32 checksum routine. The
+     * value of the checksum is returned.
      *
-     * @param file  the file to checksum, must not be null
+     * @param file the file to checksum, must not be null
      * @return the checksum value or an exception is thrown.
+     * @deprecated this is a weak hashing algorithm, and should not be used due
+     *             to its potential for collision.
+     * @hide
      */
+    @Deprecated
     public static long checksumCrc32(File file) throws FileNotFoundException, IOException {
         CRC32 checkSummer = new CRC32();
         CheckedInputStream cis = null;
@@ -632,6 +706,7 @@ public class FileUtils {
      * @param minCount Always keep at least this many files.
      * @param minAgeMs Always keep files younger than this age, in milliseconds.
      * @return if any files were deleted.
+     * @hide
      */
     public static boolean deleteOlderFiles(File dir, int minCount, long minAgeMs) {
         if (minCount < 0 || minAgeMs < 0) {
@@ -673,6 +748,8 @@ public class FileUtils {
      * Both files <em>must</em> have been resolved using
      * {@link File#getCanonicalFile()} to avoid symlink or path traversal
      * attacks.
+     *
+     * @hide
      */
     public static boolean contains(File[] dirs, File file) {
         for (File dir : dirs) {
@@ -690,12 +767,15 @@ public class FileUtils {
      * Both files <em>must</em> have been resolved using
      * {@link File#getCanonicalFile()} to avoid symlink or path traversal
      * attacks.
+     *
+     * @hide
      */
     public static boolean contains(File dir, File file) {
         if (dir == null || file == null) return false;
         return contains(dir.getAbsolutePath(), file.getAbsolutePath());
     }
 
+    /** {@hide} */
     public static boolean contains(String dirPath, String filePath) {
         if (dirPath.equals(filePath)) {
             return true;
@@ -706,6 +786,7 @@ public class FileUtils {
         return filePath.startsWith(dirPath);
     }
 
+    /** {@hide} */
     public static boolean deleteContentsAndDir(File dir) {
         if (deleteContents(dir)) {
             return dir.delete();
@@ -714,6 +795,7 @@ public class FileUtils {
         }
     }
 
+    /** {@hide} */
     public static boolean deleteContents(File dir) {
         File[] files = dir.listFiles();
         boolean success = true;
@@ -743,6 +825,8 @@ public class FileUtils {
 
     /**
      * Check if given filename is valid for an ext4 filesystem.
+     *
+     * @hide
      */
     public static boolean isValidExtFilename(String name) {
         return (name != null) && name.equals(buildValidExtFilename(name));
@@ -751,6 +835,8 @@ public class FileUtils {
     /**
      * Mutate the given filename to make it valid for an ext4 filesystem,
      * replacing any invalid characters with "_".
+     *
+     * @hide
      */
     public static String buildValidExtFilename(String name) {
         if (TextUtils.isEmpty(name) || ".".equals(name) || "..".equals(name)) {
@@ -792,6 +878,8 @@ public class FileUtils {
 
     /**
      * Check if given filename is valid for a FAT filesystem.
+     *
+     * @hide
      */
     public static boolean isValidFatFilename(String name) {
         return (name != null) && name.equals(buildValidFatFilename(name));
@@ -800,6 +888,8 @@ public class FileUtils {
     /**
      * Mutate the given filename to make it valid for a FAT filesystem,
      * replacing any invalid characters with "_".
+     *
+     * @hide
      */
     public static String buildValidFatFilename(String name) {
         if (TextUtils.isEmpty(name) || ".".equals(name) || "..".equals(name)) {
@@ -820,6 +910,7 @@ public class FileUtils {
         return res.toString();
     }
 
+    /** {@hide} */
     @VisibleForTesting
     public static String trimFilename(String str, int maxBytes) {
         final StringBuilder res = new StringBuilder(str);
@@ -827,6 +918,7 @@ public class FileUtils {
         return res.toString();
     }
 
+    /** {@hide} */
     private static void trimFilename(StringBuilder res, int maxBytes) {
         byte[] raw = res.toString().getBytes(StandardCharsets.UTF_8);
         if (raw.length > maxBytes) {
@@ -839,12 +931,14 @@ public class FileUtils {
         }
     }
 
+    /** {@hide} */
     public static String rewriteAfterRename(File beforeDir, File afterDir, String path) {
         if (path == null) return null;
         final File result = rewriteAfterRename(beforeDir, afterDir, new File(path));
         return (result != null) ? result.getAbsolutePath() : null;
     }
 
+    /** {@hide} */
     public static String[] rewriteAfterRename(File beforeDir, File afterDir, String[] paths) {
         if (paths == null) return null;
         final String[] result = new String[paths.length];
@@ -858,6 +952,8 @@ public class FileUtils {
      * Given a path under the "before" directory, rewrite it to live under the
      * "after" directory. For example, {@code /before/foo/bar.txt} would become
      * {@code /after/foo/bar.txt}.
+     *
+     * @hide
      */
     public static File rewriteAfterRename(File beforeDir, File afterDir, File file) {
         if (file == null || beforeDir == null || afterDir == null) return null;
@@ -869,6 +965,7 @@ public class FileUtils {
         return null;
     }
 
+    /** {@hide} */
     private static File buildUniqueFileWithExtension(File parent, String name, String ext)
             throws FileNotFoundException {
         File file = buildFile(parent, name, ext);
@@ -895,6 +992,7 @@ public class FileUtils {
      * 'example.txt' or 'example (1).txt', etc.
      *
      * @throws FileNotFoundException
+     * @hide
      */
     public static File buildUniqueFile(File parent, String mimeType, String displayName)
             throws FileNotFoundException {
@@ -905,6 +1003,8 @@ public class FileUtils {
     /**
      * Generates a unique file name under the given parent directory, keeping
      * any extension intact.
+     *
+     * @hide
      */
     public static File buildUniqueFile(File parent, String displayName)
             throws FileNotFoundException {
@@ -929,6 +1029,8 @@ public class FileUtils {
      * If the display name doesn't have an extension that matches the requested MIME type, the
      * extension is regarded as a part of filename and default extension for that MIME type is
      * appended.
+     *
+     * @hide
      */
     public static String[] splitFileName(String mimeType, String displayName) {
         String name;
@@ -975,6 +1077,7 @@ public class FileUtils {
         return new String[] { name, ext };
     }
 
+    /** {@hide} */
     private static File buildFile(File parent, String name, String ext) {
         if (TextUtils.isEmpty(ext)) {
             return new File(parent, name);
@@ -983,6 +1086,7 @@ public class FileUtils {
         }
     }
 
+    /** {@hide} */
     public static @NonNull String[] listOrEmpty(@Nullable File dir) {
         if (dir == null) return EmptyArray.STRING;
         final String[] res = dir.list();
@@ -993,6 +1097,7 @@ public class FileUtils {
         }
     }
 
+    /** {@hide} */
     public static @NonNull File[] listFilesOrEmpty(@Nullable File dir) {
         if (dir == null) return EMPTY;
         final File[] res = dir.listFiles();
@@ -1003,6 +1108,7 @@ public class FileUtils {
         }
     }
 
+    /** {@hide} */
     public static @NonNull File[] listFilesOrEmpty(@Nullable File dir, FilenameFilter filter) {
         if (dir == null) return EMPTY;
         final File[] res = dir.listFiles(filter);
@@ -1013,6 +1119,7 @@ public class FileUtils {
         }
     }
 
+    /** {@hide} */
     public static @Nullable File newFileOrNull(@Nullable String path) {
         return (path != null) ? new File(path) : null;
     }
@@ -1021,6 +1128,8 @@ public class FileUtils {
      * Creates a directory with name {@code name} under an existing directory {@code baseDir}.
      * Returns a {@code File} object representing the directory on success, {@code null} on
      * failure.
+     *
+     * @hide
      */
     public static @Nullable File createDir(File baseDir, String name) {
         final File dir = new File(baseDir, name);
@@ -1036,6 +1145,8 @@ public class FileUtils {
      * Round the given size of a storage device to a nice round power-of-two
      * value, such as 256MB or 32GB. This avoids showing weird values like
      * "29.5GB" in UI.
+     *
+     * @hide
      */
     public static long roundStorageSize(long size) {
         long val = 1;
@@ -1050,6 +1161,23 @@ public class FileUtils {
         return val * pow;
     }
 
+    /**
+     * Closes the given object quietly, ignoring any checked exceptions. Does
+     * nothing if the given object is {@code null}.
+     */
+    public static void closeQuietly(@Nullable AutoCloseable closeable) {
+        IoUtils.closeQuietly(closeable);
+    }
+
+    /**
+     * Closes the given object quietly, ignoring any checked exceptions. Does
+     * nothing if the given object is {@code null}.
+     */
+    public static void closeQuietly(@Nullable FileDescriptor fd) {
+        IoUtils.closeQuietly(fd);
+    }
+
+    /** {@hide} */
     @VisibleForTesting
     public static class MemoryPipe extends Thread implements AutoCloseable {
         private final FileDescriptor[] pipe;