Merge "Calculate MediaColumns.HASH when demanded." (4b773c90) · Commits · e / os / android_frameworks_base

core/java/android/os/FileUtils.java

+54 −0

Original line number	Diff line number	Diff line
		@@ -66,6 +66,9 @@ import java.io.IOException;
		import java.io.InputStream;
		import java.io.OutputStream;
		import java.nio.charset.StandardCharsets;
		import java.security.DigestInputStream;
		import java.security.MessageDigest;
		import java.security.NoSuchAlgorithmException;
		import java.util.Arrays;
		import java.util.Comparator;
		import java.util.Objects;
		@@ -716,6 +719,57 @@ public class FileUtils {
		}
		}

		/**
		* Compute the digest of the given file using the requested algorithm.
		*
		* @param algorithm Any valid algorithm accepted by
		* {@link MessageDigest#getInstance(String)}.
		* @hide
		*/
		public static byte[] digest(@NonNull File file, @NonNull String algorithm)
		throws IOException, NoSuchAlgorithmException {
		try (FileInputStream in = new FileInputStream(file)) {
		return digest(in, algorithm);
		}
		}

		/**
		* Compute the digest of the given file using the requested algorithm.
		*
		* @param algorithm Any valid algorithm accepted by
		* {@link MessageDigest#getInstance(String)}.
		* @hide
		*/
		public static byte[] digest(@NonNull InputStream in, @NonNull String algorithm)
		throws IOException, NoSuchAlgorithmException {
		// TODO: implement kernel optimizations
		return digestInternalUserspace(in, algorithm);
		}

		/**
		* Compute the digest of the given file using the requested algorithm.
		*
		* @param algorithm Any valid algorithm accepted by
		* {@link MessageDigest#getInstance(String)}.
		* @hide
		*/
		public static byte[] digest(FileDescriptor fd, String algorithm)
		throws IOException, NoSuchAlgorithmException {
		// TODO: implement kernel optimizations
		return digestInternalUserspace(new FileInputStream(fd), algorithm);
		}

		private static byte[] digestInternalUserspace(InputStream in, String algorithm)
		throws IOException, NoSuchAlgorithmException {
		final MessageDigest digest = MessageDigest.getInstance(algorithm);
		try (DigestInputStream digestStream = new DigestInputStream(in, digest)) {
		final byte[] buffer = new byte[8192];
		while (digestStream.read(buffer) != -1) {
		}
		}
		return digest.digest();
		}

		/**
		* Delete older files in a directory until only those matching the given
		* constraints remain.