media/java/android/media/ExifInterfaceUtils.java

/*
 * Copyright 2020 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.media;

import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Package private utility class for ExifInterface.
 */
class ExifInterfaceUtils {
    /**
     * Copies all of the bytes from {@code in} to {@code out}. Neither stream is closed.
     * Returns the total number of bytes transferred.
     */
    public static int copy(InputStream in, OutputStream out) throws IOException {
        int total = 0;
        byte[] buffer = new byte[8192];
        int c;
        while ((c = in.read(buffer)) != -1) {
            total += c;
            out.write(buffer, 0, c);
        }
        return total;
    }

    /**
     * Copies the given number of the bytes from {@code in} to {@code out}. Neither stream is
     * closed.
     */
    public static void copy(InputStream in, OutputStream out, int numBytes) throws IOException {
        int remainder = numBytes;
        byte[] buffer = new byte[8192];
        while (remainder > 0) {
            int bytesToRead = Math.min(remainder, 8192);
            int bytesRead = in.read(buffer, 0, bytesToRead);
            if (bytesRead != bytesToRead) {
                throw new IOException("Failed to copy the given amount of bytes from the input"
                        + "stream to the output stream.");
            }
            remainder -= bytesRead;
            out.write(buffer, 0, bytesRead);
        }
    }

    /**
     * Convert given int[] to long[]. If long[] is given, just return it.
     * Return null for other types of input.
     */
    public static long[] convertToLongArray(Object inputObj) {
        if (inputObj instanceof int[]) {
            int[] input = (int[]) inputObj;
            long[] result = new long[input.length];
            for (int i = 0; i < input.length; i++) {
                result[i] = input[i];
            }
            return result;
        } else if (inputObj instanceof long[]) {
            return (long[]) inputObj;
        }
        return null;
    }

    /**
     * Convert given byte array to hex string.
     */
    public static String byteArrayToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder(bytes.length * 2);
        for (int i = 0; i < bytes.length; i++) {
            sb.append(String.format("%02x", bytes[i]));
        }
        return sb.toString();
    }

    /**
     * Checks if the start of the first byte array is equal to the second byte array.
     */
    public static boolean startsWith(byte[] cur, byte[] val) {
        if (cur == null || val == null) return false;
        if (cur.length < val.length) return false;
        if (cur.length == 0 || val.length == 0) return false;
        for (int i = 0; i < val.length; i++) {
            if (cur[i] != val[i]) return false;
        }
        return true;
    }

    /**
     * Closes 'closeable', ignoring any checked exceptions. Does nothing if 'closeable' is null.
     */
    public static void closeQuietly(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (RuntimeException rethrown) {
                throw rethrown;
            } catch (Exception ignored) {
            }
        }
    }
}