Examples with ChainedDataSource com.android.apksig.internal.util.ChainedDataSource used on opensource projects

Example 1 with ChainedDataSource

use of com.android.apksig.internal.util.ChainedDataSource in project apksig by venshine.

the class ApkSigningBlockUtils method generateApkSigningBlockPadding.

/**
 * Generates a new DataSource representing the APK contents before the Central Directory with
 * padding, if padding is requested.  If the existing data entries before the Central Directory
 * are already aligned, or no padding is requested, the original DataSource is used.  This
 * padding is used to allow for verity-based APK verification.
 *
 * @return {@code Pair} containing the potentially new {@code DataSource} and the amount of
 *         padding used.
 */
public static Pair<DataSource, Integer> generateApkSigningBlockPadding(DataSource beforeCentralDir, boolean apkSigningBlockPaddingSupported) {
    // Ensure APK Signing Block starts from page boundary.
    int padSizeBeforeSigningBlock = 0;
    if (apkSigningBlockPaddingSupported && (beforeCentralDir.size() % ANDROID_COMMON_PAGE_ALIGNMENT_BYTES != 0)) {
        padSizeBeforeSigningBlock = (int) (ANDROID_COMMON_PAGE_ALIGNMENT_BYTES - beforeCentralDir.size() % ANDROID_COMMON_PAGE_ALIGNMENT_BYTES);
        beforeCentralDir = new ChainedDataSource(beforeCentralDir, DataSources.asDataSource(ByteBuffer.allocate(padSizeBeforeSigningBlock)));
    }
    return Pair.of(beforeCentralDir, padSizeBeforeSigningBlock);
}