Merge "Fix fsverity format"

            throws IOException, SecurityException, NoSuchAlgorithmException, DigestException {

        long signingBlockSize =

                signatureInfo.centralDirOffset - signatureInfo.apkSigningBlockOffset;

        long dataSize = apk.length() - signingBlockSize - ZIP_EOCD_CENTRAL_DIR_OFFSET_FIELD_SIZE;

        long dataSize = apk.length() - signingBlockSize;

        int[] levelOffset = calculateVerityLevelOffset(dataSize);

        ByteBuffer output = bufferFactory.create(

        }

        if (headerOutput != null) {

            headerOutput.order(ByteOrder.LITTLE_ENDIAN);

            generateFsverityHeader(headerOutput, apk.length(), levelOffset.length - 1,

                    DEFAULT_SALT);

        }

        if (extensionsOutput != null) {

            extensionsOutput.order(ByteOrder.LITTLE_ENDIAN);

            generateFsverityExtensions(extensionsOutput, signatureInfo.apkSigningBlockOffset,

                    signingBlockSize, signatureInfo.eocdOffset);

        }

        return rootHash;

    }

    private static void bufferPut(ByteBuffer buffer, byte value) {

        // FIXME(b/72459251): buffer.put(value) does NOT work surprisingly. The position() after put

        // does NOT even change. This hack workaround the problem, but the root cause remains

        // unkonwn yet.  This seems only happen when it goes through the apk install flow on my

        // setup.

        buffer.put(new byte[] { value });

    }

    private static ByteBuffer generateFsverityHeader(ByteBuffer buffer, long fileSize, int depth,

            byte[] salt) {

        if (salt.length != 8) {

        // TODO(b/30972906): update the reference when there is a better one in public.

        buffer.put("TrueBrew".getBytes());  // magic

        buffer.put((byte) 1);        // major version

        buffer.put((byte) 0);        // minor version

        buffer.put((byte) 12);       // log2(block-size): log2(4096)

        buffer.put((byte) 7);        // log2(leaves-per-node): log2(4096 / 32)

        bufferPut(buffer, (byte) 1);        // major version

        bufferPut(buffer, (byte) 0);        // minor version

        bufferPut(buffer, (byte) 12);       // log2(block-size): log2(4096)

        bufferPut(buffer, (byte) 7);        // log2(leaves-per-node): log2(4096 / 32)

        buffer.putShort((short) 1);         // meta algorithm, SHA256_MODE == 1

        buffer.putShort((short) 1);         // data algorithm, SHA256_MODE == 1

        buffer.putLong(fileSize);           // original file size

        buffer.put((byte) 0);        // auth block offset, disabled here

        bufferPut(buffer, (byte) 0);        // auth block offset, disabled here

        bufferPut(buffer, (byte) 2);        // extension count

        buffer.put(salt);                   // salt (8 bytes)

        // skip(buffer, 22);                // reserved

            long signingBlockSize, long eocdOffset) {

        // Snapshot of the FSVerity structs (subject to change once upstreamed).

        //

        // struct fsverity_header_extension {

        //   u8 extension_count;

        //   u8 reserved[7];

        // };

        //

        // struct fsverity_extension {

        //   __le16 length;

        //   u8 type;

        //   u8 databytes[];

        // };

        // struct fsverity_header_extension

        buffer.put((byte) 2);        // extension count

        skip(buffer, 3);             // reserved

        final int kSizeOfFsverityExtensionHeader = 8;

        {