diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipFile.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipFile.java
new file mode 100644
index 000000000..e985fcf5c
--- /dev/null
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipFile.java
@@ -0,0 +1,109 @@
+package nodomain.freeyourgadget.gadgetbridge.util;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipException;
+import java.util.zip.ZipInputStream;
+
+import androidx.annotation.Nullable;
+
+public class ZipFile implements AutoCloseable {
+ private static final Logger LOG = LoggerFactory.getLogger(ZipFile.class);
+ public static final byte[] ZIP_HEADER = new byte[]{
+ 0x50, 0x4B, 0x03, 0x04
+ };
+
+ private final ZipInputStream zipInputStream;
+
+ /**
+ * Open ZIP file from byte array in memory
+ * @param zipBytes
+ */
+ public ZipFile(byte[] zipBytes) {
+ zipInputStream = new ZipInputStream(new ByteArrayInputStream(zipBytes));
+ }
+
+ /**
+ * Checks if data resembles a ZIP file.
+ * The check is not infallible: it may report self-extracting or other exotic ZIP archives as not a ZIP file, and it may report a corrupted ZIP file as a ZIP file.
+ * @param data The data to check.
+ * @return Whether data resembles a ZIP file.
+ */
+ public static boolean isZipFile(byte[] data) {
+ return ArrayUtils.equals(data, ZIP_HEADER, 0);
+ }
+
+ /**
+ * Reads the contents of file at path into a byte array.
+ * @param path Path of the file in the ZIP file.
+ * @return byte array contatining the contents of the requested file.
+ * @throws ZipFileException If the specified path does not exist or references a directory, or if some other I/O error occurs. In other words, if return value would otherwise be null.
+ */
+ public byte[] getFileFromZip(final String path) throws ZipFileException {
+ try {
+ ZipEntry zipEntry;
+ while ((zipEntry = zipInputStream.getNextEntry()) != null) {
+ if (!zipEntry.getName().equals(path)) continue; // TODO: is this always a path? The documentation is very vague.
+
+ if (zipEntry.isDirectory()) {
+ throw new ZipFileException(String.format("Path in ZIP file is a directory: %s", path));
+ }
+
+ return readAllBytes(zipInputStream);
+ }
+
+ throw new ZipFileException(String.format("Path in ZIP file was not found: %s", path));
+
+ } catch (ZipException e) {
+ throw new ZipFileException("The ZIP file might be corrupted");
+ } catch (IOException e) {
+ throw new ZipFileException("General IO error");
+ }
+ }
+
+ /**
+ * Tries to obtain file from ZIP file without much hassle, but is not safe.
+ * Please only use this in place of old code where correctness of the result is checked only later on.
+ * Use getFileFromZip of ZipFile instance instead.
+ * @param zipBytes
+ * @param path Path of the file in the ZIP file.
+ * @return Contents of requested file or null.
+ */
+ @Deprecated
+ @Nullable
+ public static byte[] tryReadFileQuick(final byte[] zipBytes, final String path) {
+ try (ZipFile zip = new ZipFile(zipBytes)) {
+ return zip.getFileFromZip(path);
+ } catch (ZipFileException e) {
+ LOG.error("Quick ZIP reading failed.", e);
+ } catch (Exception e) {
+ LOG.error("Unable to close ZipFile.", e);
+ }
+
+ return null;
+ }
+
+ private static byte[] readAllBytes(final InputStream is) throws IOException {
+ final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+
+ int n;
+ byte[] buf = new byte[16384];
+
+ while ((n = is.read(buf, 0, buf.length)) != -1) {
+ buffer.write(buf, 0, n);
+ }
+
+ return buffer.toByteArray();
+ }
+
+ @Override
+ public void close() throws Exception {
+ zipInputStream.close();
+ }
+}
\ No newline at end of file
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipFileException.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipFileException.java
new file mode 100644
index 000000000..f7c87ceab
--- /dev/null
+++ b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipFileException.java
@@ -0,0 +1,7 @@
+package nodomain.freeyourgadget.gadgetbridge.util;
+
+public class ZipFileException extends Exception {
+ public ZipFileException(String message) {
+ super(String.format("Error while reading ZIP file: %s", message));
+ }
+}
diff --git a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipUtils.java b/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipUtils.java
deleted file mode 100644
index 336b229c5..000000000
--- a/app/src/main/java/nodomain/freeyourgadget/gadgetbridge/util/ZipUtils.java
+++ /dev/null
@@ -1,55 +0,0 @@
-package nodomain.freeyourgadget.gadgetbridge.util;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipInputStream;
-
-public class ZipUtils {
- private static final Logger LOG = LoggerFactory.getLogger(ZipUtils.class);
-
- public static byte[] getFileFromZip(final byte[] zipBytes, final String path) {
- try (ZipInputStream zipInputStream = new ZipInputStream(new ByteArrayInputStream(zipBytes))) {
-
- ZipEntry zipEntry;
- while ((zipEntry = zipInputStream.getNextEntry()) != null) {
- if (!zipEntry.getName().equals(path)) continue; // TODO: is this always a path? The documentation is very vague.
-
- // Found, but not a file
- if (zipEntry.isDirectory()) {
- LOG.error(String.format("Path in ZIP file is a directory: %s", path));
- return null;
- }
-
- // Found, and it is a file
- return readAllBytes(zipInputStream);
- }
-
- // Not found
- LOG.error(String.format("Path in ZIP file was not found: %s", path));
- return null;
-
- } catch (final IOException e) {
- LOG.error(String.format("Unknown error while reading file from ZIP file: %s", path), e);
- return null;
- }
- }
-
- private static byte[] readAllBytes(final InputStream is) throws IOException {
- final ByteArrayOutputStream buffer = new ByteArrayOutputStream();
-
- int n;
- byte[] buf = new byte[16384];
-
- while ((n = is.read(buf, 0, buf.length)) != -1) {
- buffer.write(buf, 0, n);
- }
-
- return buffer.toByteArray();
- }
-}