Merge branch 'compression' of https://github.com/rtreffer/Conversations into rtreffer-compression

1 files changed, 52 insertions, 0 deletions

diff --git a/src/eu/siacs/conversations/utils/zlib/ZLibInputStream.java b/src/eu/siacs/conversations/utils/zlib/ZLibInputStream.java
new file mode 100644
index 00000000..2eebf6f4
--- /dev/null
+++ b/src/eu/siacs/conversations/utils/zlib/ZLibInputStream.java
@@ -0,0 +1,52 @@
+package eu.siacs.conversations.utils.zlib;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.zip.Inflater;
+import java.util.zip.InflaterInputStream;
+
+/**
+ * ZLibInputStream is a zlib and input stream compatible version of an
+ * InflaterInputStream. This class solves the incompatibility between
+ * {@link InputStream#available()} and {@link InflaterInputStream#available()}.
+ */
+public class ZLibInputStream extends InflaterInputStream {
+
+    /**
+     * Construct a ZLibInputStream, reading data from the underlying stream.
+     *
+     * @param is The {@code InputStream} to read data from.
+     * @throws IOException If an {@code IOException} occurs.
+     */
+    public ZLibInputStream(InputStream is) throws IOException {
+        super(is, new Inflater(), 512);
+    }
+
+    /**
+     * Provide a more InputStream compatible version of available.
+     * A return value of 1 means that it is likly to read one byte without
+     * blocking, 0 means that the system is known to block for more input.
+     *
+     * @return 0 if no data is available, 1 otherwise
+     * @throws IOException
+     */
+    @Override
+    public int available() throws IOException {
+        /* This is one of the funny code blocks.
+         * InflaterInputStream.available violates the contract of
+         * InputStream.available, which breaks kXML2.
+         *
+         * I'm not sure who's to blame, oracle/sun for a broken api or the
+         * google guys for mixing a sun bug with a xml reader that can't handle
+         * it....
+         *
+         * Anyway, this simple if breaks suns distorted reality, but helps
+         * to use the api as intended.
+         */
+        if (inf.needsInput()) {
+            return 0;
+        }
+        return super.available();
+    }
+
+}