Add compression support

2 files changed, 141 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();
+    }
+
+}
diff --git a/src/eu/siacs/conversations/utils/zlib/ZLibOutputStream.java b/src/eu/siacs/conversations/utils/zlib/ZLibOutputStream.java
new file mode 100644
index 00000000..f2bff9fd
--- /dev/null
+++ b/src/eu/siacs/conversations/utils/zlib/ZLibOutputStream.java
@@ -0,0 +1,89 @@
+package eu.siacs.conversations.utils.zlib;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.security.NoSuchAlgorithmException;
+import java.util.zip.Deflater;
+import java.util.zip.DeflaterOutputStream;
+
+/**
+ * <p>Android 2.2 includes Java7 FLUSH_SYNC option, which will be used by this
+ * Implementation, preferable via reflection. The @hide was remove in API level
+ * 19. This class might thus go away in the future.</p>
+ * <p>Please use {@link ZLibOutputStream#SUPPORTED} to check for flush
+ * compatibility.</p> 
+ */
+public class ZLibOutputStream extends DeflaterOutputStream {
+
+    /**
+     * The reflection based flush method.
+     */
+
+    private final static Method method;
+    /**
+     * SUPPORTED is true if a flush compatible method exists.
+     */
+    public final static boolean SUPPORTED;
+
+    /**
+     * Static block to initialize {@link #SUPPORTED} and {@link #method}.
+     */
+    static {
+        Method m = null;
+        try {
+            m = Deflater.class.getMethod("deflate", byte[].class, int.class, int.class, int.class);
+        } catch (SecurityException e) {
+        } catch (NoSuchMethodException e) {
+        }
+        method = m;
+        SUPPORTED = (method != null);
+    }
+
+    /**
+     * Create a new ZLib compatible output stream wrapping the given low level
+     * stream. ZLib compatiblity means we will send a zlib header. 
+     * @param os OutputStream The underlying stream.
+     * @throws IOException In case of a lowlevel transfer problem.
+     * @throws NoSuchAlgorithmException In case of a {@link Deflater} error.
+     */
+    public ZLibOutputStream(OutputStream os) throws IOException,
+            NoSuchAlgorithmException {
+        super(os, new Deflater(Deflater.BEST_COMPRESSION));
+    }
+
+    /**
+     * Flush the given stream, preferring Java7 FLUSH_SYNC if available.
+     * @throws IOException In case of a lowlevel exception.
+     */
+    @Override
+    public void flush() throws IOException {
+        if (!SUPPORTED) {
+            super.flush();
+            return;
+        }
+        int count = 0;
+        if (!def.needsInput()) {
+            do {
+                count = def.deflate(buf, 0, buf.length);
+                out.write(buf, 0, count);
+            } while (count > 0);
+            out.flush();
+        }
+        try {
+            do {
+                count = (Integer) method.invoke(def, buf, 0, buf.length, 2);
+                out.write(buf, 0, count);
+            } while (count > 0);
+        } catch (IllegalArgumentException e) {
+            throw new IOException("Can't flush");
+        } catch (IllegalAccessException e) {
+            throw new IOException("Can't flush");
+        } catch (InvocationTargetException e) {
+            throw new IOException("Can't flush");
+        }
+        super.flush();
+    }
+
+}