Fixes issue 34 Implement available() method

src/main/java/org/xerial/snappy/SnappyInputStream.java

@@ -387,4 +387,21 @@ public class SnappyInputStream extends InputStream
         }
     }
 
+    /* (non-Javadoc)
+     * @see java.io.InputStream#available()
+     */
+    @Override
+    public int available() throws IOException {
+        if (uncompressedCursor < uncompressedLimit) {
+            return uncompressedLimit - uncompressedCursor;
+        }
+        else {
+            if (hasNextChunk()) {
+                return uncompressedLimit - uncompressedCursor;
+            }
+            else {
+                return 0;
+            }
+        }
+    }
 }

src/test/java/org/xerial/snappy/SnappyInputStreamTest.java

@@ -48,6 +48,7 @@ public class SnappyInputStreamTest
     }
 
     public static byte[] readFully(InputStream input) throws IOException {
+        try {
             ByteArrayOutputStream out = new ByteArrayOutputStream();
             byte[] buf = new byte[4096];
             for (int readBytes = 0; (readBytes = input.read(buf)) != -1;) {
@@ -56,6 +57,10 @@ public class SnappyInputStreamTest
             out.flush();
             return out.toByteArray();
         }
+        finally {
+            input.close();
+        }
+    }
 
     public static byte[] biteWiseReadFully(InputStream input) throws IOException {
         ByteArrayOutputStream out = new ByteArrayOutputStream();
@@ -107,6 +112,21 @@ public class SnappyInputStreamTest
 
         assertEquals(orig.length, uncompressed.length);
         assertArrayEquals(orig, uncompressed);
+
+    }
+
+    @Test
+    public void available() throws Exception {
+        byte[] orig = readResourceFile("testdata/calgary/paper6");
+        byte[] compressed = Snappy.compress(orig);
+
+        SnappyInputStream in = new SnappyInputStream(new ByteArrayInputStream(compressed));
+        byte[] buf = new byte[4];
+        for (int readBytes = 0; (readBytes = in.read(buf)) != -1;) {
+            assertTrue(in.available() >= 0);
+        }
+        assertTrue(in.available() == 0);
+        in.close();
     }
 
 }