PDFBOX-5908: refactor

git-svn-id: https://svn.apache.org/repos/asf/pdfbox/trunk@1922168 13f79535-47bb-0310-9956-ffa450edef68

Author: THausherr

pdfbox/src/main/java/org/apache/pdfbox/filter/Filter.java

@@ -232,7 +232,7 @@ public static RandomAccessRead decode(InputStream encoded, List<Filter> filterLi
             COSDictionary parameters, DecodeOptions options, List<DecodeResult> results)
             throws IOException
     {
-        int length = parameters.getInt(COSName.LENGTH,
+        long length = parameters.getLong(COSName.LENGTH,
                 RandomAccessReadBuffer.DEFAULT_CHUNK_SIZE_4KB);
         if (filterList.isEmpty())
         {
@@ -266,17 +266,19 @@ public static RandomAccessRead decode(InputStream encoded, List<Filter> filterLi
             {
                 randomAccessWriteBuffer.seek(0);
                 input = new RandomAccessInputStream(randomAccessWriteBuffer);
-                length = (int) randomAccessWriteBuffer.length();
+                length = randomAccessWriteBuffer.length();
             }
-            // avoid invalid values
-            length = length <= 0 ? RandomAccessReadBuffer.DEFAULT_CHUNK_SIZE_4KB : length;
             // we don't know the size of the decoded stream, just estimate a 4 times bigger size than the encoded stream
             // use the estimated stream size as chunk size, use the default chunk size as limit to avoid to big values
-            length <<= 2;
-            length = length <= 0 ? // PDFBOX-5908 avoid invalid values (again)
-                    RandomAccessReadBuffer.DEFAULT_CHUNK_SIZE_4KB :
-                    Math.min(length, RandomAccessReadBuffer.DEFAULT_CHUNK_SIZE_4KB);
-            randomAccessWriteBuffer = new RandomAccessReadWriteBuffer(length);
+            if (length >= RandomAccessReadBuffer.DEFAULT_CHUNK_SIZE_4KB / 4)
+            {
+                length = RandomAccessReadBuffer.DEFAULT_CHUNK_SIZE_4KB;
+            }
+            else
+            {
+                length = Math.min(length << 2, RandomAccessReadBuffer.DEFAULT_CHUNK_SIZE_4KB);
+            }
+            randomAccessWriteBuffer = new RandomAccessReadWriteBuffer((int) length);
             output = new RandomAccessOutputStream(randomAccessWriteBuffer);
             try
             {