fix issue in IOUtils.toByteArrayWithMaxLength

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1898861 13f79535-47bb-0310-9956-ffa450edef68

poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFChart.java

@@ -92,13 +92,11 @@ public class XWPFChart extends XDDFChart {
 
     public Long getChecksum() {
         if (this.checksum == null) {
-            byte[] data;
             try (InputStream is = getPackagePart().getInputStream()) {
-                data = IOUtils.toByteArrayWithMaxLength(is, XWPFPictureData.getMaxImageSize());
+                this.checksum = IOUtils.calculateChecksum(is);
             } catch (IOException e) {
                 throw new POIXMLException(e);
             }
-            this.checksum = IOUtils.calculateChecksum(data);
         }
         return this.checksum;
     }

poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFPictureData.java

@@ -163,13 +163,11 @@ public class XWPFPictureData extends POIXMLDocumentPart {
 
     public Long getChecksum() {
         if (this.checksum == null) {
-            byte[] data;
             try (InputStream is = getPackagePart().getInputStream()) {
-                data = IOUtils.toByteArrayWithMaxLength(is, getMaxImageSize());
+                this.checksum = IOUtils.calculateChecksum(is);
             } catch (IOException e) {
                 throw new POIXMLException(e);
             }
-            this.checksum = IOUtils.calculateChecksum(data);
         }
         return this.checksum;
     }

poi/src/main/java/org/apache/poi/util/IOUtils.java

@@ -202,7 +202,7 @@ public final class IOUtils {
         }
 
         final int derivedLen = Math.min(length, derivedMaxLength);
-        final int bufferLen = isLengthKnown ? derivedLen : 4096;
+        final int bufferLen = isLengthKnown ? derivedLen : Math.min(4096, derivedLen);
         try (UnsynchronizedByteArrayOutputStream baos = new UnsynchronizedByteArrayOutputStream(bufferLen)) {
             byte[] buffer = new byte[4096];
             int totalBytes = 0, readBytes;