Re: RFR [9]8134424: BlockDataInputStream.readUTFBody: examine sizing local StringBuffer with the given length

[Chris Hegarty]

On 10/02/16 13:57, Aleksey Shipilev wrote:
....
Um (Integer.MAX_VALUE + 1L) is still a positive long, you probably want:

   int ilen = (int)utflen;
   if (ilen < 0)
     return "";

   int initialCapacity = Math.min(ilen, 16384);

...or:

   if (utflen < 0 || utflen > Integer.MAX_INT)
     return "";

   int initialCapacity = Math.min((int)utflen, 16384);

Thanks Aleksey, your proposal is better. So the complete change is:

diff --git a/src/java.base/share/classes/java/io/ObjectInputStream.java 
b/src/java.base/share/classes/java/io/ObjectInputStream.java
--- a/src/java.base/share/classes/java/io/ObjectInputStream.java
+++ b/src/java.base/share/classes/java/io/ObjectInputStream.java
@@ -3144,7 +3144,12 @@
          * utflen bytes.
          */
         private String readUTFBody(long utflen) throws IOException {
-            StringBuilder sbuf = new StringBuilder();
+            if (utflen < 0 || utflen > Integer.MAX_VALUE)
+                return "";
+
+            // a reasonable initial capacity based on the UTF length
+            int initialCapacity = Math.min((int)utflen, 16384);
+            StringBuilder sbuf = new StringBuilder(initialCapacity);
             if (!blkmode) {
                 end = pos = 0;
             }

-Chris.