Clear out the remaining non-security related FindBugs warnings.

src/com/google/bitcoin/core/Block.java

@@ -18,6 +18,7 @@ package com.google.bitcoin.core;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.ObjectInputStream;
 import java.io.OutputStream;
 import java.math.BigInteger;
 import java.util.*;
@@ -78,6 +79,13 @@ public class Block extends Message {
         super(params, payloadBytes, 0);
     }
 
+    private void readObject(ObjectInputStream ois) throws ClassNotFoundException, IOException {
+        ois.defaultReadObject();
+        // This code is not actually necessary, as transient fields are initialized to the default value which is in
+        // this case null. However it clears out a FindBugs warning and makes it explicit what we're doing.
+        hash = null;
+    }
+
     void parse() throws ProtocolException {
         version = readUint32();
         prevBlockHash = readHash();
@@ -172,13 +180,13 @@ public class Block extends Message {
     public Block cloneAsHeader() {
         Block block = new Block(params);
         block.nonce = nonce;
-        block.prevBlockHash = prevBlockHash.clone();
-        block.merkleRoot = getMerkleRoot().clone();
+        block.prevBlockHash = prevBlockHash.duplicate();
+        block.merkleRoot = getMerkleRoot().duplicate();
         block.version = version;
         block.time = time;
         block.difficultyTarget = difficultyTarget;
         block.transactions = null;
-        block.hash = getHash().clone();
+        block.hash = getHash().duplicate();
         return block;
     }
 

src/com/google/bitcoin/core/NetworkParameters.java

@@ -86,6 +86,7 @@ public class NetworkParameters implements Serializable {
             t.outputs.add(new TransactionOutput(n, t, scriptPubKeyBytes.toByteArray()));
         } catch (Exception e) {
             // Cannot happen.
+            throw new RuntimeException(e);
         }
         genesisBlock.addTransaction(t);
         return genesisBlock;

src/com/google/bitcoin/core/Sha256Hash.java

@@ -74,8 +74,7 @@ public class Sha256Hash implements Serializable {
         return bytes;
     }
 
-    @Override
-    public Sha256Hash clone() {
+    public Sha256Hash duplicate() {
         return new Sha256Hash(bytes);
     }
 }

src/com/google/bitcoin/core/Transaction.java

@@ -258,12 +258,15 @@ public class Transaction extends Message implements Serializable {
         s.append(getHashAsString());
         s.append("\n");
         if (isCoinBase()) {
-            String script = "???";
-            String script2 = "???";
+            String script;
+            String script2;
             try {
                 script = inputs.get(0).getScriptSig().toString();
                 script2 = outputs.get(0).getScriptPubKey().toString();
-            } catch (ScriptException e) {}
+            } catch (ScriptException e) {
+                script = "???";
+                script2 = "???";
+            }
             return "     == COINBASE TXN (scriptSig " + script + ")  (scriptPubKey " + script2 + ")";
         }
         for (TransactionInput in : inputs) {

src/com/google/bitcoin/store/DiskBlockStore.java

@@ -75,7 +75,9 @@ public class DiskBlockStore implements BlockStore {
 
     private void load(File file) throws IOException, BlockStoreException {
         log.info("Reading block store from {}", file);
-        InputStream input = new BufferedInputStream(new FileInputStream(file));
+        InputStream input = null;
+        try {
+            input = new BufferedInputStream(new FileInputStream(file));
             // Read a version byte.
             int version = input.read();
             if (version == -1) {
@@ -87,7 +89,8 @@ public class DiskBlockStore implements BlockStore {
             }
             // Chain head pointer is the first thing in the file.
             byte[] chainHeadHash = new byte[32];
-        input.read(chainHeadHash);
+            if (input.read(chainHeadHash) < chainHeadHash.length)
+                throw new BlockStoreException("Truncated block store: cannot read chain head hash");
             this.chainHead = new Sha256Hash(chainHeadHash);
             log.info("Read chain head from disk: {}", this.chainHead);
             long now = System.currentTimeMillis();
@@ -131,6 +134,9 @@ public class DiskBlockStore implements BlockStore {
             }
             long elapsed = System.currentTimeMillis() - now;
             log.info("Block chain read complete in {}ms", elapsed);
+        } finally {
+            if (input != null) input.close();
+        }
     }
 
     public synchronized void put(StoredBlock block) throws BlockStoreException {