fix up some coverity issues

persistent-data/block.h

@@ -65,7 +65,6 @@ namespace persistent_data {
 		int fd_;
 		block_address nr_blocks_;
 		mode mode_;
-		bool writeable_;
 	};
 
 	template <uint32_t BlockSize = MD_BLOCK_SIZE>

persistent-data/cache.h

@@ -68,15 +68,29 @@ namespace base {
 				  v_(v) {
 			}
 
-			struct {
-				value_entry *next_, *prev_;
-			} lru_;
+			struct lru {
+				lru()
+					: next_(0),
+					  prev_(0) {
+				}
+
+				value_entry *next_, *prev_;
+			};
+
+			struct lookup {
+				lookup()
+					: parent_(0),
+					  left_(0),
+					  right_(0),
+					  color_() {
+				}
 
-			struct {
 				value_entry *parent_, *left_, *right_;
 				int color_;
-			} lookup_;
+			};
 
+			lru lru_;
+			lookup lookup_;
 			unsigned ref_count_;
 			value_type v_;
 		};

persistent-data/data-structures/btree.h

@@ -235,6 +235,7 @@ namespace persistent_data {
 		public:
 			typedef transaction_manager::read_ref read_ref;
 			typedef transaction_manager::write_ref write_ref;
+			typedef boost::optional<block_address> maybe_block;
 
 			shadow_spine(transaction_manager::ptr tm,
 				     block_manager<>::validator::ptr v)
@@ -282,14 +283,17 @@ namespace persistent_data {
 			}
 
 			block_address get_root() const {
-				return root_;
+				if (root_)
+					return *root_;
+
+				throw std::runtime_error("shadow spine has no root");
 			}
 
 		private:
 			transaction_manager::ptr tm_;
 			block_manager<>::validator::ptr validator_;
 			std::list<block_manager<>::write_ref> spine_;
-			block_address root_;
+		        maybe_block root_;
 		};
 
 		// Used to keep a record of a nested btree's position.

persistent-data/hex_dump.cc

@@ -29,6 +29,8 @@ void base::hex_dump(ostream &out, void const *data_, size_t len)
 {
 	unsigned char const *data = reinterpret_cast<unsigned char const *>(data_),
 		*end = data + len;
+
+	ios_base::fmtflags old_flags = out.flags();
 	out << hex;
 
 	while (data < end) {
@@ -36,7 +38,8 @@ void base::hex_dump(ostream &out, void const *data_, size_t len)
 			out << setw(2) << setfill('0') << (unsigned) *data << " ";
 		out << endl;
 	}
-	out << dec;
+
+	out.setf(old_flags);
 }
 
 //----------------------------------------------------------------