Be sure book file is closed before we leave

Move closing of file in Book destructor. This
guarantees us against leaving the file open under
any case and simplifies also Book use.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/book.cpp

@@ -344,10 +344,21 @@ namespace {
 ////
 
 
+/// Destructor. Be sure file is closed before we leave.
+
+Book::~Book() {
+
+  close();
+}
+
+
 /// Book::open() opens a book file with a given file name
 
 void Book::open(const string& fName) {
 
+  // Close old file before opening the new
+  close();
+
   fileName = fName;
   ifstream::open(fileName.c_str(), ifstream::in | ifstream::binary);
   if (!is_open())
@@ -361,7 +372,6 @@ void Book::open(const string& fName) {
   if (!good())
   {
       cerr << "Failed to open book file " << fileName << endl;
-      close();
       exit(EXIT_FAILURE);
   }
 }
@@ -479,7 +489,6 @@ void Book::read_entry(BookEntry& entry, int idx) {
   if (!good())
   {
       cerr << "Failed to read book entry at index " << idx << endl;
-      close();
       exit(EXIT_FAILURE);
   }
 }

src/book.h

@@ -53,8 +53,8 @@ struct BookEntry {
 };
 
 class Book : private std::ifstream {
-
 public:
+  ~Book();
   void open(const std::string& fName);
   void close();
   const std::string file_name() const;

src/search.cpp

@@ -371,10 +371,8 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move,
   {
       Move bookMove;
       if (get_option_value_string("Book File") != OpeningBook.file_name())
-      {
-          OpeningBook.close();
           OpeningBook.open("book.bin");
-      }
+
       bookMove = OpeningBook.get_move(pos);
       if (bookMove != MOVE_NONE)
       {
@@ -545,7 +543,6 @@ void think(const Position &pos, bool infinite, bool ponder, int side_to_move,
 
   if (Quit)
   {
-      OpeningBook.close();
       stop_threads();
       quit_eval();
       exit(0);
@@ -2561,7 +2558,6 @@ namespace {
         command = "quit";
 
       if(command == "quit") {
-        OpeningBook.close();
         stop_threads();
         quit_eval();
         exit(0);

src/uci.cpp

@@ -119,7 +119,6 @@ namespace {
 
     if (token == "quit")
     {
-        OpeningBook.close();
         stop_threads();
         quit_eval();
         exit(0);