MWL#36: Add a mysqlbinlog option to change the used database.

Add Rpl_filter to mysqlbinlog.cc
Note. Though within MWL#36 we are going to use only two Rpl_filter's
      methods (add_db_rewrite and get_rewrite_db), we look forward for
      MWL#40 where Rpl_filter is likely to be used to its more extent.
Note. Within MWL#36 we will not use Rpl_filter for supporting --database
      option: this option allows to specify only one database what
      doesn't correlate with Rpl_filter::add_do_db() (using this method
      will either appear "artificial" or require changing --database
      semantics). To be discussed within MWL#40.
To add Rpl_filter we need:
1. include sql_string.h
   There are two instances of sql_string.* files - in sql and in client
   directories. We need to use the ones from the sql dir.
2. include sql_list.h
   This requires to define a client version of sql_alloc() function.
3. include rpl_filter.h
   This requires a definition of system_charset_info variable.
   Besides, Rpl_filter::tables_ok() refers to a TABLE_LIST structure which
   encounts deep non-client dependencies and can't be used here as is. On
   the other hand, tables_ok() make use only few TABLE_LIST's members and
   none of them depends on specific server context. This allows to redefine
   TABLE_LIST in a client context so that tables_ok() becomes admissible
   (surely it's a kind of hack but (at least currently) it's better than
   #ifndef'ing this method in Rpl_filter definition).
Also add Rpl_filter::rewrite_db_is_empty() method. This is needed to be
able to check that --rewrite-db is not used jointly with --base64-output=
always (this is not supported - at least currently).

client/mysqlbinlog.cc

@@ -35,6 +35,18 @@
 #include "log_event.h"
 #include "sql_common.h"
 
+/* Needed for Rlp_filter */
+struct TABLE_LIST;
+
+/* Needed for Rpl_filter */
+CHARSET_INFO* system_charset_info= &my_charset_utf8_general_ci;
+
+#include "../sql/sql_string.h"  // needed for Rpl_filter
+#include "sql_list.h"           // needed for Rpl_filter
+#include "rpl_filter.h"
+
+Rpl_filter *binlog_filter;
+
 #define BIN_LOG_HEADER_SIZE	4
 #define PROBE_HEADER_LEN	(EVENT_LEN_OFFSET+4)
 
@@ -1986,6 +1998,8 @@ static Exit_status dump_local_log_entries(PRINT_EVENT_INFO *print_event_info,
   return retval;
 }
 
+/* Used in sql_alloc(). Inited and freed in main() */
+MEM_ROOT s_mem_root;
 
 int main(int argc, char** argv)
 {
@@ -1998,6 +2012,13 @@ int main(int argc, char** argv)
 
   my_init_time(); // for time functions
 
+  init_alloc_root(&s_mem_root, 16384, 0);
+  if (!(binlog_filter= new Rpl_filter))
+  {
+    error("Failed to create Rpl_filter");
+    exit(1);
+  }
+
   parse_args(&argc, (char***)&argv);
   defaults_argv=argv;
 
@@ -2084,6 +2105,8 @@ int main(int argc, char** argv)
   if (result_file != stdout)
     my_fclose(result_file, MYF(0));
   cleanup();
+  delete binlog_filter;
+  free_root(&s_mem_root, MYF(0));
   free_defaults(defaults_argv);
   my_free_open_file_info();
   load_processor.destroy();
@@ -2095,6 +2118,21 @@ int main(int argc, char** argv)
   DBUG_RETURN(retval == ERROR_STOP ? 1 : 0);
 }
 
+/* Redefinition for Rpl_filter::tables_ok() */
+struct TABLE_LIST
+{
+  TABLE_LIST() {}
+  TABLE_LIST *next_global, **prev_global;
+  bool  updating;
+  char* db;
+  char* table_name;
+};
+
+void *sql_alloc(size_t size)
+{
+  return alloc_root(&s_mem_root, size);
+}
+
 /*
   We must include this here as it's compiled with different options for
   the server
@@ -2105,4 +2143,7 @@ int main(int argc, char** argv)
 #include "my_decimal.cc"
 #include "log_event.cc"
 #include "log_event_old.cc"
+#include "../sql/sql_string.cc"
+#include "sql_list.cc"
+#include "rpl_filter.cc"
 

sql/rpl_filter.cc

@@ -514,6 +514,13 @@ Rpl_filter::get_wild_ignore_table(String* str)
 }
 
 
+bool
+Rpl_filter::rewrite_db_is_empty()
+{
+  return rewrite_db.is_empty();
+}
+
+
 const char*
 Rpl_filter::get_rewrite_db(const char* db, size_t *new_len)
 {

sql/rpl_filter.h

@@ -69,6 +69,7 @@ class Rpl_filter
   void get_wild_do_table(String* str);
   void get_wild_ignore_table(String* str);
 
+  bool rewrite_db_is_empty();
   const char* get_rewrite_db(const char* db, size_t *new_len);
 
   I_List<i_string>* get_do_db();