A fix and test case for Bug#5315 "mysql_change_user() doesn't free

prepared statements."


include/hash.h:
  New declaration for hash_reset() function. The old version was not used.
libmysql/client_settings.h:
  Declaration for mysql_detach_stmt_list().
libmysql/libmysql.c:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  add call to mysql_detach_stmt_list(prepared statements) to
  mysql_change_user(): all statements are freed by server, so client
  counterparts need to be marked as not usable.
mysys/hash.c:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  implementation of hash_reset(), which frees all hash elements
  and prepares the hash for reuse.
sql-common/client.c:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  implementation of mysql_detach_stmt_list(): zero connection pointer
  in given statement list, thus marking given statements as not usable.
sql/sql_class.cc:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  reset prepared statements map in THD::change_user().
sql/sql_class.h:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  implementation of Statement_map::reset().
  A little cleanup of ~Statement_map(): first empty names_hash, as st_hash
  has a free function, which will delete statements.
tests/client_test.c:
  A test case for bug #5315 "mysql_change_user() doesn't free prepared
  statements".

2 files changed, 22 insertions, 12 deletions

diff --git a/libmysql/client_settings.h b/libmysql/client_settings.h
index 5857c0c84d6..552307733ea 100644
--- a/libmysql/client_settings.h
+++ b/libmysql/client_settings.h
@@ -42,6 +42,7 @@ my_bool handle_local_infile(MYSQL *mysql, const char *net_filename);
 
 void mysql_read_default_options(struct st_mysql_options *options,
 				const char *filename,const char *group);
+void mysql_detach_stmt_list(LIST **stmt_list);
 MYSQL * STDCALL
 cli_mysql_real_connect(MYSQL *mysql,const char *host, const char *user,
 		       const char *passwd, const char *db,
diff --git a/libmysql/libmysql.c b/libmysql/libmysql.c
index 6601d3e4ad7..2ad6771cc69 100644
--- a/libmysql/libmysql.c
+++ b/libmysql/libmysql.c
@@ -662,6 +662,7 @@ my_bool	STDCALL mysql_change_user(MYSQL *mysql, const char *user,
 				  const char *passwd, const char *db)
 {
   char buff[512],*end=buff;
+  int rc;
   DBUG_ENTER("mysql_change_user");
 
   if (!user)
@@ -695,18 +696,26 @@ my_bool	STDCALL mysql_change_user(MYSQL *mysql, const char *user,
   /* Write authentication package */
   simple_command(mysql,COM_CHANGE_USER, buff,(ulong) (end-buff),1);
 
-  if ((*mysql->methods->read_change_user_result)(mysql, buff, passwd))
-    DBUG_RETURN(1);
-  /* Free old connect information */
-  my_free(mysql->user,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->passwd,MYF(MY_ALLOW_ZERO_PTR));
-  my_free(mysql->db,MYF(MY_ALLOW_ZERO_PTR));
-
-  /* alloc new connect information */
-  mysql->user=  my_strdup(user,MYF(MY_WME));
-  mysql->passwd=my_strdup(passwd,MYF(MY_WME));
-  mysql->db=    db ? my_strdup(db,MYF(MY_WME)) : 0;
-  DBUG_RETURN(0);
+  rc= (*mysql->methods->read_change_user_result)(mysql, buff, passwd);
+
+  /*
+    The server will close all statements no matter was the attempt
+    to change user successful or not.
+  */
+  mysql_detach_stmt_list(&mysql->stmts);
+  if (rc == 0)
+  {
+    /* Free old connect information */
+    my_free(mysql->user,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->passwd,MYF(MY_ALLOW_ZERO_PTR));
+    my_free(mysql->db,MYF(MY_ALLOW_ZERO_PTR));
+
+    /* alloc new connect information */
+    mysql->user=  my_strdup(user,MYF(MY_WME));
+    mysql->passwd=my_strdup(passwd,MYF(MY_WME));
+    mysql->db=    db ? my_strdup(db,MYF(MY_WME)) : 0;
+  }
+  DBUG_RETURN(rc);
 }
 
 #if defined(HAVE_GETPWUID) && defined(NO_GETPWUID_DECL)