Allow one to block an account by using GRANT max_user_connections = -1

One can set @@global.max_user_connections to -1 to block anyone, except SUPER user, to login.
If max_user_connection is 0, one can't change it without a restart (needed to get user connections counting to work correctly)


mysql-test/r/system_mysql_db.result:
  Changed max_user_connections to handle negative numbers.
mysql-test/r/user_limits-2.result:
  New test case that one can't change max_user_connection if it was 0
mysql-test/r/user_limits.result:
  Fixed wrong error messages.
mysql-test/r/variables.result:
  Store / restore max_user_connections (needed as there is now a --master.opt file that changes it)
mysql-test/t/subselect_mat_cost-master.opt:
  Enable slow query log (as this test found some errors in slow query logging)
mysql-test/t/user_limits-2.test:
  New test case that one can't change max_user_connection if it was 0
mysql-test/t/user_limits-master.opt:
  Set max_user_connections (as one can't change it if it was 0)
mysql-test/t/user_limits.test:
  Test max_user_connections -1
mysql-test/t/variables-master.opt:
  Set max_user_connections (as one can't change it if it was 0)
mysql-test/t/variables.test:
  Set/restore max_user_connections
scripts/Makefile.am:
  Add a text message to mysql_fix_privilege_tables.sql that it's automaticly generated
scripts/mysql_system_tables.sql:
  Change max_user_connections to signed
scripts/mysql_system_tables_fix.sql:
  Change max_user_connections to signed
sql/item_func.cc:
  Change SHOW_INT to be signed.
  (Needed for max_user_connections and it's probably a bug that it was not originally signed)
sql/log.cc:
  Remove some code that was not needed (All these variables are reset at start of query)
sql/mysql_priv.h:
  Made max_user_connections signed.
  Added max_user_connections_checking
sql/mysqld.cc:
  Added max_user_connections_checking so that we know if max_user_connections was 0 at startup
  (Which means that we will not do connection counting for accounts that don't have user resource limits)
  Set thd->start_utime at same time as thr_create_utime. (Before start_utime could be < thr_create_utime which lead to wrong query counting)
sql/set_var.cc:
  Don't allow one to change 'max_user_connections' if it was 0 at startup.
sql/sql_acl.cc:
  Change user_connection counting to be negative.
sql/sql_connect.cc:
  If max_user_connections is < 0 then only SUPER user can login.
  Fixed wrong variable names for error messages.
  Fixed wrong initial value for questions.
  Set thd->start_utime and thd->thr_create_utime at startup.  Needed to get time_out_user_resource_limits() to work.
sql/sql_show.cc:
  SHOW_INT is now negative
sql/sql_yacc.yy:
  Support negative values for MAX_USER_CONNECTIONS
sql/structs.h:
  Make user connect counting work with signed numbers.

1 files changed, 6 insertions, 2 deletions

diff --git a/sql/item_func.cc b/sql/item_func.cc
index b907d1f432e..ce43f90be8d 100644
--- a/sql/item_func.cc
+++ b/sql/item_func.cc
@@ -5063,12 +5063,16 @@ void Item_func_get_system_var::fix_length_and_dec()
   switch (var->show_type())
   {
     case SHOW_LONG:
-    case SHOW_INT:
     case SHOW_HA_ROWS:
       unsigned_flag= TRUE;
       max_length= MY_INT64_NUM_DECIMAL_DIGITS;
       decimals=0;
       break;
+    case SHOW_INT:
+      unsigned_flag= FALSE;
+      max_length= MY_INT64_NUM_DECIMAL_DIGITS;
+      decimals=0;
+      break;
     case SHOW_LONGLONG:
       unsigned_flag= TRUE;
       max_length= MY_INT64_NUM_DECIMAL_DIGITS;
@@ -5209,7 +5213,7 @@ longlong Item_func_get_system_var::val_int()
 
   switch (var->show_type())
   {
-    case SHOW_INT:      get_sys_var_safe (uint);
+    case SHOW_INT:      get_sys_var_safe (int);
     case SHOW_LONG:     get_sys_var_safe (ulong);
     case SHOW_LONGLONG: get_sys_var_safe (ulonglong);
     case SHOW_HA_ROWS:  get_sys_var_safe (ha_rows);