Fix for bug #6266 "Invalid DATETIME value is not handled properly".

In server we assume that datetime values stored in MYSQL_TIME struct
are normalized (and year is not greater than 9999), so we should 
perform range checks in all places then we convert something to
MYSQL_TIME. 


include/my_time.h:
  Added one more argument to set_zero_time() function to make it more 
  convinient.
  Added comment clarifying why MAX_DATE_STRING_REP_LENGTH value is 30.
include/mysql_time.h:
  Documented MySQL's internal assumptions for members of MYSQL_TIME
  structure.
libmysql/libmysql.c:
  It does not make sense to set MYSQL_TIME::time_type twice in case of 
  errors.
mysql-test/r/type_datetime.result:
  Added test for bug #6266 "Invalid DATETIME value not handled properly".
mysql-test/t/type_datetime.test:
  Added test for bug #6266 "Invalid DATETIME value not handled properly".
sql-common/my_time.c:
  str_to_datetime(): Added missing check for too big year values.
  set_zero_time(): added time_type argument, since MYSQL_TIMESTAMP_NONE
    is not the value that we want in most cases.
sql/field.cc:
  Field_datetime::store_time():
    clarified why we don't perform any range checks here.
sql/item.cc:
  Item_param::set_time():
   Added comment describing this method and range checking for TIME
   values.
sql/sql_prepare.cc:
  Removed comments about range checking for TIME values in prepared 
  statements, which are no longer true.
  set_zero_time() has one more argument now.
tests/client_test.c:
  Added test for bug #6266 "Invalid DATETIME value not handled properly"

1 files changed, 4 insertions, 3 deletions

diff --git a/sql-common/my_time.c b/sql-common/my_time.c
index 6c020466e1e..6b305944154 100644
--- a/sql-common/my_time.c
+++ b/sql-common/my_time.c
@@ -343,7 +343,8 @@ str_to_datetime(const char *str, uint length, MYSQL_TIME *l_time,
       (l_time->month || l_time->day))
     l_time->year+= (l_time->year < YY_PART_YEAR ? 2000 : 1900);
 
-  if (number_of_fields < 3 || l_time->month > 12 ||
+  if (number_of_fields < 3 ||
+      l_time->year > 9999 || l_time->month > 12 ||
       l_time->day > 31 || l_time->hour > 23 ||
       l_time->minute > 59 || l_time->second > 59 ||
       (!(flags & TIME_FUZZY_DATE) && (l_time->month == 0 || l_time->day == 0)))
@@ -720,10 +721,10 @@ my_system_gmt_sec(const MYSQL_TIME *t, long *my_timezone, bool *in_dst_time_gap)
 
 /* Set MYSQL_TIME structure to 0000-00-00 00:00:00.000000 */
 
-void set_zero_time(MYSQL_TIME *tm)
+void set_zero_time(MYSQL_TIME *tm, enum enum_mysql_timestamp_type time_type)
 {
   bzero((void*) tm, sizeof(*tm));
-  tm->time_type= MYSQL_TIMESTAMP_NONE;
+  tm->time_type= time_type;
 }