Fix for bug#44774: load_file function produces valgrind warnings

Problem: using LOAD_FILE() in some cases we pass a file name string
without a trailing '\0' to fn_format() which relies on that however.
That may lead to valgrind warnings.

Fix: add a trailing '\0' to the file name passed to fn_format().


mysql-test/r/func_str.result:
  Fix for bug#44774: load_file function produces valgrind warnings
    - test result.
mysql-test/t/func_str.test:
  Fix for bug#44774: load_file function produces valgrind warnings
    - test case.
sql/item_strfunc.cc:
  Fix for bug#44774: load_file function produces valgrind warnings
    - passing a file name to fn_format(), file_name->c_ptr() replaced
      with file_name->c_ptr_safe() to ensure we have a trailing '\0'.

mysql-test/r/func_str.result

@@ -2187,4 +2187,13 @@ SELECT DATE_FORMAT(c, GET_FORMAT(DATE, 'eur')) h, CONCAT(UPPER(aa),', ', aa) i F
 h	i
 31.12.2008	AAAAAA, aaaaaa
 DROP TABLE t1;
+#
+# BUG#44774: load_file function produces valgrind warnings
+#
+CREATE TABLE t1 (a TINYBLOB);
+INSERT INTO t1 VALUES ('aaaaaaaa');
+SELECT LOAD_FILE(a) FROM t1;
+LOAD_FILE(a)
+NULL
+DROP TABLE t1;
 End of 5.0 tests

mysql-test/t/func_str.test

@@ -1168,4 +1168,14 @@ INSERT INTO t1 VALUES ('2008-12-31','aaaaaa');
 SELECT DATE_FORMAT(c, GET_FORMAT(DATE, 'eur')) h, CONCAT(UPPER(aa),', ', aa) i FROM t1;
 DROP TABLE t1;
 
+
+--echo #
+--echo # BUG#44774: load_file function produces valgrind warnings
+--echo #
+CREATE TABLE t1 (a TINYBLOB);
+INSERT INTO t1 VALUES ('aaaaaaaa');
+SELECT LOAD_FILE(a) FROM t1;
+DROP TABLE t1;
+
+
 --echo End of 5.0 tests

sql/item_strfunc.cc

@@ -2832,7 +2832,7 @@ String *Item_load_file::val_str(String *str)
       )
     goto err;
 
-  (void) fn_format(path, file_name->c_ptr(), mysql_real_data_home, "",
+  (void) fn_format(path, file_name->c_ptr_safe(), mysql_real_data_home, "",
 		   MY_RELATIVE_PATH | MY_UNPACK_FILENAME);
 
   /* Read only allowed from within dir specified by secure_file_priv */
@@ -2858,7 +2858,7 @@ String *Item_load_file::val_str(String *str)
   }
   if (tmp_value.alloc(stat_info.st_size))
     goto err;
-  if ((file = my_open(file_name->c_ptr(), O_RDONLY, MYF(0))) < 0)
+  if ((file = my_open(file_name->ptr(), O_RDONLY, MYF(0))) < 0)
     goto err;
   if (my_read(file, (byte*) tmp_value.ptr(), stat_info.st_size, MYF(MY_NABP)))
   {