bk commit into 5.0 tree (hf:1.1943) BUG#10337

[holyfoot]

Below is the list of changes that have just been committed into a local
5.0 repository of hf. When hf does a push these changes will
be propagated to the main repository and, within 24 hours after the
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ChangeSet
  1.1943 05/06/15 19:02:35 hf@deer.(none) +4 -0
  Fix for bug #10337 (cast(NULL DECIMAL) crashes the server)

  strings/decimal.c
    1.53 05/06/15 19:01:35 hf@deer.(none) +7 -1
    we need to return specified 'scale' for the rounded decimal

  sql/item_func.cc
    1.220 05/06/15 19:01:35 hf@deer.(none) +8 -1
    checks for NULL added

  mysql-test/t/cast.test
    1.20 05/06/15 19:01:35 hf@deer.(none) +6 -0
    test case added

  mysql-test/r/cast.result
    1.30 05/06/15 19:01:35 hf@deer.(none) +3 -0
    test result fixed

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	hf
# Host:	deer.(none)
# Root:	/home/hf/work/mysql-5.0.10337

--- 1.219/sql/item_func.cc	Tue Jun 14 13:40:06 2005
+++ 1.220/sql/item_func.cc	Wed Jun 15 19:01:35 2005
@@ -1022,7 +1022,8 @@
 String *Item_decimal_typecast::val_str(String *str)
 {
   my_decimal tmp_buf, *tmp= val_decimal(&tmp_buf);
-  my_decimal_round(E_DEC_FATAL_ERROR, tmp, decimals, FALSE, &tmp_buf);
+  if (null_value)
+    return NULL;
   my_decimal2string(E_DEC_FATAL_ERROR, &tmp_buf, 0, 0, 0, str);
   return str;
 }
@@ -1032,6 +1033,8 @@
 {
   my_decimal tmp_buf, *tmp= val_decimal(&tmp_buf);
   double res;
+  if (null_value)
+    return 0.0;
   my_decimal2double(E_DEC_FATAL_ERROR, tmp, &res);
   return res;
 }
@@ -1041,6 +1044,8 @@
 {
   my_decimal tmp_buf, *tmp= val_decimal(&tmp_buf);
   longlong res;
+  if (null_value)
+    return 0;
   my_decimal2int(E_DEC_FATAL_ERROR, tmp, unsigned_flag, &res);
   return res;
 }
@@ -1049,6 +1054,8 @@
 my_decimal *Item_decimal_typecast::val_decimal(my_decimal *dec)
 {
   my_decimal tmp_buf, *tmp= args[0]->val_decimal(&tmp_buf);
+  if ((null_value= args[0]->null_value))
+    return NULL;
   my_decimal_round(E_DEC_FATAL_ERROR, tmp, decimals, FALSE, dec);
   return dec;
 }

--- 1.29/mysql-test/r/cast.result	Sat Apr 30 20:40:05 2005
+++ 1.30/mysql-test/r/cast.result	Wed Jun 15 19:01:35 2005
@@ -344,3 +344,6 @@
 cast(s1 as decimal(7,2))
 111111.00
 drop table t1;
+select cast(NULL as decimal(6)) as t1;
+t1
+NULL

--- 1.19/mysql-test/t/cast.test	Sat Apr 30 11:46:04 2005
+++ 1.20/mysql-test/t/cast.test	Wed Jun 15 19:01:35 2005
@@ -168,3 +168,9 @@
 insert into t1 values ('11:11:11');
 select cast(s1 as decimal(7,2)) from t1;
 drop table t1;
+
+#
+# Bug @10237 (CAST(NULL DECIMAL) crashes server)
+#
+select cast(NULL as decimal(6)) as t1;
+

--- 1.52/strings/decimal.c	Thu Jun  9 12:42:55 2005
+++ 1.53/strings/decimal.c	Wed Jun 15 19:01:35 2005
@@ -1563,7 +1563,13 @@
         break;
       if (buf1-- == to->buf)
       {
-        decimal_make_zero(to);
+        /* making 'zero' with the proper scale */
+        dec1 *p0= to->buf + frac0 + 1;
+        to->intg=1;
+        to->frac= max(scale, 0);
+        to->sign= 0;
+        for (buf1= to->buf; buf1<p0; buf1++)
+          *buf1= 0;
         return E_DEC_OK;
       }
     }