Fix for bug #12173 (show create table crash)

mysql-test/r/type_newdecimal.result

@@ -976,3 +976,13 @@ select * from t1;
 f1	f2	f3	f4	f5	f6	f7	f8
 1	18	99	100	104	200	1000	10000
 drop table t1;
+create table t1 (
+f0 decimal (30,30) zerofill not null DEFAULT 0,
+f1 decimal (0,0) zerofill not null default 0);
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f0` decimal(30,30) unsigned zerofill NOT NULL default '0.000000000000000000000000000000',
+  `f1` decimal(10,0) unsigned zerofill NOT NULL default '0000000000'
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;

mysql-test/t/type_newdecimal.test

@@ -1007,3 +1007,11 @@ insert into t1 (f1) values (1);
 select * from t1;
 drop table t1;
 
+#
+# Bug 12173 (show create table fails)
+#
+create table t1 (
+        f0 decimal (30,30) zerofill not null DEFAULT 0,
+        f1 decimal (0,0) zerofill not null default 0);
+show create table t1;
+drop table t1;

strings/decimal.c

@@ -351,7 +351,8 @@ int decimal2string(decimal_t *from, char *to, int *to_len,
     buf0=&tmp;
   }
 
-  intg_len= fixed_precision ? fixed_intg : (intg ? intg : 1);
+  if (!(intg_len= fixed_precision ? fixed_intg : intg))
+    intg_len= 1;
   frac_len= fixed_precision ? fixed_decimals : frac;
   len= from->sign + intg_len + test(frac) + frac_len;
   if (fixed_precision)