Reject year zero during datetime input, except when it's a 2-digit year

(then it means 2000 AD).  Formerly we silently interpreted this as 1 BC,
which at best is unwarranted familiarity with the implementation.
It's barely possible that some app somewhere expects the old behavior,
though, so we won't back-patch this into existing release branches.

diff --git a/src/backend/utils/adt/datetime.c b/src/backend/utils/adt/datetime.c
index d8fbe0a30771862ccf4b57b89b4087df5cdc1203..08f21b46b0a1769536c740ef6c2fb5062aba8772 100644 (file)
--- a/src/backend/utils/adt/datetime.c
+++ b/src/backend/utils/adt/datetime.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.186 2008/02/25 23:21:01 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/adt/datetime.c,v 1.187 2008/02/25 23:36:28 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2138,24 +2138,30 @@ ValidateDate(int fmask, bool is2digits, bool bc, struct pg_tm * tm)
 {
    if (fmask & DTK_M(YEAR))
    {
-       /* there is no year zero in AD/BC notation; i.e. "1 BC" == year 0 */
        if (bc)
        {
-           if (tm->tm_year > 0)
-               tm->tm_year = -(tm->tm_year - 1);
-           else
-               ereport(ERROR,
-                       (errcode(ERRCODE_INVALID_DATETIME_FORMAT),
-                        errmsg("inconsistent use of year %04d and \"BC\"",
-                               tm->tm_year)));
+           /* there is no year zero in AD/BC notation */
+           if (tm->tm_year <= 0)
+               return DTERR_FIELD_OVERFLOW;
+           /* internally, we represent 1 BC as year zero, 2 BC as -1, etc */
+           tm->tm_year = -(tm->tm_year - 1);
        }
        else if (is2digits)
        {
+           /* allow 2-digit input for 1970-2069 AD; 00 is allowed */
+           if (tm->tm_year < 0)                /* just paranoia */
+               return DTERR_FIELD_OVERFLOW;
            if (tm->tm_year < 70)
                tm->tm_year += 2000;
            else if (tm->tm_year < 100)
                tm->tm_year += 1900;
        }
+       else
+       {
+           /* there is no year zero in AD/BC notation */
+           if (tm->tm_year <= 0)
+               return DTERR_FIELD_OVERFLOW;
+       }
    }
 
    /* now that we have correct year, decode DOY */