Fix text_substr bug intrduced in 7.3 development

using Joe Conway's patches (submitted at pgsql-patches on 2002/04/08)
 + small fix.

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 0cd38a76bee0fb5cfb8b2fb10c21d32809c08c59..2007e78910f3564b31193a5cbcbc14854fc1e7f9 100644 (file)
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.82 2002/04/03 05:39:32 petere Exp $
+ *       $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.83 2002/04/15 07:54:37 ishii Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -373,7 +373,10 @@ text_substr(PG_FUNCTION_ARGS)
        if (eml > 1)
        {
                sm = 0;
-               sn = (m + n) * eml + 3; /* +3 to avoid mb characters overhanging slice end */
+               if (n > -1)
+                       sn = (m + n) * eml + 3; /* +3 to avoid mb characters overhanging slice end */
+               else
+                       sn = n;         /* n < 0 is special-cased by heap_tuple_untoast_attr_slice */
        }
 #endif 
 
@@ -387,7 +390,10 @@ text_substr(PG_FUNCTION_ARGS)
        PG_RETURN_NULL();   /* notreached: suppress compiler warning */
 #endif
 #ifdef MULTIBYTE
-       len = pg_mbstrlen_with_len (VARDATA (string), sn - 3);
+       if (n > -1)
+               len = pg_mbstrlen_with_len (VARDATA (string), sn - 3);
+       else    /* n < 0 is special-cased; need full string length */
+               len = pg_mbstrlen_with_len (VARDATA (string), VARSIZE(string)-VARHDRSZ);
 
        if (m > len)
        {