Avoid generating invalid character encoding sequences in make_greater_string.

Not sure how this mistake evaded detection for so long.

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index a11e85a56d512ccd6bb5c5c6e76754c5a02cbfbf..84f18dc935993a70a20459a4bfe4df0314223f05 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.155 2004/01/17 20:09:35 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.156 2004/02/02 03:07:08 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3742,6 +3742,11 @@ pattern_selectivity(Const *patt, Pattern_Type ptype)
  *
  * This could be rather slow in the worst case, but in most cases we
  * won't have to try more than one or two strings before succeeding.
+ *
+ * NOTE: at present this assumes we are in the C locale, so that simple
+ * bytewise comparison applies.  However, we might be in a multibyte
+ * encoding such as UTF-8, so we do have to watch out for generating
+ * invalid encoding sequences.
  */
 Const *
 make_greater_string(const Const *str_const)
@@ -3788,13 +3793,20 @@ make_greater_string(const Const *str_const)
        /*
         * Try to generate a larger string by incrementing the last byte.
         */
-       if (*lastchar < (unsigned char) 255)
+       while (*lastchar < (unsigned char) 255)
        {
            Const      *workstr_const;
 
            (*lastchar)++;
+
            if (datatype != BYTEAOID)
+           {
+               /* do not generate invalid encoding sequences */
+               if (!pg_verifymbstr((const unsigned char *) workstr,
+                                   len, true))
+                   continue;
                workstr_const = string_to_const(workstr, datatype);
+           }
            else
                workstr_const = string_to_bytea_const(workstr, len);