Add overflow checks to int4 and int8 versions of generate_series().

The previous code went into an infinite loop after overflow.  In fact,
an overflow is not really an error; it just means that the current
value is the last one we need to return.  So, just arrange to stop
immediately when overflow is detected.

Back-patch all the way.

diff --git a/src/backend/utils/adt/int.c b/src/backend/utils/adt/int.c
index 019fcaa..a367421 100644 (file)
--- a/src/backend/utils/adt/int.c
+++ b/src/backend/utils/adt/int.c
@@ -1382,6 +1382,10 @@ generate_series_step_int4(PG_FUNCTION_ARGS)
                /* increment current in preparation for next iteration */
                fctx->current += fctx->step;
 
+               /* if next-value computation overflows, this is the final result */
+               if (SAMESIGN(result, fctx->step) && !SAMESIGN(result, fctx->current))
+                       fctx->step = 0;
+
                /* do when there is more left to send */
                SRF_RETURN_NEXT(funcctx, Int32GetDatum(result));
        }

diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index 4519164..2e74482 100644 (file)
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -1410,6 +1410,10 @@ generate_series_step_int8(PG_FUNCTION_ARGS)
                /* increment current in preparation for next iteration */
                fctx->current += fctx->step;
 
+               /* if next-value computation overflows, this is the final result */
+               if (SAMESIGN(result, fctx->step) && !SAMESIGN(result, fctx->current))
+                       fctx->step = 0;
+
                /* do when there is more left to send */
                SRF_RETURN_NEXT(funcctx, Int64GetDatum(result));
        }