pgsql: Fix possible internal overflow in numeric division.

Fix possible internal overflow in numeric division.

div_var_fast() postpones propagating carries in the same way as mul_var(),
so it has the same corner-case overflow risk we fixed in 246693e5ae8a36f0,
namely that the size of the carries has to be accounted for when setting
the threshold for executing a carry propagation step. We've not devised
a test case illustrating the brokenness, but the required fix seems clear
enough. Like the previous fix, back-patch to all active branches.

Dean Rasheed

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/5f10b7a604c87fc61a2c20a56552301f74c9bd5f

Modified Files
--------------
src/backend/utils/adt/numeric.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)