diff options
Diffstat (limited to 'src/backend/utils/adt/numeric.c')
| -rw-r--r-- | src/backend/utils/adt/numeric.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/src/backend/utils/adt/numeric.c b/src/backend/utils/adt/numeric.c index 3ba373a15b9..3d21e33a26b 100644 --- a/src/backend/utils/adt/numeric.c +++ b/src/backend/utils/adt/numeric.c @@ -7591,6 +7591,7 @@ exp_var(NumericVar *arg, NumericVar *result, int rscale) val = numericvar_to_double_no_overflow(&x); /* Guard against overflow */ + /* If you change this limit, see also power_var()'s limit */ if (Abs(val) >= NUMERIC_MAX_RESULT_SCALE * 3) ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), @@ -7992,6 +7993,15 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result) * * We want result = e ^ (exp * ln(base)) * so result dweight = log10(result) = exp * ln(base) * log10(e) + * + * We also perform a crude overflow test here so that we can exit early if + * the full-precision result is sure to overflow, and to guard against + * integer overflow when determining the scale for the real calculation. + * exp_var() supports inputs up to NUMERIC_MAX_RESULT_SCALE * 3, so the + * result will overflow if exp * ln(base) >= NUMERIC_MAX_RESULT_SCALE * 3. + * Since the values here are only approximations, we apply a small fuzz + * factor to this overflow test and let exp_var() determine the exact + * overflow threshold so that it is consistent for all inputs. *---------- */ ln_dweight = estimate_ln_dweight(base); @@ -8006,11 +8016,13 @@ power_var(NumericVar *base, NumericVar *exp, NumericVar *result) val = numericvar_to_double_no_overflow(&ln_num); - val *= 0.434294481903252; /* approximate decimal result weight */ + /* initial overflow test with fuzz factor */ + if (Abs(val) > NUMERIC_MAX_RESULT_SCALE * 3.01) + ereport(ERROR, + (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), + errmsg("value overflows numeric format"))); - /* limit to something that won't cause integer overflow */ - val = Max(val, -NUMERIC_MAX_RESULT_SCALE); - val = Min(val, NUMERIC_MAX_RESULT_SCALE); + val *= 0.434294481903252; /* approximate decimal result weight */ /* choose the result scale */ rscale = NUMERIC_MIN_SIG_DIGITS - (int) val; |