From 93eec1238663beab8521605f08a5937dbd8ec114 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 24 Nov 2018 12:45:50 -0500 Subject: Fix float-to-integer coercions to handle edge cases correctly. ftoi4 and its sibling coercion functions did their overflow checks in a way that looked superficially plausible, but actually depended on an assumption that the MIN and MAX comparison constants can be represented exactly in the float4 or float8 domain. That fails in ftoi4, ftoi8, and dtoi8, resulting in a possibility that values near the MAX limit will be wrongly converted (to negative values) when they need to be rejected. Also, because we compared before rounding off the fractional part, the other three functions threw errors for values that really ought to get rounded to the min or max integer value. Fix by doing rint() first (requiring an assumption that it handles NaN and Inf correctly; but dtoi8 and ftoi8 were assuming that already), and by comparing to values that should coerce to float exactly, namely INTxx_MIN and -INTxx_MIN. Also remove some random cosmetic discrepancies between these six functions. This back-patches commits cbdb8b4c0 and 452b637d4. In the 9.4 branch, also back-patch the portion of 62e2a8dc2 that added PG_INTnn_MIN and related constants to c.h, so that these functions can rely on them. Per bug #15519 from Victor Petrovykh. Patch by me; thanks to Andrew Gierth for analysis and discussion. Discussion: https://postgr.es/m/15519-4fc785b483201ff1@postgresql.org --- src/backend/utils/adt/float.c | 79 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 68 insertions(+), 11 deletions(-) (limited to 'src/backend/utils/adt/float.c') diff --git a/src/backend/utils/adt/float.c b/src/backend/utils/adt/float.c index 8aa17e1dcb9..79573f14d58 100644 --- a/src/backend/utils/adt/float.c +++ b/src/backend/utils/adt/float.c @@ -1219,16 +1219,28 @@ Datum dtoi4(PG_FUNCTION_ARGS) { float8 num = PG_GETARG_FLOAT8(0); - int32 result; - /* 'Inf' is handled by INT_MAX */ - if (num < INT_MIN || num > INT_MAX || isnan(num)) + /* + * Get rid of any fractional part in the input. This is so we don't fail + * on just-out-of-range values that would round into range. Note + * assumption that rint() will pass through a NaN or Inf unchanged. + */ + num = rint(num); + + /* + * Range check. We must be careful here that the boundary values are + * expressed exactly in the float domain. We expect PG_INT32_MIN to be an + * exact power of 2, so it will be represented exactly; but PG_INT32_MAX + * isn't, and might get rounded off, so avoid using it. + */ + if (num < (float8) PG_INT32_MIN || + num >= -((float8) PG_INT32_MIN) || + isnan(num)) ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), errmsg("integer out of range"))); - result = (int32) rint(num); - PG_RETURN_INT32(result); + PG_RETURN_INT32((int32) num); } @@ -1240,12 +1252,27 @@ dtoi2(PG_FUNCTION_ARGS) { float8 num = PG_GETARG_FLOAT8(0); - if (num < SHRT_MIN || num > SHRT_MAX || isnan(num)) + /* + * Get rid of any fractional part in the input. This is so we don't fail + * on just-out-of-range values that would round into range. Note + * assumption that rint() will pass through a NaN or Inf unchanged. + */ + num = rint(num); + + /* + * Range check. We must be careful here that the boundary values are + * expressed exactly in the float domain. We expect PG_INT16_MIN to be an + * exact power of 2, so it will be represented exactly; but PG_INT16_MAX + * isn't, and might get rounded off, so avoid using it. + */ + if (num < (float8) PG_INT16_MIN || + num >= -((float8) PG_INT16_MIN) || + isnan(num)) ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), errmsg("smallint out of range"))); - PG_RETURN_INT16((int16) rint(num)); + PG_RETURN_INT16((int16) num); } @@ -1281,12 +1308,27 @@ ftoi4(PG_FUNCTION_ARGS) { float4 num = PG_GETARG_FLOAT4(0); - if (num < INT_MIN || num > INT_MAX || isnan(num)) + /* + * Get rid of any fractional part in the input. This is so we don't fail + * on just-out-of-range values that would round into range. Note + * assumption that rint() will pass through a NaN or Inf unchanged. + */ + num = rint(num); + + /* + * Range check. We must be careful here that the boundary values are + * expressed exactly in the float domain. We expect PG_INT32_MIN to be an + * exact power of 2, so it will be represented exactly; but PG_INT32_MAX + * isn't, and might get rounded off, so avoid using it. + */ + if (num < (float4) PG_INT32_MIN || + num >= -((float4) PG_INT32_MIN) || + isnan(num)) ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), errmsg("integer out of range"))); - PG_RETURN_INT32((int32) rint(num)); + PG_RETURN_INT32((int32) num); } @@ -1298,12 +1340,27 @@ ftoi2(PG_FUNCTION_ARGS) { float4 num = PG_GETARG_FLOAT4(0); - if (num < SHRT_MIN || num > SHRT_MAX || isnan(num)) + /* + * Get rid of any fractional part in the input. This is so we don't fail + * on just-out-of-range values that would round into range. Note + * assumption that rint() will pass through a NaN or Inf unchanged. + */ + num = rint(num); + + /* + * Range check. We must be careful here that the boundary values are + * expressed exactly in the float domain. We expect PG_INT16_MIN to be an + * exact power of 2, so it will be represented exactly; but PG_INT16_MAX + * isn't, and might get rounded off, so avoid using it. + */ + if (num < (float4) PG_INT16_MIN || + num >= -((float4) PG_INT16_MIN) || + isnan(num)) ereport(ERROR, (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE), errmsg("smallint out of range"))); - PG_RETURN_INT16((int16) rint(num)); + PG_RETURN_INT16((int16) num); } -- cgit v1.2.3