1 files changed, 34 insertions, 18 deletions

diff --git a/src/backend/utils/adt/int8.c b/src/backend/utils/adt/int8.c
index 3c595e800a4..437d41816a2 100644
--- a/src/backend/utils/adt/int8.c
+++ b/src/backend/utils/adt/int8.c
@@ -1204,22 +1204,29 @@ i8tod(PG_FUNCTION_ARGS)
 Datum
 dtoi8(PG_FUNCTION_ARGS)
 {
-	float8		arg = PG_GETARG_FLOAT8(0);
-	int64		result;
+	float8		num = PG_GETARG_FLOAT8(0);
 
-	/* Round arg to nearest integer (but it's still in float form) */
-	arg = rint(arg);
+	/*
+	 * 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);
 
-	if (unlikely(arg < (double) PG_INT64_MIN) ||
-		unlikely(arg > (double) PG_INT64_MAX) ||
-		unlikely(isnan(arg)))
+	/*
+	 * Range check.  We must be careful here that the boundary values are
+	 * expressed exactly in the float domain.  We expect PG_INT64_MIN to be an
+	 * exact power of 2, so it will be represented exactly; but PG_INT64_MAX
+	 * isn't, and might get rounded off, so avoid using it.
+	 */
+	if (unlikely(num < (float8) PG_INT64_MIN ||
+				 num >= -((float8) PG_INT64_MIN) ||
+				 isnan(num)))
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("bigint out of range")));
 
-	result = (int64) arg;
-
-	PG_RETURN_INT64(result);
+	PG_RETURN_INT64((int64) num);
 }
 
 Datum
@@ -1239,20 +1246,29 @@ i8tof(PG_FUNCTION_ARGS)
 Datum
 ftoi8(PG_FUNCTION_ARGS)
 {
-	float4		arg = PG_GETARG_FLOAT4(0);
-	float8		darg;
+	float4		num = PG_GETARG_FLOAT4(0);
 
-	/* Round arg to nearest integer (but it's still in float form) */
-	darg = rint(arg);
+	/*
+	 * 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);
 
-	if (unlikely(arg < (float4) PG_INT64_MIN) ||
-		unlikely(arg > (float4) PG_INT64_MAX) ||
-		unlikely(isnan(arg)))
+	/*
+	 * Range check.  We must be careful here that the boundary values are
+	 * expressed exactly in the float domain.  We expect PG_INT64_MIN to be an
+	 * exact power of 2, so it will be represented exactly; but PG_INT64_MAX
+	 * isn't, and might get rounded off, so avoid using it.
+	 */
+	if (unlikely(num < (float4) PG_INT64_MIN ||
+				 num >= -((float4) PG_INT64_MIN) ||
+				 isnan(num)))
 		ereport(ERROR,
 				(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
 				 errmsg("bigint out of range")));
 
-	PG_RETURN_INT64((int64) darg);
+	PG_RETURN_INT64((int64) num);
 }
 
 Datum