From ce654ad1e1ef5bde386d2873a19a39092d5ea6f4 Mon Sep 17 00:00:00 2001
From: Wei Congrui <crvv.mail@gmail.com>
Date: Fri, 18 Aug 2017 15:20:39 +0800
Subject: [PATCH] Fix numeric EncodeBinary bug

---
 pgtype/numeric.go      | 10 +++++++---
 pgtype/numeric_test.go | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/pgtype/numeric.go b/pgtype/numeric.go
index fded6359..fb63df75 100644
--- a/pgtype/numeric.go
+++ b/pgtype/numeric.go
@@ -16,6 +16,7 @@ import (
 const nbase = 10000
 
 var big0 *big.Int = big.NewInt(0)
+var big1 *big.Int = big.NewInt(1)
 var big10 *big.Int = big.NewInt(10)
 var big100 *big.Int = big.NewInt(100)
 var big1000 *big.Int = big.NewInt(1000)
@@ -507,6 +508,7 @@ func (src *Numeric) EncodeBinary(ci *ConnInfo, buf []byte) ([]byte, error) {
 		divisor := &big.Int{}
 		divisor.Exp(big10, big.NewInt(int64(-exp)), nil)
 		wholePart.DivMod(absInt, divisor, fracPart)
+		fracPart.Add(fracPart, divisor)
 	} else {
 		wholePart = absInt
 	}
@@ -518,9 +520,11 @@ func (src *Numeric) EncodeBinary(ci *ConnInfo, buf []byte) ([]byte, error) {
 		wholeDigits = append(wholeDigits, int16(remainder.Int64()))
 	}
 
-	for fracPart.Cmp(big0) != 0 {
-		fracPart.DivMod(fracPart, bigNBase, remainder)
-		fracDigits = append(fracDigits, int16(remainder.Int64()))
+	if fracPart.Cmp(big0) != 0 {
+		for fracPart.Cmp(big1) != 0 {
+			fracPart.DivMod(fracPart, bigNBase, remainder)
+			fracDigits = append(fracDigits, int16(remainder.Int64()))
+		}
 	}
 
 	buf = pgio.AppendInt16(buf, int16(len(wholeDigits)+len(fracDigits)))
diff --git a/pgtype/numeric_test.go b/pgtype/numeric_test.go
index 5f3a3416..9d7d83d6 100644
--- a/pgtype/numeric_test.go
+++ b/pgtype/numeric_test.go
@@ -317,3 +317,39 @@ func TestNumericAssignTo(t *testing.T) {
 		}
 	}
 }
+
+func TestNumericEncodeDecodeBinary(t *testing.T) {
+	ci := pgtype.NewConnInfo()
+	tests := []interface{}{
+		123,
+		0.000012345,
+		1.00002345,
+	}
+
+	for i, tt := range tests {
+		toString := func(n *pgtype.Numeric) string {
+			ci := pgtype.NewConnInfo()
+			text, err := n.EncodeText(ci, nil)
+			if err != nil {
+				t.Errorf("%d: %v", i, err)
+			}
+			return string(text)
+		}
+		numeric := &pgtype.Numeric{}
+		numeric.Set(tt)
+
+		encoded, err := numeric.EncodeBinary(ci, nil)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+		decoded := &pgtype.Numeric{}
+		decoded.DecodeBinary(ci, encoded)
+
+		text0 := toString(numeric)
+		text1 := toString(decoded)
+
+		if text0 != text1 {
+			t.Errorf("%d: expected %v to equal to %v, but doesn't", i, text0, text1)
+		}
+	}
+}