Fix text decoding of dates with 5 digit years

pgtype/date.go

@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 	"encoding/json"
 	"fmt"
+	"regexp"
 	"strconv"
 	"time"
 
@@ -267,6 +268,8 @@ func (scanPlanBinaryDateToDateScanner) Scan(src []byte, dst any) error {
 
 type scanPlanTextAnyToDateScanner struct{}
 
+var dateRegexp = regexp.MustCompile(`^(\d{4,})-(\d\d)-(\d\d)( BC)?$`)
+
 func (scanPlanTextAnyToDateScanner) Scan(src []byte, dst any) error {
 	scanner := (dst).(DateScanner)
 
@@ -275,36 +278,40 @@ func (scanPlanTextAnyToDateScanner) Scan(src []byte, dst any) error {
 	}
 
 	sbuf := string(src)
+	match := dateRegexp.FindStringSubmatch(sbuf)
+	if match != nil {
+		year, err := strconv.ParseInt(match[1], 10, 32)
+		if err != nil {
+			return fmt.Errorf("BUG: cannot parse date that regexp matched (year): %v", err)
+		}
+
+		month, err := strconv.ParseInt(match[2], 10, 32)
+		if err != nil {
+			return fmt.Errorf("BUG: cannot parse date that regexp matched (month): %v", err)
+		}
+
+		day, err := strconv.ParseInt(match[3], 10, 32)
+		if err != nil {
+			return fmt.Errorf("BUG: cannot parse date that regexp matched (month): %v", err)
+		}
+
+		// BC matched
+		if len(match[4]) > 0 {
+			year = -year + 1
+		}
+
+		t := time.Date(int(year), time.Month(month), int(day), 0, 0, 0, 0, time.UTC)
+		return scanner.ScanDate(Date{Time: t, Valid: true})
+	}
+
 	switch sbuf {
 	case "infinity":
 		return scanner.ScanDate(Date{InfinityModifier: Infinity, Valid: true})
 	case "-infinity":
 		return scanner.ScanDate(Date{InfinityModifier: -Infinity, Valid: true})
 	default:
-		if len(sbuf) >= 10 {
-			year, err := strconv.ParseInt(sbuf[0:4], 10, 32)
-			if err != nil {
-				return fmt.Errorf("cannot parse year: %v", err)
-			}
-			month, err := strconv.ParseInt(sbuf[5:7], 10, 32)
-			if err != nil {
-				return fmt.Errorf("cannot parse month: %v", err)
-			}
-			day, err := strconv.ParseInt(sbuf[8:10], 10, 32)
-			if err != nil {
-				return fmt.Errorf("cannot parse day: %v", err)
-			}
-
-			if len(sbuf) == 13 && sbuf[11:] == "BC" {
-				year = -year + 1
-			}
-
-			t := time.Date(int(year), time.Month(month), int(day), 0, 0, 0, 0, time.UTC)
-			return scanner.ScanDate(Date{Time: t, Valid: true})
-		} else {
 		return fmt.Errorf("date too short")
 	}
-	}
 }
 
 func (c DateCodec) DecodeDatabaseSQLValue(m *Map, oid uint32, format int16, src []byte) (driver.Value, error) {

pgtype/date_test.go

@@ -31,6 +31,7 @@ func TestDateCodec(t *testing.T) {
 		{time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC))},
 		{time.Date(2000, 1, 2, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(2000, 1, 2, 0, 0, 0, 0, time.UTC))},
 		{time.Date(2200, 1, 1, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(2200, 1, 1, 0, 0, 0, 0, time.UTC))},
+		{time.Date(12200, 1, 2, 0, 0, 0, 0, time.UTC), new(time.Time), isExpectedEqTime(time.Date(12200, 1, 2, 0, 0, 0, 0, time.UTC))},
 		{pgtype.Date{InfinityModifier: pgtype.Infinity, Valid: true}, new(pgtype.Date), isExpectedEq(pgtype.Date{InfinityModifier: pgtype.Infinity, Valid: true})},
 		{pgtype.Date{InfinityModifier: pgtype.NegativeInfinity, Valid: true}, new(pgtype.Date), isExpectedEq(pgtype.Date{InfinityModifier: pgtype.NegativeInfinity, Valid: true})},
 		{pgtype.Date{}, new(pgtype.Date), isExpectedEq(pgtype.Date{})},
@@ -51,6 +52,7 @@ func TestDateCodecTextEncode(t *testing.T) {
 		{source: pgtype.Date{Time: time.Date(789, 1, 2, 0, 0, 0, 0, time.UTC), Valid: true}, result: "0789-01-02"},
 		{source: pgtype.Date{Time: time.Date(89, 1, 2, 0, 0, 0, 0, time.UTC), Valid: true}, result: "0089-01-02"},
 		{source: pgtype.Date{Time: time.Date(9, 1, 2, 0, 0, 0, 0, time.UTC), Valid: true}, result: "0009-01-02"},
+		{source: pgtype.Date{Time: time.Date(12200, 1, 2, 0, 0, 0, 0, time.UTC), Valid: true}, result: "12200-01-02"},
 		{source: pgtype.Date{InfinityModifier: pgtype.Infinity, Valid: true}, result: "infinity"},
 		{source: pgtype.Date{InfinityModifier: pgtype.NegativeInfinity, Valid: true}, result: "-infinity"},
 	}