fix: iso8601TimeFormat padding issue for certain nanoseconds (#16207)

internal/amztime/iso8601_time.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2015-2022 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package amztime
+
+import (
+	"strings"
+	"time"
+)
+
+// RFC3339 a subset of the ISO8601 timestamp format. e.g 2014-04-29T18:30:38Z
+const iso8601TimeFormat = "2006-01-02T15:04:05.000Z" // Reply date format with nanosecond precision.
+
+// ISO8601Format converts time 't' into ISO8601 time format expected in AWS S3 spec.
+//
+// This function is needed to avoid a Go's float64 precision bug, where Go avoids
+// padding the extra '0' before the timezone.
+func ISO8601Format(t time.Time) string {
+	value := t.Format(iso8601TimeFormat)
+	if len(value) < len(iso8601TimeFormat) {
+		value = t.Format(iso8601TimeFormat[:len(iso8601TimeFormat)-1])
+		// Pad necessary zeroes to full-fill the iso8601TimeFormat
+		return value + strings.Repeat("0", (len(iso8601TimeFormat)-1)-len(value)) + "Z"
+	}
+	return value
+}
+
+// ISO8601Parse parses ISO8601 date string
+func ISO8601Parse(iso8601 string) (t time.Time, err error) {
+	for _, layout := range []string{
+		iso8601TimeFormat,
+		time.RFC3339,
+	} {
+		t, err = time.Parse(layout, iso8601)
+		if err == nil {
+			return t, nil
+		}
+	}
+
+	return t, err
+}

internal/amztime/iso8601_time_test.go

@@ -0,0 +1,58 @@
+// Copyright (c) 2015-2022 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package amztime
+
+import (
+	"testing"
+	"time"
+)
+
+func TestISO8601Format(t *testing.T) {
+	testCases := []struct {
+		date           time.Time
+		expectedOutput string
+	}{
+		{
+			date:           time.Date(2009, time.November, 13, 4, 51, 1, 940303531, time.UTC),
+			expectedOutput: "2009-11-13T04:51:01.940Z",
+		},
+		{
+			date:           time.Date(2009, time.November, 13, 4, 51, 1, 901303531, time.UTC),
+			expectedOutput: "2009-11-13T04:51:01.901Z",
+		},
+		{
+			date:           time.Date(2009, time.November, 13, 4, 51, 1, 900303531, time.UTC),
+			expectedOutput: "2009-11-13T04:51:01.900Z",
+		},
+		{
+			date:           time.Date(2009, time.November, 13, 4, 51, 1, 941303531, time.UTC),
+			expectedOutput: "2009-11-13T04:51:01.941Z",
+		},
+	}
+
+	for _, testCase := range testCases {
+		testCase := testCase
+		t.Run(testCase.expectedOutput, func(t *testing.T) {
+			gotOutput := ISO8601Format(testCase.date)
+			t.Log("Go", testCase.date.Format(iso8601TimeFormat))
+			if gotOutput != testCase.expectedOutput {
+				t.Errorf("Expected %s, got %s", testCase.expectedOutput, gotOutput)
+			}
+		})
+	}
+}