add vendoring

vendor/maunium.net/go/maulogger/v2/writer.go

@@ -0,0 +1,78 @@
+// mauLogger - A logger for Go programs
+// Copyright (c) 2021 Tulir Asokan
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package maulogger
+
+import (
+	"bytes"
+	"io"
+	"sync"
+)
+
+// LogWriter is a buffered io.Writer that writes lines to a Logger.
+type LogWriter struct {
+	log   Logger
+	lock  sync.Mutex
+	level Level
+	buf   bytes.Buffer
+}
+
+func (log *BasicLogger) Writer(level Level) io.WriteCloser {
+	return &LogWriter{
+		log:   log,
+		level: level,
+	}
+}
+
+func (log *Sublogger) Writer(level Level) io.WriteCloser {
+	return &LogWriter{
+		log:   log,
+		level: level,
+	}
+}
+
+func (lw *LogWriter) writeLine(data []byte) {
+	if lw.buf.Len() == 0 {
+		if len(data) == 0 {
+			return
+		}
+		lw.log.Logln(lw.level, string(data))
+	} else {
+		lw.buf.Write(data)
+		lw.log.Logln(lw.level, lw.buf.String())
+		lw.buf.Reset()
+	}
+}
+
+// Write will write lines from the given data to the buffer. If the data doesn't end with a line break,
+// everything after the last line break will be buffered until the next Write or Close call.
+func (lw *LogWriter) Write(data []byte) (int, error) {
+	lw.lock.Lock()
+	newline := bytes.IndexByte(data, '\n')
+	if newline == len(data)-1 {
+		lw.writeLine(data[:len(data)-1])
+	} else if newline < 0 {
+		lw.buf.Write(data)
+	} else {
+		lines := bytes.Split(data, []byte("\n"))
+		for _, line := range lines[:len(lines)-1] {
+			lw.writeLine(line)
+		}
+		lw.buf.Write(lines[len(lines)-1])
+	}
+	lw.lock.Unlock()
+	return len(data), nil
+}
+
+// Close will flush remaining data in the buffer into the logger.
+func (lw *LogWriter) Close() error {
+	lw.lock.Lock()
+	lw.log.Logln(lw.level, lw.buf.String())
+	lw.buf.Reset()
+	lw.lock.Unlock()
+	return nil
+}