switch to go-kit logger

Signed-off-by: Jan-Otto Kröpke <mail@jkroepke.de>

log/eventlog/eventlog.go

@@ -0,0 +1,124 @@
+//go:build windows
+// +build windows
+
+// Package eventlog provides a Logger that writes to Windows Event Log.
+package eventlog
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"sync"
+	"syscall"
+
+	"github.com/go-kit/log"
+	"github.com/go-kit/log/level"
+	"golang.org/x/sys/windows"
+	goeventlog "golang.org/x/sys/windows/svc/eventlog"
+)
+
+const (
+	// NeLogOemCode is a generic error log entry for OEMs to use to
+	// elog errors from OEM value added services.
+	// See: https://github.com/microsoft/win32metadata/blob/2f3c5282ce1024a712aeccd90d3aa50bf7a49e27/generation/WinSDK/RecompiledIdlHeaders/um/LMErrlog.h#L824-L845
+	neLogOemCode = uint32(3299)
+)
+
+type Priority struct {
+	etype int
+}
+
+// NewEventLogLogger returns a new Logger which writes to Windows EventLog in event log format.
+// The body of the log message is the formatted output from the Logger returned
+// by newLogger.
+func NewEventLogLogger(w *goeventlog.Log, newLogger func(io.Writer) log.Logger) log.Logger {
+	l := &eventlogLogger{
+		w:                w,
+		newLogger:        newLogger,
+		prioritySelector: defaultPrioritySelector,
+		bufPool: sync.Pool{New: func() interface{} {
+			return &loggerBuf{}
+		}},
+	}
+
+	return l
+}
+
+type eventlogLogger struct {
+	w                *goeventlog.Log
+	newLogger        func(io.Writer) log.Logger
+	prioritySelector PrioritySelector
+	bufPool          sync.Pool
+}
+
+func (l *eventlogLogger) Log(keyvals ...interface{}) error {
+	priority := l.prioritySelector(keyvals...)
+
+	lb := l.getLoggerBuf()
+	defer l.putLoggerBuf(lb)
+	if err := lb.logger.Log(keyvals...); err != nil {
+		return err
+	}
+
+	// golang.org/x/sys/windows/svc/eventlog does not provide func which allows to send more than one string.
+	// See: https://github.com/golang/go/issues/59780
+
+	msg, err := syscall.UTF16PtrFromString(lb.buf.String())
+	if err != nil {
+		return fmt.Errorf("error convert string to UTF-16: %v", err)
+	}
+
+	ss := []*uint16{msg, nil, nil, nil, nil, nil, nil, nil, nil}
+	return windows.ReportEvent(l.w.Handle, uint16(priority.etype), 0, neLogOemCode, 0, 9, 0, &ss[0], nil)
+}
+
+type loggerBuf struct {
+	buf    *bytes.Buffer
+	logger log.Logger
+}
+
+func (l *eventlogLogger) getLoggerBuf() *loggerBuf {
+	lb := l.bufPool.Get().(*loggerBuf)
+	if lb.buf == nil {
+		lb.buf = &bytes.Buffer{}
+		lb.logger = l.newLogger(lb.buf)
+	} else {
+		lb.buf.Reset()
+	}
+	return lb
+}
+
+func (l *eventlogLogger) putLoggerBuf(lb *loggerBuf) {
+	l.bufPool.Put(lb)
+}
+
+// PrioritySelector inspects the list of keyvals and selects an eventlog priority.
+type PrioritySelector func(keyvals ...interface{}) Priority
+
+// defaultPrioritySelector convert a kit/log level into a Windows Eventlog level
+func defaultPrioritySelector(keyvals ...interface{}) Priority {
+	l := len(keyvals)
+
+	eType := windows.EVENTLOG_SUCCESS
+
+	for i := 0; i < l; i += 2 {
+		if keyvals[i] == level.Key() {
+			var val interface{}
+			if i+1 < l {
+				val = keyvals[i+1]
+			}
+			if v, ok := val.(level.Value); ok {
+				switch v {
+				case level.ErrorValue():
+					eType = windows.EVENTLOG_ERROR_TYPE
+				case level.WarnValue():
+					eType = windows.EVENTLOG_WARNING_TYPE
+				case level.InfoValue():
+					eType = windows.EVENTLOG_INFORMATION_TYPE
+				}
+			}
+		}
+	}
+
+	return Priority{etype: eType}
+}