use contexts for logging

1 files changed, 30 insertions, 0 deletions

diff --git a/nslcd_server/ctx.go b/nslcd_server/ctx.go
index 5214adc..9722017 100644
--- a/nslcd_server/ctx.go
+++ b/nslcd_server/ctx.go
@@ -20,9 +20,26 @@ package nslcd_server
 import (
 	"context"
 
+	"git.lukeshu.com/go/libsystemd/sd_daemon"
 	"golang.org/x/sys/unix"
 )
 
+// Logger is the common interface between
+// `"git.lukeshu.com/go/libsystemd/sd_daemon".Logger` and
+// `"log/syslog".Writer`.
+type Logger interface {
+	Emerg(m string) error
+	Alert(m string) error
+	Crit(m string) error
+	Err(m string) error
+	Warning(m string) error
+	Notice(m string) error
+	Info(m string) error
+	Debug(m string) error
+
+	Write(m []byte) (int, error)
+}
+
 // contextKey is a value for use with context.WithValue.  It's used as
 // a pointer so it fits in an interface{} without allocation.
 type contextKey struct {
@@ -35,6 +52,11 @@ var (
 	// The associated value will be of type
 	// "golang.org/x/sys/unix".Ucred
 	PeerCredKey = &contextKey{"peercred"}
+
+	// LoggerKey is a context key.  It can be used in the backend
+	// methods to access a logger.  The associated value will be
+	// an implementation of Logger.
+	LoggerKey = &contextKey{"log"}
 )
 
 // PeerCredFromContext is a convenience function for
@@ -44,3 +66,11 @@ func PeerCredFromContext(ctx context.Context) (unix.Ucred, bool) {
 	cred, ok := ctx.Value(PeerCredKey).(unix.Ucred)
 	return cred, ok
 }
+
+func LoggerFromContext(ctx context.Context) Logger {
+	logger, ok := ctx.Value(LoggerKey).(Logger)
+	if !ok {
+		return sd_daemon.Log
+	}
+	return logger
+}