add emitter

log/emitter.go

@@ -0,0 +1,42 @@
+package log
+
+import (
+	"io"
+	"runtime"
+	"strings"
+	"time"
+
+	glog "gvisor.dev/gvisor/pkg/log"
+)
+
+func init() {
+	EnableStackLog(true)
+}
+
+func EnableStackLog(v bool) {
+	if v {
+		glog.SetTarget(&emitter{}) // built-in logger
+	} else {
+		glog.SetTarget(&glog.Writer{Next: io.Discard})
+	}
+}
+
+type emitter struct{}
+
+func (*emitter) level(level glog.Level) Level {
+	return 1 - Level(level)
+}
+
+func (*emitter) prefix(format string) string {
+	return "[STACK] " + format
+}
+
+func (e *emitter) Emit(depth int, level glog.Level, _ time.Time, format string, args ...any) {
+	if _, file, line, ok := runtime.Caller(depth + 1); ok {
+		// Ignore: gvisor.dev/gvisor/pkg/tcpip/adapters/gonet/gonet.go:457
+		if line == 457 && strings.HasSuffix(file, "gonet/gonet.go") {
+			return
+		}
+	}
+	logf(e.level(level), e.prefix(format), args...)
+}