Recover from panics caused by dereferencing a nil pointer to a value receiver implementation of the fmt.Stringer or error interfaces.
Chris Hines
8 years ago
| 3 | 3 |
"encoding/json"
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"fmt"
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"io"
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"reflect"
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)
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type jsonLogger struct {
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return json.NewEncoder(l.Writer).Encode(m)
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}
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func merge(dst map[string]interface{}, k, v interface{}) map[string]interface{} {
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func merge(dst map[string]interface{}, k, v interface{}) {
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var key string
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switch x := k.(type) {
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case string:
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key = x
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case fmt.Stringer:
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key = x.String()
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key = safeString(x)
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default:
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key = fmt.Sprintf("%v", x)
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key = fmt.Sprint(x)
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}
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if x, ok := v.(error); ok {
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| 43 | |
v = x.Error()
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v = safeError(x)
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}
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dst[key] = v
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return dst
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}
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func safeString(str fmt.Stringer) (s string) {
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defer func() {
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if panicVal := recover(); panicVal != nil {
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if v := reflect.ValueOf(str); v.Kind() == reflect.Ptr && v.IsNil() {
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s = "NULL"
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} else {
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panic(panicVal)
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}
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}
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}()
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s = str.String()
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return
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}
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func safeError(err error) (s interface{}) {
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defer func() {
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if panicVal := recover(); panicVal != nil {
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if v := reflect.ValueOf(err); v.Kind() == reflect.Ptr && v.IsNil() {
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s = nil
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} else {
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panic(panicVal)
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}
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}
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}()
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s = err.Error()
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return
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}
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}
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}
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func TestJSONLoggerNilStringerKey(t *testing.T) {
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t.Parallel()
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buf := &bytes.Buffer{}
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logger := log.NewJSONLogger(buf)
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if err := logger.Log((*stringer)(nil), "v"); err != nil {
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t.Fatal(err)
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}
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if want, have := `{"NULL":"v"}`+"\n", buf.String(); want != have {
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t.Errorf("want %#v, have %#v", want, have)
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}
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}
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func TestJSONLoggerNilErrorValue(t *testing.T) {
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t.Parallel()
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buf := &bytes.Buffer{}
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logger := log.NewJSONLogger(buf)
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if err := logger.Log("err", (*stringError)(nil)); err != nil {
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t.Fatal(err)
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}
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if want, have := `{"err":null}`+"\n", buf.String(); want != have {
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t.Errorf("want %#v, have %#v", want, have)
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}
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}
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type stringer string
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func (s stringer) String() string {
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return string(s)
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}
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type stringError string
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func (s stringError) Error() string {
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return string(s)
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}
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| 35 | 73 |
func BenchmarkJSONLoggerSimple(b *testing.B) {
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| 36 | 74 |
benchmarkRunner(b, log.NewJSONLogger(ioutil.Discard), baseMessage)
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| 37 | 75 |
}
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