From d3f442ccd002affbdb996e2481afd0d9a56a2760 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Mon, 27 Apr 2020 10:42:52 +0200
Subject: [PATCH 1/2] format: stricter quoting based on strconv

---
 format.go | 52 ++++++++++------------------------------------------
 1 file changed, 10 insertions(+), 42 deletions(-)

diff --git a/format.go b/format.go
index 4e8e160..18cf5e5 100644
--- a/format.go
+++ b/format.go
@@ -7,7 +7,6 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 )
 
@@ -208,10 +207,9 @@ func formatJSONValue(value interface{}) interface{} {
 
 // formatValue formats a value for serialization
 func formatLogfmtValue(value interface{}) string {
-	if value == nil {
+	if value == nil || (reflect.ValueOf(value).Kind() == reflect.Ptr && reflect.ValueOf(value).IsNil()) {
 		return "nil"
 	}
-
 	if t, ok := value.(time.Time); ok {
 		// Performance optimization: No need for escaping since the provided
 		// timeFormat doesn't have any escape characters, and escaping is
@@ -235,49 +233,19 @@ func formatLogfmtValue(value interface{}) string {
 	}
 }
 
-var stringBufPool = sync.Pool{
-	New: func() interface{} { return new(bytes.Buffer) },
-}
-
+// escapeString checks if the provided string needs escaping/quoting, and
+// calls strconv.Quote if needed
 func escapeString(s string) string {
-	needsQuotes := false
-	needsEscape := false
+	needsQuoting := false
 	for _, r := range s {
-		if r <= ' ' || r == '=' || r == '"' {
-			needsQuotes = true
-		}
-		if r == '\\' || r == '"' || r == '\n' || r == '\r' || r == '\t' {
-			needsEscape = true
+		// quote everything below " (0x34) and above~ (0x7E), plus equal-sign
+		if r <= '"' || r > '~' || r == '=' {
+			needsQuoting = true
+			break
 		}
 	}
-	if needsEscape == false && needsQuotes == false {
+	if !needsQuoting {
 		return s
 	}
-	e := stringBufPool.Get().(*bytes.Buffer)
-	e.WriteByte('"')
-	for _, r := range s {
-		switch r {
-		case '\\', '"':
-			e.WriteByte('\\')
-			e.WriteByte(byte(r))
-		case '\n':
-			e.WriteString("\\n")
-		case '\r':
-			e.WriteString("\\r")
-		case '\t':
-			e.WriteString("\\t")
-		default:
-			e.WriteRune(r)
-		}
-	}
-	e.WriteByte('"')
-	var ret string
-	if needsQuotes {
-		ret = e.String()
-	} else {
-		ret = string(e.Bytes()[1 : e.Len()-1])
-	}
-	e.Reset()
-	stringBufPool.Put(e)
-	return ret
+	return strconv.Quote(s)
 }

From a6a1bb2925779ec7e9cdebcd941d7ffed17f1c8d Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Tue, 28 Apr 2020 12:33:46 +0200
Subject: [PATCH 2/2] format, test: test for nil-interface vs nil-value

---
 format.go     | 2 +-
 log15_test.go | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/format.go b/format.go
index 18cf5e5..cf364fc 100644
--- a/format.go
+++ b/format.go
@@ -207,7 +207,7 @@ func formatJSONValue(value interface{}) interface{} {
 
 // formatValue formats a value for serialization
 func formatLogfmtValue(value interface{}) string {
-	if value == nil || (reflect.ValueOf(value).Kind() == reflect.Ptr && reflect.ValueOf(value).IsNil()) {
+	if value == nil {
 		return "nil"
 	}
 	if t, ok := value.(time.Time); ok {
diff --git a/log15_test.go b/log15_test.go
index fb85fc3..b9a5ba6 100644
--- a/log15_test.go
+++ b/log15_test.go
@@ -158,11 +158,11 @@ func TestLogfmt(t *testing.T) {
 
 	l, buf := testFormatter(LogfmtFormat())
 	l.Error("some message", "x", 1, "y", 3.2, "equals", "=", "quote", "\"",
-		"nil", nilVal, "carriage_return", "bang"+string('\r')+"foo", "tab", "bar	baz", "newline", "foo\nbar")
+		"nilval", nilVal, "nil", nil, "carriage_return", "bang"+string('\r')+"foo", "tab", "bar	baz", "newline", "foo\nbar")
 
 	// skip timestamp in comparison
 	got := buf.Bytes()[27:buf.Len()]
-	expected := []byte(`lvl=eror msg="some message" x=1 y=3.200 equals="=" quote="\"" nil=nil carriage_return="bang\rfoo" tab="bar\tbaz" newline="foo\nbar"` + "\n")
+	expected := []byte(`lvl=eror msg="some message" x=1 y=3.200 equals="=" quote="\"" nilval=nil nil=nil carriage_return="bang\rfoo" tab="bar\tbaz" newline="foo\nbar"` + "\n")
 	if !bytes.Equal(got, expected) {
 		t.Fatalf("Got %s, expected %s", got, expected)
 	}