From ce9cf882a54e9c55dcc7970398ae79c3b251f79e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B8rn=20Erik=20Pedersen?=
 <bjorn.erik.pedersen@gmail.com>
Date: Thu, 14 Nov 2024 09:43:37 +0100
Subject: [PATCH] server: Strip ANSI escape codes from browser error log

Fixes #13037
---
 common/loggers/handlerterminal.go      | 24 +++++++++++-----
 common/loggers/handlerterminal_test.go | 40 ++++++++++++++++++++++++++
 common/loggers/logger.go               |  4 +--
 3 files changed, 59 insertions(+), 9 deletions(-)
 create mode 100644 common/loggers/handlerterminal_test.go

diff --git a/common/loggers/handlerterminal.go b/common/loggers/handlerterminal.go
index 53f6e41da..c5f8fcce8 100644
--- a/common/loggers/handlerterminal.go
+++ b/common/loggers/handlerterminal.go
@@ -18,18 +18,19 @@ package loggers
 import (
 	"fmt"
 	"io"
+	"regexp"
 	"strings"
 	"sync"
 
 	"github.com/bep/logg"
 )
 
-// newNoColoursHandler creates a new NoColoursHandler
-func newNoColoursHandler(outWriter, errWriter io.Writer, noLevelPrefix bool, predicate func(*logg.Entry) bool) *noColoursHandler {
+// newNoAnsiEscapeHandler creates a new noAnsiEscapeHandler
+func newNoAnsiEscapeHandler(outWriter, errWriter io.Writer, noLevelPrefix bool, predicate func(*logg.Entry) bool) *noAnsiEscapeHandler {
 	if predicate == nil {
 		predicate = func(e *logg.Entry) bool { return true }
 	}
-	return &noColoursHandler{
+	return &noAnsiEscapeHandler{
 		noLevelPrefix: noLevelPrefix,
 		outWriter:     outWriter,
 		errWriter:     errWriter,
@@ -37,7 +38,7 @@ func newNoColoursHandler(outWriter, errWriter io.Writer, noLevelPrefix bool, pre
 	}
 }
 
-type noColoursHandler struct {
+type noAnsiEscapeHandler struct {
 	mu            sync.Mutex
 	outWriter     io.Writer // Defaults to os.Stdout.
 	errWriter     io.Writer // Defaults to os.Stderr.
@@ -45,7 +46,7 @@ type noColoursHandler struct {
 	noLevelPrefix bool
 }
 
-func (h *noColoursHandler) HandleLog(e *logg.Entry) error {
+func (h *noAnsiEscapeHandler) HandleLog(e *logg.Entry) error {
 	if !h.predicate(e) {
 		return nil
 	}
@@ -71,10 +72,12 @@ func (h *noColoursHandler) HandleLog(e *logg.Entry) error {
 		prefix = prefix + ": "
 	}
 
+	msg := stripANSI(e.Message)
+
 	if h.noLevelPrefix {
-		fmt.Fprintf(w, "%s%s", prefix, e.Message)
+		fmt.Fprintf(w, "%s%s", prefix, msg)
 	} else {
-		fmt.Fprintf(w, "%s %s%s", levelString[e.Level], prefix, e.Message)
+		fmt.Fprintf(w, "%s %s%s", levelString[e.Level], prefix, msg)
 	}
 
 	for _, field := range e.Fields {
@@ -88,3 +91,10 @@ func (h *noColoursHandler) HandleLog(e *logg.Entry) error {
 
 	return nil
 }
+
+var ansiRe = regexp.MustCompile(`\x1b\[[0-9;]*m`)
+
+// stripANSI removes ANSI escape codes from s.
+func stripANSI(s string) string {
+	return ansiRe.ReplaceAllString(s, "")
+}
diff --git a/common/loggers/handlerterminal_test.go b/common/loggers/handlerterminal_test.go
new file mode 100644
index 000000000..f45ce80df
--- /dev/null
+++ b/common/loggers/handlerterminal_test.go
@@ -0,0 +1,40 @@
+// Copyright 2024 The Hugo Authors. All rights reserved.
+// Some functions in this file (see comments) is based on the Go source code,
+// copyright The Go Authors and  governed by a BSD-style license.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package loggers
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/bep/logg"
+	qt "github.com/frankban/quicktest"
+	"github.com/gohugoio/hugo/common/terminal"
+)
+
+func TestNoAnsiEscapeHandler(t *testing.T) {
+	c := qt.New(t)
+
+	test := func(s string) {
+		c.Assert(stripANSI(terminal.Notice(s)), qt.Equals, s)
+	}
+	test(`error in "file.md:1:2"`)
+
+	var buf bytes.Buffer
+	h := newNoAnsiEscapeHandler(&buf, &buf, false, nil)
+	h.HandleLog(&logg.Entry{Message: terminal.Notice(`error in "file.md:1:2"`), Level: logg.LevelInfo})
+
+	c.Assert(buf.String(), qt.Equals, "INFO  error in \"file.md:1:2\"\n")
+}
diff --git a/common/loggers/logger.go b/common/loggers/logger.go
index 4e2f3ab21..75c8102c7 100644
--- a/common/loggers/logger.go
+++ b/common/loggers/logger.go
@@ -62,7 +62,7 @@ func New(opts Options) Logger {
 	if terminal.PrintANSIColors(os.Stdout) {
 		logHandler = newDefaultHandler(opts.Stdout, opts.Stderr)
 	} else {
-		logHandler = newNoColoursHandler(opts.Stdout, opts.Stderr, false, nil)
+		logHandler = newNoAnsiEscapeHandler(opts.Stdout, opts.Stderr, false, nil)
 	}
 
 	errorsw := &strings.Builder{}
@@ -95,7 +95,7 @@ func New(opts Options) Logger {
 	}
 
 	if opts.StoreErrors {
-		h := newNoColoursHandler(io.Discard, errorsw, true, func(e *logg.Entry) bool {
+		h := newNoAnsiEscapeHandler(io.Discard, errorsw, true, func(e *logg.Entry) bool {
 			return e.Level >= logg.LevelError
 		})