From 320909a1d1c68f134603469f866a6991c753639f Mon Sep 17 00:00:00 2001
From: Pavel Bychko <box@abordage.dev>
Date: Sun, 26 Jun 2022 12:34:03 +0300
Subject: [PATCH] Fix replaceNewlines method to avoid replacing escaped
 backslashes, closes #1721, fixes #1720

---
 src/Monolog/Formatter/LineFormatter.php       | 6 +++++-
 tests/Monolog/Formatter/LineFormatterTest.php | 8 ++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/Monolog/Formatter/LineFormatter.php b/src/Monolog/Formatter/LineFormatter.php
index 69dfee5ce..b31b2971a 100644
--- a/src/Monolog/Formatter/LineFormatter.php
+++ b/src/Monolog/Formatter/LineFormatter.php
@@ -186,7 +186,11 @@ protected function replaceNewlines(string $str): string
     {
         if ($this->allowInlineLineBreaks) {
             if (0 === strpos($str, '{')) {
-                return str_replace(array('\r', '\n'), array("\r", "\n"), $str);
+                $str = preg_replace('/(?<!\\\\)\\\\[rn]/', "\n", $str);
+                if (null === $str) {
+                    $pcreErrorCode = preg_last_error();
+                    throw new \RuntimeException('Failed to run preg_replace: ' . $pcreErrorCode . ' / ' . Utils::pcreLastErrorMessage($pcreErrorCode));
+                }
             }
 
             return $str;
diff --git a/tests/Monolog/Formatter/LineFormatterTest.php b/tests/Monolog/Formatter/LineFormatterTest.php
index d4d7c6588..74802c3fa 100644
--- a/tests/Monolog/Formatter/LineFormatterTest.php
+++ b/tests/Monolog/Formatter/LineFormatterTest.php
@@ -155,6 +155,14 @@ public function testDefFormatWithExceptionAndStacktrace()
         $this->assertRegexp('{^\['.date('Y-m-d').'] core\.CRITICAL: foobar \{"exception":"\[object] \(RuntimeException\(code: 0\): Foo at '.preg_quote(substr($path, 1, -1)).':'.(__LINE__ - 8).'\)\n\[stacktrace]\n#0}', $message);
     }
 
+    public function testInlineLineBreaksRespectsEscapedBackslashes()
+    {
+        $formatter = new LineFormatter(null, 'Y-m-d');
+        $formatter->allowInlineLineBreaks();
+
+        self::assertSame('{"test":"foo'."\n".'bar\\\\name-with-n"}', $formatter->stringify(["test" => "foo\nbar\\name-with-n"]));
+    }
+
     public function testDefFormatWithExceptionAndStacktraceParserFull()
     {
         $formatter = new LineFormatter(null, 'Y-m-d');