SERVER-25926 Windows audit bson output erroneously translates LF to CR LF

2 files changed, 35 insertions, 30 deletions

diff --git a/src/mongo/logger/message_event_utf8_encoder.cpp b/src/mongo/logger/message_event_utf8_encoder.cpp
index 827876d46f5..68fc6923f0f 100644
--- a/src/mongo/logger/message_event_utf8_encoder.cpp
+++ b/src/mongo/logger/message_event_utf8_encoder.cpp
@@ -46,6 +46,14 @@ MessageEventDetailsEncoder::DateFormatter MessageEventDetailsEncoder::getDateFor
     return _dateFormatter;
 }
 
+namespace {
+#ifdef _WIN32
+constexpr auto kEOL = "\r\n"_sd;
+#else
+constexpr auto kEOL = "\n"_sd;
+#endif
+} // namespace
+
 MessageEventDetailsEncoder::~MessageEventDetailsEncoder() {}
 std::ostream& MessageEventDetailsEncoder::encode(const MessageEventEphemeral& event,
                                                  std::ostream& os) {
@@ -67,6 +75,26 @@ std::ostream& MessageEventDetailsEncoder::encode(const MessageEventEphemeral& ev
     }
 
     StringData msg = event.getMessage();
+
+#ifdef _WIN32
+    // We need to translate embedded Unix style line endings into Windows style endings.
+    std::string tempstr;
+    size_t embeddedNewLine = msg.find('\n');
+
+    if (embeddedNewLine != std::string::npos) {
+        tempstr = msg.toString().replace(embeddedNewLine, 1, "\r\n");
+
+        embeddedNewLine = tempstr.find('\n', embeddedNewLine + 2);
+        while (embeddedNewLine != std::string::npos) {
+            tempstr = tempstr.replace(embeddedNewLine, 1, "\r\n");
+
+            embeddedNewLine = tempstr.find('\n', embeddedNewLine + 2);
+        }
+
+        msg = tempstr;
+    }
+#endif
+
     if (event.isTruncatable() && msg.size() > maxLogLine) {
         os << "warning: log line attempted (" << msg.size() / 1024 << "kB) over max size ("
            << maxLogLine / 1024 << "kB), printing beginning and end ... ";
@@ -76,8 +104,10 @@ std::ostream& MessageEventDetailsEncoder::encode(const MessageEventEphemeral& ev
     } else {
         os << msg;
     }
-    if (!msg.endsWith(StringData("\n"_sd)))
-        os << '\n';
+
+    if (!msg.endsWith(kEOL))
+        os << kEOL;
+
     return os;
 }
 
diff --git a/src/mongo/logger/rotatable_file_writer.cpp b/src/mongo/logger/rotatable_file_writer.cpp
index 561869645ca..4c053f19615 100644
--- a/src/mongo/logger/rotatable_file_writer.cpp
+++ b/src/mongo/logger/rotatable_file_writer.cpp
@@ -97,8 +97,6 @@ private:
     virtual std::streamsize xsputn(const char* s, std::streamsize count);
     virtual int_type overflow(int_type ch = traits_type::eof());
 
-    std::streamsize writeToFile(const char* s, std::streamsize count);
-
     HANDLE _fileHandle;
 };
 
@@ -163,7 +161,8 @@ bool Win32FileStreambuf::open(StringData fileName, bool append) {
     return false;
 }
 
-std::streamsize Win32FileStreambuf::writeToFile(const char* s, std::streamsize count) {
+// Called when strings are written to ostream
+std::streamsize Win32FileStreambuf::xsputn(const char* s, std::streamsize count) {
     DWORD totalBytesWritten = 0;
 
     while (count > totalBytesWritten) {
@@ -171,32 +170,8 @@ std::streamsize Win32FileStreambuf::writeToFile(const char* s, std::streamsize c
         if (!WriteFile(_fileHandle, s, count - totalBytesWritten, &bytesWritten, NULL)) {
             break;
         }
-        totalBytesWritten += bytesWritten;
-    }
-
-    return totalBytesWritten;
-}
-
-// Called when strings are written to ostream
-std::streamsize Win32FileStreambuf::xsputn(const char* s, std::streamsize count) {
-    DWORD totalBytesWritten = 0;
-
-    // Scan for embedded newlines before end
-    // this should be rare since the newline should only be at the end
-    const char* startPos = s;
-    for (int i = 0; i < count; i++) {
-        if (s[i] == '\n') {
-            totalBytesWritten += writeToFile(startPos, i - (startPos - s));
-            writeToFile("\r\n", 2);
-            totalBytesWritten += 1;  // Caller expected we only wrote 1 char, so tell them so
-            startPos = &s[i + 1];
-        }
-    }
 
-    // Did the string not end on "\n"? Write the remaining, no need for CRLF
-    // as upper layers are responsible for it
-    if ((startPos - s) != count) {
-        totalBytesWritten += writeToFile(startPos, count - (startPos - s));
+        totalBytesWritten += bytesWritten;
     }
 
     return totalBytesWritten;