Adds new logging type SYSLOG which logs to the system log.

base/syslog_logging.cc

Index: base/syslog_logging.cc
diff --git a/base/syslog_logging.cc b/base/syslog_logging.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2fc7541dd0f504ed42ead70f7c632974563848b7
--- /dev/null
+++ b/base/syslog_logging.cc
@@ -0,0 +1,86 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/debug/stack_trace.h"
+#include "base/syslog_logging.h"
+
+#if defined(OS_POSIX)
+#include <syslog.h>
+#endif
+
+#include <cstring>
+#include <ostream>
+#include <string>
+
+namespace logging {
+
+EventLogMessage::EventLogMessage(const char* file,
+                                 int line,
+                                 LogSeverity severity)
+    : log_message_(file, line, severity) {
+}
+
+EventLogMessage::~EventLogMessage() {
+  const char kEventSource[] = "chrome";
+  std::string message(log_message_.str());
+
+#if defined(OS_WIN)
+  HANDLE event_log_handle = RegisterEventSourceA(NULL, kEventSource);

[brettw, 2016/09/14 22:33:48]

I'm not familiar with this API, but MSDN says the name "must be a subkey of a
log under the Eventlog registry key". Is that true for the string "chrome" here?

[pastarmovj, 2016/09/15 21:27:10]

Actually this string appears in the log as the "source application" field. It
can be registered as a known log source or not (as is now) in which case it
always goes in the "Applications" event log.

Here is the remark about it: "If the source name cannot be found, the event
logging service uses the Application log. Although events will be reported , the
events will not include descriptions because there are no message and category
message files for looking up descriptions related to the event identifiers."

The TODO below refers to eventually register our events with the event log if we
ever decide to do more sophisticated logging. For now simple string reporting in
the logs is sufficient for the purpose it serves. 

+  if (event_log_handle == NULL) {
+    stream() << " !!NOT ADDED TO EVENTLOG!!";
+    return;
+  }
+
+  LPCSTR strings[1] = {message.data()};
+  WORD log_type = EVENTLOG_ERROR_TYPE;
+  switch (log_message_.severity()) {
+    case LOG_INFO:
+      log_type = EVENTLOG_INFORMATION_TYPE;
+      break;
+    case LOG_WARNING:
+      log_type = EVENTLOG_WARNING_TYPE;
+      break;
+    case LOG_ERROR:
+    case LOG_FATAL:
+      // The price of getting the stack trace is not worth the hassle for
+      // non-error conditions.
+      base::debug::StackTrace trace;
+      message.append(trace.ToString());
+      log_type = EVENTLOG_ERROR_TYPE;
+      break;
+  }
+  // TODO(pastarmovj): Register Chrome's event log resource types to make the
+  // entries nicer. 1337 is just a made up event id type.
+  if (!ReportEventA(event_log_handle, log_type, 0, 1337, NULL, 1, 0,
+                    strings, NULL)) {
+    stream() << " !!NOT ADDED TO EVENTLOG!!";
+  }
+  DeregisterEventSource(event_log_handle);
+#elif defined(OS_POSIX)
+  openlog(kEventSource, LOG_NOWAIT, LOG_USER);
+  // We can't use the defined names for the logging severity from syslog.h
+  // because they collide with the names of our own severity levels. Therefore
+  // we use the actual values which of course do no match ours. See sys/syslog.h

[brettw, 2016/09/14 22:33:48]

"do no" -> "do not"

[pastarmovj, 2016/09/15 21:27:10]

Done.

+  // for reference.
+  int priority = 3;
+  switch (log_message_.severity()) {
+    case LOG_INFO:
+      priority = 6;
+      break;
+    case LOG_WARNING:
+      priority = 4;
+      break;
+    case LOG_ERROR:
+      priority = 3;
+      break;
+    case LOG_FATAL:
+      priority = 2;
+      break;
+  }
+  syslog(priority, "%s", message.c_str());
+  closelog();
+#endif
+}
+
+}  // namespace logging