crash-reporter: Add diagnostics to help diagnose failures in the wild

system_logging.cc

 // Copyright (c) 2010 The Chromium OS 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 <stdarg.h>
+#include "crash-reporter/system_logging.h"
+
 #include <syslog.h>
 
-#include "crash-reporter/system_logging.h"
+#include "base/stringprintf.h"
 
 std::string SystemLoggingImpl::identity_;
 
-SystemLoggingImpl::SystemLoggingImpl() {
+SystemLoggingImpl::SystemLoggingImpl() : is_accumulating_(false) {
 }
 
 SystemLoggingImpl::~SystemLoggingImpl() {
 }
 
 void SystemLoggingImpl::Initialize(const char *ident) {
   // Man page does not specify if openlog copies its string or assumes
   // the pointer is always valid, so make its scope global.
   identity_ = ident;
   openlog(identity_.c_str(), LOG_PID, LOG_USER);
 }
 
+void SystemLoggingImpl::LogWithLevel(int level, const char *format,
+                                     va_list arg_list) {
+  std::string message = StringPrintV(format, arg_list);
+  syslog(level, "%s", message.c_str());
+  if (is_accumulating_) {
+    accumulator_.append(message);
+    accumulator_.push_back('\n');
+  }
+}
+
 void SystemLoggingImpl::LogInfo(const char *format, ...) {
   va_list vl;
   va_start(vl, format);
-  vsyslog(LOG_INFO, format, vl);
+  LogWithLevel(LOG_INFO, format, vl);
   va_end(vl);
 }
 
 void SystemLoggingImpl::LogWarning(const char *format, ...) {
   va_list vl;
   va_start(vl, format);
-  vsyslog(LOG_WARNING, format, vl);
+  LogWithLevel(LOG_WARNING, format, vl);
   va_end(vl);
 }
 
 void SystemLoggingImpl::LogError(const char *format, ...) {
   va_list vl;
   va_start(vl, format);
-  vsyslog(LOG_ERR, format, vl);
+  LogWithLevel(LOG_ERR, format, vl);
   va_end(vl);
 }