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

system_logging.cc

Index: system_logging.cc
diff --git a/system_logging.cc b/system_logging.cc
index 578951418500d2f2d7782f327a1d13fe3bdf1418..543ef78ff29279ccaa1e15a1a344e36935ccf195 100644
--- a/system_logging.cc
+++ b/system_logging.cc
@@ -2,12 +2,14 @@
 // 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_;
+std::string *SystemLoggingImpl::accumulator_;
 
 SystemLoggingImpl::SystemLoggingImpl() {
 }
@@ -22,23 +24,33 @@ void SystemLoggingImpl::Initialize(const char *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 (accumulator_ != NULL) {
+    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);
 }