Added check for invalid histogram data, added additional diagnostics to find the source of troubles…

chrome/browser/chromeos/external_metrics.cc

 // 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 "chrome/browser/chromeos/external_metrics.h"
 
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 16 matching lines @@
 #include "content/public/browser/user_metrics.h"
 
 using content::BrowserThread;
 using content::UserMetricsAction;
 
 namespace chromeos {
 
 // The interval between external metrics collections in seconds
 static const int kExternalMetricsCollectionIntervalSeconds = 30;
 
+class SystemHistogram : public base::Histogram {
+ public:
+  static bool CheckValues(const std::string& name,
+                                           int minimum,
+                                           int maximum,
+                                           size_t bucket_count) {

[hshi1, 2012/08/03 02:24:24]

nit: please vertically left-align the arguments

[zel, 2012/08/03 02:29:45]

Done.

+    return base::Histogram::InspectConstructionArguments(
+        name, &minimum, &maximum, &bucket_count);
+  }
+};
+
 ExternalMetrics::ExternalMetrics()
     : test_recorder_(NULL) {
 }
 
 ExternalMetrics::~ExternalMetrics() {}
 
 void ExternalMetrics::Start() {
   // Register user actions external to the browser.
   // chrome/tools/extract_actions.py won't understand these lines, so all of
   // these are explicitly added in that script.
@@ skipping 35 matching lines @@
 
 void ExternalMetrics::RecordHistogram(const char* histogram_data) {
   int sample, min, max, nbuckets;
   char name[128];   // length must be consistent with sscanf format below.
   int n = sscanf(histogram_data, "%127s %d %d %d %d",
                  name, &sample, &min, &max, &nbuckets);
   if (n != 5) {
     LOG(ERROR) << "bad histogram request: " << histogram_data;
     return;
   }
+
+  if (!SystemHistogram::CheckValues(name, min, max, nbuckets)) {
+    LOG(ERROR) << "Invalid histogram " << name
+               << ", min=" << min
+               << ", max=" << max
+               << ", nbuckets=" << nbuckets;
+    return;
+  }
   // Do not use the UMA_HISTOGRAM_... macros here.  They cache the Histogram
   // instance and thus only work if |name| is constant.
   base::Histogram* counter = base::Histogram::FactoryGet(
       name, min, max, nbuckets, base::Histogram::kUmaTargetedHistogramFlag);
   counter->Add(sample);
 }
 
 void ExternalMetrics::RecordLinearHistogram(const char* histogram_data) {
   int sample, max;
   char name[128];   // length must be consistent with sscanf format below.
@@ skipping 130 matching lines @@
 void ExternalMetrics::ScheduleCollector() {
   bool result;
   result = BrowserThread::PostDelayedTask(
     BrowserThread::FILE, FROM_HERE,
     base::Bind(&chromeos::ExternalMetrics::CollectEventsAndReschedule, this),
     base::TimeDelta::FromSeconds(kExternalMetricsCollectionIntervalSeconds));
   DCHECK(result);
 }
 
 }  // namespace chromeos