Fixing Time::Max()'s behavior with Time::ToTimeT() and friends.

base/time.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 "base/time.h"
 
 #include <math.h>
 #if defined(OS_WIN)
 #include <float.h>
 #endif
@@ skipping 56 matching lines @@
 
 // static
 Time Time::Max() {
   return Time(std::numeric_limits<int64>::max());
 }
 
 // static
 Time Time::FromTimeT(time_t tt) {
   if (tt == 0)
     return Time();  // Preserve 0 so we can tell it doesn't exist.
+  if (tt == std::numeric_limits<time_t>::max())
+    return Max();
   return Time((tt * kMicrosecondsPerSecond) + kTimeTToMicrosecondsOffset);
 }
 
 time_t Time::ToTimeT() const {
-  if (us_ == 0)
+  if (is_null())
     return 0;  // Preserve 0 so we can tell it doesn't exist.
+  if (is_max()) {
+    // Preserve max without offset to prevent overflow.
+    return std::numeric_limits<time_t>::max();
+  }
+  if (std::numeric_limits<int64>::max() - kTimeTToMicrosecondsOffset <= us_) {
+    DLOG(WARNING) << "Overflow when converting base::Time with internal " <<
+                     "value " << us_ << " to time_t.";
+    return std::numeric_limits<time_t>::max();
+  }
   return (us_ - kTimeTToMicrosecondsOffset) / kMicrosecondsPerSecond;
 }
 
 // static
 Time Time::FromDoubleT(double dt) {
   if (dt == 0 || isnan(dt))
     return Time();  // Preserve 0 so we can tell it doesn't exist.
+  if (dt == std::numeric_limits<double>::max())
+    return Max();
   return Time(static_cast<int64>((dt *
                                   static_cast<double>(kMicrosecondsPerSecond)) +
                                  kTimeTToMicrosecondsOffset));
 }
 
 double Time::ToDoubleT() const {
-  if (us_ == 0)
+  if (is_null())
     return 0;  // Preserve 0 so we can tell it doesn't exist.
+  if (is_max()) {
+    // Preserve max without offset to prevent overflow.
+    return std::numeric_limits<double>::max();
+  }
   return (static_cast<double>(us_ - kTimeTToMicrosecondsOffset) /
           static_cast<double>(kMicrosecondsPerSecond));
 }
 
 // static
 Time Time::FromJsTime(double ms_since_epoch) {
   // The epoch is a valid time, so this constructor doesn't interpret
   // 0 as the null time.
+  if (ms_since_epoch == std::numeric_limits<double>::max())
+    return Max();
   return Time(static_cast<int64>(ms_since_epoch * kMicrosecondsPerMillisecond) +
               kTimeTToMicrosecondsOffset);
 }
 
 double Time::ToJsTime() const {
-  if (us_ == 0) {
+  if (is_null()) {
     // Preserve 0 so the invalid result doesn't depend on the platform.
     return 0;
   }
+  if (is_max()) {
+    // Preserve max without offset to prevent overflow.
+    return std::numeric_limits<double>::max();
+  }
   return (static_cast<double>(us_ - kTimeTToMicrosecondsOffset) /
           kMicrosecondsPerMillisecond);
 }
 
 // static
 Time Time::UnixEpoch() {
   Time time;
   time.us_ = kTimeTToMicrosecondsOffset;
   return time;
 }
@@ skipping 36 matching lines @@
   return is_in_range(month, 1, 12) &&
          is_in_range(day_of_week, 0, 6) &&
          is_in_range(day_of_month, 1, 31) &&
          is_in_range(hour, 0, 23) &&
          is_in_range(minute, 0, 59) &&
          is_in_range(second, 0, 60) &&
          is_in_range(millisecond, 0, 999);
 }
 
 }  // namespace base