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

base/time.cc

Index: base/time.cc
diff --git a/base/time.cc b/base/time.cc
index 7055311e80e7d53df843b61dd63a67b816a74faa..f2f3168e9f5112160d54b69ffa60ed14ee33cdff 100644
--- a/base/time.cc
+++ b/base/time.cc
@@ -74,12 +74,23 @@ Time Time::Max() {
 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;
 }
 
@@ -87,14 +98,20 @@ time_t Time::ToTimeT() const {
 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));
 }
@@ -103,15 +120,21 @@ double Time::ToDoubleT() const {
 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);
 }