Reapply "Set the TZ env to get the UTC-ms since epoch."

runtime/lib/date.cc

Index: runtime/lib/date.cc
diff --git a/runtime/lib/date.cc b/runtime/lib/date.cc
index 9a993428627f1649eb3abb23b9f4f31b35ce8dfd..90158c9a345475fcf072595be66597ccd2079842 100644
--- a/runtime/lib/date.cc
+++ b/runtime/lib/date.cc
@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+#include <time.h>
+
 #include "vm/bootstrap_natives.h"
 
 #include "vm/bigint_operations.h"
@@ -11,13 +13,98 @@
 
 namespace dart {
 
+typedef struct BrokenDownDate {
+  intptr_t year;
+  intptr_t month;  // [1..12]
+  intptr_t day;    // [1..31]
+  intptr_t hours;
+  intptr_t minutes;
+  intptr_t seconds;
+} BrokenDownDate;
+
+
+// Takes the seconds since epoch (midnight, January 1, 1970 UTC) and breaks it
+// down into date and time.
+// If 'dart_is_utc', then the broken down date and time are in the UTC timezone,
+// otherwise the local timezone is used.
+// The returned year is offset by 1900. The returned month is 0-based.
+// Returns true if the conversion succeeds, false otherwise.
 static bool BreakDownSecondsSinceEpoch(const Integer& dart_seconds,
                                        const Bool& dart_is_utc,
-                                       OS::BrokenDownDate* result) {
+                                       BrokenDownDate* result) {
+  // Always fill the result to avoid unitialized use warnings.
+  result->year = 0;
+  result->month = 0;
+  result->day = 0;
+  result->hours = 0;
+  result->minutes = 0;
+  result->seconds = 0;
+
   bool is_utc = dart_is_utc.value();
-  int64_t value = dart_seconds.AsInt64Value();
-  time_t seconds = static_cast<time_t>(value);
-  return OS::BreakDownSecondsSinceEpoch(seconds, is_utc, result);
+  int64_t seconds = dart_seconds.AsInt64Value();
+
+  struct tm tm_result;
+  bool succeeded;
+  if (is_utc) {
+    succeeded = OS::GmTime(seconds, &tm_result);
+  } else {
+    succeeded = OS::LocalTime(seconds, &tm_result);
+  }
+  if (succeeded) {
+    result->year = tm_result.tm_year;
+    // C uses years since 1900, and not full years.
+    // Adding 1900 could overflow the intptr_t.
+    if (result->year > kIntptrMax - 1900) return false;
+    result->year += 1900;
+    // Dart has 1-based months (contrary to C's 0-based).
+    result->month= tm_result.tm_mon + 1;
+    result->day = tm_result.tm_mday;
+    result->hours = tm_result.tm_hour;
+    result->minutes = tm_result.tm_min;
+    result->seconds = tm_result.tm_sec;
+  }
+  return succeeded;
+}
+
+
+static bool BrokenDownToSecondsSinceEpoch(const BrokenDownDate& broken_down,
+                                          bool in_utc,
+                                          int64_t* result) {
+  // Always set the result to avoid unitialized use warnings.
+  *result = 0;
+
+  struct tm tm_broken_down;
+  intptr_t year = broken_down.year;
+  // C works with years since 1900.
+  // Removing 1900 could underflow the intptr_t.
+  if (year < kIntptrMin + 1900) return false;
+  year -= 1900;
+  intptr_t month = broken_down.month;
+  // C works with 0-based months.
+  // Avoid underflows (even though they should not matter since the date would
+  // be invalid anyways.
+  if (month < 0) return false;
+  month--;
+  tm_broken_down.tm_year = static_cast<int>(year);
+  tm_broken_down.tm_mon = static_cast<int>(month);
+  tm_broken_down.tm_mday = static_cast<int>(broken_down.day);
+  tm_broken_down.tm_hour = static_cast<int>(broken_down.hours);
+  tm_broken_down.tm_min = static_cast<int>(broken_down.minutes);
+  tm_broken_down.tm_sec = static_cast<int>(broken_down.seconds);
+  // Verify that casting to int did not change the value.
+  if (tm_broken_down.tm_year != year
+      || tm_broken_down.tm_mon != month
+      || tm_broken_down.tm_mday != broken_down.day
+      || tm_broken_down.tm_hour != broken_down.hours
+      || tm_broken_down.tm_min != broken_down.minutes
+      || tm_broken_down.tm_sec != broken_down.seconds) {
+    return false;
+  }
+  if (in_utc) {
+    return OS::MkGmTime(&tm_broken_down, result);
+  } else {
+    return OS::MkTime(&tm_broken_down, result);
+  }
 }
 
 
@@ -34,24 +121,17 @@ DEFINE_NATIVE_ENTRY(DateNatives_brokenDownToSecondsSinceEpoch, 7) {
   }
   Smi& smi_years = Smi::Handle();
   smi_years ^= dart_years.raw();
-  OS::BrokenDownDate broken_down;
-  // mktime takes the years since 1900.
-  // TODO(floitsch): Removing 1900 could underflow the intptr_t.
-  intptr_t year = smi_years.Value() - 1900;
-  // TODO(1143): We don't handle the case yet where intptr_t and int have
-  // different sizes.
-  // ASSERT(sizeof(year) <= sizeof(broken_down.year));
-  broken_down.year = static_cast<int>(year);
-  // libc months are 0-based (contrary to Dart' 1-based months).
-  broken_down.month = dart_month.Value() - 1;
+  BrokenDownDate broken_down;
+  broken_down.year = smi_years.Value();
+  broken_down.month = dart_month.Value();
   broken_down.day = dart_day.Value();
   broken_down.hours = dart_hours.Value();
   broken_down.minutes = dart_minutes.Value();
   broken_down.seconds = dart_seconds.Value();
-  time_t value;
-  bool succeeded = OS::BrokenDownToSecondsSinceEpoch(broken_down,
-                                                     dart_is_utc.value(),
-                                                     &value);
+  int64_t value;
+  bool succeeded = BrokenDownToSecondsSinceEpoch(broken_down,
+                                                 dart_is_utc.value(),
+                                                 &value);
   if (!succeeded) {
     UNIMPLEMENTED();
   }
@@ -69,15 +149,13 @@ DEFINE_NATIVE_ENTRY(DateNatives_currentTimeMillis, 0) {
 DEFINE_NATIVE_ENTRY(DateNatives_getYear, 2) {
   GET_NATIVE_ARGUMENT(Integer, dart_seconds, arguments->At(0));
   GET_NATIVE_ARGUMENT(Bool, dart_is_utc, arguments->At(1));
-  OS::BrokenDownDate broken_down;
+  BrokenDownDate broken_down;
   bool succeeded =
       BreakDownSecondsSinceEpoch(dart_seconds, dart_is_utc, &broken_down);
   if (!succeeded) {
     UNIMPLEMENTED();
   }
-  // C uses years since 1900, and not full years.
-  // TODO(floitsch): adding 1900 could overflow the intptr_t.
-  intptr_t year = broken_down.year + 1900;
+  intptr_t year = broken_down.year;
   arguments->SetReturn(Integer::Handle(Integer::New(year)));
 }
 
@@ -85,14 +163,13 @@ DEFINE_NATIVE_ENTRY(DateNatives_getYear, 2) {
 DEFINE_NATIVE_ENTRY(DateNatives_getMonth, 2) {
   GET_NATIVE_ARGUMENT(Integer, dart_seconds, arguments->At(0));
   GET_NATIVE_ARGUMENT(Bool, dart_is_utc, arguments->At(1));
-  OS::BrokenDownDate broken_down;
+  BrokenDownDate broken_down;
   bool succeeded =
       BreakDownSecondsSinceEpoch(dart_seconds, dart_is_utc, &broken_down);
   if (!succeeded) {
     UNIMPLEMENTED();
   }
-  // Dart has 1-based months (contrary to C's 0-based).
-  const Smi& result = Smi::Handle(Smi::New(broken_down.month + 1));
+  const Smi& result = Smi::Handle(Smi::New(broken_down.month));
   arguments->SetReturn(result);
 }
 
@@ -100,7 +177,7 @@ DEFINE_NATIVE_ENTRY(DateNatives_getMonth, 2) {
 DEFINE_NATIVE_ENTRY(DateNatives_getDay, 2) {
   GET_NATIVE_ARGUMENT(Integer, dart_seconds, arguments->At(0));
   GET_NATIVE_ARGUMENT(Bool, dart_is_utc, arguments->At(1));
-  OS::BrokenDownDate broken_down;
+  BrokenDownDate broken_down;
   bool succeeded =
       BreakDownSecondsSinceEpoch(dart_seconds, dart_is_utc, &broken_down);
   if (!succeeded) {
@@ -114,7 +191,7 @@ DEFINE_NATIVE_ENTRY(DateNatives_getDay, 2) {
 DEFINE_NATIVE_ENTRY(DateNatives_getHours, 2) {
   GET_NATIVE_ARGUMENT(Integer, dart_seconds, arguments->At(0));
   GET_NATIVE_ARGUMENT(Bool, dart_is_utc, arguments->At(1));
-  OS::BrokenDownDate broken_down;
+  BrokenDownDate broken_down;
   bool succeeded =
       BreakDownSecondsSinceEpoch(dart_seconds, dart_is_utc, &broken_down);
   if (!succeeded) {
@@ -128,7 +205,7 @@ DEFINE_NATIVE_ENTRY(DateNatives_getHours, 2) {
 DEFINE_NATIVE_ENTRY(DateNatives_getMinutes, 2) {
   GET_NATIVE_ARGUMENT(Integer, dart_seconds, arguments->At(0));
   GET_NATIVE_ARGUMENT(Bool, dart_is_utc, arguments->At(1));
-  OS::BrokenDownDate broken_down;
+  BrokenDownDate broken_down;
   bool succeeded =
       BreakDownSecondsSinceEpoch(dart_seconds, dart_is_utc, &broken_down);
   if (!succeeded) {
@@ -142,7 +219,7 @@ DEFINE_NATIVE_ENTRY(DateNatives_getMinutes, 2) {
 DEFINE_NATIVE_ENTRY(DateNatives_getSeconds, 2) {
   GET_NATIVE_ARGUMENT(Integer, dart_seconds, arguments->At(0));
   GET_NATIVE_ARGUMENT(Bool, dart_is_utc, arguments->At(1));
-  OS::BrokenDownDate broken_down;
+  BrokenDownDate broken_down;
   bool succeeded =
       BreakDownSecondsSinceEpoch(dart_seconds, dart_is_utc, &broken_down);
   if (!succeeded) {