android: fix base::Time::FromLocalExploded() crash.

base/time/time_posix.cc

Index: base/time/time_posix.cc
diff --git a/base/time/time_posix.cc b/base/time/time_posix.cc
index 5e06ce93cf039fd420549a345915e2d0ffd62bea..c1edb7a27298a4e7ec5a31ad2383e11879336bbe 100644
--- a/base/time/time_posix.cc
+++ b/base/time/time_posix.cc
@@ -214,9 +214,41 @@ Time Time::FromExploded(bool is_local, const Exploded& exploded) {
   timestruct.tm_zone   = NULL;  // not a POSIX field, so mktime/timegm ignore
 #endif
 
-  SysTime seconds = SysTimeFromTimeStruct(&timestruct, is_local);
 
   int64 milliseconds;
+  SysTime seconds;
+
+  // Certain exploded dates do not really exist due to daylight saving times,
+  // and this causes mktime() to return implementation-defined values when
+  // tm_isdst is set to -1. On Android, the function will return -1, while the
+  // C libraries of other platforms typically return a liberally-chosen value.
+  // Handling this requires the special code below.
+
+  // SysTimeFromTimeStruct() modifies the input structure, save current value.
+  struct tm timestruct0 = timestruct;
+
+  seconds = SysTimeFromTimeStruct(&timestruct, is_local);
+  if (seconds == -1) {
+    // Get the time values with tm_isdst == 0 and 1, then select the closest one
+    // to UTC 00:00:00 that isn't -1.
+    timestruct = timestruct0;
+    timestruct.tm_isdst = 0;
+    int64 seconds_isdst0 = SysTimeFromTimeStruct(&timestruct, is_local);
+
+    timestruct = timestruct0;
+    timestruct.tm_isdst = 1;
+    int64 seconds_isdst1 = SysTimeFromTimeStruct(&timestruct, is_local);
+
+    // seconds_isdst0 or seconds_isdst1 can be -1 for some timezones.
+    // E.g. "CLST" (Chile Summer Time) returns -1 for 'tm_isdt == 1'.
+    if (seconds_isdst0 < 0)
+      seconds = seconds_isdst1;
+    else if (seconds_isdst1 < 0)
+      seconds = seconds_isdst0;
+    else
+      seconds = std::min(seconds_isdst0, seconds_isdst1);
+  }
+
   // Handle overflow.  Clamping the range to what mktime and timegm might
   // return is the best that can be done here.  It's not ideal, but it's better
   // than failing here or ignoring the overflow case and treating each time
@@ -237,14 +269,19 @@ Time Time::FromExploded(bool is_local, const Exploded& exploded) {
     // When representing the most distant time in the future, add in an extra
     // 999ms to avoid the time being less than any other possible value that
     // this function can return.
+
+    // On Android, SysTime is int64, special care must be taken to avoid
+    // overflows.
+    const int64 min_seconds = (sizeof(SysTime) < sizeof(int64))
+                                  ? std::numeric_limits<SysTime>::min()
+                                  : std::numeric_limits<int32_t>::min();
+    const int64 max_seconds = (sizeof(SysTime) < sizeof(int64))
+                                  ? std::numeric_limits<SysTime>::max()
+                                  : std::numeric_limits<int32_t>::max();
     if (exploded.year < 1969) {
-      CHECK(sizeof(SysTime) < sizeof(int64)) << "integer overflow";
-      milliseconds = std::numeric_limits<SysTime>::min();
-      milliseconds *= kMillisecondsPerSecond;
+      milliseconds = min_seconds * kMillisecondsPerSecond;
     } else {
-      CHECK(sizeof(SysTime) < sizeof(int64)) << "integer overflow";
-      milliseconds = std::numeric_limits<SysTime>::max();
-      milliseconds *= kMillisecondsPerSecond;
+      milliseconds = max_seconds * kMillisecondsPerSecond;
       milliseconds += (kMillisecondsPerSecond - 1);
     }
   } else {