Android doesn't have timegm function. So add custom implementation.

1 files changed, 57 insertions, 0 deletions

diff --git a/base/timegm.cpp b/base/timegm.cpp
new file mode 100644
index 0000000000..8aff002f18
--- /dev/null
+++ b/base/timegm.cpp
@@ -0,0 +1,57 @@
+#include "timegm.hpp"
+
+// There are issues with this implementation due to absence
+// of time_t fromat specification. There are no guarantees
+// of its internal structure so we cannot rely on + or -.
+
+// It could be possible to substitute time_t with boost::ptime
+// in contexts where we need some arithmetical and logical operations
+// on time and we don't have to use precisely time_t.
+
+namespace
+{
+// Number of days elapsed since Jan 01 up to each month
+// (except for February in leap years).
+int const g_monoff[] = {
+  0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
+};
+
+bool IsLeapYear(int year)
+{
+  return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
+}
+
+int LeapDaysCount(int y1, int y2)
+{
+  --y1;
+  --y2;
+  return (y2/4 - y1/4) - (y2/100 - y1/100) + (y2/400 - y1/400);
+}
+} // namespace
+
+namespace base
+{
+// Inspired by python's calendar.py
+time_t TimeGM(std::tm const & tm)
+{
+  int year;
+  time_t days;
+  time_t hours;
+  time_t minutes;
+  time_t seconds;
+
+  year = 1900 + tm.tm_year;
+  days = 365 * (year - 1970) + LeapDaysCount(1970, year);
+  days += g_monoff[tm.tm_mon];
+
+  if (tm.tm_mon > 1 && IsLeapYear(year))
+    ++days;
+  days += tm.tm_mday - 1;
+
+  hours = days * 24 + tm.tm_hour;
+  minutes = hours * 60 + tm.tm_min;
+  seconds = minutes * 60 + tm.tm_sec;
+
+  return seconds;
+}
+} // namespace base