Emulate localtime, gmtime and mktime to enable negative time_t

2 files changed, 279 insertions, 12 deletions

diff --git a/erts/emulator/sys/win32/erl_win_sys.h b/erts/emulator/sys/win32/erl_win_sys.h
index 4ed0b94e2d..ac5639b701 100644
--- a/erts/emulator/sys/win32/erl_win_sys.h
+++ b/erts/emulator/sys/win32/erl_win_sys.h
@@ -118,9 +118,14 @@ int erts_check_io_debug(void);
 #define SYS_CLOCK_RESOLUTION 1
 
 struct tm *sys_localtime_r(time_t *epochs, struct tm *ptm);
+struct tm *sys_gmtime_r(time_t *epochs, struct tm *ptm);
+time_t sys_mktime( struct tm *ptm);
 
 #define localtime_r sys_localtime_r
 #define HAVE_LOCALTIME_R 1
+#define gmtime_r sys_gmtime_r
+#define HAVE_GMTIME_R
+#define mktime sys_mktime
 
 typedef struct {
     long tv_sec;
diff --git a/erts/emulator/sys/win32/sys_time.c b/erts/emulator/sys/win32/sys_time.c
index af903aacfd..6362c1a06d 100644
--- a/erts/emulator/sys/win32/sys_time.c
+++ b/erts/emulator/sys/win32/sys_time.c
@@ -35,49 +35,222 @@
 /******************* Routines for time measurement *********************/
 
 #define EPOCH_JULIAN_DIFF LL_LITERAL(11644473600)
-#define TICKS_PER_SECOND (10000000LL)
+#define TICKS_PER_SECOND LL_LITERAL(10000000)
+#define SECONDS_PER_DAY LL_LITERAL(86400)
+
+#define ULI_TO_FILETIME(ft,ull)			\
+ do {						\
+     (ft).dwLowDateTime = (ull).LowPart;	\
+     (ft).dwHighDateTime = (ull).HighPart;	\
+ } while (0)
+
+#define FILETIME_TO_ULI(ull,ft)			\
+ do {						\
+     (ull).LowPart = (ft).dwLowDateTime;	\
+     (ull).HighPart = (ft).dwHighDateTime;	\
+ } while (0)
+
 
 #define EPOCH_TO_FILETIME(ft, epoch) \
     do { \
 	ULARGE_INTEGER ull; \
 	ull.QuadPart = (((epoch) + EPOCH_JULIAN_DIFF) * TICKS_PER_SECOND); \
-	(ft).dwLowDateTime = ull.LowPart; \
-	(ft).dwHighDateTime = ull.HighPart; \
+	ULI_TO_FILETIME(ft,ull); \
     } while(0)
 
 #define FILETIME_TO_EPOCH(epoch, ft) \
     do { \
 	ULARGE_INTEGER ull; \
-	ull.LowPart  = (ft).dwLowDateTime; \
-	ull.HighPart = (ft).dwHighDateTime; \
+	FILETIME_TO_ULI(ull,ft); \
 	(epoch) = ((ull.QuadPart / TICKS_PER_SECOND) - EPOCH_JULIAN_DIFF); \
     } while(0)
  
 static SysHrTime wrap = 0;
 static DWORD last_tick_count = 0;
 
+/* Getting timezone information is a heavy operation, so we want to do this 
+   only once */
+
+static TIME_ZONE_INFORMATION static_tzi;
+static int have_static_tzi = 0;
+
+static int days_in_month[2][13] = {
+    {0,31,28,31,30,31,30,31,31,30,31,30,31},
+    {0,31,29,31,30,31,30,31,31,30,31,30,31}};
+
 int 
 sys_init_time(void)
 {
+    if(GetTimeZoneInformation(&static_tzi) && 
+       static_tzi.StandardDate.wMonth != 0 &&
+       static_tzi.DaylightDate.wMonth != 0) {
+	have_static_tzi = 1;
+    }
     return 1;
 }
 
-struct tm * sys_localtime_r(time_t *epochs, struct tm *ptm)
+/* Returns a switchtimes for DST as UTC filetimes given data from a 
+   TIME_ZONE_INFORMATION, see sys_localtime_r for usage. */ 
+static void 
+get_dst_switchtime(DWORD year, 
+		   SYSTEMTIME dstinfo, LONG bias,
+		   FILETIME *utc_switchtime) 
+{
+    DWORD occu;
+    DWORD weekday,wday_1st;
+    DWORD day, days_in;
+    FILETIME tmp,tmp2;
+    ULARGE_INTEGER ull;
+    int leap_year = 0;
+    if (dstinfo.wYear != 0) {
+	/* A year specific transition, in which case the data in the structure
+	   is already properly set for a specific year. Compare year
+	   with parameter and see if they correspond, in that case generate a 
+	   filetime directly, otherwise set the filetime to 0 */
+	if (year != dstinfo.wYear) {
+	    utc_switchtime->dwLowDateTime = utc_switchtime->dwHighDateTime = 0;
+	    return;
+	} 
+    } else {
+	occu = dstinfo.wDay;
+	weekday = dstinfo.wDayOfWeek;
+
+	dstinfo.wDayOfWeek = 0;
+	dstinfo.wDay = 1;
+	dstinfo.wYear = year;
+	
+	SystemTimeToFileTime(&dstinfo,&tmp);
+	ull.LowPart = tmp.dwLowDateTime;
+	ull.HighPart = tmp.dwHighDateTime;
+    
+	ull.QuadPart /= (TICKS_PER_SECOND*SECONDS_PER_DAY); /* Julian Day */
+	wday_1st = (DWORD) ((ull.QuadPart + LL_LITERAL(1)) % LL_LITERAL(7));
+	day = (weekday >= wday_1st) ? 
+	    weekday - wday_1st + 1 :
+	    weekday - wday_1st + 8;
+	--occu;
+	if (((dstinfo.wYear % 4) == 0 && (dstinfo.wYear % 100) > 0) ||
+	    ((dstinfo.wYear % 400) == 0)) {
+	    leap_year = 1;
+	}
+	days_in = days_in_month[leap_year][dstinfo.wMonth];
+	while (occu > 0 && (day + 7 <= days_in)) {
+	    --occu;
+	    day += 7;
+	}
+	dstinfo.wDay = day;
+    }
+    SystemTimeToFileTime(&dstinfo,&tmp);
+    /* correct for bias */
+    ull.LowPart = tmp.dwLowDateTime;
+    ull.HighPart = tmp.dwHighDateTime;
+    ull.QuadPart += (((LONGLONG) bias) * LL_LITERAL(60) * TICKS_PER_SECOND);
+    utc_switchtime->dwLowDateTime = ull.LowPart;
+    utc_switchtime->dwHighDateTime = ull.HighPart;
+    return;
+}
+
+/* This function gives approximately the correct year from a FILETIME
+   Around the actual new year, it may return the wrong value, but that's OK
+   as DST never switches around new year. */
+static DWORD 
+approx_year(FILETIME ft)
+{
+    ULARGE_INTEGER ull;
+    FILETIME_TO_ULI(ull,ft);
+    ull.QuadPart /= LL_LITERAL(1000);
+    ull.QuadPart /= SECONDS_PER_DAY;
+    ull.QuadPart /= LL_LITERAL(3652425);
+    ull.QuadPart += 1601;
+    return (DWORD) ull.QuadPart;
+}
+
+struct tm *
+sys_localtime_r(time_t *epochs, struct tm *ptm)
 {
     FILETIME ft,lft;
     SYSTEMTIME st;
     
     if ((((*epochs) + EPOCH_JULIAN_DIFF) * TICKS_PER_SECOND) < 0LL) {
+	fprintf(stderr,"1\r\n"); fflush(stderr);
 	return NULL;
     }
     
     EPOCH_TO_FILETIME(ft,*epochs);
+    ptm->tm_isdst = 0;
+    if (have_static_tzi) {
+	FILETIME dst_start, dst_stop;
+	ULARGE_INTEGER ull;
+	DWORD year = approx_year(ft);
+	get_dst_switchtime(year,static_tzi.DaylightDate,
+			   static_tzi.Bias+static_tzi.StandardBias,&dst_start);
+	get_dst_switchtime(year,static_tzi.StandardDate,
+			   static_tzi.Bias+static_tzi.StandardBias+
+			   static_tzi.DaylightBias,
+			   &dst_stop);
+	FILETIME_TO_ULI(ull,ft);
+
+	if (CompareFileTime(&ft,&dst_start) >= 0 && 
+	    CompareFileTime(&ft,&dst_stop) < 0) {
+	    ull.QuadPart -= 
+		((LONGLONG) static_tzi.Bias+static_tzi.StandardBias+
+		 static_tzi.DaylightBias) * 
+		LL_LITERAL(60) * TICKS_PER_SECOND;
+	    ptm->tm_isdst = 1;
+	} else {
+	    ull.QuadPart -= 
+		((LONGLONG) static_tzi.Bias+static_tzi.StandardBias) 
+		* LL_LITERAL(60) * TICKS_PER_SECOND;
+	}
+	ULI_TO_FILETIME(ft,ull);
+    } else {
+	if (!FileTimeToLocalFileTime(&ft,&lft)) {
+	    return NULL;
+	}
+	ft = lft;
+    }
+    
+    if (!FileTimeToSystemTime(&ft,&st)) {
+	return NULL;
+    }
+    
+    ptm->tm_year = (int) st.wYear - 1900;
+    ptm->tm_mon  = (int) st.wMonth - 1;
+    ptm->tm_mday = (int) st.wDay;
+    ptm->tm_hour = (int) st.wHour;
+    ptm->tm_min  = (int) st.wMinute;
+    ptm->tm_sec  = (int) st.wSecond;
+    ptm->tm_wday  = (int) st.wDayOfWeek;
+    {
+	int yday = ptm->tm_mday - 1;
+	int m =  ptm->tm_mon;
+	int leap_year = 0;
+	if (((st.wYear % 4) == 0 && (st.wYear % 100) > 0) ||
+	    ((st.wYear % 400) == 0)) {
+	    leap_year = 1;
+	}
+	while (m > 0) {
+	    yday +=days_in_month[leap_year][m];
+	    --m;
+	}
+	ptm->tm_yday = yday;
+    }
+    return ptm;
+}
+
+struct tm * 
+sys_gmtime_r(time_t *epochs, struct tm *ptm)
+{
+    FILETIME ft;
+    SYSTEMTIME st;
     
-    if (!FileTimeToLocalFileTime(&ft,&lft)) {
+    if ((((*epochs) + EPOCH_JULIAN_DIFF) * TICKS_PER_SECOND) < 0LL) {
 	return NULL;
     }
     
-    if (!FileTimeToSystemTime(&lft,&st)) {
+    EPOCH_TO_FILETIME(ft,*epochs);
+    
+    if (!FileTimeToSystemTime(&ft,&st)) {
 	return NULL;
     }
     
@@ -87,22 +260,111 @@ struct tm * sys_localtime_r(time_t *epochs, struct tm *ptm)
     ptm->tm_hour = (int) st.wHour;
     ptm->tm_min  = (int) st.wMinute;
     ptm->tm_sec  = (int) st.wSecond;
+    ptm->tm_wday  = (int) st.wDayOfWeek;
+    ptm->tm_isdst  = 0;
+    {
+	int yday = ptm->tm_mday - 1;
+	int m =  ptm->tm_mon;
+	int leap_year = 0;
+	if (((st.wYear % 4) == 0 && (st.wYear % 100) > 0) ||
+	    ((st.wYear % 400) == 0)) {
+	    leap_year = 1;
+	}
+	while (m > 0) {
+	    yday +=days_in_month[leap_year][m];
+	    --m;
+	}
+	ptm->tm_yday = yday;
+    }
 
     return ptm;
 }
 
+time_t 
+sys_mktime(struct tm *ptm) 
+{
+    FILETIME ft;
+    SYSTEMTIME st;
+    int dst = 0;
+    time_t epochs;
+
+    memset(&st,0,sizeof(st));
+    /* Convert relevant parts of truct tm to SYSTEMTIME */
+    st.wYear =  (USHORT) (ptm->tm_year + 1900);
+    st.wMonth =  (USHORT) (ptm->tm_mon + 1);
+    st.wDay =  (USHORT) ptm->tm_mday;
+    st.wHour =  (USHORT) ptm->tm_hour;
+    st.wMinute =  (USHORT) ptm->tm_min;
+    st.wSecond = (USHORT) ptm->tm_sec;
+
+    SystemTimeToFileTime(&st,&ft);
+    
+    /* ft is now some kind of local file time, but it may be wrong depending 
+       on what is in the tm_dst field. We need to manually convert it to
+       UTC before turning it into epochs */
+
+    if (have_static_tzi) {
+	FILETIME dst_start, dst_stop;
+	ULARGE_INTEGER ull_start,ull_stop,ull_ft;
+
+	FILETIME_TO_ULI(ull_ft,ft);
+
+	/* Correct everything except DST */
+	ull_ft.QuadPart += (static_tzi.Bias+static_tzi.StandardBias) 
+	    * LL_LITERAL(60) * TICKS_PER_SECOND;
+
+	/* Determine if DST is active */
+	if (ptm->tm_isdst >= 0) {
+	    dst = ptm->tm_isdst;
+	} else if (static_tzi.DaylightDate.wMonth != 0){
+	    /* This is how windows mktime does it, meaning it does not
+	       take nonexisting local times into account */
+	    get_dst_switchtime(st.wYear,static_tzi.DaylightDate,
+			       static_tzi.Bias+static_tzi.StandardBias,
+			       &dst_start);
+	    get_dst_switchtime(st.wYear,static_tzi.StandardDate,
+			       static_tzi.Bias+static_tzi.StandardBias+
+			       static_tzi.DaylightBias,
+			       &dst_stop);
+	    FILETIME_TO_ULI(ull_start,dst_start);
+	    FILETIME_TO_ULI(ull_stop,dst_stop);
+	    if ((ull_ft.QuadPart >= ull_start.QuadPart) &&
+		(ull_ft.QuadPart < ull_stop.QuadPart)) {
+		/* We are in DST */
+		dst = 1;
+	    }
+	}
+	/* Correct for DST */
+	if (dst) {
+	    ull_ft.QuadPart += static_tzi.DaylightBias * 
+		LL_LITERAL(60) * TICKS_PER_SECOND;
+	}
+	epochs = ((ull_ft.QuadPart / TICKS_PER_SECOND) - EPOCH_JULIAN_DIFF);
+    } else {
+	/* No DST, life is easy... */
+	FILETIME lft;
+	LocalFileTimeToFileTime(&ft,&lft);
+	FILETIME_TO_EPOCH(epochs,lft);
+    }
+    /* Normalize the struct tm */
+    sys_localtime_r(&epochs,ptm);
+    return epochs;
+}
+
 void 
 sys_gettimeofday(SysTimeval *tv)
 {
     SYSTEMTIME t;
     FILETIME ft;
-    LONGLONG lft;
+    ULARGE_INTEGER ull;
 
     GetSystemTime(&t);
     SystemTimeToFileTime(&t, &ft);
-    memcpy(&lft, &ft, sizeof(lft));
-    tv->tv_usec = (long) ((lft / LL_LITERAL(10)) % LL_LITERAL(1000000));
-    tv->tv_sec = (long) ((lft / LL_LITERAL(10000000)) - EPOCH_JULIAN_DIFF);
+    FILETIME_TO_ULI(ull,ft);
+    tv->tv_usec = (long) ((ull.QuadPart / LL_LITERAL(10)) % 
+			  LL_LITERAL(1000000));
+    tv->tv_sec = (long) ((ull.QuadPart / LL_LITERAL(10000000)) - 
+			 EPOCH_JULIAN_DIFF);
 }
 
 SysHrTime