Do not use date.c:tm_to_time_t() from compat/mingw.c

To implement gettimeofday(), a broken-down UTC time was requested from the
system using GetSystemTime(), then tm_to_time_t() was used to convert it
to a time_t because it does not look at the current timezone, which
mktime() would do.

Use GetSystemTimeAsFileTime() and a different conversion path to avoid this
back-reference from the compatibility layer to the generic code.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/compat/mingw.c b/compat/mingw.c
index 74ffc1834f5ad07d711da4ee6c2edabd56f7dad4..ab65f77ab99500d99d24a9b7266669f37bb02cb2 100644 (file)
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -140,12 +140,20 @@ int mingw_open (const char *filename, int oflags, ...)
        return fd;
 }
 
-static inline time_t filetime_to_time_t(const FILETIME *ft)
+/*
+ * The unit of FILETIME is 100-nanoseconds since January 1, 1601, UTC.
+ * Returns the 100-nanoseconds ("hekto nanoseconds") since the epoch.
+ */
+static inline long long filetime_to_hnsec(const FILETIME *ft)
 {
        long long winTime = ((long long)ft->dwHighDateTime << 32) + ft->dwLowDateTime;
-       winTime -= 116444736000000000LL; /* Windows to Unix Epoch conversion */
-       winTime /= 10000000;             /* Nano to seconds resolution */
-       return (time_t)winTime;
+       /* Windows to Unix Epoch conversion */
+       return winTime - 116444736000000000LL;
+}
+
+static inline time_t filetime_to_time_t(const FILETIME *ft)
+{
+       return (time_t)(filetime_to_hnsec(ft) / 10000000);
 }
 
 /* We keep the do_lstat code in a separate function to avoid recursion.
@@ -281,19 +289,13 @@ int mkstemp(char *template)
 
 int gettimeofday(struct timeval *tv, void *tz)
 {
-       SYSTEMTIME st;
-       struct tm tm;
-       GetSystemTime(&st);
-       tm.tm_year = st.wYear-1900;
-       tm.tm_mon = st.wMonth-1;
-       tm.tm_mday = st.wDay;
-       tm.tm_hour = st.wHour;
-       tm.tm_min = st.wMinute;
-       tm.tm_sec = st.wSecond;
-       tv->tv_sec = tm_to_time_t(&tm);
-       if (tv->tv_sec < 0)
-               return -1;
-       tv->tv_usec = st.wMilliseconds*1000;
+       FILETIME ft;
+       long long hnsec;
+
+       GetSystemTimeAsFileTime(&ft);
+       hnsec = filetime_to_hnsec(&ft);
+       tv->tv_sec = hnsec / 10000000;
+       tv->tv_usec = (hnsec % 10000000) / 10;
        return 0;
 }