From: Christopher Dykes <cdykes@fb.com>
Date: Tue, 1 Mar 2016 18:01:25 +0000 (-0800)
Subject: Listen to the Windows docs in portability/SysTime.cpp
X-Git-Tag: deprecate-dynamic-initializer~26
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=ad1f7851de7ded56aad94871442a8704b76af94c;p=folly.git

Listen to the Windows docs in portability/SysTime.cpp

Summary:As-per the documenation of FILETIME:

"Do not cast a pointer to a FILETIME structure to either a ULARGE_INTEGER* or __int64* value because it can cause alignment faults on 64-bit Windows."

Reviewed By: yfeldblum

Differential Revision: D2989434

fb-gh-sync-id: cf57d569a785e0eb7225b346730bf2ed4c50dc55
shipit-source-id: cf57d569a785e0eb7225b346730bf2ed4c50dc55
---

diff --git a/folly/portability/SysTime.cpp b/folly/portability/SysTime.cpp
index 9969a171..41638e97 100755
--- a/folly/portability/SysTime.cpp
+++ b/folly/portability/SysTime.cpp
@@ -26,8 +26,13 @@ int gettimeofday(timeval* tv, timezone*) {
 
   if (tv) {
     FILETIME ft;
+    ULARGE_INTEGER lft;
     GetSystemTimeAsFileTime(&ft);
-    uint64_t ns = *(uint64_t*)&ft;
+    // As per the docs of FILETIME, don't just do an indirect
+    // pointer cast, to avoid alignment faults.
+    lft.HighPart = ft.dwHighDateTime;
+    lft.LowPart = ft.dwLowDateTime;
+    uint64_t ns = lft.QuadPart;
     tv->tv_usec = (long)((ns / 10ULL) % 1000000ULL);
     tv->tv_sec = (long)((ns - posixWinFtOffset) / 10000000ULL);
   }