[10/31] mesos git commit: Windows: Fixed `os::lseek()` to use `SetFilePointerEx()`.

[an...@apache.org]

Windows: Fixed `os::lseek()` to use `SetFilePointerEx()`.

Note the TODO, we may want to synchronize this code later.

Review: https://reviews.apache.org/r/66428


Project: http://git-wip-us.apache.org/repos/asf/mesos/repo
Commit: http://git-wip-us.apache.org/repos/asf/mesos/commit/2d22336f
Tree: http://git-wip-us.apache.org/repos/asf/mesos/tree/2d22336f
Diff: http://git-wip-us.apache.org/repos/asf/mesos/diff/2d22336f

Branch: refs/heads/master
Commit: 2d22336f81378bea083f221690684a4ea826a6ec
Parents: e7d4b3a
Author: Andrew Schwartzmeyer <an...@schwartzmeyer.com>
Authored: Fri Mar 16 22:39:04 2018 -0700
Committer: Andrew Schwartzmeyer <an...@schwartzmeyer.com>
Committed: Tue May 1 18:36:04 2018 -0700

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 .../stout/include/stout/os/windows/lseek.hpp    | 26 +++++++++++++++-----
 1 file changed, 20 insertions(+), 6 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/mesos/blob/2d22336f/3rdparty/stout/include/stout/os/windows/lseek.hpp
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diff --git a/3rdparty/stout/include/stout/os/windows/lseek.hpp b/3rdparty/stout/include/stout/os/windows/lseek.hpp
index d34c022..c0ec71c 100644
--- a/3rdparty/stout/include/stout/os/windows/lseek.hpp
+++ b/3rdparty/stout/include/stout/os/windows/lseek.hpp
@@ -13,10 +13,9 @@
 #ifndef __STOUT_OS_WINDOWS_LSEEK_HPP__
 #define __STOUT_OS_WINDOWS_LSEEK_HPP__
 
-#include <io.h>
-
 #include <stout/error.hpp>
 #include <stout/try.hpp>
+#include <stout/windows.hpp>
 
 #include <stout/os/int_fd.hpp>
 
@@ -24,11 +23,26 @@ namespace os {
 
 inline Try<off_t> lseek(int_fd fd, off_t offset, int whence)
 {
-  off_t result = ::_lseek(fd.crt(), offset, whence);
-  if (result < 0) {
-    return ErrnoError();
+  // NOTE: The values for `SEEK_SET`, `SEEK_CUR`, and `SEEK_END` are
+  // 0, 1, 2, the same as `FILE_BEGIN`, `FILE_CURRENT`, and
+  // `FILE_END`. Thus we don't need to map them, and they can be
+  // casted to a `DWORD` safely.
+
+  LARGE_INTEGER offset_;
+  offset_.QuadPart = offset;
+
+  LARGE_INTEGER new_offset;
+
+  // TODO(andschwa): This may need to be synchronized if users aren't
+  // careful about sharing their file handles among threads.
+  const BOOL result =
+    ::SetFilePointerEx(fd, offset_, &new_offset, static_cast<DWORD>(whence));
+
+  if (result == FALSE) {
+    return WindowsError();
   }
-  return result;
+
+  return static_cast<off_t>(new_offset.QuadPart);
 }
 
 } // namespace os {