[libcxx] Implement the stat function family on top of native windows APIs

While the windows CRTs (the modern UCRT, and the legacy msvcrt.dll
that mingw still often defaults to) do provide stat functions, they're
a bit lacking - they only provide second precision on the modification
time, lack support for symlinks and a few other details.

Instead reimplement them using a couple windows native functions,
getting exactly the info we need. (Technically, the implementation
within the CRT calls these functions anyway.)

If we only need a few fields, we could also do with fewer calls, as a
later optimization.

Differential Revision: https://reviews.llvm.org/D91141

1 files changed, 6 insertions, 4 deletions

diff --git a/libcxx/src/filesystem/operations.cpp b/libcxx/src/filesystem/operations.cpp
index 50a895d..548a027 100644
--- a/libcxx/src/filesystem/operations.cpp
+++ b/libcxx/src/filesystem/operations.cpp
@@ -17,6 +17,8 @@
 
 #include "filesystem_common.h"
 
+#include "posix_compat.h"
+
 #if defined(_LIBCPP_WIN32API)
 # define WIN32_LEAN_AND_MEAN
 # define NOMINMAX
@@ -495,7 +497,7 @@ file_status create_file_status(error_code& m_ec, path const& p,
 
 file_status posix_stat(path const& p, StatT& path_stat, error_code* ec) {
   error_code m_ec;
-  if (::stat(p.c_str(), &path_stat) == -1)
+  if (detail::stat(p.c_str(), &path_stat) == -1)
     m_ec = detail::capture_errno();
   return create_file_status(m_ec, p, path_stat, ec);
 }
@@ -507,7 +509,7 @@ file_status posix_stat(path const& p, error_code* ec) {
 
 file_status posix_lstat(path const& p, StatT& path_stat, error_code* ec) {
   error_code m_ec;
-  if (::lstat(p.c_str(), &path_stat) == -1)
+  if (detail::lstat(p.c_str(), &path_stat) == -1)
     m_ec = detail::capture_errno();
   return create_file_status(m_ec, p, path_stat, ec);
 }
@@ -545,7 +547,7 @@ file_status FileDescriptor::refresh_status(error_code& ec) {
   m_status = file_status{};
   m_stat = {};
   error_code m_ec;
-  if (::fstat(fd, &m_stat) == -1)
+  if (detail::fstat(fd, &m_stat) == -1)
     m_ec = capture_errno();
   m_status = create_file_status(m_ec, name, m_stat, &ec);
   return m_status;
@@ -1197,7 +1199,7 @@ path __read_symlink(const path& p, error_code* ec) {
   auto buff = std::unique_ptr<char[], NullDeleter>(stack_buff);
 #else
   StatT sb;
-  if (::lstat(p.c_str(), &sb) == -1) {
+  if (detail::lstat(p.c_str(), &sb) == -1) {
     return err.report(capture_errno());
   }
   const size_t size = sb.st_size + 1;