[libc++] Cache file attributes during directory iteration (#93316)

This patch adds caching of file attributes during directory iteration
on Windows. This improves the performance when working with files being
iterated on in a directory.

2 files changed, 17 insertions, 10 deletions

diff --git a/libcxx/src/filesystem/directory_iterator.cpp b/libcxx/src/filesystem/directory_iterator.cpp
index dceb348..d7ed9a3 100644
--- a/libcxx/src/filesystem/directory_iterator.cpp
+++ b/libcxx/src/filesystem/directory_iterator.cpp
@@ -77,13 +77,13 @@ public:
   bool assign() {
     if (!wcscmp(__data_.cFileName, L".") || !wcscmp(__data_.cFileName, L".."))
       return false;
-    // FIXME: Cache more of this
-    // directory_entry::__cached_data cdata;
-    // cdata.__type_ = get_file_type(__data_);
-    // cdata.__size_ = get_file_size(__data_);
-    // cdata.__write_time_ = get_write_time(__data_);
     __entry_.__assign_iter_entry(
-        __root_ / __data_.cFileName, directory_entry::__create_iter_result(detail::get_file_type(__data_)));
+        __root_ / __data_.cFileName,
+        directory_entry::__create_iter_cached_result(
+            detail::get_file_type(__data_),
+            detail::get_file_size(__data_),
+            detail::get_file_perm(__data_),
+            detail::get_write_time(__data_)));
     return true;
   }
 
diff --git a/libcxx/src/filesystem/file_descriptor.h b/libcxx/src/filesystem/file_descriptor.h
index f86eb60..db66ad5 100644
--- a/libcxx/src/filesystem/file_descriptor.h
+++ b/libcxx/src/filesystem/file_descriptor.h
@@ -97,11 +97,18 @@ inline uintmax_t get_file_size(const WIN32_FIND_DATAW& data) {
   return (static_cast<uint64_t>(data.nFileSizeHigh) << 32) + data.nFileSizeLow;
 }
 inline file_time_type get_write_time(const WIN32_FIND_DATAW& data) {
-  ULARGE_INTEGER tmp;
+  using detail::fs_time;
   const FILETIME& time = data.ftLastWriteTime;
-  tmp.u.LowPart        = time.dwLowDateTime;
-  tmp.u.HighPart       = time.dwHighDateTime;
-  return file_time_type(file_time_type::duration(tmp.QuadPart));
+  auto ts              = filetime_to_timespec(time);
+  if (!fs_time::is_representable(ts))
+    return file_time_type::min();
+  return fs_time::convert_from_timespec(ts);
+}
+inline perms get_file_perm(const WIN32_FIND_DATAW& data) {
+  unsigned st_mode = 0555; // Read-only
+  if (!(data.dwFileAttributes & FILE_ATTRIBUTE_READONLY))
+    st_mode |= 0222; // Write
+  return static_cast<perms>(st_mode) & perms::mask;
 }
 
 #endif // !_LIBCPP_WIN32API