From a63d6cfe95ad2cbb097e4eead04c6d825f71c5f5 Mon Sep 17 00:00:00 2001
From: Tomasz Kalisiak <tomasz.kalisiak3@gmail.com>
Date: Wed, 31 Jul 2024 05:27:28 +0200
Subject: [PATCH] Fix buffer size decrementation for racy dir enumeration for
 issue #137

---
 include/llfio/v2.0/detail/impl/windows/directory_handle.ipp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/llfio/v2.0/detail/impl/windows/directory_handle.ipp b/include/llfio/v2.0/detail/impl/windows/directory_handle.ipp
index 7c21aac8..d07b657e 100644
--- a/include/llfio/v2.0/detail/impl/windows/directory_handle.ipp
+++ b/include/llfio/v2.0/detail/impl/windows/directory_handle.ipp
@@ -501,8 +501,9 @@ result<directory_handle::buffers_type> directory_handle::read(io_request<buffers
         if(done)
         {
           auto whattoadd = (7 + offsetof(what_to_enumerate_type, FileName) + ffdi->FileNameLength) & ~7;
-          buffer_ = reinterpret_cast<what_to_enumerate_type *>(reinterpret_cast<uintptr_t>(ffdi) + whattoadd);
-          bytes -= whattoadd;
+          auto new_buffer_start = reinterpret_cast<what_to_enumerate_type *>(reinterpret_cast<uintptr_t>(ffdi) + whattoadd);
+          bytes -= reinterpret_cast<uintptr_t>(new_buffer_start) - reinterpret_cast<uintptr_t>(buffer_);
+          buffer_ = new_buffer_start;
         }
       }
     }