From 8c05cf2e1cb0a90d50c2935d49bd7344acc134f6 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Mon, 27 Aug 2018 14:17:50 +1000
Subject: [PATCH] posix/fd: double check the user has specified binary mode

---
 posix/fd.cpp | 9 ++++++++-
 posix/fd.hpp | 3 +++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/posix/fd.cpp b/posix/fd.cpp
index 091916f0..64a226b4 100644
--- a/posix/fd.cpp
+++ b/posix/fd.cpp
@@ -27,7 +27,14 @@ fd::fd (const std::experimental::filesystem::path &path, int flags):
 //-----------------------------------------------------------------------------
 fd::fd (const std::experimental::filesystem::path &path, int flags, mode_t mode):
     m_fd (error::try_value (::open (path.u8string ().c_str (), flags, mode)))
-{ ; }
+{
+    // You always want binary mode. Always.
+    //
+    // But we want the user to have considered this platform issue regardless
+    // so we won't forcibly set the flag, but we will abort the program when
+    // debugging if they've failed to do so.
+    CHECK_EQ (flags & O_BINARY, O_BINARY);
+}
 
 
 ///////////////////////////////////////////////////////////////////////////////
diff --git a/posix/fd.hpp b/posix/fd.hpp
index 8e59b0e8..afbfff8b 100644
--- a/posix/fd.hpp
+++ b/posix/fd.hpp
@@ -23,6 +23,9 @@ namespace cruft::posix {
     class fd {
     public:
         ///////////////////////////////////////////////////////////////////////
+        // If you are using a system which delineates between binary/text mode
+        // for descriptors the behaviour is undefined if you don't set the
+        // necessary flags for binary mode.
         fd (const std::experimental::filesystem::path &path, int flags);
         fd (const std::experimental::filesystem::path &path, int flags, mode_t);