From c92f450ff8159239fe8bf740cd56c10f65f3ea88 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Fri, 4 Jan 2019 17:11:41 +1100
Subject: [PATCH] win32/file: add basic file wrapper

---
 CMakeLists.txt |   2 +
 win32/file.cpp | 116 +++++++++++++++++++++++++++++++++++++++++++++++++
 win32/file.hpp |  45 +++++++++++++++++++
 3 files changed, 163 insertions(+)
 create mode 100644 win32/file.cpp
 create mode 100644 win32/file.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3f7ef1e3..fcfb1c4e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -142,6 +142,8 @@ if (WIN32)
         win32/windows.hpp
         win32/except.cpp
         win32/except.hpp
+        win32/file.cpp
+        win32/file.hpp
         win32/handle.cpp
         win32/handle.hpp
         win32/registry.cpp
diff --git a/win32/file.cpp b/win32/file.cpp
new file mode 100644
index 00000000..412a7f6e
--- /dev/null
+++ b/win32/file.cpp
@@ -0,0 +1,116 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2019 Danny Robson <danny@nerdcruft.net>
+ */
+
+#include "file.hpp"
+
+#include "except.hpp"
+#include "../cast.hpp"
+
+using cruft::win32::file;
+
+
+///////////////////////////////////////////////////////////////////////////////
+file::file (std::filesystem::path const &src, DWORD access, DWORD share, DWORD create, DWORD flags)
+    : m_handle (
+        error::try_call (
+            CreateFileW,
+            src.c_str (),
+            access,
+            share,
+            nullptr, // security
+            create,
+            flags,
+            nullptr // template
+        )
+    )
+{ ; }
+
+
+//-----------------------------------------------------------------------------
+file::file (file &&src) noexcept
+    : m_handle (std::move (src.m_handle))
+{ ; }
+
+
+//-----------------------------------------------------------------------------
+file::file (handle &&src) noexcept
+    : m_handle (std::move (src))
+{ ; }
+
+
+//-----------------------------------------------------------------------------
+file::file (posix::fd &&src)
+    : file (handle (std::move (src)))
+{ ; }
+
+
+
+///////////////////////////////////////////////////////////////////////////////
+DWORD
+file::read(void *buf, size_t available)
+{
+    DWORD total_read;
+    error::try_call (ReadFile, m_handle, buf, available, &total_read, nullptr);
+    return total_read;
+}
+
+
+//-----------------------------------------------------------------------------
+DWORD
+file::write (void *buf, size_t available)
+{
+    DWORD total_written;
+    error::try_call (WriteFile, m_handle, buf, available, &total_written, nullptr);
+    return total_written;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+DWORD
+file::read(void *buf, size_t available, OVERLAPPED &overlapped)
+{
+    DWORD total_read;
+    auto const res = ReadFile (m_handle, buf, available, &total_read, &overlapped);
+
+    // If we're performing async IO then a value of FALSE is always returned.
+    if (!overlapped.hEvent && res == FALSE)
+        error::throw_code();
+
+    return total_read;
+}
+
+
+//-----------------------------------------------------------------------------
+DWORD
+file::write (void *buf, size_t available, OVERLAPPED &overlapped)
+{
+    DWORD total_written;
+    auto const res = WriteFile (m_handle, buf, available, &total_written, &overlapped);
+
+    // If we're performing async IO then a value of FALSE is always returned.
+    if (!overlapped.hEvent && res == FALSE)
+        error::throw_code();
+
+    return total_written;
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+u64
+file::set_pointer(u64 request, DWORD method)
+{
+    LONG const lo = request & 0xffffffff;
+    LONG       hi = request >> 32u;
+
+    auto result = SetFilePointer (m_handle, lo, &hi, method);
+    if (result == INVALID_SET_FILE_POINTER)
+        error::throw_code();
+
+    u64 offset = cruft::cast::lossless<u64> (result) | cruft::cast::lossless<u64> (hi) << 32;
+    return offset;
+}
diff --git a/win32/file.hpp b/win32/file.hpp
new file mode 100644
index 00000000..4f4ddbb2
--- /dev/null
+++ b/win32/file.hpp
@@ -0,0 +1,45 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 2019 Danny Robson <danny@nerdcruft.net>
+ */
+
+#pragma once
+
+#include "handle.hpp"
+#include "../std.hpp"
+
+#include <filesystem>
+
+
+///////////////////////////////////////////////////////////////////////////////
+namespace cruft::win32 {
+    class file {
+    public:
+        file (std::filesystem::path const &, DWORD access, DWORD share, DWORD create, DWORD flags);
+        explicit file (handle&&) noexcept;
+        explicit file (posix::fd&&);
+        file (file&&) noexcept;
+        file& operator= (file&&) noexcept;
+
+        file (file const&) = delete;
+        file& operator= (file const&) = delete;
+
+        [[nodiscard]] DWORD read  (void* buf, size_t count);
+        [[nodiscard]] DWORD write (void* buf, size_t count);
+
+        [[nodiscard]] DWORD read  (void* buf, size_t count, OVERLAPPED&);
+        [[nodiscard]] DWORD write (void* buf, size_t count, OVERLAPPED&);
+
+        [[nodiscard]] u64 set_pointer (u64 offset, DWORD method);
+
+        decltype(auto) native (void) { return m_handle.native (); }
+
+        operator auto () { return m_handle.native (); }
+
+    private:
+        handle m_handle;
+    };
+}