From 072dce88919af298800862c6fd9e4959bf1741d0 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Wed, 19 Dec 2018 17:13:06 +1100
Subject: [PATCH] io: ensure write/pwrite views use pointer iterators

---
 io.hpp | 25 +++++++++++--------------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/io.hpp b/io.hpp
index 37f78308..bf8aef17 100644
--- a/io.hpp
+++ b/io.hpp
@@ -9,6 +9,7 @@
 #ifndef __UTIL_IO_HPP
 #define __UTIL_IO_HPP
 
+#include "std.hpp"
 #include "platform.hpp"
 #include "posix/fd.hpp"
 
@@ -67,25 +68,23 @@ namespace cruft {
     ///
     /// An exception may be throw in the event forward progress is impossible
     /// (depending on the supplied FunctionT).
+    ///
+    /// TODO: enforce constness of view iterators
     template <
         typename DstT,
         typename FunctionT,
-        typename IteratorA,
-        typename IteratorB,
+        typename ValueT,
         typename ...Args
     >
     [[nodiscard]] decltype(auto)
     drain (
         DstT &&dst,
         FunctionT &&func,
-        cruft::view<IteratorA,IteratorB> const &src,
+        cruft::view<ValueT*> const &src,
         Args&& ...args
     ) {
-        static_assert (std::is_pointer_v<IteratorA>);
-        static_assert (std::is_pointer_v<IteratorB>);
-
-        auto cursor = reinterpret_cast<std::byte const*> (src.data ());
-        auto remain = src.size ();
+        auto cursor = reinterpret_cast<u08 const*> (src.data ());
+        auto remain = src.size () * sizeof (ValueT);
 
         while (remain) {
             auto count = std::invoke (func, dst, cursor, remain, args...);
@@ -105,11 +104,10 @@ namespace cruft {
     /// to `src`.
     template <
         typename DstT,
-        typename IteratorA,
-        typename IteratorB
+        typename ValueT
     >
     decltype(auto)
-    write (DstT &&dst, const cruft::view<IteratorA, IteratorB> &src)
+    write (DstT &&dst, cruft::view<ValueT*> const &src)
     {
         constexpr auto func = &std::decay_t<DstT>::write;
         return drain (std::forward<DstT> (dst), func, src);
@@ -124,11 +122,10 @@ namespace cruft {
     /// to `src`.
     template <
         typename DstT,
-        typename IteratorA,
-        typename IteratorB
+        typename ValueT
     >
     decltype(auto)
-    pwrite (DstT &&dst, const cruft::view<IteratorA, IteratorB> &src, size_t offset)
+    pwrite (DstT &&dst, cruft::view<ValueT*> const &src, size_t offset)
     {
         return drain (std::forward<DstT> (dst), &std::decay_t<DstT>::pwrite, src, offset);
     }