posix/interface: add initial interface query logic

CMakeLists.txt

@@ -118,6 +118,8 @@ if (NOT WIN32)
         library_posix.hpp
         library_posix.cpp
         posix/fwd.hpp
+        posix/interface.hpp
+        posix/interface.cpp
         posix/map.cpp
         posix/map.hpp
         posix/socket.cpp

posix/interface.cpp

@@ -0,0 +1,12 @@
+/*
+ * 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 "interface.hpp"
+
+
+///////////////////////////////////////////////////////////////////////////////

posix/interface.hpp

@@ -0,0 +1,54 @@
+/*
+ * 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 "except.hpp"
+
+#include <sys/types.h>
+#include <ifaddrs.h>
+
+
+namespace cruft::posix {
+    auto
+    interface (void)
+    {
+        struct iterator {
+            iterator ()
+            {
+                error::try_call (getifaddrs, &cursor);
+            }
+
+            iterator (ifaddrs *_cursor):
+                cursor (_cursor)
+            { ; }
+
+            ifaddrs *cursor;
+
+            decltype (auto) operator*  (void) { return *cursor; }
+            decltype (auto) operator-> (void) { return  cursor; }
+
+            iterator& operator++ (void)
+            {
+                cursor = cursor->ifa_next;
+                return *this;
+            }
+
+            bool operator== (iterator const &rhs) const noexcept { return cursor == rhs.cursor; }
+            bool operator!= (iterator const &rhs) const noexcept { return cursor != rhs.cursor; }
+        };
+
+
+        struct container {
+            auto begin (void) { return iterator (       ); }
+            auto end   (void) { return iterator (nullptr); }
+        };
+
+        return container ();
+    }
+}