ircd: Add strncpy++ tool.

configure.ac

@@ -912,6 +912,8 @@ AC_CHECK_FUNCS([        \
 	strlcat             \
 	strlcpy             \
 	strnlen             \
+	strncpy             \
+	strcpy              \
 	vsnprintf           \
 ])
 

include/ircd/ircd.h

@@ -37,6 +37,7 @@
 #include "base.h"
 #include "stringops.h"
 #include "strl.h"
+#include "strn.h"
 #include "cmp.h"
 #include "globular.h"
 #include "tokens.h"

include/ircd/strn.h

@@ -0,0 +1,57 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2019 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_STRN_H
+
+// Vintage
+namespace ircd
+{
+	struct strncpy;
+}
+
+/// This is a function. It works the same as the standard strncpy() but it has
+/// some useful modernizations and may be informally referred to as strncpy++.
+/// See ircd::strlcpy() documentation for reasoning details.
+///
+struct ircd::strncpy
+{
+	mutable_buffer ret;
+
+  public:
+	operator string_view() const
+	{
+		return ret;
+	}
+
+	operator size_t() const
+	{
+		return size(ret);
+	}
+
+	strncpy(char *const &dst, const string_view &src, const size_t &max)
+	:ret{[&]() -> mutable_buffer
+	{
+		const auto len(std::min(src.size(), max));
+		buffer::copy(mutable_buffer(dst, len), src);
+		return { dst, len };
+	}()}
+	{}
+
+	#ifndef HAVE_STRNCPY
+	strncpy(char *const &dst, const char *const &src, const size_t &max)
+	:strncpy{dst, string_view{src, strnlen(src, max)}, max}
+	{}
+	#endif
+
+	strncpy(const mutable_buffer &dst, const string_view &src)
+	:strncpy{data(dst), src, size(dst)}
+	{}
+};