From d3e5cb7f73f069d6ba1d9f13e00bb31aebf03b90 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Fri, 17 Mar 2017 21:03:15 -0700
Subject: [PATCH] ircd::fmt: Add the %p format specifier for pointer types.

---
 ircd/fmt.cc | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/ircd/fmt.cc b/ircd/fmt.cc
index 7aecf3755..07d4ed462 100644
--- a/ircd/fmt.cc
+++ b/ircd/fmt.cc
@@ -189,6 +189,17 @@ const char_specifier
 	"c"s
 };
 
+struct pointer_specifier
+:specifier
+{
+	bool operator()(char *&out, const size_t &max, const spec &, const arg &val) const override;
+	using specifier::specifier;
+}
+const pointer_specifier
+{
+	"p"s
+};
+
 } // namespace fmt
 } // namespace ircd
 
@@ -335,6 +346,40 @@ catch(const illegal &e)
 	              e.what());
 }
 
+bool
+fmt::pointer_specifier::operator()(char *&out,
+                                   const size_t &max,
+                                   const spec &,
+                                   const arg &val)
+const
+{
+	using karma::ulong_;
+	using karma::eps;
+	using karma::maxwidth;
+
+	static const auto throw_illegal([]
+	{
+		throw illegal("Not a pointer");
+	});
+
+	struct generator
+	:karma::grammar<char *, uintptr_t()>
+	{
+		karma::rule<char *, uintptr_t()> pointer_hex
+		{
+			lit("0x") << karma::hex
+		};
+
+		generator(): generator::base_type{pointer_hex} {}
+	}
+	static const generator;
+
+	const auto &ptr(get<0>(val));
+	const auto &type(get<1>(val));
+	const void *const p(*reinterpret_cast<const void *const *>(ptr));
+	return karma::generate(out, maxwidth(max)[generator] | eps[throw_illegal], uintptr_t(p));
+}
+
 bool
 fmt::char_specifier::operator()(char *&out,
                                 const size_t &max,