From 8a6e9158fed893fed409fcafb69f6ed59bf54cfe Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Tue, 4 Jun 2019 03:18:03 -0700
Subject: [PATCH] ircd::mods::ldso: Add a DT_NEEDED iterator.

---
 include/ircd/mods/ldso.h |  2 ++
 ircd/mods_ldso.cc        | 27 +++++++++++++++++++++++++++
 modules/console.cc       | 27 +++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/include/ircd/mods/ldso.h b/include/ircd/mods/ldso.h
index 0bebd72bc..167852fb2 100644
--- a/include/ircd/mods/ldso.h
+++ b/include/ircd/mods/ldso.h
@@ -28,6 +28,7 @@ namespace ircd::mods::ldso
 	IRCD_EXCEPTION(error, not_found);
 
 	using link_closure = std::function<bool (struct link_map &)>;
+	using string_closure = std::function<bool (const string_view &)>;
 	using semantic_version = std::array<long, 3>;
 
 	// Util
@@ -52,4 +53,5 @@ namespace ircd::mods::ldso
 
 	// Query link
 	string_view string(const struct link_map &, const size_t &idx);
+	bool for_each_needed(const struct link_map &, const string_closure &);
 }
diff --git a/ircd/mods_ldso.cc b/ircd/mods_ldso.cc
index 0283501b4..2b768cbd6 100644
--- a/ircd/mods_ldso.cc
+++ b/ircd/mods_ldso.cc
@@ -21,6 +21,33 @@
 // mods/ldso.h
 //
 
+bool
+ircd::mods::ldso::for_each_needed(const struct link_map &map,
+                                  const string_closure &closure)
+{
+	const char *strtab {nullptr};
+	for(auto d(map.l_ld); d->d_tag != DT_NULL; ++d)
+		if(d->d_tag == DT_STRTAB)
+		{
+			strtab = reinterpret_cast<const char *>(d->d_un.d_ptr);
+			break;
+		}
+
+	if(!strtab)
+		return true;
+
+	for(auto d(map.l_ld); d->d_tag != DT_NULL; ++d)
+	{
+		if(d->d_tag != DT_NEEDED)
+			continue;
+
+		if(!closure(strtab + d->d_un.d_val))
+			return false;
+	}
+
+	return true;
+}
+
 ircd::string_view
 ircd::mods::ldso::string(const struct link_map &map,
                          const size_t &idx)
diff --git a/modules/console.cc b/modules/console.cc
index ec88c7024..39ff71cac 100644
--- a/modules/console.cc
+++ b/modules/console.cc
@@ -1690,6 +1690,33 @@ console_cmd__mod__links(opt &out, const string_view &line)
 	return true;
 }
 
+bool
+console_cmd__mod__needed(opt &out, const string_view &line)
+{
+	const params param{line, " ",
+	{
+		"name"
+	}};
+
+	const string_view name
+	{
+		param.at("name")
+	};
+
+	size_t i(0);
+	mods::ldso::for_each_needed(mods::ldso::get(name), [&out, &i]
+	(const string_view &name)
+	{
+		out << std::setw(2) << (i++)
+		    << " " << name
+		    << std::endl;
+
+		return true;
+	});
+
+	return true;
+}
+
 //
 // ctx
 //