libc: late intialization of plugins

- for-each plugin iterator
* Call 'init(Genode::env &)' for each plugin bofore 'Libc::construct' or
'main' is called

repos/libports/include/libc-plugin/plugin.h

@@ -23,11 +23,14 @@
 #include <sys/stat.h>
 #include <sys/mount.h>  /* for 'struct statfs' */
 
+namespace Genode { class Env; }
+
 namespace Libc {
 
 	using namespace Genode;
 	
 	class File_descriptor;
+
 	
 	typedef Genode::Path<PATH_MAX> Absolute_path;
 
@@ -70,6 +73,11 @@ namespace Libc {
 			virtual bool supports_unlink(const char *path);
 			virtual bool supports_mmap();
 
+			/*
+			 * Should be overwritten for plugins that require the Genode environment
+			 */
+			virtual void init(Genode::Env &env) { }
+
 			virtual File_descriptor *accept(File_descriptor *,
 			                                struct ::sockaddr *addr,
 			                                socklen_t *addrlen);

repos/libports/include/libc-plugin/plugin_registry.h

@@ -46,6 +46,15 @@ struct Libc::Plugin_registry : List<Plugin>
 	Plugin *get_plugin_for_stat(const char *path, struct stat *);
 	Plugin *get_plugin_for_symlink(const char *oldpath, const char *newpath);
 	Plugin *get_plugin_for_unlink(const char *path);
+
+	template <typename FUNC>
+	void for_each_plugin(FUNC const &fn) const
+	{
+		for (Plugin *plugin = plugin_registry()->first(); plugin;
+		     plugin = plugin->next()) {
+			fn(*plugin);
+		}
+	}
 };
 
 #endif /* _LIBC_PLUGIN__PLUGIN_REGISTRY_H_ */

repos/libports/src/lib/libc/task.cc

@@ -26,6 +26,7 @@
 
 /* libc includes */
 #include <libc/component.h>
+#include <libc-plugin/plugin_registry.h>
 
 /* libc-internal includes */
 #include <internal/call_func.h>
@@ -656,6 +657,12 @@ void Component::construct(Genode::Env &env)
 	Libc::init_mem_alloc(env);
 	Libc::init_dl(env);
 
+	/* initialize plugins that require Genode::Env */
+	auto init_plugin = [&] (Libc::Plugin &plugin) {
+		plugin.init(env);
+	};
+	Libc::plugin_registry()->for_each_plugin(init_plugin);
+
 	kernel = unmanaged_singleton<Libc::Kernel>(env);
 	kernel->run();
 }