libc: remove use of unmanaged_singleton

Issue #5418

repos/libports/lib/mk/libc.mk

@@ -40,10 +40,6 @@ CC_OPT_dummies += -I$(LIBC_DIR)/sys
 INC_DIR += $(REP_DIR)/src/lib/libc
 INC_DIR += $(REP_DIR)/src/lib/libc/include
 
-# needed for base/internal/unmanaged_singleton.h
-INC_DIR += $(BASE_DIR)/src/include
-INC_DIR += $(BASE_DIR)/sys
-
 #
 # Files from string library that are not included in libc-raw_string because
 # they depend on the locale library.

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

@@ -15,9 +15,6 @@
 /* Genode includes */
 #include <base/component.h>
 
-/* base-internal includes */
-#include <base/internal/unmanaged_singleton.h>
-
 /* libc-internal includes */
 #include <internal/plugin_registry.h>
 #include <internal/kernel.h>
@@ -35,8 +32,8 @@ void Component::construct(Genode::Env &env)
 	static char *null_env = nullptr;
 	if (!environ) environ = &null_env;
 
-	Genode::Allocator &heap =
-		*unmanaged_singleton<Genode::Heap>(env.ram(), env.rm());
+	/* call of '__cxa_atexit' is ignored prior 'init_atexit' */
+	static Genode::Heap heap { env.ram(), env.rm() };
 
 	/* pass Genode::Env to libc subsystems that depend on it */
 	Libc::init_fd_alloc(heap);
@@ -44,7 +41,9 @@ void Component::construct(Genode::Env &env)
 	Libc::init_dl(env);
 	Libc::sysctl_init(env);
 
-	Libc::Kernel &kernel = *unmanaged_singleton<Libc::Kernel>(env, heap);
+	/* prevent call of '__cxa_atexit' for the 'Kernel' object */
+	static long _kernel_obj[(sizeof(Libc::Kernel) + sizeof(long))/sizeof(long)];
+	Libc::Kernel &kernel = *new (_kernel_obj) Libc::Kernel(env, heap);
 
 	Libc::libc_config_init(kernel.libc_env().libc_config());
 

repos/libports/src/lib/libc/internal/kernel.h

@@ -412,6 +412,9 @@ struct Libc::Kernel final : Vfs::Read_ready_response_handler,
 
 		~Kernel() { error(__PRETTY_FUNCTION__, " should not be executed!"); }
 
+		/* use placement new instead of 'construct_at' because 'Kernel' is final */
+		void *operator new (size_t, void *ptr) { return ptr; }
+
 		Libc::Env & libc_env() { return _libc_env; }
 
 		/**

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

@@ -26,9 +26,6 @@ extern "C" {
 #include <stdlib.h>
 }
 
-/* Genode-internal includes */
-#include <base/internal/unmanaged_singleton.h>
-
 /* libc-internal includes */
 #include <internal/init.h>
 #include <internal/clone_session.h>
@@ -285,34 +282,24 @@ int posix_memalign(void **memptr, size_t alignment, size_t size)
 }
 
 
-static Genode::Constructible<Malloc> &constructible_malloc()
-{
-	return *unmanaged_singleton<Genode::Constructible<Malloc> >();
-}
+/* space for singleton object w/o destructor */
+static long _malloc_obj[(sizeof(Malloc) + sizeof(long))/sizeof(long)];
 
 
 void Libc::init_malloc(Genode::Allocator &heap)
 {
-
-	Constructible<Malloc> &_malloc = constructible_malloc();
-
-	_malloc.construct(heap);
-
-	mallocator = _malloc.operator->();
+	mallocator = construct_at<Malloc>(_malloc_obj, heap);
 }
 
 
 void Libc::init_malloc_cloned(Clone_connection &clone_connection)
 {
-	clone_connection.object_content(constructible_malloc());
-
-	mallocator = constructible_malloc().operator->();
+	clone_connection.object_content(_malloc_obj);
+	mallocator = (Malloc *)_malloc_obj;
 }
 
 
 void Libc::reinit_malloc(Genode::Allocator &heap)
 {
-	Malloc &malloc = *constructible_malloc();
-
-	construct_at<Malloc>(&malloc, heap);
+	construct_at<Libc::Malloc>(_malloc_obj, heap);
 }

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

@@ -18,9 +18,6 @@
 #include <util/list.h>
 #include <libc/allocator.h>
 
-/* Genode-internal includes */
-#include <base/internal/unmanaged_singleton.h>
-
 /* libc includes */
 #include <errno.h>
 #include <pthread.h>
@@ -751,11 +748,16 @@ extern "C" {
 		/*
 		 * We create a pthread object associated to the main thread's Thread
 		 * object. We ensure the pthread object does never get deleted by
-		 * allocating it as unmanaged_singleton. Otherwise, the static
+		 * allocating it as unmanaged singleton '_obj'. Otherwise, the static
 		 * destruction of the pthread object would also destruct the 'Thread'
 		 * of the main thread.
 		 */
-		return unmanaged_singleton<pthread>(*Thread::myself(), &pthread_myself);
+		static pthread_t main_pthread_t = nullptr;
+		if (!main_pthread_t) {
+			static long _obj[(sizeof(pthread) + sizeof(long))/sizeof(long)];
+			main_pthread_t = construct_at<pthread>(_obj, *Thread::myself(), &pthread_myself);
+		}
+		return main_pthread_t;
 	}
 
 	typeof(pthread_self) _pthread_self

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

@@ -16,9 +16,6 @@
 #include <base/log.h>
 #include <vfs/vfs_handle.h>
 
-/* Genode-internal includes */
-#include <base/internal/unmanaged_singleton.h>
-
 /* libc includes */
 #include <sys/time.h>
 #include <sys/types.h>