Merge pull request #1092 from Qwinci/fini

options/rtld: Call fini functions on exit

options/internal/gcc/initfini.cpp

@@ -10,6 +10,8 @@ typedef void (*InitPtr)();
 
 extern InitPtr __CTOR_LIST__ [[ gnu::visibility("hidden") ]] [];
 extern InitPtr __CTOR_END__ [[ gnu::visibility("hidden") ]] [];
+extern InitPtr __DTOR_LIST__ [[ gnu::visibility("hidden") ]] [];
+extern InitPtr __DTOR_END__ [[ gnu::visibility("hidden") ]] [];
 
 extern "C" [[ gnu::visibility("hidden") ]] void __mlibc_do_ctors() {
 	const size_t n = __CTOR_END__ - __CTOR_LIST__;
@@ -24,6 +26,13 @@ extern "C" [[ gnu::visibility("hidden") ]] void __mlibc_do_ctors() {
 }
 
 extern "C" [[ gnu::visibility("hidden") ]] void __mlibc_do_dtors() {
-	mlibc::sys_libc_log("__mlibc_do_dtors() called");
-}
+	const size_t n = __DTOR_END__ - __DTOR_LIST__;
+	if(!n)
+		return;
+
+	size_t num = frg::min(n - 1, size_t(__DTOR_LIST__[0]));
 
+	for(size_t i = num; i >= 1; i--) {
+		__DTOR_LIST__[i]();
+	}
+}

options/lsb/generic/dso_exit.cpp

@@ -32,11 +32,40 @@ extern "C" int __cxa_atexit(void (*function)(void *), void *argument, void *hand
 	return 0;
 }
 
+extern "C" void __dlapi_exit();
+
+extern "C" void __cxa_finalize(void *dso) {
+	ExitQueue &eq = getExitQueue();
+	if(!dso) {
+		for(size_t i = eq.size(); i > 0; i--) {
+			auto handler = &eq[i - 1];
+			if(!handler->function)
+				continue;
+
+			handler->function(handler->argument);
+			handler->function = nullptr;
+		}
+	}else {
+		for(size_t i = eq.size(); i > 0; i--) {
+			auto handler = &eq[i - 1];
+			if(handler->dsoHandle != dso || !handler->function)
+				continue;
+
+			handler->function(handler->argument);
+			handler->function = nullptr;
+		}
+	}
+}
+
 void __mlibc_do_finalize() {
 	ExitQueue &eq = getExitQueue();
 	for(size_t i = eq.size(); i > 0; i--) {
 		auto handler = &eq[i - 1];
+		if(handler->dsoHandle || !handler->function)
+			continue;
 		handler->function(handler->argument);
+		handler->function = nullptr;
 	}
-}
 
+	__dlapi_exit();
+}

options/rtld/generic/linker.cpp

@@ -54,6 +54,8 @@ extern frg::manual_box<frg::vector<frg::string_view, MemoryAllocator>> preloads;
 #if MLIBC_STATIC_BUILD
 extern "C" size_t __init_array_start[];
 extern "C" size_t __init_array_end[];
+extern "C" size_t __fini_array_start[];
+extern "C" size_t __fini_array_end[];
 extern "C" size_t __preinit_array_start[];
 extern "C" size_t __preinit_array_end[];
 #endif
@@ -102,7 +104,8 @@ uintptr_t alignUp(uintptr_t address, size_t align) {
 
 ObjectRepository::ObjectRepository()
 : loadedObjects{getAllocator()},
-	_nameMap{frg::hash<frg::string_view>{}, getAllocator()} {}
+	_nameMap{frg::hash<frg::string_view>{}, getAllocator()},
+	_destructQueue{getAllocator()} {}
 
 SharedObject *ObjectRepository::injectObjectFromDts(frg::string_view name,
 		frg::string<MemoryAllocator> path, uintptr_t base_address,
@@ -151,6 +154,9 @@ SharedObject *ObjectRepository::injectStaticObject(frg::string_view name,
 	object->initArray = reinterpret_cast<InitFuncPtr*>(__init_array_start);
 	object->initArraySize = static_cast<size_t>((uintptr_t)__init_array_end -
 			(uintptr_t)__init_array_start);
+	object->finiArray = reinterpret_cast<InitFuncPtr*>(__fini_array_start);
+	object->finiArraySize = static_cast<size_t>((uintptr_t)__fini_array_end -
+			(uintptr_t)__fini_array_start);
 	object->preInitArray = reinterpret_cast<InitFuncPtr*>(__preinit_array_start);
 	object->preInitArraySize = static_cast<size_t>((uintptr_t)__preinit_array_end -
 			(uintptr_t)__preinit_array_start);
@@ -356,6 +362,19 @@ SharedObject *ObjectRepository::findLoadedObject(frg::string_view name) {
 	return nullptr;
 }
 
+void ObjectRepository::addObjectToDestructQueue(SharedObject *object) {
+	_destructQueue.push_back(object);
+}
+
+void doDestruct(SharedObject *object);
+
+void ObjectRepository::destructObjects() {
+	for (size_t i = _destructQueue.size(); i > 0; i--) {
+		doDestruct(_destructQueue[i - 1]);
+	}
+	_destructQueue.clear();
+}
+
 // --------------------------------------------------------
 // ObjectRepository: Fetching methods.
 // --------------------------------------------------------
@@ -699,13 +718,24 @@ void ObjectRepository::_parseDynamic(SharedObject *object) {
 			if(dynamic->d_un.d_ptr != 0)
 				object->initPtr = (InitFuncPtr)(object->baseAddress + dynamic->d_un.d_ptr);
 			break;
+		case DT_FINI:
+			if(dynamic->d_un.d_ptr != 0)
+				object->finiPtr = (InitFuncPtr)(object->baseAddress + dynamic->d_un.d_ptr);
+			break;
 		case DT_INIT_ARRAY:
 			if(dynamic->d_un.d_ptr != 0)
 				object->initArray = (InitFuncPtr *)(object->baseAddress + dynamic->d_un.d_ptr);
 			break;
+		case DT_FINI_ARRAY:
+			if(dynamic->d_un.d_ptr != 0)
+				object->finiArray = (InitFuncPtr *)(object->baseAddress + dynamic->d_un.d_ptr);
+			break;
 		case DT_INIT_ARRAYSZ:
 			object->initArraySize = dynamic->d_un.d_val;
 			break;
+		case DT_FINI_ARRAYSZ:
+			object->finiArraySize = dynamic->d_un.d_val;
+			break;
 		case DT_PREINIT_ARRAY:
 			if(dynamic->d_un.d_ptr != 0) {
 				// Only the main object is allowed pre-initializers.
@@ -730,7 +760,6 @@ void ObjectRepository::_parseDynamic(SharedObject *object) {
 			break;
 		// ignore unimportant tags
 		case DT_NEEDED: // we handle this later
-		case DT_FINI: case DT_FINI_ARRAY: case DT_FINI_ARRAYSZ:
 		case DT_RELA: case DT_RELASZ: case DT_RELAENT: case DT_RELACOUNT:
 		case DT_REL: case DT_RELSZ: case DT_RELENT: case DT_RELCOUNT:
 		case DT_RELR: case DT_RELRSZ: case DT_RELRENT:
@@ -924,9 +953,22 @@ void doInitialize(SharedObject *object) {
 	__ensure(object->wasLinked);
 	__ensure(!object->wasInitialized);
 
-	// if the object has dependencies we initialize them first
-	for(size_t i = 0; i < object->dependencies.size(); i++)
-		__ensure(object->dependencies[i]->wasInitialized);
+	// If the object has dependencies we initialize them first
+	// except in the case of a circular dependency.
+	for(auto dep : object->dependencies) {
+		bool circular = false;
+		for(auto dep2 : dep->dependencies) {
+			if(dep2 == object) {
+				circular = true;
+				break;
+			}
+		}
+
+		if(circular)
+			continue;
+
+		__ensure(dep->wasInitialized);
+	}
 
 	if(verbose)
 		mlibc::infoLogger() << "rtld: Initialize " << object->name << frg::endlog;
@@ -947,6 +989,46 @@ void doInitialize(SharedObject *object) {
 	object->wasInitialized = true;
 }
 
+void doDestruct(SharedObject *object) {
+	if(!object->wasInitialized || object->wasDestroyed)
+		return;
+
+	// If the object has dependencies they are destroyed after this object
+	// except in the case of a circular dependency.
+	for(auto dep : object->dependencies) {
+		bool circular = false;
+		for(auto dep2 : dep->dependencies) {
+			if(dep2 == object) {
+				circular = true;
+				break;
+			}
+		}
+
+		if(circular)
+			continue;
+
+		__ensure(!dep->wasDestroyed);
+	}
+
+	if(verbose)
+		mlibc::infoLogger() << "rtld: Destruct " << object->name << frg::endlog;
+
+	if(verbose)
+		mlibc::infoLogger() << "rtld: Running DT_FINI_ARRAY functions" << frg::endlog;
+	__ensure((object->finiArraySize % sizeof(InitFuncPtr)) == 0);
+	for(size_t i = object->finiArraySize / sizeof(InitFuncPtr); i > 0; i--)
+		object->finiArray[i - 1]();
+
+	if(verbose)
+		mlibc::infoLogger() << "rtld: Running DT_FINI function" << frg::endlog;
+	if(object->finiPtr != nullptr)
+		object->finiPtr();
+
+	if(verbose)
+		mlibc::infoLogger() << "rtld: Object destruction complete" << frg::endlog;
+	object->wasDestroyed = true;
+}
+
 // --------------------------------------------------------
 // RuntimeTlsMap
 // --------------------------------------------------------
@@ -1500,7 +1582,7 @@ void Loader::_buildTlsMaps() {
 	}
 }
 
-void Loader::initObjects() {
+void Loader::initObjects(ObjectRepository *repository) {
 	initTlsObjects(mlibc::get_current_tcb(), _linkBfs, true);
 
 	if (_mainExecutable && _mainExecutable->preInitArray) {
@@ -1522,8 +1604,10 @@ void Loader::initObjects() {
 	}
 
 	for(auto object : _initQueue) {
-		if(!object->wasInitialized)
+		if(!object->wasInitialized) {
 			doInitialize(object);
+			repository->addObjectToDestructQueue(object);
+		}
 	}
 }
 

options/rtld/generic/linker.hpp

@@ -69,6 +69,9 @@ struct ObjectRepository {
 
 	SharedObject *findLoadedObject(frg::string_view name);
 
+	void addObjectToDestructQueue(SharedObject *object);
+	void destructObjects();
+
 	// Used by dl_iterate_phdr: stores objects in the order they are loaded.
 	frg::vector<SharedObject *, MemoryAllocator> loadedObjects;
 
@@ -86,6 +89,9 @@ struct ObjectRepository {
 
 	frg::hash_map<frg::string_view, SharedObject *,
 			frg::hash<frg::string_view>, MemoryAllocator> _nameMap;
+
+	// Used for destructing the objects, stores all the objects in the order they are initialized.
+	frg::vector<SharedObject *, MemoryAllocator> _destructQueue;
 };
 
 // --------------------------------------------------------
@@ -148,9 +154,12 @@ struct SharedObject {
 
 	// object initialization information
 	InitFuncPtr initPtr = nullptr;
+	InitFuncPtr finiPtr = nullptr;
 	InitFuncPtr *initArray = nullptr;
+	InitFuncPtr *finiArray = nullptr;
 	InitFuncPtr *preInitArray = nullptr;
 	size_t initArraySize = 0;
+	size_t finiArraySize = 0;
 	size_t preInitArraySize = 0;
 
 
@@ -190,6 +199,8 @@ struct SharedObject {
 	bool onInitStack;
 	bool wasInitialized;
 
+	bool wasDestroyed = false;
+
 	// PHDR related stuff, we only set these for the main executable
 	void *phdrPointer = nullptr;
 	size_t phdrEntrySize = 0;
@@ -372,7 +383,7 @@ struct Loader {
 	void _processRelocations(Relocation &rel);
 
 public:
-	void initObjects();
+	void initObjects(ObjectRepository *repository);
 
 private:
 	void _scheduleInit(SharedObject *object);

options/rtld/generic/main.cpp

@@ -303,6 +303,8 @@ extern "C" void *interpreterMain(uintptr_t *entry_stack) {
 		case DT_RELRSZ:
 		case DT_RELRENT:
 		case DT_PLTGOT:
+		case DT_FLAGS:
+		case DT_FLAGS_1:
 			continue;
 		default:
 			mlibc::panicLogger() << "rtld: unexpected dynamic entry " << ent->d_tag << " in program interpreter" << frg::endlog;
@@ -453,9 +455,13 @@ extern "C" void *interpreterMain(uintptr_t *entry_stack) {
 	auto ldso = initialRepository->injectObjectFromDts(ldso_soname,
 		frg::string<MemoryAllocator> { getAllocator() },
 		ldso_base, _DYNAMIC, 1);
-	ldso->phdrPointer = phdr_pointer;
-	ldso->phdrCount = phdr_count;
-	ldso->phdrEntrySize = phdr_entry_size;
+
+	auto ldso_ehdr = reinterpret_cast<elf_ehdr *>(__ehdr_start);
+	auto ldso_phdr = reinterpret_cast<elf_phdr *>(ldso_base + ldso_ehdr->e_phoff);
+
+	ldso->phdrPointer = ldso_phdr;
+	ldso->phdrCount = ldso_ehdr->e_phnum;
+	ldso->phdrEntrySize = ldso_ehdr->e_phentsize;
 
 	// TODO: support non-zero base addresses?
 	executableSO = initialRepository->injectObjectFromPhdrs(execfn,
@@ -491,7 +497,7 @@ extern "C" void *interpreterMain(uintptr_t *entry_stack) {
 	globalDebugInterface.state = 0;
 	dl_debug_state();
 
-	linker.initObjects();
+	linker.initObjects(initialRepository.get());
 
 	if(logEntryExit)
 		mlibc::infoLogger() << "Leaving ld.so, jump to "
@@ -522,6 +528,10 @@ const mlibc::RtldConfig &__dlapi_get_config() {
 	return rtldConfig;
 }
 
+extern "C" [[ gnu::visibility("default") ]] void __dlapi_exit() {
+	initialRepository->destructObjects();
+}
+
 #if __MLIBC_POSIX_OPTION
 
 extern "C" [[ gnu::visibility("default") ]]
@@ -594,7 +604,7 @@ void *__dlapi_open(const char *file, int flags, void *returnAddress) {
 
 		Loader linker{object->localScope, nullptr, false, rts};
 		linker.linkObjects(object);
-		linker.initObjects();
+		linker.initObjects(initialRepository.get());
 	}
 
 	dl_debug_state();

tests/rtld/destroy/test.c

@@ -0,0 +1,9 @@
+#include <unistd.h>
+
+__attribute__((destructor)) void destroy() {
+	_exit(0);
+}
+
+int main() {
+	return 1;
+}

tests/rtld/meson.build

@@ -6,6 +6,7 @@ rtld_test_cases = [
 	'rtld_next',
 	'soname',
 	'preinit',
+	'destroy',
 	'scope1',
 	'scope2',
 	'scope3',