Kernel: Implement deletion of SMO objects

kernel/include/kernel/Memory/SharedMemoryObject.h

@@ -21,6 +21,7 @@ namespace Kernel
 		static SharedMemoryObjectManager& get();
 
 		BAN::ErrorOr<Key> create_object(size_t size, PageTable::flags_t);
+		BAN::ErrorOr<void> delete_object(Key);
 		BAN::ErrorOr<BAN::UniqPtr<SharedMemoryObject>> map_object(Key, PageTable&, AddressRange);
 
 	private:
@@ -29,6 +30,8 @@ namespace Kernel
 	private:
 		struct Object : public BAN::RefCounted<Object>
 		{
+			~Object();
+
 			size_t size;
 			PageTable::flags_t flags;
 			BAN::Vector<paddr_t> paddrs;

kernel/include/kernel/Process.h

@@ -159,6 +159,7 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_msync(void* addr, size_t len, int flags);
 
 		BAN::ErrorOr<long> sys_smo_create(size_t len, int prot);
+		BAN::ErrorOr<long> sys_smo_delete(SharedMemoryObjectManager::Key);
 		BAN::ErrorOr<long> sys_smo_map(SharedMemoryObjectManager::Key);
 
 		BAN::ErrorOr<long> sys_tty_ctrl(int fildes, int command, int flags);

kernel/kernel/Memory/SharedMemoryObject.cpp

@@ -21,6 +21,13 @@ namespace Kernel
 		return *s_instance;
 	}
 
+	SharedMemoryObjectManager::Object::~Object()
+	{
+		for (auto paddr : paddrs)
+			if (paddr)
+				Heap::get().release_page(paddr);
+	}
+
 	BAN::ErrorOr<SharedMemoryObjectManager::Key> SharedMemoryObjectManager::create_object(size_t size, PageTable::flags_t flags)
 	{
 		ASSERT(size % PAGE_SIZE == 0);
@@ -43,6 +50,18 @@ namespace Kernel
 		return key;
 	}
 
+	BAN::ErrorOr<void> SharedMemoryObjectManager::delete_object(Key key)
+	{
+		LockGuard _(m_mutex);
+
+		auto it = m_objects.find(key);
+		if (it == m_objects.end())
+			return BAN::Error::from_errno(ENOENT);
+
+		m_objects.remove(it);
+		return {};
+	}
+
 	BAN::ErrorOr<BAN::UniqPtr<SharedMemoryObject>> SharedMemoryObjectManager::map_object(Key key, PageTable& page_table, AddressRange address_range)
 	{
 		LockGuard _(m_mutex);

kernel/kernel/Process.cpp

@@ -1418,6 +1418,12 @@ namespace Kernel
 		return TRY(SharedMemoryObjectManager::get().create_object(len, page_flags));
 	}
 
+	BAN::ErrorOr<long> Process::sys_smo_delete(SharedMemoryObjectManager::Key key)
+	{
+		TRY(SharedMemoryObjectManager::get().delete_object(key));
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_smo_map(SharedMemoryObjectManager::Key key)
 	{
 		auto region = TRY(SharedMemoryObjectManager::get().map_object(key, page_table(), { .start = 0x400000, .end = KERNEL_OFFSET }));

libc/include/sys/banan-os.h

@@ -38,7 +38,9 @@ int load_keymap(const char* path);
 
 // Create shared memory object and return its key or -1 on error
 long smo_create(size_t size, int prot);
-// Map shared memory object defined by its key and return address or null on error
+// Delete shared memory object such that it will be no longer accessible with smo_map(). Existing mappings are still valid
+int smo_delete(long key);
+// Map shared memory object defined by its key and return address or null on error. Mappings can be unmapped using munmap()
 void* smo_map(long key);
 
 __END_DECLS

libc/include/sys/syscall.h

@@ -75,6 +75,7 @@ __BEGIN_DECLS
 	O(SYS_PSELECT,			pselect)		\
 	O(SYS_TRUNCATE,			truncate)		\
 	O(SYS_SMO_CREATE,		smo_create)		\
+	O(SYS_SMO_DELETE,		smo_delete)		\
 	O(SYS_SMO_MAP,			smo_map)		\
 
 enum Syscall

libc/sys/banan-os.cpp

@@ -22,6 +22,11 @@ long smo_create(size_t size, int prot)
 	return syscall(SYS_SMO_CREATE, size, prot);
 }
 
+int smo_delete(long key)
+{
+	return syscall(SYS_SMO_DELETE, key);
+}
+
 void* smo_map(long key)
 {
 	long ret = syscall(SYS_SMO_MAP, key);