VFS: close handles via handle method

The using pattern 'handle->close' is less error prone than attempting
'handle->ds().close(handle)' or 'fs.close(handle)'.

Ref #2782

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

@@ -299,7 +299,7 @@ int Libc::Vfs_plugin::close(Libc::File_descriptor *fd)
 {
 	Vfs::Vfs_handle *handle = vfs_handle(fd);
 	_vfs_sync(handle);
-	handle->ds().close(handle);
+	handle->close();
 	Libc::file_descriptor_allocator()->free(fd);
 	return 0;
 }
@@ -341,7 +341,7 @@ int Libc::Vfs_plugin::mkdir(const char *path, mode_t mode)
 
 	switch (_root_dir.opendir(path, true, &dir_handle, _alloc)) {
 	case Opendir_result::OPENDIR_OK:
-		dir_handle->ds().close(dir_handle);
+		dir_handle->close();
 		break;
 	case Opendir_result::OPENDIR_ERR_LOOKUP_FAILED:
 		return Errno(ENOENT);
@@ -955,7 +955,7 @@ int Libc::Vfs_plugin::symlink(const char *oldpath, const char *newpath)
 	} while (check.retry);
 
 	_vfs_sync(handle);
-	handle->ds().close(handle);
+	handle->close();
 
 	if (out_count != count)
 		return Errno(ENAMETOOLONG);
@@ -1064,7 +1064,7 @@ ssize_t Libc::Vfs_plugin::readlink(const char *path, char *buf, ::size_t buf_siz
 	case Result::READ_QUEUED: /* handled above, so never reached */ break;
 	};
 
-	symlink_handle->ds().close(symlink_handle);
+	symlink_handle->close();
 
 	return out_len;
 }

repos/os/include/vfs/dir_file_system.h

@@ -79,7 +79,7 @@ class Vfs::Dir_file_system : public File_system
 			{
 				/* close all sub-handles */
 				auto f = [&] (Subdir_handle_element &e) {
-					e.vfs_handle.ds().close(&e.vfs_handle);
+					e.vfs_handle.close();
 					destroy(alloc(), &e);
 				};
 				subdir_handle_registry.for_each(f);
@@ -118,7 +118,7 @@ class Vfs::Dir_file_system : public File_system
 			{
 				/* close all sub-handles */
 				auto f = [&] (Watch_handle_element &e) {
-					e.watch_handle.fs().close(&e.watch_handle);
+					e.watch_handle.close();
 					destroy(alloc(), &e);
 				};
 				handle_registry.for_each(f);
@@ -700,8 +700,9 @@ class Vfs::Dir_file_system : public File_system
 					Vfs_handle *tmp_handle;
 					Opendir_result opendir_result =
 						fs.opendir(path, true, &tmp_handle, alloc);
-					if (opendir_result == OPENDIR_OK)
+					if (opendir_result == OPENDIR_OK) {
-						fs.close(tmp_handle);
+						tmp_handle->close();
+					}
 					return opendir_result; /* return from lambda */
 				};
 

repos/os/include/vfs/vfs_handle.h

@@ -68,7 +68,7 @@ class Vfs::Vfs_handle
 				~Guard()
 				{
 					if (_handle)
-						_handle->_ds.close(_handle);
+						_handle->close();
 				}
 		};
 
@@ -108,6 +108,13 @@ class Vfs::Vfs_handle
 		 * Advance seek offset by 'incr' bytes
 		 */
 		void advance_seek(file_size incr) { _seek += incr; }
+
+		/**
+		 * Close handle at backing file-system.
+		 *
+		 * This leaves the handle pointer in an invalid and unsafe state.
+		 */
+		inline void close() { ds().close(this); }
 };
 
 
@@ -122,7 +129,7 @@ class Vfs::Vfs_watch_handle
 
 	private:
 
-		File_system       &_fs;
+		Directory_service &_fs;
 		Genode::Allocator &_alloc;
 		Context           *_context = nullptr;
 
@@ -134,7 +141,7 @@ class Vfs::Vfs_watch_handle
 
 	public:
 
-		Vfs_watch_handle(File_system       &fs,
+		Vfs_watch_handle(Directory_service &fs,
 		                 Genode::Allocator &alloc)
 		:
 			_fs(fs), _alloc(alloc)
@@ -142,10 +149,17 @@ class Vfs::Vfs_watch_handle
 
 		virtual ~Vfs_watch_handle() { }
 
-		File_system &fs() { return _fs; }
+		Directory_service &fs() { return _fs; }
 		Allocator &alloc() { return _alloc; }
 		virtual void context(Context *context) { _context = context; }
 		Context *context() const { return _context; }
+
+		/**
+		 * Close handle at backing file-system.
+		 *
+		 * This leaves the handle pointer in an invalid and unsafe state.
+		 */
+		inline void close() { fs().close(this); }
 };
 
 #endif /* _INCLUDE__VFS__VFS_HANDLE_H_ */

repos/os/src/server/vfs/node.h

@@ -335,7 +335,7 @@ class Vfs_server::Watch_node final : public  Vfs_server::Node,
 		~Watch_node()
 		{
 			_watch_handle.context((Vfs::Vfs_watch_handle::Context*)~0ULL);
-			_watch_handle.fs().close(&_watch_handle);
+			_watch_handle.close();
 		}
 
 		static Watch_node &node_by_context(Vfs::Vfs_watch_handle::Context &context)
@@ -368,6 +368,7 @@ struct Vfs_server::Symlink : Io_node
 		_handle->context = &context();
 	}
 
+	~Symlink() { _handle->close(); }
 
 	/********************
 	 ** Node interface **
@@ -444,7 +445,7 @@ class Vfs_server::File : public Io_node
 			_handle->context = &context();
 		}
 
-		~File() { _handle->ds().close(_handle); }
+		~File() { _handle->close(); }
 
 		size_t read(char *dst, size_t len, seek_off_t seek_offset) override
 		{
@@ -497,7 +498,7 @@ struct Vfs_server::Directory : Io_node
 		_handle->context = &context();
 	}
 
-	~Directory() { _handle->ds().close(_handle); }
+	~Directory() { _handle->close(); }
 
 	Node_space::Id file(Node_space        &space,
 	                    Vfs::File_system  &vfs,

repos/os/src/test/vfs_stress/main.cc

@@ -171,7 +171,7 @@ struct Mkdir_test : public Stress_test
 		path.append("/b");
 		Vfs::Vfs_handle *dir_handle;
 		assert_opendir(vfs.opendir(path.base(), true, &dir_handle, alloc));
-		vfs.close(dir_handle);
+		dir_handle->close();
 		++count;
 		mkdir_b(depth);
 	}
@@ -186,7 +186,7 @@ struct Mkdir_test : public Stress_test
 
 		path.append("/b");
 		assert_opendir(vfs.opendir(path.base(), true, &dir_handle, alloc));
-		vfs.close(dir_handle);
+		dir_handle->close();
 		++count;
 		mkdir_b(depth);
 
@@ -194,7 +194,7 @@ struct Mkdir_test : public Stress_test
 
 		path.append("/a");
 		assert_opendir(vfs.opendir(path.base(), true, &dir_handle, alloc));
-		vfs.close(dir_handle);
+		dir_handle->close();
 		++count;
 		mkdir_a(depth);
 	}
@@ -474,7 +474,7 @@ struct Unlink_test : public Stress_test
 			}
 		}
 
-		vfs.close(dir_handle);
+		dir_handle->close();
 	}
 
 	Unlink_test(Vfs::File_system &vfs, Genode::Allocator &alloc,
@@ -561,7 +561,7 @@ void Component::construct(Genode::Env &env)
 			snprintf(path, 3, "/%d", i);
 			Vfs::Vfs_handle *dir_handle;
 			vfs_root.opendir(path, true, &dir_handle, heap);
-			vfs_root.close(dir_handle);
+			dir_handle->close();
 			Mkdir_test test(vfs_root, heap, path);
 			count += test.wait();
 		}