Kernel: Update ErrorOr API and add path find to VFS

These two are done on the same commit since Changes to Shell were
annoying to make work with only one change

BAN/include/BAN/Errors.h

@@ -1,18 +1,18 @@
 #pragma once
 
 #include <BAN/Formatter.h>
+#include <BAN/Variant.h>
 
 #include <string.h>
 
 #if defined(__is_kernel)
 	#include <kernel/Panic.h>
-	#define MUST(error)	({ auto e = error; if (e.is_error()) Kernel::panic("{}", e.get_error()); e.value(); })
-	#define ASSERT(cond) do { if (!(cond)) Kernel::panic("ASSERT("#cond") failed"); } while(false)
+	#define MUST(expr)	({ auto e = expr; if (e.is_error()) Kernel::panic("{}", e.error()); e.release_value(); })
 #else
 	#error "NOT IMPLEMENTED"
 #endif
 
-#define TRY(error) ({ auto e = error; if (e.is_error()) return e.get_error(); e.value(); })
+#define TRY(expr) ({ auto e = expr; if (e.is_error()) return e.error(); e.release_value(); })
 
 namespace BAN
 {
@@ -22,6 +22,7 @@ namespace BAN
 	public:
 		static Error from_string(const char* message)
 		{
+			static_assert(sizeof(message) < 128);
 			Error result;
 			strncpy(result.m_message, message, sizeof(m_message));
 			result.m_message[sizeof(result.m_message) - 1] = '\0';
@@ -41,34 +42,66 @@ namespace BAN
 	class [[nodiscard]] ErrorOr
 	{
 	public:
-		ErrorOr(const T& value)		: m_has_error(false)	{ m_data = (void*)new T(value); }
-		ErrorOr(const Error& error) : m_has_error(true)		{ m_data = (void*)new Error(error); }
-		template<typename S> ErrorOr(const ErrorOr<S>& other) : ErrorOr(other.get_error()) {}
-		~ErrorOr()											{ is_error() ? (delete reinterpret_cast<Error*>(m_data)) : (delete reinterpret_cast<T*>(m_data)); }
+		ErrorOr(const T& value)
+			: m_data(value)
+		{}
+		ErrorOr(T&& value)
+			: m_data(move(value))
+		{}
+		ErrorOr(const Error& error)
+			: m_data(error)
+		{}
+		ErrorOr(Error&& error)
+			: m_data(move(error))
+		{}
+		template<typename U>
+		ErrorOr(const ErrorOr<U>& other)
+			: m_data(other.m_data)
+		{}
+		template<typename U>
+		ErrorOr(ErrorOr<U>&& other)
+			: m_data(move(other.m_data))
+		{}
+		template<typename U>
+		ErrorOr<T>& operator=(const ErrorOr<U>& other)
+		{
+			m_data = other.m_data;
+			return *this;
+		}
+		template<typename U>
+		ErrorOr<T>& operator=(ErrorOr<U>&& other)
+		{
+			m_data = move(other.m_data);
+			return *this;
+		}
 
-		bool is_error() const			{ return m_has_error; }
-		const Error& get_error() const	{ return *reinterpret_cast<Error*>(m_data); }
-		T& value()						{ return *reinterpret_cast<T*>(m_data); }
+		bool is_error() const			{ return m_data.template is<Error>(); }
+		const Error& error() const		{ return m_data.template get<Error>(); }
+		Error& error()					{ return m_data.template get<Error>(); }
+		const T& value() const			{ return m_data.template get<T>(); }
+		T& value()						{ return m_data.template get<T>(); }
+		T release_value()				{ return move(value()); m_data.clear(); }
 
 	private:
-		bool	m_has_error	= false;
-		void*	m_data		= nullptr;
+		Variant<Error, T> m_data;
 	};
 
 	template<>
 	class [[nodiscard]] ErrorOr<void>
 	{
 	public:
-		ErrorOr()														{ }
-		ErrorOr(const Error& error) : m_error(error), m_has_error(true)	{ }
-		~ErrorOr()														{ }
+		ErrorOr()														{}
+		ErrorOr(const Error& error) : m_data(error), m_has_error(true)	{}
+		ErrorOr(Error&& error) : m_data(move(error)), m_has_error(true)	{}
 
 		bool is_error() const			{ return m_has_error; }
-		const Error& get_error() const	{ return m_error; }
+		Error& error()					{ return m_data; }
+		const Error& error() const		{ return m_data; }
 		void value()					{ }
+		void release_value()			{ m_data = Error(); }
 
 	private:
-		Error m_error;
+		Error m_data;
 		bool m_has_error = false;
 	};
 

kernel/include/kernel/FS/VirtualFileSystem.h

@@ -14,6 +14,8 @@ namespace Kernel
 
 		virtual const BAN::RefCounted<Inode> root_inode() const override { return m_root_inode; }
 
+		BAN::ErrorOr<BAN::RefCounted<Inode>> from_absolute_path(BAN::StringView);
+
 	private:
 		VirtualFileSystem(BAN::RefCounted<Inode> root_inode)
 			: m_root_inode(root_inode)

kernel/kernel/FS/VirtualFileSystem.cpp

@@ -1,3 +1,5 @@
+#include <BAN/StringView.h>
+#include <BAN/Vector.h>
 #include <kernel/FS/VirtualFileSystem.h>
 
 namespace Kernel
@@ -23,4 +25,18 @@ namespace Kernel
 		return s_instance != nullptr;
 	}
 
+	BAN::ErrorOr<BAN::RefCounted<Inode>> VirtualFileSystem::from_absolute_path(BAN::StringView path)
+	{
+		if (path.front() != '/')
+			return BAN::Error::from_string("Path must be an absolute path");
+
+		auto inode = root_inode();
+		auto path_parts = TRY(path.split('/'));
+		
+		for (BAN::StringView part : path_parts)
+			inode = TRY(inode->directory_find(part));
+		
+		return inode;
+	}
+
 }

kernel/kernel/Input.cpp

@@ -512,7 +512,7 @@ namespace Input
 		{
 			auto error_or = s_key_event_queue.push({ .key = key, .modifiers = modifiers, .pressed = pressed });
 			if (error_or.is_error())
-				dwarnln("{}", error_or.get_error());
+				dwarnln("{}", error_or.error());
 		}
 		s_keyboard_key_buffer_size -= index + 1;
 		memmove(s_keyboard_key_buffer, s_keyboard_key_buffer + index, s_keyboard_key_buffer_size);

kernel/kernel/Shell.cpp

@@ -268,28 +268,16 @@ argument_done:
 			BAN::StringView path = (arguments.size() == 2) ? arguments[1].sv() : "/";
 			if (path.front() != '/')
 				return TTY_PRINTLN("ls currently works only with absolute paths");
-			path = path.substring(1);
 
-			auto directory = VirtualFileSystem::get().root_inode();
+			auto directory_or_error = VirtualFileSystem::get().from_absolute_path(path);
+			if (directory_or_error.is_error())
+				return TTY_PRINTLN("{}", directory_or_error.error());
+			auto directory = directory_or_error.release_value();
 			ASSERT(directory->ifdir());
 
-			if (arguments.size() == 2)
-			{
-				auto path_parts = MUST(arguments[1].sv().split('/'));
-				for (auto part : path_parts)
-				{
-					auto inode_or_error = directory->directory_find(part);
-					if (inode_or_error.is_error())
-						return TTY_PRINTLN("{}", inode_or_error.get_error().get_message());
-					directory = inode_or_error.value();
-					if (!directory->ifdir())
-						return TTY_PRINTLN("expected argument to be path to directory");
-				}
-			}
-
 			auto inodes_or_error = directory->directory_inodes();
 			if (inodes_or_error.is_error())
-				return TTY_PRINTLN("{}", inodes_or_error.get_error().get_message());
+				return TTY_PRINTLN("{}", inodes_or_error.error());
 			auto& inodes = inodes_or_error.value();
 
 			auto mode_string = [](Inode::Mode mode)
@@ -324,22 +312,16 @@ argument_done:
 			if (arguments.size() > 2)
 				return TTY_PRINTLN("usage: 'cat path'");
 			
-			auto file = VirtualFileSystem::get().root_inode();
-
-			auto path_parts = MUST(arguments[1].sv().split('/'));
-			for (auto part : path_parts)
-			{
-				auto inode_or_error = file->directory_find(part);
-				if (inode_or_error.is_error())
-					return TTY_PRINTLN("{}", inode_or_error.get_error().get_message());
-				file = inode_or_error.value();
-			}
+			auto file_or_error = VirtualFileSystem::get().from_absolute_path(arguments[1]);
+			if (file_or_error.is_error())
+				return TTY_PRINTLN("{}", file_or_error.error());
+			auto file = file_or_error.release_value();
 
 			auto data_or_error = file->read_all();
 			if (data_or_error.is_error())
-				return TTY_PRINTLN("{}", data_or_error.get_error().get_message());
+				return TTY_PRINTLN("{}", data_or_error.error());
+			auto data = data_or_error.release_value();
 
-			auto& data = data_or_error.value();
 			TTY_PRINTLN("{}", BAN::StringView((const char*)data.data(), data.size()));
 		}
 		else