fs: Add path class

src/common/overflow.h

@@ -19,4 +19,21 @@ inline T WrappingAdd(T lhs, T rhs) {
     return BitCast<T>(lhs_u + rhs_u);
 }
 
+template <typename T>
+    requires(std::is_integral_v<T> && std::is_signed_v<T>)
+inline bool CanAddWithoutOverflow(T lhs, T rhs) {
+#ifdef _MSC_VER
+    if (lhs >= 0 && rhs >= 0) {
+        return WrappingAdd(lhs, rhs) >= std::max(lhs, rhs);
+    } else if (lhs < 0 && rhs < 0) {
+        return WrappingAdd(lhs, rhs) <= std::min(lhs, rhs);
+    } else {
+        return true;
+    }
+#else
+    T res;
+    return !__builtin_add_overflow(lhs, rhs, &res);
+#endif
+}
+
 } // namespace Common

src/core/CMakeLists.txt

@@ -58,7 +58,7 @@ add_library(core STATIC
     file_sys/fs_operate_range.h
     file_sys/fs_path.h
     file_sys/fs_path_utility.h
-    file_sys/fs_util_character_encoding.h
+    file_sys/fs_string_util.h
     file_sys/fsmitm_romfsbuild.cpp
     file_sys/fsmitm_romfsbuild.h
     file_sys/fssystem/fs_i_storage.h
@@ -104,25 +104,10 @@ add_library(core STATIC
     file_sys/fssystem/fssystem_switch_storage.h
     file_sys/fssystem/fssystem_utility.cpp
     file_sys/fssystem/fssystem_utility.h
-    file_sys/fssystem/fs_types.h
-    file_sys/bis_factory.cpp
-    file_sys/bis_factory.h
-    file_sys/card_image.cpp
-    file_sys/card_image.h
-    file_sys/common_funcs.h
-    file_sys/content_archive.cpp
-    file_sys/content_archive.h
-    file_sys/control_metadata.cpp
-    file_sys/control_metadata.h
-    file_sys/directory.h
-    file_sys/errors.h
-    file_sys/fsmitm_romfsbuild.cpp
-    file_sys/fsmitm_romfsbuild.h
     file_sys/ips_layer.cpp
     file_sys/ips_layer.h
     file_sys/kernel_executable.cpp
     file_sys/kernel_executable.h
-    file_sys/mode.h
     file_sys/nca_metadata.cpp
     file_sys/nca_metadata.h
     file_sys/partition_filesystem.cpp
@@ -215,7 +200,6 @@ add_library(core STATIC
     hle/kernel/board/nintendo/nx/secure_monitor.h
     hle/kernel/code_set.cpp
     hle/kernel/code_set.h
-    hle/kernel/svc_results.h
     hle/kernel/global_scheduler_context.cpp
     hle/kernel/global_scheduler_context.h
     hle/kernel/init/init_slab_setup.cpp
@@ -225,11 +209,11 @@ add_library(core STATIC
     hle/kernel/k_address_arbiter.h
     hle/kernel/k_address_space_info.cpp
     hle/kernel/k_address_space_info.h
+    hle/kernel/k_affinity_mask.h
     hle/kernel/k_auto_object.cpp
     hle/kernel/k_auto_object.h
     hle/kernel/k_auto_object_container.cpp
     hle/kernel/k_auto_object_container.h
-    hle/kernel/k_affinity_mask.h
     hle/kernel/k_capabilities.cpp
     hle/kernel/k_capabilities.h
     hle/kernel/k_class_token.cpp
@@ -253,9 +237,9 @@ add_library(core STATIC
     hle/kernel/k_event_info.h
     hle/kernel/k_handle_table.cpp
     hle/kernel/k_handle_table.h
-    hle/kernel/k_hardware_timer_base.h
     hle/kernel/k_hardware_timer.cpp
     hle/kernel/k_hardware_timer.h
+    hle/kernel/k_hardware_timer_base.h
     hle/kernel/k_interrupt_manager.cpp
     hle/kernel/k_interrupt_manager.h
     hle/kernel/k_light_client_session.cpp
@@ -282,10 +266,10 @@ add_library(core STATIC
     hle/kernel/k_page_bitmap.h
     hle/kernel/k_page_buffer.cpp
     hle/kernel/k_page_buffer.h
-    hle/kernel/k_page_heap.cpp
-    hle/kernel/k_page_heap.h
     hle/kernel/k_page_group.cpp
     hle/kernel/k_page_group.h
+    hle/kernel/k_page_heap.cpp
+    hle/kernel/k_page_heap.h
     hle/kernel/k_page_table.h
     hle/kernel/k_page_table_base.cpp
     hle/kernel/k_page_table_base.h
@@ -350,8 +334,6 @@ add_library(core STATIC
     hle/kernel/slab_helpers.h
     hle/kernel/svc.cpp
     hle/kernel/svc.h
-    hle/kernel/svc_common.h
-    hle/kernel/svc_types.h
     hle/kernel/svc/svc_activity.cpp
     hle/kernel/svc/svc_address_arbiter.cpp
     hle/kernel/svc/svc_address_translation.cpp
@@ -389,6 +371,9 @@ add_library(core STATIC
     hle/kernel/svc/svc_thread_profiler.cpp
     hle/kernel/svc/svc_tick.cpp
     hle/kernel/svc/svc_transfer_memory.cpp
+    hle/kernel/svc_common.h
+    hle/kernel/svc_results.h
+    hle/kernel/svc_types.h
     hle/result.h
     hle/service/acc/acc.cpp
     hle/service/acc/acc.h
@@ -519,17 +504,17 @@ add_library(core STATIC
     hle/service/filesystem/fsp/fs_i_filesystem.h
     hle/service/filesystem/fsp/fs_i_storage.cpp
     hle/service/filesystem/fsp/fs_i_storage.h
+    hle/service/filesystem/fsp/fsp_ldr.cpp
+    hle/service/filesystem/fsp/fsp_ldr.h
+    hle/service/filesystem/fsp/fsp_pr.cpp
+    hle/service/filesystem/fsp/fsp_pr.h
     hle/service/filesystem/fsp/fsp_srv.cpp
     hle/service/filesystem/fsp/fsp_srv.h
-    hle/service/filesystem/fsp_ldr.cpp
-    hle/service/filesystem/fsp_ldr.h
-    hle/service/filesystem/fsp_pr.cpp
-    hle/service/filesystem/fsp_pr.h
+    hle/service/filesystem/fsp/fsp_util.h
     hle/service/filesystem/romfs_controller.cpp
     hle/service/filesystem/romfs_controller.h
     hle/service/filesystem/save_data_controller.cpp
     hle/service/filesystem/save_data_controller.h
-    hle/service/filesystem/fsp_util.h
     hle/service/fgm/fgm.cpp
     hle/service/fgm/fgm.h
     hle/service/friend/friend.cpp

src/core/file_sys/errors.h

@@ -73,10 +73,21 @@ constexpr Result ResultUnexpectedInCompressedStorageA{ErrorModule::FS, 5324};
 constexpr Result ResultUnexpectedInCompressedStorageB{ErrorModule::FS, 5325};
 constexpr Result ResultUnexpectedInCompressedStorageC{ErrorModule::FS, 5326};
 constexpr Result ResultUnexpectedInCompressedStorageD{ErrorModule::FS, 5327};
+constexpr Result ResultUnexpectedInPathA{ErrorModule::FS, 5328};
 constexpr Result ResultInvalidArgument{ErrorModule::FS, 6001};
+constexpr Result ResultInvalidPath{ErrorModule::FS, 6002};
+constexpr Result ResultTooLongPath{ErrorModule::FS, 6003};
+constexpr Result ResultInvalidCharacter{ErrorModule::FS, 6004};
+constexpr Result ResultInvalidPathFormat{ErrorModule::FS, 6005};
+constexpr Result ResultDirectoryUnobtainable{ErrorModule::FS, 6006};
+constexpr Result ResultNotNormalized{ErrorModule::FS, 6007};
 constexpr Result ResultInvalidOffset{ErrorModule::FS, 6061};
 constexpr Result ResultInvalidSize{ErrorModule::FS, 6062};
 constexpr Result ResultNullptrArgument{ErrorModule::FS, 6063};
+constexpr Result ResultInvalidOpenMode{ErrorModule::FS, 6072};
+constexpr Result ResultFileExtensionWithoutOpenModeAllowAppend{ErrorModule::FS, 6201};
+constexpr Result ResultReadNotPermitted{ErrorModule::FS, 6202};
+constexpr Result ResultWriteNotPermitted{ErrorModule::FS, 6203};
 constexpr Result ResultUnsupportedSetSizeForIndirectStorage{ErrorModule::FS, 6325};
 constexpr Result ResultUnsupportedWriteForCompressedStorage{ErrorModule::FS, 6387};
 constexpr Result ResultUnsupportedOperateRangeForCompressedStorage{ErrorModule::FS, 6388};

src/core/file_sys/fs_file.h

@@ -0,0 +1,63 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+namespace FileSys {
+
+struct ReadOption {
+    u32 _value;
+
+    static const ReadOption None;
+};
+
+enum ReadOptionFlag : u32 {
+    ReadOptionFlag_None = (0 << 0),
+};
+
+inline constexpr const ReadOption ReadOption::None = {ReadOptionFlag_None};
+
+inline constexpr bool operator==(const ReadOption& lhs, const ReadOption& rhs) {
+    return lhs._value == rhs._value;
+}
+
+inline constexpr bool operator!=(const ReadOption& lhs, const ReadOption& rhs) {
+    return !(lhs == rhs);
+}
+
+static_assert(sizeof(ReadOption) == sizeof(u32));
+
+enum WriteOptionFlag : u32 {
+    WriteOptionFlag_None = (0 << 0),
+    WriteOptionFlag_Flush = (1 << 0),
+};
+
+struct WriteOption {
+    u32 _value;
+
+    constexpr inline bool HasFlushFlag() const {
+        return _value & WriteOptionFlag_Flush;
+    }
+
+    static const WriteOption None;
+    static const WriteOption Flush;
+};
+
+inline constexpr const WriteOption WriteOption::None = {WriteOptionFlag_None};
+inline constexpr const WriteOption WriteOption::Flush = {WriteOptionFlag_Flush};
+
+inline constexpr bool operator==(const WriteOption& lhs, const WriteOption& rhs) {
+    return lhs._value == rhs._value;
+}
+
+inline constexpr bool operator!=(const WriteOption& lhs, const WriteOption& rhs) {
+    return !(lhs == rhs);
+}
+
+static_assert(sizeof(WriteOption) == sizeof(u32));
+
+struct FileHandle {
+    void* handle;
+};
+
+} // namespace FileSys

src/core/file_sys/fs_memory_management.h

@@ -0,0 +1,48 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <mutex>
+#include "common/alignment.h"
+
+namespace FileSys {
+
+std::mutex g_mutex;
+
+constexpr size_t RequiredAlignment = alignof(u64);
+
+void* AllocateUnsafe(size_t size) {
+    /* Allocate. */
+    void* const ptr = ::operator new(size, std::align_val_t{RequiredAlignment});
+
+    /* Check alignment. */
+    ASSERT(Common::IsAligned(reinterpret_cast<uintptr_t>(ptr), RequiredAlignment));
+
+    /* Return allocated pointer. */
+    return ptr;
+}
+
+void DeallocateUnsafe(void* ptr, size_t size) {
+    /* Deallocate the pointer. */
+    ::operator delete(ptr, std::align_val_t{RequiredAlignment});
+}
+
+void* Allocate(size_t size) {
+    /* Lock the allocator. */
+    std::scoped_lock lk(g_mutex);
+
+    return AllocateUnsafe(size);
+}
+
+void Deallocate(void* ptr, size_t size) {
+    /* If the pointer is non-null, deallocate it. */
+    if (ptr != nullptr) {
+        /* Lock the allocator. */
+        std::scoped_lock lk(g_mutex);
+
+        DeallocateUnsafe(ptr, size);
+    }
+}
+
+} // namespace FileSys

src/core/file_sys/fs_operate_range.h

@@ -0,0 +1,20 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+namespace FileSys {
+
+enum class OperationId : s64 {
+    FillZero = 0,
+    DestroySignature = 1,
+    Invalidate = 2,
+    QueryRange = 3,
+    QueryUnpreparedRange = 4,
+    QueryLazyLoadCompletionRate = 5,
+    SetLazyLoadPriority = 6,
+
+    ReadLazyLoadFileForciblyForDebug = 10001,
+};
+
+} // namespace FileSys

src/core/file_sys/fs_path.h

@@ -0,0 +1,570 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "common/alignment.h"
+#include "common/common_funcs.h"
+#include "core/file_sys/errors.h"
+#include "core/file_sys/fs_memory_management.h"
+#include "core/file_sys/fs_path_utility.h"
+#include "core/file_sys/fs_string_util.h"
+#include "core/hle/result.h"
+
+namespace FileSys {
+class DirectoryPathParser;
+
+class Path {
+    YUZU_NON_COPYABLE(Path);
+    YUZU_NON_MOVEABLE(Path);
+
+private:
+    static constexpr const char* EmptyPath = "";
+    static constexpr size_t WriteBufferAlignmentLength = 8;
+
+private:
+    friend class DirectoryPathParser;
+
+public:
+    class WriteBuffer {
+        YUZU_NON_COPYABLE(WriteBuffer);
+
+    private:
+        char* m_buffer;
+        size_t m_length_and_is_normalized;
+
+    public:
+        constexpr WriteBuffer() : m_buffer(nullptr), m_length_and_is_normalized(0) { /* ... */
+        }
+
+        constexpr ~WriteBuffer() {
+            if (m_buffer != nullptr) {
+                Deallocate(m_buffer, this->GetLength());
+                this->ResetBuffer();
+            }
+        }
+
+        constexpr WriteBuffer(WriteBuffer&& rhs)
+            : m_buffer(rhs.m_buffer), m_length_and_is_normalized(rhs.m_length_and_is_normalized) {
+            rhs.ResetBuffer();
+        }
+
+        constexpr WriteBuffer& operator=(WriteBuffer&& rhs) {
+            if (m_buffer != nullptr) {
+                Deallocate(m_buffer, this->GetLength());
+            }
+
+            m_buffer = rhs.m_buffer;
+            m_length_and_is_normalized = rhs.m_length_and_is_normalized;
+
+            rhs.ResetBuffer();
+
+            return *this;
+        }
+
+        constexpr void ResetBuffer() {
+            m_buffer = nullptr;
+            this->SetLength(0);
+        }
+
+        constexpr char* Get() const {
+            return m_buffer;
+        }
+
+        constexpr size_t GetLength() const {
+            return m_length_and_is_normalized >> 1;
+        }
+
+        constexpr bool IsNormalized() const {
+            return static_cast<bool>(m_length_and_is_normalized & 1);
+        }
+
+        constexpr void SetNormalized() {
+            m_length_and_is_normalized |= static_cast<size_t>(1);
+        }
+
+        constexpr void SetNotNormalized() {
+            m_length_and_is_normalized &= ~static_cast<size_t>(1);
+        }
+
+    private:
+        constexpr WriteBuffer(char* buffer, size_t length)
+            : m_buffer(buffer), m_length_and_is_normalized(0) {
+            this->SetLength(length);
+        }
+
+    public:
+        static WriteBuffer Make(size_t length) {
+            if (void* alloc = Allocate(length); alloc != nullptr) {
+                return WriteBuffer(static_cast<char*>(alloc), length);
+            } else {
+                return WriteBuffer();
+            }
+        }
+
+    private:
+        constexpr void SetLength(size_t size) {
+            m_length_and_is_normalized = (m_length_and_is_normalized & 1) | (size << 1);
+        }
+    };
+
+private:
+    const char* m_str;
+    WriteBuffer m_write_buffer;
+
+public:
+    constexpr Path() : m_str(EmptyPath), m_write_buffer() {
+        /* ... */
+    }
+
+    constexpr Path(const char* s) : m_str(s), m_write_buffer() {
+        m_write_buffer.SetNormalized();
+    }
+
+    constexpr ~Path() { /* ... */
+    }
+
+    constexpr Result SetShallowBuffer(const char* buffer) {
+        /* Check pre-conditions. */
+        ASSERT(m_write_buffer.GetLength() == 0);
+
+        /* Check the buffer is valid. */
+        R_UNLESS(buffer != nullptr, ResultNullptrArgument);
+
+        /* Set buffer. */
+        this->SetReadOnlyBuffer(buffer);
+
+        /* Note that we're normalized. */
+        this->SetNormalized();
+
+        R_SUCCEED();
+    }
+
+    constexpr const char* GetString() const {
+        /* Check pre-conditions. */
+        ASSERT(this->IsNormalized());
+
+        return m_str;
+    }
+
+    constexpr size_t GetLength() const {
+        if (std::is_constant_evaluated()) {
+            return Strlen(this->GetString());
+        } else {
+            return std::strlen(this->GetString());
+        }
+    }
+
+    constexpr bool IsEmpty() const {
+        return *m_str == '\x00';
+    }
+
+    constexpr bool IsMatchHead(const char* p, size_t len) const {
+        return Strncmp(this->GetString(), p, len) == 0;
+    }
+
+    Result Initialize(const Path& rhs) {
+        /* Check the other path is normalized. */
+        const bool normalized = rhs.IsNormalized();
+        R_UNLESS(normalized, ResultNotNormalized);
+
+        /* Allocate buffer for our path. */
+        const auto len = rhs.GetLength();
+        R_TRY(this->Preallocate(len + 1));
+
+        /* Copy the path. */
+        const size_t copied = Strlcpy<char>(m_write_buffer.Get(), rhs.GetString(), len + 1);
+        R_UNLESS(copied == len, ResultUnexpectedInPathA);
+
+        /* Set normalized. */
+        this->SetNormalized();
+        R_SUCCEED();
+    }
+
+    Result Initialize(const char* path, size_t len) {
+        /* Check the path is valid. */
+        R_UNLESS(path != nullptr, ResultNullptrArgument);
+
+        /* Initialize. */
+        R_TRY(this->InitializeImpl(path, len));
+
+        /* Set not normalized. */
+        this->SetNotNormalized();
+
+        R_SUCCEED();
+    }
+
+    Result Initialize(const char* path) {
+        /* Check the path is valid. */
+        R_UNLESS(path != nullptr, ResultNullptrArgument);
+
+        R_RETURN(this->Initialize(path, std::strlen(path)));
+    }
+
+    Result InitializeWithReplaceBackslash(const char* path) {
+        /* Check the path is valid. */
+        R_UNLESS(path != nullptr, ResultNullptrArgument);
+
+        /* Initialize. */
+        R_TRY(this->InitializeImpl(path, std::strlen(path)));
+
+        /* Replace slashes as desired. */
+        if (const auto write_buffer_length = m_write_buffer.GetLength(); write_buffer_length > 1) {
+            Replace(m_write_buffer.Get(), write_buffer_length - 1, '\\', '/');
+        }
+
+        /* Set not normalized. */
+        this->SetNotNormalized();
+
+        R_SUCCEED();
+    }
+
+    Result InitializeWithReplaceForwardSlashes(const char* path) {
+        /* Check the path is valid. */
+        R_UNLESS(path != nullptr, ResultNullptrArgument);
+
+        /* Initialize. */
+        R_TRY(this->InitializeImpl(path, std::strlen(path)));
+
+        /* Replace slashes as desired. */
+        if (m_write_buffer.GetLength() > 1) {
+            if (auto* p = m_write_buffer.Get(); p[0] == '/' && p[1] == '/') {
+                p[0] = '\\';
+                p[1] = '\\';
+            }
+        }
+
+        /* Set not normalized. */
+        this->SetNotNormalized();
+
+        R_SUCCEED();
+    }
+
+    Result InitializeWithNormalization(const char* path, size_t size) {
+        /* Check the path is valid. */
+        R_UNLESS(path != nullptr, ResultNullptrArgument);
+
+        /* Initialize. */
+        R_TRY(this->InitializeImpl(path, size));
+
+        /* Set not normalized. */
+        this->SetNotNormalized();
+
+        /* Perform normalization. */
+        PathFlags path_flags;
+        if (IsPathRelative(m_str)) {
+            path_flags.AllowRelativePath();
+        } else if (IsWindowsPath(m_str, true)) {
+            path_flags.AllowWindowsPath();
+        } else {
+            /* NOTE: In this case, Nintendo checks is normalized, then sets is normalized, then
+             * returns success. */
+            /* This seems like a bug. */
+            size_t dummy;
+            bool normalized;
+            R_TRY(PathFormatter::IsNormalized(std::addressof(normalized), std::addressof(dummy),
+                                              m_str));
+
+            this->SetNormalized();
+            R_SUCCEED();
+        }
+
+        /* Normalize. */
+        R_TRY(this->Normalize(path_flags));
+
+        this->SetNormalized();
+        R_SUCCEED();
+    }
+
+    Result InitializeWithNormalization(const char* path) {
+        /* Check the path is valid. */
+        R_UNLESS(path != nullptr, ResultNullptrArgument);
+
+        R_RETURN(this->InitializeWithNormalization(path, std::strlen(path)));
+    }
+
+    Result InitializeAsEmpty() {
+        /* Clear our buffer. */
+        this->ClearBuffer();
+
+        /* Set normalized. */
+        this->SetNormalized();
+
+        R_SUCCEED();
+    }
+
+    Result AppendChild(const char* child) {
+        /* Check the path is valid. */
+        R_UNLESS(child != nullptr, ResultNullptrArgument);
+
+        /* Basic checks. If we hvea a path and the child is empty, we have nothing to do. */
+        const char* c = child;
+        if (m_str[0]) {
+            /* Skip an early separator. */
+            if (*c == '/') {
+                ++c;
+            }
+
+            R_SUCCEED_IF(*c == '\x00');
+        }
+
+        /* If we don't have a string, we can just initialize. */
+        auto cur_len = std::strlen(m_str);
+        if (cur_len == 0) {
+            R_RETURN(this->Initialize(child));
+        }
+
+        /* Remove a trailing separator. */
+        if (m_str[cur_len - 1] == '/' || m_str[cur_len - 1] == '\\') {
+            --cur_len;
+        }
+
+        /* Get the child path's length. */
+        auto child_len = std::strlen(c);
+
+        /* Reset our write buffer. */
+        WriteBuffer old_write_buffer;
+        if (m_write_buffer.Get() != nullptr) {
+            old_write_buffer = std::move(m_write_buffer);
+            this->ClearBuffer();
+        }
+
+        /* Pre-allocate the new buffer. */
+        R_TRY(this->Preallocate(cur_len + 1 + child_len + 1));
+
+        /* Get our write buffer. */
+        auto* dst = m_write_buffer.Get();
+        if (old_write_buffer.Get() != nullptr && cur_len > 0) {
+            Strlcpy<char>(dst, old_write_buffer.Get(), cur_len + 1);
+        }
+
+        /* Add separator. */
+        dst[cur_len] = '/';
+
+        /* Copy the child path. */
+        const size_t copied = Strlcpy<char>(dst + cur_len + 1, c, child_len + 1);
+        R_UNLESS(copied == child_len, ResultUnexpectedInPathA);
+
+        R_SUCCEED();
+    }
+
+    Result AppendChild(const Path& rhs) {
+        R_RETURN(this->AppendChild(rhs.GetString()));
+    }
+
+    Result Combine(const Path& parent, const Path& child) {
+        /* Get the lengths. */
+        const auto p_len = parent.GetLength();
+        const auto c_len = child.GetLength();
+
+        /* Allocate our buffer. */
+        R_TRY(this->Preallocate(p_len + c_len + 1));
+
+        /* Initialize as parent. */
+        R_TRY(this->Initialize(parent));
+
+        /* If we're empty, we can just initialize as child. */
+        if (this->IsEmpty()) {
+            R_TRY(this->Initialize(child));
+        } else {
+            /* Otherwise, we should append the child. */
+            R_TRY(this->AppendChild(child));
+        }
+
+        R_SUCCEED();
+    }
+
+    Result RemoveChild() {
+        /* If we don't have a write-buffer, ensure that we have one. */
+        if (m_write_buffer.Get() == nullptr) {
+            if (const auto len = std::strlen(m_str); len > 0) {
+                R_TRY(this->Preallocate(len));
+                Strlcpy<char>(m_write_buffer.Get(), m_str, len + 1);
+            }
+        }
+
+        /* Check that it's possible for us to remove a child. */
+        auto* p = m_write_buffer.Get();
+        s32 len = std::strlen(p);
+        R_UNLESS(len != 1 || (p[0] != '/' && p[0] != '.'), ResultNotImplemented);
+
+        /* Handle a trailing separator. */
+        if (len > 0 && (p[len - 1] == '\\' || p[len - 1] == '/')) {
+            --len;
+        }
+
+        /* Remove the child path segment. */
+        while ((--len) >= 0 && p[len]) {
+            if (p[len] == '/' || p[len] == '\\') {
+                if (len > 0) {
+                    p[len] = 0;
+                } else {
+                    p[1] = 0;
+                    len = 1;
+                }
+                break;
+            }
+        }
+
+        /* Check that length remains > 0. */
+        R_UNLESS(len > 0, ResultNotImplemented);
+
+        R_SUCCEED();
+    }
+
+    Result Normalize(const PathFlags& flags) {
+        /* If we're already normalized, nothing to do. */
+        R_SUCCEED_IF(this->IsNormalized());
+
+        /* Check if we're normalized. */
+        bool normalized;
+        size_t dummy;
+        R_TRY(PathFormatter::IsNormalized(std::addressof(normalized), std::addressof(dummy), m_str,
+                                          flags));
+
+        /* If we're not normalized, normalize. */
+        if (!normalized) {
+            /* Determine necessary buffer length. */
+            auto len = m_write_buffer.GetLength();
+            if (flags.IsRelativePathAllowed() && IsPathRelative(m_str)) {
+                len += 2;
+            }
+            if (flags.IsWindowsPathAllowed() && IsWindowsPath(m_str, true)) {
+                len += 1;
+            }
+
+            /* Allocate a new buffer. */
+            const size_t size = Common::AlignUp(len, WriteBufferAlignmentLength);
+            auto buf = WriteBuffer::Make(size);
+            R_UNLESS(buf.Get() != nullptr, ResultAllocationMemoryFailedMakeUnique);
+
+            /* Normalize into it. */
+            R_TRY(PathFormatter::Normalize(buf.Get(), size, m_write_buffer.Get(),
+                                           m_write_buffer.GetLength(), flags));
+
+            /* Set the normalized buffer as our buffer. */
+            this->SetModifiableBuffer(std::move(buf));
+        }
+
+        /* Set normalized. */
+        this->SetNormalized();
+        R_SUCCEED();
+    }
+
+private:
+    void ClearBuffer() {
+        m_write_buffer.ResetBuffer();
+        m_str = EmptyPath;
+    }
+
+    void SetModifiableBuffer(WriteBuffer&& buffer) {
+        /* Check pre-conditions. */
+        ASSERT(buffer.Get() != nullptr);
+        ASSERT(buffer.GetLength() > 0);
+        ASSERT(Common::IsAligned(buffer.GetLength(), WriteBufferAlignmentLength));
+
+        /* Get whether we're normalized. */
+        if (m_write_buffer.IsNormalized()) {
+            buffer.SetNormalized();
+        } else {
+            buffer.SetNotNormalized();
+        }
+
+        /* Set write buffer. */
+        m_write_buffer = std::move(buffer);
+        m_str = m_write_buffer.Get();
+    }
+
+    constexpr void SetReadOnlyBuffer(const char* buffer) {
+        m_str = buffer;
+        m_write_buffer.ResetBuffer();
+    }
+
+    Result Preallocate(size_t length) {
+        /* Allocate additional space, if needed. */
+        if (length > m_write_buffer.GetLength()) {
+            /* Allocate buffer. */
+            const size_t size = Common::AlignUp(length, WriteBufferAlignmentLength);
+            auto buf = WriteBuffer::Make(size);
+            R_UNLESS(buf.Get() != nullptr, ResultAllocationMemoryFailedMakeUnique);
+
+            /* Set write buffer. */
+            this->SetModifiableBuffer(std::move(buf));
+        }
+
+        R_SUCCEED();
+    }
+
+    Result InitializeImpl(const char* path, size_t size) {
+        if (size > 0 && path[0]) {
+            /* Pre allocate a buffer for the path. */
+            R_TRY(this->Preallocate(size + 1));
+
+            /* Copy the path. */
+            const size_t copied = Strlcpy<char>(m_write_buffer.Get(), path, size + 1);
+            R_UNLESS(copied >= size, ResultUnexpectedInPathA);
+        } else {
+            /* We can just clear the buffer. */
+            this->ClearBuffer();
+        }
+
+        R_SUCCEED();
+    }
+
+    constexpr char* GetWriteBuffer() {
+        ASSERT(m_write_buffer.Get() != nullptr);
+        return m_write_buffer.Get();
+    }
+
+    constexpr size_t GetWriteBufferLength() const {
+        return m_write_buffer.GetLength();
+    }
+
+    constexpr bool IsNormalized() const {
+        return m_write_buffer.IsNormalized();
+    }
+
+    constexpr void SetNormalized() {
+        m_write_buffer.SetNormalized();
+    }
+
+    constexpr void SetNotNormalized() {
+        m_write_buffer.SetNotNormalized();
+    }
+
+public:
+    bool operator==(const FileSys::Path& rhs) const {
+        return std::strcmp(this->GetString(), rhs.GetString()) == 0;
+    }
+    bool operator!=(const FileSys::Path& rhs) const {
+        return !(*this == rhs);
+    }
+    bool operator==(const char* p) const {
+        return std::strcmp(this->GetString(), p) == 0;
+    }
+    bool operator!=(const char* p) const {
+        return !(*this == p);
+    }
+};
+
+inline Result SetUpFixedPath(FileSys::Path* out, const char* s) {
+    /* Verify the path is normalized. */
+    bool normalized;
+    size_t dummy;
+    R_TRY(PathNormalizer::IsNormalized(std::addressof(normalized), std::addressof(dummy), s));
+
+    R_UNLESS(normalized, ResultInvalidPathFormat);
+
+    /* Set the fixed path. */
+    R_RETURN(out->SetShallowBuffer(s));
+}
+
+constexpr inline bool IsWindowsDriveRootPath(const FileSys::Path& path) {
+    const char* const str = path.GetString();
+    return IsWindowsDrive(str) &&
+           (str[2] == StringTraits::DirectorySeparator ||
+            str[2] == StringTraits::AlternateDirectorySeparator) &&
+           str[3] == StringTraits::NullTerminator;
+}
+
+} // namespace FileSys

src/core/file_sys/fs_string_util.h

@@ -0,0 +1,241 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "common/assert.h"
+
+namespace FileSys {
+
+template <typename T>
+constexpr int Strlen(const T* str) {
+    ASSERT(str != nullptr);
+
+    int length = 0;
+    while (*str++) {
+        ++length;
+    }
+
+    return length;
+}
+
+template <typename T>
+constexpr int Strnlen(const T* str, int count) {
+    ASSERT(str != nullptr);
+    ASSERT(count >= 0);
+
+    int length = 0;
+    while (count-- && *str++) {
+        ++length;
+    }
+
+    return length;
+}
+
+template <typename T>
+constexpr int Strncmp(const T* lhs, const T* rhs, int count) {
+    ASSERT(lhs != nullptr);
+    ASSERT(rhs != nullptr);
+    ASSERT(count >= 0);
+
+    if (count == 0) {
+        return 0;
+    }
+
+    T l, r;
+    do {
+        l = *(lhs++);
+        r = *(rhs++);
+    } while (l && (l == r) && (--count));
+
+    return l - r;
+}
+
+template <typename T>
+static constexpr int Strlcpy(T* dst, const T* src, int count) {
+    ASSERT(dst != nullptr);
+    ASSERT(src != nullptr);
+
+    const T* cur = src;
+    if (count > 0) {
+        while ((--count) && *cur) {
+            *(dst++) = *(cur++);
+        }
+        *dst = 0;
+    }
+
+    while (*cur) {
+        cur++;
+    }
+
+    return static_cast<int>(cur - src);
+}
+
+/* std::size() does not support zero-size C arrays. We're fixing that. */
+template <class C>
+constexpr auto size(const C& c) -> decltype(c.size()) {
+    return std::size(c);
+}
+
+template <class C>
+constexpr std::size_t size(const C& c) {
+    if constexpr (sizeof(C) == 0) {
+        return 0;
+    } else {
+        return std::size(c);
+    }
+}
+
+enum CharacterEncodingResult {
+    CharacterEncodingResult_Success = 0,
+    CharacterEncodingResult_InsufficientLength = 1,
+    CharacterEncodingResult_InvalidFormat = 2,
+};
+
+namespace impl {
+
+class CharacterEncodingHelper {
+public:
+    static constexpr int8_t Utf8NBytesInnerTable[0x100 + 1] = {
+        -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+        1,  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+        1,  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+        1,  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+        1,  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+        2,  2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3,
+        3,  3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8,
+    };
+
+    static constexpr char GetUtf8NBytes(size_t i) {
+        return static_cast<char>(Utf8NBytesInnerTable[1 + i]);
+    }
+};
+
+} // namespace impl
+
+constexpr inline CharacterEncodingResult ConvertCharacterUtf8ToUtf32(u32* dst, const char* src) {
+    /* Check pre-conditions. */
+    ASSERT(dst != nullptr);
+    ASSERT(src != nullptr);
+
+    /* Perform the conversion. */
+    const auto* p = src;
+    switch (impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[0]))) {
+    case 1:
+        *dst = static_cast<u32>(p[0]);
+        return CharacterEncodingResult_Success;
+    case 2:
+        if ((static_cast<u32>(p[0]) & 0x1E) != 0) {
+            if (impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[1])) ==
+                0) {
+                *dst = (static_cast<u32>(p[0] & 0x1F) << 6) | (static_cast<u32>(p[1] & 0x3F) << 0);
+                return CharacterEncodingResult_Success;
+            }
+        }
+        break;
+    case 3:
+        if (impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[1])) == 0 &&
+            impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[2])) == 0) {
+            const u32 c = (static_cast<u32>(p[0] & 0xF) << 12) |
+                          (static_cast<u32>(p[1] & 0x3F) << 6) |
+                          (static_cast<u32>(p[2] & 0x3F) << 0);
+            if ((c & 0xF800) != 0 && (c & 0xF800) != 0xD800) {
+                *dst = c;
+                return CharacterEncodingResult_Success;
+            }
+        }
+        return CharacterEncodingResult_InvalidFormat;
+    case 4:
+        if (impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[1])) == 0 &&
+            impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[2])) == 0 &&
+            impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[3])) == 0) {
+            const u32 c =
+                (static_cast<u32>(p[0] & 0x7) << 18) | (static_cast<u32>(p[1] & 0x3F) << 12) |
+                (static_cast<u32>(p[2] & 0x3F) << 6) | (static_cast<u32>(p[3] & 0x3F) << 0);
+            if (c >= 0x10000 && c < 0x110000) {
+                *dst = c;
+                return CharacterEncodingResult_Success;
+            }
+        }
+        return CharacterEncodingResult_InvalidFormat;
+    default:
+        break;
+    }
+
+    /* We failed to convert. */
+    return CharacterEncodingResult_InvalidFormat;
+}
+
+constexpr inline CharacterEncodingResult PickOutCharacterFromUtf8String(char* dst,
+                                                                        const char** str) {
+    /* Check pre-conditions. */
+    ASSERT(dst != nullptr);
+    ASSERT(str != nullptr);
+    ASSERT(*str != nullptr);
+
+    /* Clear the output. */
+    dst[0] = 0;
+    dst[1] = 0;
+    dst[2] = 0;
+    dst[3] = 0;
+
+    /* Perform the conversion. */
+    const auto* p = *str;
+    u32 c = static_cast<u32>(*p);
+    switch (impl::CharacterEncodingHelper::GetUtf8NBytes(c)) {
+    case 1:
+        dst[0] = (*str)[0];
+        ++(*str);
+        break;
+    case 2:
+        if ((p[0] & 0x1E) != 0) {
+            if (impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[1])) ==
+                0) {
+                c = (static_cast<u32>(p[0] & 0x1F) << 6) | (static_cast<u32>(p[1] & 0x3F) << 0);
+                dst[0] = (*str)[0];
+                dst[1] = (*str)[1];
+                (*str) += 2;
+                break;
+            }
+        }
+        return CharacterEncodingResult_InvalidFormat;
+    case 3:
+        if (impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[1])) == 0 &&
+            impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[2])) == 0) {
+            c = (static_cast<u32>(p[0] & 0xF) << 12) | (static_cast<u32>(p[1] & 0x3F) << 6) |
+                (static_cast<u32>(p[2] & 0x3F) << 0);
+            if ((c & 0xF800) != 0 && (c & 0xF800) != 0xD800) {
+                dst[0] = (*str)[0];
+                dst[1] = (*str)[1];
+                dst[2] = (*str)[2];
+                (*str) += 3;
+                break;
+            }
+        }
+        return CharacterEncodingResult_InvalidFormat;
+    case 4:
+        if (impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[1])) == 0 &&
+            impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[2])) == 0 &&
+            impl::CharacterEncodingHelper::GetUtf8NBytes(static_cast<unsigned char>(p[3])) == 0) {
+            c = (static_cast<u32>(p[0] & 0x7) << 18) | (static_cast<u32>(p[1] & 0x3F) << 12) |
+                (static_cast<u32>(p[2] & 0x3F) << 6) | (static_cast<u32>(p[3] & 0x3F) << 0);
+            if (c >= 0x10000 && c < 0x110000) {
+                dst[0] = (*str)[0];
+                dst[1] = (*str)[1];
+                dst[2] = (*str)[2];
+                dst[3] = (*str)[3];
+                (*str) += 4;
+                break;
+            }
+        }
+        return CharacterEncodingResult_InvalidFormat;
+    default:
+        return CharacterEncodingResult_InvalidFormat;
+    }
+
+    return CharacterEncodingResult_Success;
+}
+
+} // namespace FileSys

src/core/hle/service/filesystem/fsp/fs_i_directory.cpp

@@ -1,6 +1,7 @@
 // SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include "core/file_sys/fs_filesystem.h"
 #include "core/file_sys/savedata_factory.h"
 #include "core/hle/service/filesystem/fsp/fs_i_directory.h"
 #include "core/hle/service/ipc_helpers.h"

src/core/hle/service/filesystem/fsp/fs_i_directory.h

@@ -3,12 +3,14 @@
 
 #pragma once
 
-#include "core/file_sys/fs_filesystem.h"
 #include "core/file_sys/vfs/vfs.h"
 #include "core/hle/service/filesystem/filesystem.h"
-#include "core/hle/service/filesystem/fsp/fsp_util.h"
 #include "core/hle/service/service.h"
 
+namespace FileSys {
+struct DirectoryEntry;
+}
+
 namespace Service::FileSystem {
 
 class IDirectory final : public ServiceFramework<IDirectory> {