From b3c2ec362bbbdd89da9c0aa84b425717f5e3d351 Mon Sep 17 00:00:00 2001
From: Zach Hilman <zachhilman@gmail.com>
Date: Sun, 23 Sep 2018 21:50:16 -0400
Subject: fsmitm: Cleanup and modernize fsmitm port

---
 src/core/CMakeLists.txt                 |   2 +-
 src/core/file_sys/bis_factory.cpp       |   2 +-
 src/core/file_sys/bis_factory.h         |   2 +-
 src/core/file_sys/fsmitm_romfsbuild.cpp | 358 ++++++++++++++++----------------
 src/core/file_sys/fsmitm_romfsbuild.h   |  70 +++++++
 src/core/file_sys/fsmitm_romfsbuild.hpp | 106 ----------
 src/core/file_sys/patch_manager.cpp     |  66 +++---
 src/core/file_sys/registered_cache.cpp  |   9 +-
 src/core/file_sys/romfs.cpp             |   9 +-
 src/core/file_sys/romfs.h               |   8 +-
 src/core/file_sys/vfs.cpp               |   4 +-
 src/core/file_sys/vfs.h                 |   5 +-
 src/core/file_sys/vfs_concat.cpp        |  21 +-
 src/core/file_sys/vfs_concat.h          |  58 +++---
 src/core/file_sys/vfs_layered.cpp       |  15 +-
 src/core/file_sys/vfs_layered.h         |   2 +
 src/core/file_sys/vfs_real.cpp          |   4 +-
 src/core/file_sys/vfs_real.h            |   2 +-
 src/core/file_sys/vfs_static.h          |   3 +-
 src/core/file_sys/vfs_vector.cpp        |   7 +-
 src/core/file_sys/vfs_vector.h          |   1 +
 21 files changed, 377 insertions(+), 377 deletions(-)
 create mode 100644 src/core/file_sys/fsmitm_romfsbuild.h
 delete mode 100644 src/core/file_sys/fsmitm_romfsbuild.hpp

(limited to 'src/core')

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index ead86fd85..23fd6e920 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -33,7 +33,7 @@ add_library(core STATIC
     file_sys/directory.h
     file_sys/errors.h
     file_sys/fsmitm_romfsbuild.cpp
-    file_sys/fsmitm_romfsbuild.hpp
+    file_sys/fsmitm_romfsbuild.h
     file_sys/mode.h
     file_sys/nca_metadata.cpp
     file_sys/nca_metadata.h
diff --git a/src/core/file_sys/bis_factory.cpp b/src/core/file_sys/bis_factory.cpp
index 012e08e7d..6102ef476 100644
--- a/src/core/file_sys/bis_factory.cpp
+++ b/src/core/file_sys/bis_factory.cpp
@@ -2,9 +2,9 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <fmt/format.h>
 #include "core/file_sys/bis_factory.h"
 #include "core/file_sys/registered_cache.h"
-#include "fmt/format.h"
 
 namespace FileSys {
 
diff --git a/src/core/file_sys/bis_factory.h b/src/core/file_sys/bis_factory.h
index 0d81967cc..c352e0925 100644
--- a/src/core/file_sys/bis_factory.h
+++ b/src/core/file_sys/bis_factory.h
@@ -17,7 +17,7 @@ class RegisteredCache;
 /// registered caches.
 class BISFactory {
 public:
-    BISFactory(VirtualDir nand_root, VirtualDir load_root);
+    explicit BISFactory(VirtualDir nand_root, VirtualDir load_root);
     ~BISFactory();
 
     std::shared_ptr<RegisteredCache> GetSystemNANDContents() const;
diff --git a/src/core/file_sys/fsmitm_romfsbuild.cpp b/src/core/file_sys/fsmitm_romfsbuild.cpp
index a6fe6719d..21fc3d796 100644
--- a/src/core/file_sys/fsmitm_romfsbuild.cpp
+++ b/src/core/file_sys/fsmitm_romfsbuild.cpp
@@ -24,9 +24,9 @@
 
 #include <cstring>
 #include "common/assert.h"
-#include "fsmitm_romfsbuild.hpp"
-#include "vfs.h"
-#include "vfs_vector.h"
+#include "core/file_sys/fsmitm_romfsbuild.h"
+#include "core/file_sys/vfs.h"
+#include "core/file_sys/vfs_vector.h"
 
 namespace FileSys {
 
@@ -35,7 +35,7 @@ constexpr u64 FS_MAX_PATH = 0x301;
 constexpr u32 ROMFS_ENTRY_EMPTY = 0xFFFFFFFF;
 constexpr u32 ROMFS_FILEPARTITION_OFS = 0x200;
 
-/* Types for building a RomFS. */
+// Types for building a RomFS.
 struct RomFSHeader {
     u64 header_size;
     u64 dir_hash_table_ofs;
@@ -57,7 +57,6 @@ struct RomFSDirectoryEntry {
     u32 file;
     u32 hash;
     u32 name_size;
-    char name[];
 };
 static_assert(sizeof(RomFSDirectoryEntry) == 0x18, "RomFSDirectoryEntry has incorrect size.");
 
@@ -68,37 +67,63 @@ struct RomFSFileEntry {
     u64 size;
     u32 hash;
     u32 name_size;
-    char name[];
 };
 static_assert(sizeof(RomFSFileEntry) == 0x20, "RomFSFileEntry has incorrect size.");
 
 struct RomFSBuildFileContext;
 
 struct RomFSBuildDirectoryContext {
-    char* path;
-    u32 cur_path_ofs;
-    u32 path_len;
+    std::string path = "";
+    u32 cur_path_ofs = 0;
+    u32 path_len = 0;
     u32 entry_offset = 0;
-    RomFSBuildDirectoryContext* parent = nullptr;
-    RomFSBuildDirectoryContext* child = nullptr;
-    RomFSBuildDirectoryContext* sibling = nullptr;
-    RomFSBuildFileContext* file = nullptr;
+    std::shared_ptr<RomFSBuildDirectoryContext> parent;
+    std::shared_ptr<RomFSBuildDirectoryContext> child;
+    std::shared_ptr<RomFSBuildDirectoryContext> sibling;
+    std::shared_ptr<RomFSBuildFileContext> file;
 };
 
 struct RomFSBuildFileContext {
-    char* path;
-    u32 cur_path_ofs;
-    u32 path_len;
+    std::string path = "";
+    u32 cur_path_ofs = 0;
+    u32 path_len = 0;
     u32 entry_offset = 0;
     u64 offset = 0;
     u64 size = 0;
-    RomFSBuildDirectoryContext* parent = nullptr;
-    RomFSBuildFileContext* sibling = nullptr;
+    std::shared_ptr<RomFSBuildDirectoryContext> parent;
+    std::shared_ptr<RomFSBuildFileContext> sibling;
     VirtualFile source = nullptr;
+
+    RomFSBuildFileContext() : path(""), cur_path_ofs(0), path_len(0) {}
 };
 
-void RomFSBuildContext::VisitDirectory(VirtualDir root_romfs, RomFSBuildDirectoryContext* parent) {
-    std::vector<RomFSBuildDirectoryContext*> child_dirs;
+static u32 romfs_calc_path_hash(u32 parent, std::string path, u32 start, size_t path_len) {
+    u32 hash = parent ^ 123456789;
+    for (u32 i = 0; i < path_len; i++) {
+        hash = (hash >> 5) | (hash << 27);
+        hash ^= path[start + i];
+    }
+
+    return hash;
+}
+
+static u32 romfs_get_hash_table_count(u32 num_entries) {
+    if (num_entries < 3) {
+        return 3;
+    } else if (num_entries < 19) {
+        return num_entries | 1;
+    }
+    u32 count = num_entries;
+    while (count % 2 == 0 || count % 3 == 0 || count % 5 == 0 || count % 7 == 0 ||
+           count % 11 == 0 || count % 13 == 0 || count % 17 == 0) {
+        count++;
+    }
+    return count;
+}
+
+void RomFSBuildContext::VisitDirectory(VirtualDir root_romfs,
+                                       std::shared_ptr<RomFSBuildDirectoryContext> parent) {
+    std::vector<std::shared_ptr<RomFSBuildDirectoryContext>> child_dirs;
 
     VirtualDir dir;
 
@@ -111,41 +136,33 @@ void RomFSBuildContext::VisitDirectory(VirtualDir root_romfs, RomFSBuildDirector
 
     for (const auto& kv : entries) {
         if (kv.second == VfsEntryType::Directory) {
-            RomFSBuildDirectoryContext* child = new RomFSBuildDirectoryContext({0});
-            /* Set child's path. */
+            const auto child = std::make_shared<RomFSBuildDirectoryContext>();
+            // Set child's path.
             child->cur_path_ofs = parent->path_len + 1;
             child->path_len = child->cur_path_ofs + kv.first.size();
-            child->path = new char[child->path_len + 1];
-            strcpy(child->path, parent->path);
+            child->path = parent->path + "/" + kv.first;
+
+            // Sanity check on path_len
             ASSERT(child->path_len < FS_MAX_PATH);
-            strcat(child->path + parent->path_len, "/");
-            strcat(child->path + parent->path_len, kv.first.c_str());
 
-            if (!this->AddDirectory(parent, child, nullptr)) {
-                delete child->path;
-                delete child;
-            } else {
+            if (AddDirectory(parent, child)) {
                 child_dirs.push_back(child);
             }
         } else {
-            RomFSBuildFileContext* child = new RomFSBuildFileContext({0});
-            /* Set child's path. */
+            const auto child = std::make_shared<RomFSBuildFileContext>();
+            // Set child's path.
             child->cur_path_ofs = parent->path_len + 1;
             child->path_len = child->cur_path_ofs + kv.first.size();
-            child->path = new char[child->path_len + 1];
-            strcpy(child->path, parent->path);
+            child->path = parent->path + "/" + kv.first;
+
+            // Sanity check on path_len
             ASSERT(child->path_len < FS_MAX_PATH);
-            strcat(child->path + parent->path_len, "/");
-            strcat(child->path + parent->path_len, kv.first.c_str());
 
             child->source = root_romfs->GetFileRelative(child->path);
 
             child->size = child->source->GetSize();
 
-            if (!this->AddFile(parent, child)) {
-                delete child->path;
-                delete child;
-            }
+            AddFile(parent, child);
         }
     }
 
@@ -154,213 +171,200 @@ void RomFSBuildContext::VisitDirectory(VirtualDir root_romfs, RomFSBuildDirector
     }
 }
 
-bool RomFSBuildContext::AddDirectory(RomFSBuildDirectoryContext* parent_dir_ctx,
-                                     RomFSBuildDirectoryContext* dir_ctx,
-                                     RomFSBuildDirectoryContext** out_dir_ctx) {
-    /* Check whether it's already in the known directories. */
-    auto existing = this->directories.find(dir_ctx->path);
-    if (existing != this->directories.end()) {
-        if (out_dir_ctx) {
-            *out_dir_ctx = existing->second;
-        }
+bool RomFSBuildContext::AddDirectory(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                                     std::shared_ptr<RomFSBuildDirectoryContext> dir_ctx) {
+    // Check whether it's already in the known directories.
+    const auto existing = directories.find(dir_ctx->path);
+    if (existing != directories.end())
         return false;
-    }
 
-    /* Add a new directory. */
-    this->num_dirs++;
-    this->dir_table_size +=
+    // Add a new directory.
+    num_dirs++;
+    dir_table_size +=
         sizeof(RomFSDirectoryEntry) + ((dir_ctx->path_len - dir_ctx->cur_path_ofs + 3) & ~3);
     dir_ctx->parent = parent_dir_ctx;
-    this->directories.insert({dir_ctx->path, dir_ctx});
+    directories.emplace(dir_ctx->path, dir_ctx);
 
-    if (out_dir_ctx) {
-        *out_dir_ctx = dir_ctx;
-    }
     return true;
 }
 
-bool RomFSBuildContext::AddFile(RomFSBuildDirectoryContext* parent_dir_ctx,
-                                RomFSBuildFileContext* file_ctx) {
-    /* Check whether it's already in the known files. */
-    auto existing = this->files.find(file_ctx->path);
-    if (existing != this->files.end()) {
+bool RomFSBuildContext::AddFile(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                                std::shared_ptr<RomFSBuildFileContext> file_ctx) {
+    // Check whether it's already in the known files.
+    const auto existing = files.find(file_ctx->path);
+    if (existing != files.end()) {
         return false;
     }
 
-    /* Add a new file. */
-    this->num_files++;
-    this->file_table_size +=
+    // Add a new file.
+    num_files++;
+    file_table_size +=
         sizeof(RomFSFileEntry) + ((file_ctx->path_len - file_ctx->cur_path_ofs + 3) & ~3);
     file_ctx->parent = parent_dir_ctx;
-    this->files.insert({file_ctx->path, file_ctx});
+    files.emplace(file_ctx->path, file_ctx);
 
     return true;
 }
 
 RomFSBuildContext::RomFSBuildContext(VirtualDir base_) : base(std::move(base_)) {
-    this->root = new RomFSBuildDirectoryContext({0});
-    this->root->path = new char[1];
-    this->root->path[0] = '\x00';
-    this->directories.insert({this->root->path, this->root});
-    this->num_dirs = 1;
-    this->dir_table_size = 0x18;
-
-    VisitDirectory(base, this->root);
+    root = std::make_shared<RomFSBuildDirectoryContext>();
+    root->path = "\0";
+    directories.emplace(root->path, root);
+    num_dirs = 1;
+    dir_table_size = 0x18;
+
+    VisitDirectory(base, root);
 }
 
+RomFSBuildContext::~RomFSBuildContext() = default;
+
 std::map<u64, VirtualFile> RomFSBuildContext::Build() {
-    std::map<u64, VirtualFile> out;
-    RomFSBuildFileContext* cur_file;
-    RomFSBuildDirectoryContext* cur_dir;
-
-    const auto dir_hash_table_entry_count = romfs_get_hash_table_count(this->num_dirs);
-    const auto file_hash_table_entry_count = romfs_get_hash_table_count(this->num_files);
-    this->dir_hash_table_size = 4 * dir_hash_table_entry_count;
-    this->file_hash_table_size = 4 * file_hash_table_entry_count;
-
-    /* Assign metadata pointers */
-    RomFSHeader* header = new RomFSHeader({0});
-    auto metadata = new u8[this->dir_hash_table_size + this->dir_table_size +
-                           this->file_hash_table_size + this->file_table_size];
-    auto dir_hash_table = reinterpret_cast<u32*>(metadata);
-    const auto dir_table = reinterpret_cast<RomFSDirectoryEntry*>(
-        reinterpret_cast<uintptr_t>(dir_hash_table) + this->dir_hash_table_size);
-    auto file_hash_table =
-        reinterpret_cast<u32*>(reinterpret_cast<uintptr_t>(dir_table) + this->dir_table_size);
-    const auto file_table = reinterpret_cast<RomFSFileEntry*>(
-        reinterpret_cast<uintptr_t>(file_hash_table) + this->file_hash_table_size);
-
-    /* Clear out hash tables. */
+    const auto dir_hash_table_entry_count = romfs_get_hash_table_count(num_dirs);
+    const auto file_hash_table_entry_count = romfs_get_hash_table_count(num_files);
+    dir_hash_table_size = 4 * dir_hash_table_entry_count;
+    file_hash_table_size = 4 * file_hash_table_entry_count;
+
+    // Assign metadata pointers
+    RomFSHeader header{};
+
+    std::vector<u32> dir_hash_table(dir_hash_table_entry_count, ROMFS_ENTRY_EMPTY);
+    std::vector<u32> file_hash_table(file_hash_table_entry_count, ROMFS_ENTRY_EMPTY);
+
+    std::vector<u8> dir_table(dir_table_size);
+    std::vector<u8> file_table(file_table_size);
+
+    // Clear out hash tables.
     for (u32 i = 0; i < dir_hash_table_entry_count; i++)
         dir_hash_table[i] = ROMFS_ENTRY_EMPTY;
     for (u32 i = 0; i < file_hash_table_entry_count; i++)
         file_hash_table[i] = ROMFS_ENTRY_EMPTY;
 
-    out.clear();
+    std::shared_ptr<RomFSBuildFileContext> cur_file;
 
-    /* Determine file offsets. */
+    // Determine file offsets.
     u32 entry_offset = 0;
-    RomFSBuildFileContext* prev_file = nullptr;
-    for (const auto& it : this->files) {
+    std::shared_ptr<RomFSBuildFileContext> prev_file = nullptr;
+    for (const auto& it : files) {
         cur_file = it.second;
-        this->file_partition_size = (this->file_partition_size + 0xFULL) & ~0xFULL;
-        cur_file->offset = this->file_partition_size;
-        this->file_partition_size += cur_file->size;
+        file_partition_size = (file_partition_size + 0xFULL) & ~0xFULL;
+        cur_file->offset = file_partition_size;
+        file_partition_size += cur_file->size;
         cur_file->entry_offset = entry_offset;
         entry_offset +=
             sizeof(RomFSFileEntry) + ((cur_file->path_len - cur_file->cur_path_ofs + 3) & ~3);
         prev_file = cur_file;
     }
-    /* Assign deferred parent/sibling ownership. */
-    for (auto it = this->files.rbegin(); it != this->files.rend(); it++) {
+    // Assign deferred parent/sibling ownership.
+    for (auto it = files.rbegin(); it != files.rend(); ++it) {
         cur_file = it->second;
         cur_file->sibling = cur_file->parent->file;
         cur_file->parent->file = cur_file;
     }
 
-    /* Determine directory offsets. */
+    std::shared_ptr<RomFSBuildDirectoryContext> cur_dir;
+
+    // Determine directory offsets.
     entry_offset = 0;
-    for (const auto& it : this->directories) {
+    for (const auto& it : directories) {
         cur_dir = it.second;
         cur_dir->entry_offset = entry_offset;
         entry_offset +=
             sizeof(RomFSDirectoryEntry) + ((cur_dir->path_len - cur_dir->cur_path_ofs + 3) & ~3);
     }
-    /* Assign deferred parent/sibling ownership. */
-    for (auto it = this->directories.rbegin(); it->second != this->root; it++) {
+    // Assign deferred parent/sibling ownership.
+    for (auto it = directories.rbegin(); it->second != root; ++it) {
         cur_dir = it->second;
         cur_dir->sibling = cur_dir->parent->child;
         cur_dir->parent->child = cur_dir;
     }
 
-    /* Populate file tables. */
-    for (const auto& it : this->files) {
+    std::map<u64, VirtualFile> out;
+
+    // Populate file tables.
+    for (const auto& it : files) {
         cur_file = it.second;
-        RomFSFileEntry* cur_entry = romfs_get_fentry(file_table, cur_file->entry_offset);
+        RomFSFileEntry cur_entry{};
 
-        cur_entry->parent = cur_file->parent->entry_offset;
-        cur_entry->sibling =
-            (cur_file->sibling == nullptr) ? ROMFS_ENTRY_EMPTY : cur_file->sibling->entry_offset;
-        cur_entry->offset = cur_file->offset;
-        cur_entry->size = cur_file->size;
+        cur_entry.parent = cur_file->parent->entry_offset;
+        cur_entry.sibling =
+            cur_file->sibling == nullptr ? ROMFS_ENTRY_EMPTY : cur_file->sibling->entry_offset;
+        cur_entry.offset = cur_file->offset;
+        cur_entry.size = cur_file->size;
 
         const auto name_size = cur_file->path_len - cur_file->cur_path_ofs;
-        const auto hash = romfs_calc_path_hash(cur_file->parent->entry_offset,
-                                               reinterpret_cast<unsigned char*>(cur_file->path) +
-                                                   cur_file->cur_path_ofs,
-                                               0, name_size);
-        cur_entry->hash = file_hash_table[hash % file_hash_table_entry_count];
+        const auto hash = romfs_calc_path_hash(cur_file->parent->entry_offset, cur_file->path,
+                                               cur_file->cur_path_ofs, name_size);
+        cur_entry.hash = file_hash_table[hash % file_hash_table_entry_count];
         file_hash_table[hash % file_hash_table_entry_count] = cur_file->entry_offset;
 
-        cur_entry->name_size = name_size;
-        memset(cur_entry->name, 0, (cur_entry->name_size + 3) & ~3);
-        memcpy(cur_entry->name, cur_file->path + cur_file->cur_path_ofs, name_size);
+        cur_entry.name_size = name_size;
 
         out.emplace(cur_file->offset + ROMFS_FILEPARTITION_OFS, cur_file->source);
+        std::memcpy(file_table.data() + cur_file->entry_offset, &cur_entry, sizeof(RomFSFileEntry));
+        std::memset(file_table.data() + cur_file->entry_offset + sizeof(RomFSFileEntry), 0,
+                    (cur_entry.name_size + 3) & ~3);
+        std::memcpy(file_table.data() + cur_file->entry_offset + sizeof(RomFSFileEntry),
+                    cur_file->path.data() + cur_file->cur_path_ofs, name_size);
     }
 
-    /* Populate dir tables. */
-    for (const auto& it : this->directories) {
+    // Populate dir tables.
+    for (const auto& it : directories) {
         cur_dir = it.second;
-        RomFSDirectoryEntry* cur_entry = romfs_get_direntry(dir_table, cur_dir->entry_offset);
-        cur_entry->parent = cur_dir == this->root ? 0 : cur_dir->parent->entry_offset;
-        cur_entry->sibling =
-            (cur_dir->sibling == nullptr) ? ROMFS_ENTRY_EMPTY : cur_dir->sibling->entry_offset;
-        cur_entry->child =
-            (cur_dir->child == nullptr) ? ROMFS_ENTRY_EMPTY : cur_dir->child->entry_offset;
-        cur_entry->file =
-            (cur_dir->file == nullptr) ? ROMFS_ENTRY_EMPTY : cur_dir->file->entry_offset;
-
-        u32 name_size = cur_dir->path_len - cur_dir->cur_path_ofs;
-        u32 hash = romfs_calc_path_hash(
-            cur_dir == this->root ? 0 : cur_dir->parent->entry_offset,
-            reinterpret_cast<unsigned char*>(cur_dir->path) + cur_dir->cur_path_ofs, 0, name_size);
-        cur_entry->hash = dir_hash_table[hash % dir_hash_table_entry_count];
+        RomFSDirectoryEntry cur_entry{};
+
+        cur_entry.parent = cur_dir == root ? 0 : cur_dir->parent->entry_offset;
+        cur_entry.sibling =
+            cur_dir->sibling == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->sibling->entry_offset;
+        cur_entry.child =
+            cur_dir->child == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->child->entry_offset;
+        cur_entry.file = cur_dir->file == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->file->entry_offset;
+
+        const auto name_size = cur_dir->path_len - cur_dir->cur_path_ofs;
+        const auto hash = romfs_calc_path_hash(cur_dir == root ? 0 : cur_dir->parent->entry_offset,
+                                               cur_dir->path, cur_dir->cur_path_ofs, name_size);
+        cur_entry.hash = dir_hash_table[hash % dir_hash_table_entry_count];
         dir_hash_table[hash % dir_hash_table_entry_count] = cur_dir->entry_offset;
 
-        cur_entry->name_size = name_size;
-        memset(cur_entry->name, 0, (cur_entry->name_size + 3) & ~3);
-        memcpy(cur_entry->name, cur_dir->path + cur_dir->cur_path_ofs, name_size);
-    }
+        cur_entry.name_size = name_size;
 
-    /* Delete directories. */
-    for (const auto& it : this->directories) {
-        cur_dir = it.second;
-        delete cur_dir->path;
-        delete cur_dir;
+        std::memcpy(dir_table.data() + cur_dir->entry_offset, &cur_entry,
+                    sizeof(RomFSDirectoryEntry));
+        std::memcpy(dir_table.data() + cur_dir->entry_offset, &cur_entry,
+                    sizeof(RomFSDirectoryEntry));
+        std::memset(dir_table.data() + cur_dir->entry_offset + sizeof(RomFSDirectoryEntry), 0,
+                    (cur_entry.name_size + 3) & ~3);
+        std::memcpy(dir_table.data() + cur_dir->entry_offset + sizeof(RomFSDirectoryEntry),
+                    cur_dir->path.data() + cur_dir->cur_path_ofs, name_size);
     }
-    this->root = nullptr;
-    this->directories.clear();
 
-    /* Delete files. */
-    for (const auto& it : this->files) {
-        cur_file = it.second;
-        delete cur_file->path;
-        delete cur_file;
-    }
-    this->files.clear();
-
-    /* Set header fields. */
-    header->header_size = sizeof(*header);
-    header->file_hash_table_size = this->file_hash_table_size;
-    header->file_table_size = this->file_table_size;
-    header->dir_hash_table_size = this->dir_hash_table_size;
-    header->dir_table_size = this->dir_table_size;
-    header->file_partition_ofs = ROMFS_FILEPARTITION_OFS;
-    header->dir_hash_table_ofs =
-        (header->file_partition_ofs + this->file_partition_size + 3ULL) & ~3ULL;
-    header->dir_table_ofs = header->dir_hash_table_ofs + header->dir_hash_table_size;
-    header->file_hash_table_ofs = header->dir_table_ofs + header->dir_table_size;
-    header->file_table_ofs = header->file_hash_table_ofs + header->file_hash_table_size;
+    // Set header fields.
+    header.header_size = sizeof(RomFSHeader);
+    header.file_hash_table_size = file_hash_table_size;
+    header.file_table_size = file_table_size;
+    header.dir_hash_table_size = dir_hash_table_size;
+    header.dir_table_size = dir_table_size;
+    header.file_partition_ofs = ROMFS_FILEPARTITION_OFS;
+    header.dir_hash_table_ofs = (header.file_partition_ofs + file_partition_size + 3ULL) & ~3ULL;
+    header.dir_table_ofs = header.dir_hash_table_ofs + header.dir_hash_table_size;
+    header.file_hash_table_ofs = header.dir_table_ofs + header.dir_table_size;
+    header.file_table_ofs = header.file_hash_table_ofs + header.file_hash_table_size;
 
     std::vector<u8> header_data(sizeof(RomFSHeader));
-    std::memcpy(header_data.data(), header, header_data.size());
+    std::memcpy(header_data.data(), &header, header_data.size());
     out.emplace(0, std::make_shared<VectorVfsFile>(header_data));
 
-    std::vector<u8> meta_out(this->file_hash_table_size + this->file_table_size +
-                             this->dir_hash_table_size + this->dir_table_size);
-    std::memcpy(meta_out.data(), metadata, meta_out.size());
-    out.emplace(header->dir_hash_table_ofs, std::make_shared<VectorVfsFile>(meta_out));
+    std::vector<u8> metadata(file_hash_table_size + file_table_size + dir_hash_table_size +
+                             dir_table_size);
+    auto index = 0;
+    std::memcpy(metadata.data(), dir_hash_table.data(), dir_hash_table.size() * sizeof(u32));
+    index += dir_hash_table.size() * sizeof(u32);
+    std::memcpy(metadata.data() + index, dir_table.data(), dir_table.size());
+    index += dir_table.size();
+    std::memcpy(metadata.data() + index, file_hash_table.data(),
+                file_hash_table.size() * sizeof(u32));
+    index += file_hash_table.size() * sizeof(u32);
+    std::memcpy(metadata.data() + index, file_table.data(), file_table.size());
+    out.emplace(header.dir_hash_table_ofs, std::make_shared<VectorVfsFile>(metadata));
 
     return out;
 }
diff --git a/src/core/file_sys/fsmitm_romfsbuild.h b/src/core/file_sys/fsmitm_romfsbuild.h
new file mode 100644
index 000000000..b0c3c123b
--- /dev/null
+++ b/src/core/file_sys/fsmitm_romfsbuild.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * Adapted by DarkLordZach for use/interaction with yuzu
+ *
+ * Modifications Copyright 2018 yuzu emulator team
+ * Licensed under GPLv2 or any later version
+ * Refer to the license.txt file included.
+ */
+
+#pragma once
+
+#include <map>
+#include <memory>
+#include <string>
+#include <boost/detail/container_fwd.hpp>
+#include "common/common_types.h"
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+struct RomFSBuildDirectoryContext;
+struct RomFSBuildFileContext;
+struct RomFSDirectoryEntry;
+struct RomFSFileEntry;
+
+class RomFSBuildContext {
+public:
+    explicit RomFSBuildContext(VirtualDir base);
+    ~RomFSBuildContext();
+
+    // This finalizes the context.
+    std::map<u64, VirtualFile> Build();
+
+private:
+    VirtualDir base;
+    std::shared_ptr<RomFSBuildDirectoryContext> root;
+    std::map<std::string, std::shared_ptr<RomFSBuildDirectoryContext>, std::less<>> directories;
+    std::map<std::string, std::shared_ptr<RomFSBuildFileContext>, std::less<>> files;
+    u64 num_dirs = 0;
+    u64 num_files = 0;
+    u64 dir_table_size = 0;
+    u64 file_table_size = 0;
+    u64 dir_hash_table_size = 0;
+    u64 file_hash_table_size = 0;
+    u64 file_partition_size = 0;
+
+    void VisitDirectory(VirtualDir filesys, std::shared_ptr<RomFSBuildDirectoryContext> parent);
+
+    bool AddDirectory(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                      std::shared_ptr<RomFSBuildDirectoryContext> dir_ctx);
+    bool AddFile(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                 std::shared_ptr<RomFSBuildFileContext> file_ctx);
+};
+
+} // namespace FileSys
diff --git a/src/core/file_sys/fsmitm_romfsbuild.hpp b/src/core/file_sys/fsmitm_romfsbuild.hpp
deleted file mode 100644
index b897aab21..000000000
--- a/src/core/file_sys/fsmitm_romfsbuild.hpp
+++ /dev/null
@@ -1,106 +0,0 @@
-/*
- * Copyright (c) 2018 Atmosphère-NX
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms and conditions of the GNU General Public License,
- * version 2, as published by the Free Software Foundation.
- *
- * This program is distributed in the hope it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
- * more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-/*
- * Adapted by DarkLordZach for use/interaction with yuzu
- *
- * Modifications Copyright 2018 yuzu emulator team
- * Licensed under GPLv2 or any later version
- * Refer to the license.txt file included.
- */
-
-#pragma once
-#include <map>
-#include <boost/detail/container_fwd.hpp>
-#include "common/common_types.h"
-#include "vfs.h"
-
-namespace FileSys {
-
-/* Used as comparator for std::map<char *, RomFSBuild*Context> */
-struct build_ctx_cmp {
-    bool operator()(const char* a, const char* b) const {
-        return strcmp(a, b) < 0;
-    }
-};
-
-struct RomFSDirectoryEntry;
-struct RomFSFileEntry;
-struct RomFSBuildDirectoryContext;
-struct RomFSBuildFileContext;
-
-class RomFSBuildContext {
-private:
-    VirtualDir base;
-    RomFSBuildDirectoryContext* root;
-    std::map<char*, RomFSBuildDirectoryContext*, build_ctx_cmp> directories;
-    std::map<char*, RomFSBuildFileContext*, build_ctx_cmp> files;
-    u64 num_dirs = 0;
-    u64 num_files = 0;
-    u64 dir_table_size = 0;
-    u64 file_table_size = 0;
-    u64 dir_hash_table_size = 0;
-    u64 file_hash_table_size = 0;
-    u64 file_partition_size = 0;
-
-    void VisitDirectory(VirtualDir filesys, RomFSBuildDirectoryContext* parent);
-
-    bool AddDirectory(RomFSBuildDirectoryContext* parent_dir_ctx,
-                      RomFSBuildDirectoryContext* dir_ctx,
-                      RomFSBuildDirectoryContext** out_dir_ctx);
-    bool AddFile(RomFSBuildDirectoryContext* parent_dir_ctx, RomFSBuildFileContext* file_ctx);
-
-public:
-    explicit RomFSBuildContext(VirtualDir base);
-
-    /* This finalizes the context. */
-    std::map<u64, VirtualFile> Build();
-};
-
-static inline RomFSDirectoryEntry* romfs_get_direntry(void* directories, uint32_t offset) {
-    return (RomFSDirectoryEntry*)((uintptr_t)directories + offset);
-}
-
-static inline RomFSFileEntry* romfs_get_fentry(void* files, uint32_t offset) {
-    return (RomFSFileEntry*)((uintptr_t)files + offset);
-}
-
-static inline uint32_t romfs_calc_path_hash(uint32_t parent, const unsigned char* path,
-                                            uint32_t start, size_t path_len) {
-    uint32_t hash = parent ^ 123456789;
-    for (uint32_t i = 0; i < path_len; i++) {
-        hash = (hash >> 5) | (hash << 27);
-        hash ^= path[start + i];
-    }
-
-    return hash;
-}
-
-static inline uint32_t romfs_get_hash_table_count(uint32_t num_entries) {
-    if (num_entries < 3) {
-        return 3;
-    } else if (num_entries < 19) {
-        return num_entries | 1;
-    }
-    uint32_t count = num_entries;
-    while (count % 2 == 0 || count % 3 == 0 || count % 5 == 0 || count % 7 == 0 ||
-           count % 11 == 0 || count % 13 == 0 || count % 17 == 0) {
-        count++;
-    }
-    return count;
-}
-
-} // namespace FileSys
diff --git a/src/core/file_sys/patch_manager.cpp b/src/core/file_sys/patch_manager.cpp
index 74a0acf1a..af3f9a78f 100644
--- a/src/core/file_sys/patch_manager.cpp
+++ b/src/core/file_sys/patch_manager.cpp
@@ -68,33 +68,10 @@ VirtualDir PatchManager::PatchExeFS(VirtualDir exefs) const {
     return exefs;
 }
 
-VirtualFile PatchManager::PatchRomFS(VirtualFile romfs, u64 ivfc_offset,
-                                     ContentRecordType type) const {
-    LOG_INFO(Loader, "Patching RomFS for title_id={:016X}, type={:02X}", title_id,
-             static_cast<u8>(type));
-
-    if (romfs == nullptr)
-        return romfs;
-
-    const auto installed = Service::FileSystem::GetUnionContents();
-
-    // Game Updates
-    const auto update_tid = GetUpdateTitleID(title_id);
-    const auto update = installed->GetEntryRaw(update_tid, type);
-    if (update != nullptr) {
-        const auto new_nca = std::make_shared<NCA>(update, romfs, ivfc_offset);
-        if (new_nca->GetStatus() == Loader::ResultStatus::Success &&
-            new_nca->GetRomFS() != nullptr) {
-            LOG_INFO(Loader, "    RomFS: Update ({}) applied successfully",
-                     FormatTitleVersion(installed->GetEntryVersion(update_tid).get_value_or(0)));
-            romfs = new_nca->GetRomFS();
-        }
-    }
-
-    // LayeredFS
+static void ApplyLayeredFS(VirtualFile& romfs, u64 title_id, ContentRecordType type) {
     const auto load_dir = Service::FileSystem::GetModificationLoadRoot(title_id);
     if (type == ContentRecordType::Program && load_dir != nullptr && load_dir->GetSize() > 0) {
-        const auto extracted = ExtractRomFS(romfs);
+        auto extracted = ExtractRomFS(romfs);
 
         if (extracted != nullptr) {
             auto patch_dirs = load_dir->GetSubdirectories();
@@ -106,25 +83,52 @@ VirtualFile PatchManager::PatchRomFS(VirtualFile romfs, u64 ivfc_offset,
             std::vector<VirtualDir> layers;
             layers.reserve(patch_dirs.size() + 1);
             for (const auto& subdir : patch_dirs) {
-                const auto romfs_dir = subdir->GetSubdirectory("romfs");
+                auto romfs_dir = subdir->GetSubdirectory("romfs");
                 if (romfs_dir != nullptr)
-                    layers.push_back(romfs_dir);
+                    layers.push_back(std::move(romfs_dir));
             }
 
-            layers.push_back(extracted);
+            layers.push_back(std::move(extracted));
 
             const auto layered = LayerDirectories(layers);
 
             if (layered != nullptr) {
-                const auto packed = CreateRomFS(layered);
+                auto packed = CreateRomFS(layered);
 
                 if (packed != nullptr) {
                     LOG_INFO(Loader, "    RomFS: LayeredFS patches applied successfully");
-                    romfs = packed;
+                    romfs = std::move(packed);
                 }
             }
         }
     }
+}
+
+VirtualFile PatchManager::PatchRomFS(VirtualFile romfs, u64 ivfc_offset,
+                                     ContentRecordType type) const {
+    LOG_INFO(Loader, "Patching RomFS for title_id={:016X}, type={:02X}", title_id,
+             static_cast<u8>(type));
+
+    if (romfs == nullptr)
+        return romfs;
+
+    const auto installed = Service::FileSystem::GetUnionContents();
+
+    // Game Updates
+    const auto update_tid = GetUpdateTitleID(title_id);
+    const auto update = installed->GetEntryRaw(update_tid, type);
+    if (update != nullptr) {
+        const auto new_nca = std::make_shared<NCA>(update, romfs, ivfc_offset);
+        if (new_nca->GetStatus() == Loader::ResultStatus::Success &&
+            new_nca->GetRomFS() != nullptr) {
+            LOG_INFO(Loader, "    RomFS: Update ({}) applied successfully",
+                     FormatTitleVersion(installed->GetEntryVersion(update_tid).get_value_or(0)));
+            romfs = new_nca->GetRomFS();
+        }
+    }
+
+    // LayeredFS
+    ApplyLayeredFS(romfs, title_id, type);
 
     return romfs;
 }
@@ -153,7 +157,7 @@ std::map<PatchType, std::string> PatchManager::GetPatchVersionNames() const {
 
     const auto lfs_dir = Service::FileSystem::GetModificationLoadRoot(title_id);
     if (lfs_dir != nullptr && lfs_dir->GetSize() > 0)
-        out[PatchType::LayeredFS] = "";
+        out.insert_or_assign(PatchType::LayeredFS, "");
 
     return out;
 }
diff --git a/src/core/file_sys/registered_cache.cpp b/src/core/file_sys/registered_cache.cpp
index 0dda0b861..653ef2e7b 100644
--- a/src/core/file_sys/registered_cache.cpp
+++ b/src/core/file_sys/registered_cache.cpp
@@ -18,6 +18,10 @@
 #include "core/loader/loader.h"
 
 namespace FileSys {
+
+// The size of blocks to use when vfs raw copying into nand.
+constexpr size_t VFS_RC_LARGE_COPY_BLOCK = 0x400000;
+
 std::string RegisteredCacheEntry::DebugInfo() const {
     return fmt::format("title_id={:016X}, content_type={:02X}", title_id, static_cast<u8>(type));
 }
@@ -121,7 +125,7 @@ VirtualFile RegisteredCache::OpenFileOrDirectoryConcat(const VirtualDir& dir,
             if (concat.empty())
                 return nullptr;
 
-            file = FileSys::ConcatenateFiles(concat);
+            file = FileSys::ConcatenateFiles(concat, concat.front()->GetName());
         }
 
         return file;
@@ -480,7 +484,8 @@ InstallResult RegisteredCache::RawInstallNCA(std::shared_ptr<NCA> nca, const Vfs
     auto out = dir->CreateFileRelative(path);
     if (out == nullptr)
         return InstallResult::ErrorCopyFailed;
-    return copy(in, out, 0x400000) ? InstallResult::Success : InstallResult::ErrorCopyFailed;
+    return copy(in, out, VFS_RC_LARGE_COPY_BLOCK) ? InstallResult::Success
+                                                  : InstallResult::ErrorCopyFailed;
 }
 
 bool RegisteredCache::RawInstallYuzuMeta(const CNMT& cnmt) {
diff --git a/src/core/file_sys/romfs.cpp b/src/core/file_sys/romfs.cpp
index 71e4e0e2f..205284a4d 100644
--- a/src/core/file_sys/romfs.cpp
+++ b/src/core/file_sys/romfs.cpp
@@ -4,7 +4,7 @@
 
 #include "common/common_types.h"
 #include "common/swap.h"
-#include "core/file_sys/fsmitm_romfsbuild.hpp"
+#include "core/file_sys/fsmitm_romfsbuild.h"
 #include "core/file_sys/romfs.h"
 #include "core/file_sys/vfs.h"
 #include "core/file_sys/vfs_concat.h"
@@ -100,7 +100,7 @@ void ProcessDirectory(VirtualFile file, std::size_t dir_offset, std::size_t file
     }
 }
 
-VirtualDir ExtractRomFS(VirtualFile file, bool traverse_into_data) {
+VirtualDir ExtractRomFS(VirtualFile file, RomFSExtractionType type) {
     RomFSHeader header{};
     if (file->ReadObject(&header) != sizeof(RomFSHeader))
         return nullptr;
@@ -119,8 +119,9 @@ VirtualDir ExtractRomFS(VirtualFile file, bool traverse_into_data) {
 
     VirtualDir out = std::move(root);
 
-    while (out->GetSubdirectories().size() == 1 && out->GetFiles().size() == 0) {
-        if (out->GetSubdirectories().front()->GetName() == "data" && !traverse_into_data)
+    while (out->GetSubdirectories().size() == 1 && out->GetFiles().empty()) {
+        if (out->GetSubdirectories().front()->GetName() == "data" &&
+            type == RomFSExtractionType::Truncated)
             break;
         out = out->GetSubdirectories().front();
     }
diff --git a/src/core/file_sys/romfs.h b/src/core/file_sys/romfs.h
index 8e82585a0..ecd1eb725 100644
--- a/src/core/file_sys/romfs.h
+++ b/src/core/file_sys/romfs.h
@@ -32,9 +32,15 @@ struct IVFCHeader {
 };
 static_assert(sizeof(IVFCHeader) == 0xE0, "IVFCHeader has incorrect size.");
 
+enum class RomFSExtractionType {
+    Full,      // Includes data directory
+    Truncated, // Traverses into data directory
+};
+
 // Converts a RomFS binary blob to VFS Filesystem
 // Returns nullptr on failure
-VirtualDir ExtractRomFS(VirtualFile file, bool traverse_into_data = true);
+VirtualDir ExtractRomFS(VirtualFile file,
+                        RomFSExtractionType type = RomFSExtractionType::Truncated);
 
 // Converts a VFS filesystem into a RomFS binary
 // Returns nullptr on failure
diff --git a/src/core/file_sys/vfs.cpp b/src/core/file_sys/vfs.cpp
index 218cfde66..5fbea1739 100644
--- a/src/core/file_sys/vfs.cpp
+++ b/src/core/file_sys/vfs.cpp
@@ -399,8 +399,8 @@ bool VfsDirectory::Copy(std::string_view src, std::string_view dest) {
     return f2->WriteBytes(f1->ReadAllBytes()) == f1->GetSize();
 }
 
-std::map<std::string, VfsEntryType> VfsDirectory::GetEntries() const {
-    std::map<std::string, VfsEntryType> out;
+std::map<std::string, VfsEntryType, std::less<>> VfsDirectory::GetEntries() const {
+    std::map<std::string, VfsEntryType, std::less<>> out;
     for (const auto& dir : GetSubdirectories())
         out.emplace(dir->GetName(), VfsEntryType::Directory);
     for (const auto& file : GetFiles())
diff --git a/src/core/file_sys/vfs.h b/src/core/file_sys/vfs.h
index 6aec4c164..cea4aa8b8 100644
--- a/src/core/file_sys/vfs.h
+++ b/src/core/file_sys/vfs.h
@@ -268,7 +268,7 @@ public:
 
     // Gets all of the entries directly in the directory (files and dirs), returning a map between
     // item name -> type.
-    virtual std::map<std::string, VfsEntryType> GetEntries() const;
+    virtual std::map<std::string, VfsEntryType, std::less<>> GetEntries() const;
 
     // Interprets the file with name file instead as a directory of type directory.
     // The directory must have a constructor that takes a single argument of type
@@ -323,6 +323,9 @@ bool DeepEquals(const VirtualFile& file1, const VirtualFile& file2, size_t block
 // directory of src/dest.
 bool VfsRawCopy(const VirtualFile& src, const VirtualFile& dest, size_t block_size = 0x1000);
 
+// A method that performs a similar function to VfsRawCopy above, but instead copies entire
+// directories. It suffers the same performance penalties as above and an implementation-specific
+// Copy should always be preferred.
 bool VfsRawCopyD(const VirtualDir& src, const VirtualDir& dest, size_t block_size = 0x1000);
 
 // Checks if the directory at path relative to rel exists. If it does, returns that. If it does not
diff --git a/src/core/file_sys/vfs_concat.cpp b/src/core/file_sys/vfs_concat.cpp
index 0c07e162e..d9f9911da 100644
--- a/src/core/file_sys/vfs_concat.cpp
+++ b/src/core/file_sys/vfs_concat.cpp
@@ -10,8 +10,9 @@
 
 namespace FileSys {
 
-bool VerifyConcatenationMap(std::map<u64, VirtualFile> map) {
-    for (auto iter = map.begin(); iter != --map.end();) {
+static bool VerifyConcatenationMapContinuity(const std::map<u64, VirtualFile>& map) {
+    const auto last_valid = --map.end();
+    for (auto iter = map.begin(); iter != last_valid;) {
         const auto old = iter++;
         if (old->first + old->second->GetSize() != iter->first) {
             return false;
@@ -41,9 +42,11 @@ ConcatenatedVfsFile::ConcatenatedVfsFile(std::vector<VirtualFile> files_, std::s
 
 ConcatenatedVfsFile::ConcatenatedVfsFile(std::map<u64, VirtualFile> files_, std::string name)
     : files(std::move(files_)), name(std::move(name)) {
-    ASSERT(VerifyConcatenationMap(files));
+    ASSERT(VerifyConcatenationMapContinuity(files));
 }
 
+ConcatenatedVfsFile::~ConcatenatedVfsFile() = default;
+
 std::string ConcatenatedVfsFile::GetName() const {
     if (files.empty())
         return "";
@@ -77,25 +80,25 @@ bool ConcatenatedVfsFile::IsReadable() const {
 }
 
 std::size_t ConcatenatedVfsFile::Read(u8* data, std::size_t length, std::size_t offset) const {
-    std::pair<u64, VirtualFile> entry = *files.rbegin();
+    auto entry = --files.end();
     for (auto iter = files.begin(); iter != files.end(); ++iter) {
         if (iter->first > offset) {
-            entry = *--iter;
+            entry = --iter;
             break;
         }
     }
 
-    if (entry.first + entry.second->GetSize() <= offset)
+    if (entry->first + entry->second->GetSize() <= offset)
         return 0;
 
     const auto read_in =
-        std::min(entry.first + entry.second->GetSize() - offset, entry.second->GetSize());
+        std::min<u64>(entry->first + entry->second->GetSize() - offset, entry->second->GetSize());
     if (length > read_in) {
-        return entry.second->Read(data, read_in, offset - entry.first) +
+        return entry->second->Read(data, read_in, offset - entry->first) +
                Read(data + read_in, length - read_in, offset + read_in);
     }
 
-    return entry.second->Read(data, std::min(read_in, length), offset - entry.first);
+    return entry->second->Read(data, std::min<u64>(read_in, length), offset - entry->first);
 }
 
 std::size_t ConcatenatedVfsFile::Write(const u8* data, std::size_t length, std::size_t offset) {
diff --git a/src/core/file_sys/vfs_concat.h b/src/core/file_sys/vfs_concat.h
index c65c20d15..76211d38a 100644
--- a/src/core/file_sys/vfs_concat.h
+++ b/src/core/file_sys/vfs_concat.h
@@ -13,35 +13,6 @@
 
 namespace FileSys {
 
-class ConcatenatedVfsFile;
-
-// Wrapper function to allow for more efficient handling of files.size() == 0, 1 cases.
-VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name = "");
-
-// Convenience function that turns a map of offsets to files into a concatenated file, filling gaps
-// with template parameter.
-template <u8 filler_byte>
-VirtualFile ConcatenateFiles(std::map<u64, VirtualFile> files, std::string name = "") {
-    if (files.empty())
-        return nullptr;
-    if (files.size() == 1)
-        return files.begin()->second;
-
-    for (auto iter = files.begin(); iter != --files.end();) {
-        const auto old = iter++;
-        if (old->first + old->second->GetSize() != iter->first) {
-            files.emplace(old->first + old->second->GetSize(),
-                          std::make_shared<StaticVfsFile<filler_byte>>(iter->first - old->first -
-                                                                       old->second->GetSize()));
-        }
-    }
-
-    if (files.begin()->first != 0)
-        files.emplace(0, std::make_shared<StaticVfsFile<filler_byte>>(files.begin()->first));
-
-    return std::shared_ptr<VfsFile>(new ConcatenatedVfsFile(std::move(files), std::move(name)));
-}
-
 // Class that wraps multiple vfs files and concatenates them, making reads seamless. Currently
 // read-only.
 class ConcatenatedVfsFile : public VfsFile {
@@ -72,4 +43,33 @@ private:
     std::string name;
 };
 
+// Wrapper function to allow for more efficient handling of files.size() == 0, 1 cases.
+VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name);
+
+// Convenience function that turns a map of offsets to files into a concatenated file, filling gaps
+// with template parameter.
+template <u8 filler_byte>
+VirtualFile ConcatenateFiles(std::map<u64, VirtualFile> files, std::string name) {
+    if (files.empty())
+        return nullptr;
+    if (files.size() == 1)
+        return files.begin()->second;
+
+    const auto last_valid = --files.end();
+    for (auto iter = files.begin(); iter != last_valid;) {
+        const auto old = iter++;
+        if (old->first + old->second->GetSize() != iter->first) {
+            files.emplace(old->first + old->second->GetSize(),
+                          std::make_shared<StaticVfsFile<filler_byte>>(iter->first - old->first -
+                                                                       old->second->GetSize()));
+        }
+    }
+
+    // Ensure the map starts at offset 0 (start of file), otherwise pad to fill.
+    if (files.begin()->first != 0)
+        files.emplace(0, std::make_shared<StaticVfsFile<filler_byte>>(files.begin()->first));
+
+    return std::shared_ptr<VfsFile>(new ConcatenatedVfsFile(std::move(files), std::move(name)));
+}
+
 } // namespace FileSys
diff --git a/src/core/file_sys/vfs_layered.cpp b/src/core/file_sys/vfs_layered.cpp
index 802f49384..45563d7ae 100644
--- a/src/core/file_sys/vfs_layered.cpp
+++ b/src/core/file_sys/vfs_layered.cpp
@@ -20,10 +20,11 @@ VirtualDir LayerDirectories(std::vector<VirtualDir> dirs, std::string name) {
 LayeredVfsDirectory::LayeredVfsDirectory(std::vector<VirtualDir> dirs, std::string name)
     : dirs(std::move(dirs)), name(std::move(name)) {}
 
+LayeredVfsDirectory::~LayeredVfsDirectory() = default;
+
 std::shared_ptr<VfsFile> LayeredVfsDirectory::GetFileRelative(std::string_view path) const {
-    VirtualFile file;
     for (const auto& layer : dirs) {
-        file = layer->GetFileRelative(path);
+        const auto file = layer->GetFileRelative(path);
         if (file != nullptr)
             return file;
     }
@@ -35,12 +36,12 @@ std::shared_ptr<VfsDirectory> LayeredVfsDirectory::GetDirectoryRelative(
     std::string_view path) const {
     std::vector<VirtualDir> out;
     for (const auto& layer : dirs) {
-        const auto dir = layer->GetDirectoryRelative(path);
+        auto dir = layer->GetDirectoryRelative(path);
         if (dir != nullptr)
-            out.push_back(dir);
+            out.push_back(std::move(dir));
     }
 
-    return LayerDirectories(out);
+    return LayerDirectories(std::move(out));
 }
 
 std::shared_ptr<VfsFile> LayeredVfsDirectory::GetFile(std::string_view name) const {
@@ -61,8 +62,9 @@ std::vector<std::shared_ptr<VfsFile>> LayeredVfsDirectory::GetFiles() const {
         for (const auto& file : layer->GetFiles()) {
             if (std::find_if(out.begin(), out.end(), [&file](const VirtualFile& comp) {
                     return comp->GetName() == file->GetName();
-                }) == out.end())
+                }) == out.end()) {
                 out.push_back(file);
+            }
         }
     }
 
@@ -79,6 +81,7 @@ std::vector<std::shared_ptr<VfsDirectory>> LayeredVfsDirectory::GetSubdirectorie
     }
 
     std::vector<VirtualDir> out;
+    out.reserve(names.size());
     for (const auto& subdir : names)
         out.push_back(GetSubdirectory(subdir));
 
diff --git a/src/core/file_sys/vfs_layered.h b/src/core/file_sys/vfs_layered.h
index f345c2fb6..4f6e341ab 100644
--- a/src/core/file_sys/vfs_layered.h
+++ b/src/core/file_sys/vfs_layered.h
@@ -21,6 +21,8 @@ class LayeredVfsDirectory : public VfsDirectory {
     LayeredVfsDirectory(std::vector<VirtualDir> dirs, std::string name);
 
 public:
+    ~LayeredVfsDirectory() override;
+
     std::shared_ptr<VfsFile> GetFileRelative(std::string_view path) const override;
     std::shared_ptr<VfsDirectory> GetDirectoryRelative(std::string_view path) const override;
     std::shared_ptr<VfsFile> GetFile(std::string_view name) const override;
diff --git a/src/core/file_sys/vfs_real.cpp b/src/core/file_sys/vfs_real.cpp
index a58a02de7..9defad04c 100644
--- a/src/core/file_sys/vfs_real.cpp
+++ b/src/core/file_sys/vfs_real.cpp
@@ -413,11 +413,11 @@ std::string RealVfsDirectory::GetFullPath() const {
     return out;
 }
 
-std::map<std::string, VfsEntryType> RealVfsDirectory::GetEntries() const {
+std::map<std::string, VfsEntryType, std::less<>> RealVfsDirectory::GetEntries() const {
     if (perms == Mode::Append)
         return {};
 
-    std::map<std::string, VfsEntryType> out;
+    std::map<std::string, VfsEntryType, std::less<>> out;
     FileUtil::ForeachDirectoryEntry(
         nullptr, path,
         [&out](u64* entries_out, const std::string& directory, const std::string& filename) {
diff --git a/src/core/file_sys/vfs_real.h b/src/core/file_sys/vfs_real.h
index 3af2a6961..5b61db90d 100644
--- a/src/core/file_sys/vfs_real.h
+++ b/src/core/file_sys/vfs_real.h
@@ -98,7 +98,7 @@ public:
     bool DeleteFile(std::string_view name) override;
     bool Rename(std::string_view name) override;
     std::string GetFullPath() const override;
-    std::map<std::string, VfsEntryType> GetEntries() const override;
+    std::map<std::string, VfsEntryType, std::less<>> GetEntries() const override;
 
 protected:
     bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
diff --git a/src/core/file_sys/vfs_static.h b/src/core/file_sys/vfs_static.h
index 5bc8ca52e..4dd47ffcc 100644
--- a/src/core/file_sys/vfs_static.h
+++ b/src/core/file_sys/vfs_static.h
@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <algorithm>
 #include <memory>
 #include <string_view>
 
@@ -15,7 +16,7 @@ template <u8 value>
 class StaticVfsFile : public VfsFile {
 public:
     explicit StaticVfsFile(size_t size = 0, std::string name = "", VirtualDir parent = nullptr)
-        : size(size), name(name), parent(parent) {}
+        : size(size), name(std::move(name)), parent(std::move(parent)) {}
 
     std::string GetName() const override {
         return name;
diff --git a/src/core/file_sys/vfs_vector.cpp b/src/core/file_sys/vfs_vector.cpp
index efca3d4ad..7033e2c88 100644
--- a/src/core/file_sys/vfs_vector.cpp
+++ b/src/core/file_sys/vfs_vector.cpp
@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 
 #include <algorithm>
+#include <cstring>
 #include <utility>
 #include "core/file_sys/vfs_vector.h"
 
@@ -10,6 +11,8 @@ namespace FileSys {
 VectorVfsFile::VectorVfsFile(std::vector<u8> initial_data, std::string name, VirtualDir parent)
     : data(std::move(initial_data)), name(std::move(name)), parent(std::move(parent)) {}
 
+VectorVfsFile::~VectorVfsFile() = default;
+
 std::string VectorVfsFile::GetName() const {
     return name;
 }
@@ -20,7 +23,7 @@ size_t VectorVfsFile::GetSize() const {
 
 bool VectorVfsFile::Resize(size_t new_size) {
     data.resize(new_size);
-    return data.size() == new_size;
+    return true;
 }
 
 std::shared_ptr<VfsDirectory> VectorVfsFile::GetContainingDirectory() const {
@@ -55,7 +58,7 @@ bool VectorVfsFile::Rename(std::string_view name_) {
 }
 
 void VectorVfsFile::Assign(std::vector<u8> new_data) {
-    data = new_data;
+    data = std::move(new_data);
 }
 
 VectorVfsDirectory::VectorVfsDirectory(std::vector<VirtualFile> files_,
diff --git a/src/core/file_sys/vfs_vector.h b/src/core/file_sys/vfs_vector.h
index c84e137a9..115c3ae95 100644
--- a/src/core/file_sys/vfs_vector.h
+++ b/src/core/file_sys/vfs_vector.h
@@ -13,6 +13,7 @@ class VectorVfsFile : public VfsFile {
 public:
     explicit VectorVfsFile(std::vector<u8> initial_data = {}, std::string name = "",
                            VirtualDir parent = nullptr);
+    ~VectorVfsFile() override;
 
     std::string GetName() const override;
     size_t GetSize() const override;
-- 
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