From 6758c77c39b094555ab2797b0419217de40e202e Mon Sep 17 00:00:00 2001
From: Starsam80 <samraskauskas@gmail.com>
Date: Wed, 29 Dec 2021 17:49:16 -0700
Subject: [PATCH] NANDImporter: Reduce recursion in `ProcessEntry`

It also simplifies the code flow, as it no longer goes backwards
through the filesystem chain.
---
 Source/Core/DiscIO/NANDImporter.cpp | 46 +++++++++++++----------------
 Source/Core/DiscIO/NANDImporter.h   |  4 +--
 2 files changed, 22 insertions(+), 28 deletions(-)

diff --git a/Source/Core/DiscIO/NANDImporter.cpp b/Source/Core/DiscIO/NANDImporter.cpp
index 32dafdd58d..322dd548d7 100644
--- a/Source/Core/DiscIO/NANDImporter.cpp
+++ b/Source/Core/DiscIO/NANDImporter.cpp
@@ -129,44 +129,38 @@ std::string NANDImporter::GetPath(const NANDFSTEntry& entry, const std::string&
 void NANDImporter::ProcessEntry(u16 entry_number, const std::string& parent_path)
 {
   NANDFSTEntry entry;
-  memcpy(&entry, &m_nand[m_nand_fst_offset + sizeof(NANDFSTEntry) * entry_number],
-         sizeof(NANDFSTEntry));
+  while (entry_number != 0xffff)
+  {
+    memcpy(&entry, &m_nand[m_nand_fst_offset + sizeof(NANDFSTEntry) * entry_number],
+           sizeof(NANDFSTEntry));
 
-  if (entry.sib != 0xffff)
-    ProcessEntry(entry.sib, parent_path);
+    const std::string path = GetPath(entry, parent_path);
+    INFO_LOG_FMT(DISCIO, "Entry: {} Path: {}", entry, path);
+    m_update_callback();
 
-  Type type = static_cast<Type>(entry.mode & 3);
-  if (type == Type::File)
-    ProcessFile(entry, parent_path);
-  else if (type == Type::Directory)
-    ProcessDirectory(entry, parent_path);
-  else
-    ERROR_LOG_FMT(DISCIO, "Ignoring unknown entry type for {}", entry);
+    Type type = static_cast<Type>(entry.mode & 3);
+    if (type == Type::File)
+      ProcessFile(entry, path);
+    else if (type == Type::Directory)
+      ProcessDirectory(entry, path);
+    else
+      ERROR_LOG_FMT(DISCIO, "Ignoring unknown entry type for {}", entry);
+
+    entry_number = entry.sib;
+  }
 }
 
-void NANDImporter::ProcessDirectory(const NANDFSTEntry& entry, const std::string& parent_path)
+void NANDImporter::ProcessDirectory(const NANDFSTEntry& entry, const std::string& path)
 {
-  m_update_callback();
-  INFO_LOG_FMT(DISCIO, "Path: {}", FormatDebugString(entry));
-
-  const std::string path = GetPath(entry, parent_path);
   File::CreateDir(m_nand_root + path);
-
-  if (entry.sub != 0xffff)
-    ProcessEntry(entry.sub, path);
-
-  INFO_LOG_FMT(DISCIO, "Path: {}", parent_path);
+  ProcessEntry(entry.sub, path);
 }
 
-void NANDImporter::ProcessFile(const NANDFSTEntry& entry, const std::string& parent_path)
+void NANDImporter::ProcessFile(const NANDFSTEntry& entry, const std::string& path)
 {
   constexpr size_t NAND_AES_KEY_OFFSET = 0x158;
   constexpr size_t NAND_FAT_BLOCK_SIZE = 0x4000;
 
-  m_update_callback();
-  INFO_LOG_FMT(DISCIO, "File: {}", FormatDebugString(entry));
-
-  const std::string path = GetPath(entry, parent_path);
   File::IOFile file(m_nand_root + path, "wb");
   std::array<u8, 16> key{};
   std::copy(&m_nand_keys[NAND_AES_KEY_OFFSET], &m_nand_keys[NAND_AES_KEY_OFFSET + key.size()],
diff --git a/Source/Core/DiscIO/NANDImporter.h b/Source/Core/DiscIO/NANDImporter.h
index 7c266d6840..eeb12c87bc 100644
--- a/Source/Core/DiscIO/NANDImporter.h
+++ b/Source/Core/DiscIO/NANDImporter.h
@@ -55,8 +55,8 @@ private:
   std::string GetPath(const NANDFSTEntry& entry, const std::string& parent_path);
   std::string FormatDebugString(const NANDFSTEntry& entry);
   void ProcessEntry(u16 entry_number, const std::string& parent_path);
-  void ProcessFile(const NANDFSTEntry& entry, const std::string& parent_path);
-  void ProcessDirectory(const NANDFSTEntry& entry, const std::string& parent_path);
+  void ProcessFile(const NANDFSTEntry& entry, const std::string& path);
+  void ProcessDirectory(const NANDFSTEntry& entry, const std::string& path);
   void ExportKeys();
 
   std::string m_nand_root;