From 8b4d0c5d8da1260c06e5edc6bf3afc116c36ea2c Mon Sep 17 00:00:00 2001
From: noah the goodra <peterpan0413@live.com>
Date: Wed, 15 Mar 2017 15:24:22 -0500
Subject: [PATCH] implemented basic cia loader

---
 src/citra_qt/game_list.cpp |  2 +-
 src/core/loader/loader.cpp |  1 +
 src/core/loader/ncch.cpp   | 52 ++++++++++++++++++++++++++++++++++++++
 src/core/loader/ncch.h     | 13 +++++++++-
 4 files changed, 66 insertions(+), 2 deletions(-)

diff --git a/src/citra_qt/game_list.cpp b/src/citra_qt/game_list.cpp
index a9ec9e830..96da4579f 100644
--- a/src/citra_qt/game_list.cpp
+++ b/src/citra_qt/game_list.cpp
@@ -141,7 +141,7 @@ void GameList::LoadInterfaceLayout() {
 }
 
 const QStringList GameList::supported_file_extensions = {"3ds", "3dsx", "elf", "axf",
-                                                         "cci", "cxi",  "app"};
+                                                         "cci", "cxi",  "app", "cia"};
 
 static bool HasSupportedFileExtension(const std::string& file_name) {
     QFileInfo file = QFileInfo(file_name.c_str());
diff --git a/src/core/loader/loader.cpp b/src/core/loader/loader.cpp
index be719d74c..382f5f127 100644
--- a/src/core/loader/loader.cpp
+++ b/src/core/loader/loader.cpp
@@ -113,6 +113,7 @@ static std::unique_ptr<AppLoader> GetFileLoader(FileUtil::IOFile&& file, FileTyp
     // NCCH/NCSD container formats.
     case FileType::CXI:
     case FileType::CCI:
+    case FileType::CIA:
         return std::make_unique<AppLoader_NCCH>(std::move(file), filepath);
 
     default:
diff --git a/src/core/loader/ncch.cpp b/src/core/loader/ncch.cpp
index 1a4e3efa8..270182a61 100644
--- a/src/core/loader/ncch.cpp
+++ b/src/core/loader/ncch.cpp
@@ -26,6 +26,44 @@ namespace Loader {
 static const int kMaxSections = 8;   ///< Maximum number of sections (files) in an ExeFs
 static const int kBlockSize = 0x200; ///< Size of ExeFS blocks (in bytes)
 
+static u32 FindNCCHOffsetInCIA(FileUtil::IOFile& file) {
+    // Reset read pointer in case this file has been read before.
+    file.Seek(0, SEEK_SET);
+    CIAHeader cia_header;
+
+    file.ReadBytes(&cia_header, sizeof(CIAHeader));
+    u32 certs_offset = Common::AlignUp(cia_header.header_size, 64);
+    u32 tik_offset = Common::AlignUp(certs_offset + cia_header.cert_size, 64);
+    u32 tmd_offset = Common::AlignUp(tik_offset + cia_header.ticket_size, 64);
+    u32 content_offset = Common::AlignUp(tmd_offset + cia_header.tmd_size, 64);
+    return content_offset;
+}
+
+static bool IsValidCia(FileUtil::IOFile& file) {
+    // Reset read pointer in case this file has been read before.
+    file.Seek(0, SEEK_SET);
+
+    bool is_valid = false;
+    u32 magic;
+    u32 offset = FindNCCHOffsetInCIA(file);
+    file.Seek(offset, SEEK_SET);
+    file.ReadArray<u32>(&magic, 1);
+    if (MakeMagic('N', 'C', 'C', 'H') != magic) {
+        // this additional if check was made to account for the possible
+        // padding which always seems to exist as 256 extra bytes
+        // TODO: see if the padding can be other sizes as well as 256
+        file.Seek(offset + 256, SEEK_SET);
+        file.ReadArray<u32>(&magic, 1);
+        if (MakeMagic('N', 'C', 'C', 'H') == magic) {
+            is_valid = true;
+        }
+    } else {
+        is_valid = true;
+    }
+
+    return is_valid;
+}
+
 /**
  * Get the decompressed size of an LZSS compressed ExeFS file
  * @param buffer Buffer of compressed file
@@ -117,6 +155,9 @@ FileType AppLoader_NCCH::IdentifyType(FileUtil::IOFile& file) {
     if (MakeMagic('N', 'C', 'C', 'H') == magic)
         return FileType::CXI;
 
+    if (IsValidCia(file))
+        return FileType::CIA;
+
     return FileType::Error;
 }
 
@@ -260,6 +301,17 @@ ResultStatus AppLoader_NCCH::LoadExeFS() {
         file.ReadBytes(&ncch_header, sizeof(NCCH_Header));
     }
 
+    if (IsValidCia(file)) {
+        LOG_DEBUG(Loader, "Loading CIA");
+        ncch_offset = FindNCCHOffsetInCIA(file);
+        file.Seek(ncch_offset, SEEK_SET);
+        file.ReadBytes(&ncch_header, sizeof(NCCH_Header));
+        // the padding check
+        if (MakeMagic('N', 'C', 'C', 'H') != ncch_header.magic) {
+            ncch_offset += 256;
+        }
+    }
+
     // Verify we are loading the correct file type...
     if (MakeMagic('N', 'C', 'C', 'H') != ncch_header.magic)
         return ResultStatus::ErrorInvalidFormat;
diff --git a/src/core/loader/ncch.h b/src/core/loader/ncch.h
index 4ef95b5c6..3b17080c6 100644
--- a/src/core/loader/ncch.h
+++ b/src/core/loader/ncch.h
@@ -5,10 +5,22 @@
 #pragma once
 
 #include <memory>
+#include "common/alignment.h"
 #include "common/bit_field.h"
 #include "common/common_types.h"
 #include "common/swap.h"
 #include "core/loader/loader.h"
+struct CIAHeader {
+    u32_le header_size;
+    u8 type[2];
+    u8 version[2];
+    u32_le cert_size;
+    u32_le ticket_size;
+    u32_le tmd_size;
+    u32_le meta_size;
+    u64_le content_size;
+    u8 content_index[0x2000];
+};
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 /// NCCH header (Note: "NCCH" appears to be a publicly unknown acronym)
@@ -251,5 +263,4 @@ private:
 
     std::string filepath;
 };
-
 } // namespace Loader