Initial work on homebrew return to loader

arm7/source/fat/dldi.cpp

@@ -95,3 +95,8 @@ bool dldi_patchTo(dldi_header_t* stub)
 {
     return sDldiDriver.PatchTo(stub);
 }
+
+void dldi_copyTo(void* target)
+{
+    memcpy(target, sDldiBuffer, sizeof(sDldiBuffer));
+}

arm7/source/fat/dldi.h

@@ -3,6 +3,7 @@
 
 bool dldi_init();
 bool dldi_patchTo(dldi_header_t* stub);
+void dldi_copyTo(void* target);
 
 #ifdef __cplusplus
 extern "C" {

arm7/source/header.cpp

@@ -10,5 +10,6 @@ extern u8 __bss_size[];
 pload_header7_t gLoaderHeader
 {
     .entryPoint = (void*)&_start,
-    .apiVersion = PICO_LOADER_API_VERSION
+    .apiVersion = PICO_LOADER_API_VERSION,
+    .launcherPath = "/_picoboot.nds"
 };

arm7/source/loader/NdsLoader.cpp

@@ -344,6 +344,7 @@ void NdsLoader::Load(BootMode bootMode)
     if (isHomebrew)
     {
         InsertArgv();
+        HandleHomebrewPatching();
     }
 
     HandleDldiPatching();
@@ -429,6 +430,22 @@ void NdsLoader::InsertArgv()
     HOMEBREW_ARGV->length = argSize;
 }
 
+void NdsLoader::HandleHomebrewPatching()
+{
+    sendToArm9(IPC_COMMAND_ARM9_APPLY_HOMEBREW_PATCHES);
+    sendToArm9(16 * 1024); // required dldi space
+    void* dldiSpace = (void*)receiveFromArm9();
+    char* launcherPath = (char*)receiveFromArm9();
+    if (dldiSpace != nullptr)
+    {
+        dldi_copyTo(dldiSpace);
+    }
+    if (launcherPath != nullptr)
+    {
+        strncpy(launcherPath, _launcherPath, 256);
+    }
+}
+
 void NdsLoader::ApplyArm7Patches()
 {
     sendToArm9(IPC_COMMAND_ARM9_APPLY_ARM7_PATCHES);

arm7/source/loader/NdsLoader.h

@@ -26,6 +26,13 @@ public:
         _savePath = savePath;
     }
 
+    /// @brief Sets the \p launcherPath to use.
+    /// @param launcherPath The launcher path to use.
+    void SetLauncherPath(const TCHAR* launcherPath)
+    {
+        _launcherPath = launcherPath;
+    }
+
     /// @brief Sets the argv arguments to pass to the rom.
     /// @param arguments The argv arguments.
     /// @param argumentsLength The length of the argv arguments.
@@ -41,8 +48,9 @@ public:
 
 private:
     FIL _romFile;
-    const TCHAR* _romPath;
-    const TCHAR* _savePath;
+    const TCHAR* _romPath = nullptr;
+    const TCHAR* _savePath = nullptr;
+    const TCHAR* _launcherPath = nullptr;
     u32 _argumentsLength = 0;
     const char* _arguments = nullptr;
     nds_header_twl_t _romHeader;
@@ -71,6 +79,7 @@ private:
         char driveLetter, const char* deviceName, const char* path, u8 flags, u8 accessRights);
     void SetupDsiDeviceList();
     void InsertArgv();
+    void HandleHomebrewPatching();
     bool TrySetupDsiWareSave();
     bool TryDecryptSecureArea();
     ConsoleRegion GetRomRegion(u32 gameCode);

arm7/source/loader/dldiHeader.h

@@ -1,5 +1,4 @@
 #pragma once
-#include "common.h"
 
 #define DLDI_MAGIC              0xBF8DA5ED
 #define DLDI_DRIVER_MAGIC_NONE  0x49444C44

arm7/source/main.cpp

@@ -222,6 +222,7 @@ extern "C" void loaderMain()
         sLoader.SetRomPath(gLoaderHeader.loadParams.romPath);
         handleSavePath();
         sLoader.SetArguments(gLoaderHeader.loadParams.arguments, gLoaderHeader.loadParams.argumentsLength);
+        sLoader.SetLauncherPath(gLoaderHeader.launcherPath);
         sLoader.Load(BootMode::Normal);
     }