Hack to allow input of any characters in Unicode windows

reaper_widemsg.cpp

// cl /nologo /O2 reaper_widemsg.cpp User32.lib /link /DLL /OUT:reaper_widemsg.dll

#include <cstdint>

#define REAPERAPI_IMPLEMENT
#include "reaper_plugin_functions.h"

template<typename T>
bool patch(const uintptr_t addr, const T newCode, T *backup = nullptr)
{
  uint8_t *firstByte { reinterpret_cast<uint8_t *>(addr) };

  if(backup)
    memcpy(backup, firstByte, sizeof(T));

  DWORD oldProtect;
  if(!VirtualProtect(firstByte, sizeof(T), PAGE_READWRITE, &oldProtect))
    return false;

  memcpy(firstByte, &newCode, sizeof(T));

  VirtualProtect(firstByte, sizeof(T), oldProtect, &oldProtect);

  return true;
}

#pragma pack(push, 1)
struct Jump {
#if defined(_WIN64)
  // uint8_t int3 = 0xcc;
  uint8_t mov = 0x48, reg = 0xb8; uint64_t dest; // mov rax, dest
  uint8_t jmp = 0xff, modr_m = 0xe0;             // jmp rax
#else
#  error Unimplemented architecture
#endif
};
#pragma pack(pop)

class Redirect {
public:
  Redirect(const uintptr_t funcAddr, const uintptr_t redirect)
    : m_funcAddr { funcAddr }
  {
    Jump jump;
    jump.dest = redirect;
    patch(m_funcAddr, jump, &m_code);
  }

  ~Redirect()
  {
    patch(m_funcAddr, m_code);
  }

private:
  uintptr_t m_funcAddr;
  Jump m_code;
};

#define ATOW(api) new Redirect { reinterpret_cast<uintptr_t>(api##A), \
                                 reinterpret_cast<uintptr_t>(api##W) }

extern "C" REAPER_PLUGIN_DLL_EXPORT int REAPER_PLUGIN_ENTRYPOINT(
  REAPER_PLUGIN_HINSTANCE instance, reaper_plugin_info_t *rec)
{
  if(!rec || rec->caller_version != REAPER_PLUGIN_VERSION)
    return 0;
 
  ATOW(GetMessage);
  ATOW(PeekMessage);
  ATOW(DispatchMessage);

  return 1;
}