text: // Copyright (c) 2011-2016 Ryan Prichard
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to
  // deal in the Software without restriction, including without limitation the
  // rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  // sell copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  // IN THE SOFTWARE.
  
  #include "AgentLocation.h"
  
  #include <windows.h>
  
  #include <string>
  
  #include "../shared/WinptyAssert.h"
  
  #include "LibWinptyException.h"
  
  #define AGENT_EXE L"winpty-agent.exe"
  
  static HMODULE getCurrentModule() {
      HMODULE module;
      if (!GetModuleHandleExW(
                  GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
                  GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
                  reinterpret_cast<LPCWSTR>(getCurrentModule),
                  &module)) {
          ASSERT(false && "GetModuleHandleEx failed");
      }
      return module;
  }
  
  static std::wstring getModuleFileName(HMODULE module) {
      const int bufsize = 4096;
      wchar_t path[bufsize];
      int size = GetModuleFileNameW(module, path, bufsize);
      ASSERT(size != 0 && size != bufsize);
      return std::wstring(path);
  }
  
  static std::wstring dirname(const std::wstring &path) {
      std::wstring::size_type pos = path.find_last_of(L"\\/");
      if (pos == std::wstring::npos) {
          return L"";
      } else {
          return path.substr(0, pos);
      }
  }
  
  static bool pathExists(const std::wstring &path) {
      return GetFileAttributesW(path.c_str()) != 0xFFFFFFFF;
  }
  
  std::wstring findAgentProgram() {
      std::wstring progDir = dirname(getModuleFileName(getCurrentModule()));
      std::wstring ret = progDir + (L"\\" AGENT_EXE);
      if (!pathExists(ret)) {
          throw LibWinptyException(
              WINPTY_ERROR_AGENT_EXE_MISSING,
              (L"agent executable does not exist: '" + ret + L"'").c_str());
      }
      return ret;
  }
  