Function processPath

src/env.cpp:952–1002

returns the filename of the given process or the current one

// returns the filename of the given process or the current one
//
std::filesystem::path processPath(HANDLE process = INVALID_HANDLE_VALUE)
{
  // double the buffer size 10 times
  const int MaxTries = 10;

  DWORD bufferSize = MAX_PATH;

  for (int tries = 0; tries < MaxTries; ++tries) {
    auto buffer = std::make_unique<wchar_t[]>(bufferSize + 1);
    std::fill(buffer.get(), buffer.get() + bufferSize + 1, 0);

    DWORD writtenSize = 0;

    if (process == INVALID_HANDLE_VALUE) {
      // query this process
      writtenSize = GetModuleFileNameW(0, buffer.get(), bufferSize);
    } else {
      // query another process
      writtenSize = GetModuleBaseNameW(process, 0, buffer.get(), bufferSize);
    }

    if (writtenSize == 0) {
      // hard failure
      const auto e = GetLastError();
      std::wcerr << formatSystemMessage(e) << L"\n";
      break;
    } else if (writtenSize >= bufferSize) {
      // buffer is too small, try again
      bufferSize *= 2;
    } else {
      // if GetModuleFileName() works, `writtenSize` does not include the null
      // terminator
      const std::wstring s(buffer.get(), writtenSize);
      const std::filesystem::path path(s);

      return path;
    }
  }

  // something failed or the path is way too long to make sense

  std::wstring what;
  if (process == INVALID_HANDLE_VALUE) {
    what = L"the current process";
  } else {
    what = L"pid " + std::to_wstring(reinterpret_cast<std::uintptr_t>(process));
  }

  std::wcerr << L"failed to get filename for " << what << L"\n";
  return {};
}

std::wstring processFilename(HANDLE process = INVALID_HANDLE_VALUE)
{