Class PythonFile

python/pyarrow/src/arrow/python/io.cc:45–181

A common interface to a Python file-like object. Must acquire GIL before calling any methods

// A common interface to a Python file-like object. Must acquire GIL before
// calling any methods
class PythonFile {
 public:
  explicit PythonFile(PyObject* file) : file_(file), checked_read_buffer_(false) {
    Py_INCREF(file);
  }

  Status CheckClosed() const {
    if (!file_) {
      return Status::Invalid("operation on closed Python file");
    }
    return Status::OK();
  }

  Status Close() {
    if (file_) {
      PyObject* result = cpp_PyObject_CallMethod(file_.obj(), "close", "()");
      Py_XDECREF(result);
      file_.reset();
      PY_RETURN_IF_ERROR(StatusCode::IOError);
    }
    return Status::OK();
  }

  Status Abort() {
    file_.reset();
    return Status::OK();
  }

  bool closed() const {
    if (!file_) {
      return true;
    }
    PyObject* result = PyObject_GetAttrString(file_.obj(), "closed");
    if (result == NULL) {
      // Can't propagate the error, so write it out and return an arbitrary value
      PyErr_WriteUnraisable(NULL);
      return true;
    }
    int ret = PyObject_IsTrue(result);
    Py_XDECREF(result);
    if (ret < 0) {
      PyErr_WriteUnraisable(NULL);
      return true;
    }
    return ret != 0;
  }

  Status Seek(int64_t position, int whence) {
    RETURN_NOT_OK(CheckClosed());

    // NOTE: `long long` is at least 64 bits in the C standard, the cast below is
    // therefore safe.

    // whence: 0 for relative to start of file, 2 for end of file
    PyObject* result = cpp_PyObject_CallMethod(file_.obj(), "seek", "(Li)",
                                               static_cast<long long>(position), whence);
    Py_XDECREF(result);
    PY_RETURN_IF_ERROR(StatusCode::IOError);