Function npy_PyFile_DupClose2

numpy/core/include/numpy/npy_3kcompat.h:331–396

* Close the dup-ed file handle, and seek the Python one to the current position */

 * Close the dup-ed file handle, and seek the Python one to the current position
 */
static inline int
npy_PyFile_DupClose2(PyObject *file, FILE* handle, npy_off_t orig_pos)
{
    int fd, unbuf;
    PyObject *ret, *io, *io_raw;
    npy_off_t position;

    /* For Python 2 PyFileObject, do nothing */
#if !defined(NPY_PY3K)
    if (PyFile_Check(file)) {
        return 0;
    }
#endif

    position = npy_ftell(handle);

    /* Close the FILE* handle */
    fclose(handle);

    /*
     * Restore original file handle position, in order to not confuse
     * Python-side data structures
     */
    fd = PyObject_AsFileDescriptor(file);
    if (fd == -1) {
        return -1;
    }

    if (npy_lseek(fd, orig_pos, SEEK_SET) == -1) {

        /* The io module is needed to determine if buffering is used */
        io = PyImport_ImportModule("io");
        if (io == NULL) {
            return -1;
        }
        /* File object instances of RawIOBase are unbuffered */
        io_raw = PyObject_GetAttrString(io, "RawIOBase");
        Py_DECREF(io);
        if (io_raw == NULL) {
            return -1;
        }
        unbuf = PyObject_IsInstance(file, io_raw);
        Py_DECREF(io_raw);
        if (unbuf == 1) {
            /* Succeed if the IO is unbuffered */
            return 0;
        }
        else {
            PyErr_SetString(PyExc_IOError, "seeking file failed");
            return -1;
        }
    }

    if (position == -1) {
        PyErr_SetString(PyExc_IOError, "obtaining file position failed");
        return -1;
    }