Add file

[FlaveFlav20]

I created a file-like type for PyO3. Since file is a fundamental type in Python, I believe it should be supported by this library.

Example:

use pyo3::types::pyo3file::Pyo3File;

#[pyfunction]
fn my_custom_file(mut file: Pyo3File) -> PyResult<String> {
    let mut contents = String::new();

    file.getfile().read_to_string(&mut contents)?;

    Ok(contents)
}

I created a pyo3 type because the Python file uses three parameters that are not directly available in Rust::

• name
• opening mode
• encoding (we can't know the file encoding with rust file type)

I opened this pull request to check if this approach is acceptable.

[bschoenmaeckers]

This is not a full review yet. But you can avoid using additional dependencies on winapi/nix by using File::try_clone.

#[cfg(unix)]
let python_handle = unsafe {
    File::from_raw_fd(fd)
};

#[cfg(windows)]
let python_handle = unsafe {
    let raw_handle = libc::get_osfhandle(fd);
    if raw_handle == -1 {
        return Err(PyOSError::new_err("Cannot convert file descriptor to RawHandle"));
    }
    File::from_raw_handle(raw_handle as _)
};


let new_handle = python_handle.try_clone()?;
// Do not steal the handle from Python, as it is still used by the python object.
mem::forget(python_handle);
Ok(new_handle)

[bschoenmaeckers]

Or using the lower-level BorrowedFd/BorrowedHandle:

#[cfg(unix)]
let file: File = unsafe {
    BorrowedFd::borrow_raw(fd)
        .try_clone_to_owned()?
        .into();
};

#[cfg(windows)]
let file: File = unsafe {
    let raw_handle = libc::get_osfhandle(fd);
    if raw_handle == -1 {
        return Err(PyOSError::new_err("Cannot convert file descriptor to RawHandle"));
    }
    BorrowedHandle::borrow_raw(raw_handle as _)
    .try_clone_to_owned()?
        .into()
};

Ok(file)

[FlaveFlav20]

I removed the winapi/nix dependencies and used File::try_clone. I also added a test.

[bschoenmaeckers]

I don't think this symbol exported in python 3.