Function fopen

crates/common/src/fileutils.rs:447–509

_Py_fopen_obj in cpython (Python/fileutils.c:1757-1835) Open a file using std::fs::File and convert to FILE Automatically handles path encoding and EINTR retries

(path: &std::path::Path, mode: &str)

// Open a file using std::fs::File and convert to FILE*
// Automatically handles path encoding and EINTR retries
pub fn fopen(path: &std::path::Path, mode: &str) -> std::io::Result<*mut libc::FILE> {
    use alloc::ffi::CString;
    use std::fs::File;

    // Currently only supports read mode
    // Can be extended to support "wb", "w+b", etc. if needed
    if mode != "rb" {
        return Err(std::io::Error::new(
            std::io::ErrorKind::InvalidInput,
            format!("unsupported mode: {}", mode),
        ));
    }

    // Open file using std::fs::File (handles path encoding and EINTR automatically)
    let file = File::open(path)?;

    #[cfg(windows)]
    {
        use std::os::windows::io::IntoRawHandle;

        // Convert File handle to CRT file descriptor
        let handle = file.into_raw_handle();
        let fd = unsafe { libc::open_osfhandle(handle as isize, libc::O_RDONLY) };
        if fd == -1 {
            return Err(std::io::Error::last_os_error());
        }

        // Convert fd to FILE*
        let mode_cstr = CString::new(mode).unwrap();
        let fp = unsafe { libc::fdopen(fd, mode_cstr.as_ptr()) };
        if fp.is_null() {
            unsafe { libc::close(fd) };
            return Err(std::io::Error::last_os_error());
        }

        // Set non-inheritable (Windows needs this explicitly)
        if let Err(e) = set_inheritable(fd, false) {
            unsafe { libc::fclose(fp) };
            return Err(e);
        }

        Ok(fp)
    }

    #[cfg(not(windows))]
    {
        use std::os::fd::IntoRawFd;

        // Convert File to raw fd
        let fd = file.into_raw_fd();

        // Convert fd to FILE*
        let mode_cstr = CString::new(mode).unwrap();
        let fp = unsafe { libc::fdopen(fd, mode_cstr.as_ptr()) };
        if fp.is_null() {
            unsafe { libc::close(fd) };
            return Err(std::io::Error::last_os_error());
        }