Function get_fd_from_file_opt

crates/stdlib/src/faulthandler.rs:799–831

(file: OptionalArg<PyObjectRef>, vm: &VirtualMachine)

    }

    fn get_fd_from_file_opt(file: OptionalArg<PyObjectRef>, vm: &VirtualMachine) -> PyResult<i32> {
        match file {
            OptionalArg::Present(f) if !vm.is_none(&f) => {
                // Check if it's an integer (file descriptor)
                if let Ok(fd) = f.try_to_value::<i32>(vm) {
                    if fd < 0 {
                        return Err(vm.new_value_error("file is not a valid file descriptor"));
                    }
                    return Ok(fd);
                }
                // Try to get fileno() from file object
                let fileno = vm.call_method(&f, "fileno", ())?;
                let fd: i32 = fileno.try_to_value(vm)?;
                if fd < 0 {
                    return Err(vm.new_value_error("file is not a valid file descriptor"));
                }
                // Try to flush the file
                let _ = vm.call_method(&f, "flush", ());
                Ok(fd)
            }
            _ => {
                // file=None or file not passed: fall back to sys.stderr
                let stderr = vm.sys_module.get_attr("stderr", vm)?;
                if vm.is_none(&stderr) {
                    return Err(vm.new_runtime_error("sys.stderr is None"));
                }
                let fileno = vm.call_method(&stderr, "fileno", ())?;
                let fd: i32 = fileno.try_to_value(vm)?;
                let _ = vm.call_method(&stderr, "flush", ());
                Ok(fd)
            }
        }
    }

    fn watchdog_thread(state: WatchdogHandle) {
        let (lock, cvar) = &*state;