You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: chdir.rs
    path of file: ./repos/rustix/src/process
    
    the code of the file until where you have to start completion: #[cfg(not(target_os = "fuchsia"))]
use crate::backend::fd::AsFd;
#[cfg(feature = "fs")]
use crate::path;
#[cfg(any(feature = "fs", not(target_os = "fuchsia")))]
use crate::{backend, io};
#[cfg(all(feature = "alloc", feature = "fs"))]
use {
    crate::ffi::{CStr, CString},
    crate::path::SMALL_PATH_BUFFER_SIZE,
    alloc::vec::Vec,
};

/// `chdir(path
    
fn _getcwd(mut buffer: Vec<u8>) -> io::Result<CString> {
    buffer.clear();
    buffer.reserve(SMALL_PATH_BUFFER_SIZE);

    loop {
        match backend::process::syscalls::getcwd(buffer.spare_capacity_mut()) {
            Err(io::Errno::RANGE) => {
                // Use `Vec` reallocation strategy to grow capacity
                // exponentially.
                buffer.reserve(buffer.capacity() + 1);
            }
            Ok(_) => {
                // SAFETY:
                // - "These functions return a null-terminated string"
                // - [POSIX definition 3.375: String]: "A contiguous sequence
                //   of bytes terminated by and including the first null byte."
                //
                // Thus, there will be a single NUL byte at the end of the
                // string.
                //
                // [POSIX definition 3.375: String]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_375
                unsafe {
                    buffer.set_len(
                        CStr::from_ptr(buffer.as_ptr().cast())
                            .to_bytes_with_nul()
                            .len(),
                    );

                    return Ok(CString::from_vec_with_nul_unchecked(buffer));
                }
            }
            Err(errno) => return Err(errno),
        }
    }
}