Function _getcwd

src/process/chdir.rs:64–98

(mut buffer: Vec<u8>)

#[cfg(all(feature = "alloc", feature = "fs"))]
#[allow(unsafe_code)]
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/9799919799/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),
        }
    }
}