nc 0.9.7

Access system calls directly
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31

/// Read value of a symbolic link.
///
/// # Examples
///
/// ```
/// let oldname = "/etc/passwd";
/// let newname = "/tmp/nc-readlinkat";
/// let ret = unsafe { nc::symlinkat(oldname, nc::AT_FDCWD, newname) };
/// assert!(ret.is_ok());
/// let mut buf = [0_u8; nc::PATH_MAX as usize + 1];
/// let buf_len = buf.len();
/// let ret = unsafe { nc::readlinkat(nc::AT_FDCWD, newname, &mut buf) };
/// assert!(ret.is_ok());
/// let n_read = ret.unwrap() as usize;
/// assert_eq!(n_read, oldname.len());
/// assert_eq!(oldname.as_bytes(), &buf[0..n_read]);
/// let ret = unsafe { nc::unlinkat(nc::AT_FDCWD, newname, 0) };
/// assert!(ret.is_ok());
/// ```
pub unsafe fn readlinkat<P: AsRef<Path>>(
    dirfd: i32,
    filename: P,
    buf: &mut [u8],
) -> Result<ssize_t, Errno> {
    let dirfd = dirfd as usize;
    let filename = CString::new(filename.as_ref());
    let filename_ptr = filename.as_ptr() as usize;
    let buf_ptr = buf.as_mut_ptr() as usize;
    let buf_len = buf.len();
    syscall4(SYS_READLINKAT, dirfd, filename_ptr, buf_ptr, buf_len).map(|ret| ret as ssize_t)
}