readlink ffi in fsharp

test.fs

open System
open System.Collections.Generic
open System.Runtime.InteropServices


[<DllImport("libc", SetLastError=true)>]
extern int readlink(string path, byte[] buffer, int buflen);

let readlink2 path =
  let buf: byte []  = Array.zeroCreate(512)
  let ret = readlink(path, buf, buf.Length)
  if ret = -1 then
    None
  else
    let cbuf: char[] = Array.zeroCreate(512)
    let chars = System.Text.Encoding.Default.GetChars(buf, 0, ret, cbuf, 0)
    String(cbuf, 0, chars) |> Some

readlink2 "/Users/z/Projects/Strawberry/strawberry-backend/test_link2" |> printfn "%A"