build_symlink
s = build_symlink(vp, cr, &strsz);
s = build_symlink(vp, cs->cr, &strsz);
s = build_symlink(vp, cr, &strsz);
extern char *build_symlink(vnode_t *, cred_t *, size_t *);
extern char *build_symlink(vnode_t *, cred_t *, size_t *);