Return_Values

   n                  Upon successful completion, the count of bytes
                      placed in the user_buffer
   -1                 Indicates an error. The buffer is unchanged,
                      and errno is set to indicate the error:

                      o  EACCES - Read permission is denied in the
                         directory where the symbolic link is being
                         read, or search permission is denied for a
                         component of the path prefix of link_name.

                      o  ENAMETOOLONG - The length of the link_name
                         argument exceeds PATH_MAX, or a pathname
                         component is longer than NAME_MAX.

                      o  Any errno value from close, open, or read.