Return_Values

   n                  The number of bytes read.
   -1                 Upon failure, the file pointer remains
                      unchanged and pread sets errno to one of the
                      following values:

                      o  EINVAL - The offset argument is invalid.
                         The value is negative.

                      o  EOVERFLOW - The file is a regular file, and
                         an attempt was made to read or write at or
                         beyond the offset maximum associated with
                         the file.

                      o  ENXIO - A request was outside the
                         capabilities of the device.

                      o  ESPIPE - fildes is associated with a pipe
                         or FIFO.