write_nonblock

/*
 *  call-seq:
 *     ios.write_nonblock(string)   => integer
 *
 *  Writes the given string to <em>ios</em> using
 *  write(2) system call after O_NONBLOCK is set for
 *  the underlying file descriptor.
 *
 *  write_nonblock just calls write(2).
 *  It causes all errors write(2) causes: EAGAIN, EINTR, etc.
 *  The result may also be smaller than string.length (partial write).
 *  The caller should care such errors and partial write.
 *
 */

static VALUE
rb_io_write_nonblock(VALUE io, VALUE str)
{
    rb_io_t *fptr;
    FILE *f;
    long n;

    rb_secure(4);
    if (TYPE(str) != T_STRING)
        str = rb_obj_as_string(str);

    GetOpenFile(io, fptr);
    rb_io_check_writable(fptr);

    f = GetWriteFile(fptr);

    rb_io_set_nonblock(fptr);
    n = write(fileno(f), RSTRING(str)->ptr, RSTRING(str)->len);

    if (n == -1) rb_sys_fail(fptr->path);

    return LONG2FIX(n);
}