45 static int s_fd = -1;    /* fd of the AT channel */  variable
372             while (s_fd > 0) {  in readline()
373                 struct pollfd pollfds[1] = {{s_fd, POLLIN, 0}};  in readline()
387             count = (s_fd == -1) ? 0 : read(s_fd, p_read,  in readline()
499     if (s_fd < 0 || s_readerClosed > 0) {  in writeline()
518             written = write (s_fd, s + cur, len - cur);  in writeline()
537         written = write (s_fd, "\r" , 1);  in writeline()
552     if (s_fd < 0 || s_readerClosed > 0) {  in writeCtrlZ()
563             written = write (s_fd, s + cur, len - cur);  in writeCtrlZ()
576         written = write (s_fd, "\032" , 1);  in writeCtrlZ()
590     if (s_fd < 0 || s_readerClosed > 0) {  in writeraw()
596         struct pollfd pollfds[1] = {{s_fd, POLLOUT, 0}};  in writeraw()
604             written = write (s_fd, s + cur, len - cur);  in writeraw()
642     s_fd = fd;  in at_open()
668     if (s_fd >= 0) {  in at_close()
669         close(s_fd);  in at_close()
671     s_fd = -1;  in at_close()