Chapter 18. A Modem Dialer

	Example	Relevant Functions
18.1	calld.h Header for Modem-Dialer Unified Service	See below
18.2	main.c The modem server main function Get options, initialize daemon, request-loop.	loop
18.3	loop.c The main server loop: Lock modem, serve client dial requests, and hand-back modem full-duplex descriptor to client.	signal_intr (Stevens' lib), log_sys, log_msg, log_quit (Stevens' lib), serv_listen (Stevens' func), FD_ZERO, FD_SET, FD_CLR, FD_ISSET, strcpy, select, read, serv_accept (Stevens' func), client_add, client_del (Stevens' func), lock_rel (Stevens' func), request (Stevens' func), send_err (Stevens' func), close
18.4	cli_args Process client arguments	strcmp, strcpy, sprintf, getopt, optind, opterr,
18.5	client.c Functions to manipulate the client array. (Client bookkeeping in the modem server) client_alloc, client_add, client_del, client_sigchld	malloc, realloc, err_sys, log_quit (Stevens' lib)
18.6	lock.c Functions for managing client device locks	strcmp, strcpy, malloc, realloc, err_sys, log_msg (Stevens' lib),
18.7	sysfile.c Handle UUCP style Systems file	fopen, fgets, strtok, log_sys, log_quit (Stevens' lib), ftell, rewind, fseek
18.8	devfile.c Handle UUCP style Devices file	fopen, fgets, strtok, log_sys, log_quit (Stevens' lib), rewind, strcmp, sprintf
18.9	dialfile.c Handle UUCP style Dialers file	fopen, fgets, strtok, log_sys, log_quit (Stevens' lib), rewind, strcmp, sprintf
18.10	request Client request function	sys_posn, sys_next, child_dial (Stevens' func), DEBUG, is_locked, lock_set (Stevens' func), dev_find (Stevens' func), strcmp, sprintf, fork, TELL_WAIT, TELL_CHILD (Stevens' lib), WAIT_PARENT, log_sys (Stevens' lib),
18.11	sig_chld The SIGCHLD signal handler	waitpid client_sigchld log_sys (Stevens' lib), log_msg (Stevens' lib)
18.12	childdial.c Client dialing function Done in child process	DEBUG (Stevens' func), tty_open, tty_dial, dial_find (Stevens' func), send_fd, log_sys, writen (Stevens' lib), strcmp, strlen
18.13	debug.c Debugging functions: DEBUG, DEBUG_NONL.	va_start, va_end, vsprintf, strlen, log_sys, writen (Stevens' lib),
18.14	tty_open Open modem device or direct connect device, set tty modes based on Devices entry.	strcmp, strcpy, strcat, sprintf, open, isatty, tcgetattr, tcsetattr, cfsetispeed, cfsetospeed, clr_fl (Stevens' lib)
18.15	tty_dial Modem dialing function	strtok, expect_str, send_str (Stevens' func)
18.16	calld/sendstr.c Send string to modem	sprintf, DEBUG, DEBUG_NONL (Stevens' funcs), read, write, log_sys (Stevens' lib)
18.17	ctl_str convert CTRL char to printable string	sprintf
18.18	expect_str Parse expect strings from modem.	strcmp, strncmp, strlen, sprintf, signal, alarm, read, log_quit, log_sys (Stevens' lib), DEBUG (Stevens' func)
18.19	The Client: call.h Client side Interface header file	See below
18.20	main.c Client main program: asks the server to dial and connect to the remote system and then loops multiplexing on input and output streams to/from remote.	getopt, optind, opterr, call.c (Stevens' func.), strcat, printf, atexit, exit, tty_raw, err_sys (Stevens' lib), loop (main client loop)
18.21	call Client: Setup the call request server to establish connection and get back file descriptor to talk to remote via the modem.	cli_conn (Stevens' func.), strlen, writev, err_sys, recv_fd (Stevens' lib)
18.22	loop Client: main loop Multiplex I/O to/from modem and to/from user terminal (4 streams in total) Implementation using poll(2).	setbuf, poll, read, err_sys (Stevens' lib), doescape (Stevens' func), writen (Stevens' lib), write
18.23	doescape Handles escape characters from user (requiring out-of-band special handling).	read, write, err_sys, tty_reset, tty_raw (Stevens' lib), getpid, kill, tcsendbreak, take, put (Stevens' func)
18.24	take Get a filename to copy (src, dest) Using the escape mechanism, and then Copy the file from remote to local	prompt_read (Stevens' func), printf, fopen, err_ret, err_sys (Stevens' lib), putc, fflush, sprintf, strlen, write, ferror, fclose, read
18.25	take_put_args, prompt_read User prompting, getting args via the out-of-band escape mechanism.	tty_reset, tty_raw, err_sys (Stevens' lib), strlen, write, read, buf_args (Stevens' func),
18.26	put Copy file from local to remote.	prompt_read (Stevens' func), printf, fopen, err_ret, err_sys (Stevens' lib), putc, fflush, sprintf, strlen, write, tcdrain, sleep, getc, tty_termios (Stevens' lib), tcflush, ferror, fclose