tty.c

举世闻名的joe记事本源程序

	}
	if (ackkbd != -1) {
		if (!have) {	/* Wait for input */
			stat = read(mpxfd, &pack, sizeof(struct packet) - 1024);

			if (pack.size && stat > 0) {
				joe_read(mpxfd, pack.data, pack.size);
			} else if (stat < 1) {
				if (winched || ticked)
					goto loop;
				else
					ttsig(0);
			}
			accept = pack.ch;
		}
		have = 0;
		if (pack.who) {	/* Got bknd input */
			if (accept != NO_MORE_DATA) {
				if (pack.who->func) {
					pack.who->func(pack.who->object, pack.data, pack.size);
					edupd(1);
				}
			} else
				mpxdied(pack.who);
			goto loop;
		} else {
			if (accept != NO_MORE_DATA) {
				tickoff();
				return accept;
			}
			else {
				tickoff();
				ttsig(0);
				return 0;
			}
		}
	}
	if (have) {
		have = 0;
	} else {
		if (read(fileno(termin), &havec, 1) < 1) {
			if (winched || ticked)
				goto loop;
			else
				ttsig(0);
		}
	}
	tickoff();
	return havec;
}

/* Write string to output */

void ttputs(unsigned char *s)
{
	while (*s) {
		obuf[obufp++] = *s++;
		if (obufp == obufsiz)
			ttflsh();
	}
}

/* Get window size */

void ttgtsz(int *x, int *y)
{
#ifdef TIOCGSIZE
	struct ttysize getit;
#else
#ifdef TIOCGWINSZ
	struct winsize getit;
#endif
#endif

	*x = 0;
	*y = 0;

#ifdef TIOCGSIZE
	if (ioctl(fileno(termout), TIOCGSIZE, &getit) != -1) {
		*x = getit.ts_cols;
		*y = getit.ts_lines;
	}
#else
#ifdef TIOCGWINSZ
	if (ioctl(fileno(termout), TIOCGWINSZ, &getit) != -1) {
		*x = getit.ws_col;
		*y = getit.ws_row;
	}
#endif
#endif
}

int ttshell(unsigned char *cmd)
{
	int x, omode = ttymode;
	int stat= -1;
	unsigned char *s = (unsigned char *)getenv("SHELL");

	if (!s) {
		s = USTR "/bin/sh";
		/* return; */
	}
	ttclsn();
#ifdef HAVE_FORK
	if ((x = fork()) != 0) {
#else
	if ((x = vfork()) != 0) { /* For AMIGA only  */
#endif
		if (x != -1)
			wait(&stat);
		if (omode)
			ttopnn();
		return stat;
	} else {
		signrm();
		if (cmd)
			execl((char *)s, (char *)s, "-c", cmd, NULL);
		else {
			fprintf(stderr, (char *)joe_gettext(_("You are at the command shell.  Type 'exit' to return\n")));
			execl((char *)s, (char *)s, NULL);
		}
		_exit(0);
		return 0;
	}
}

/* Create keyboard task */

static void mpxresume(void)
{
	int fds[2];
	pipe(fds);
	accept = NO_MORE_DATA;
	have = 0;
	if (!(kbdpid = fork())) {
		close(fds[1]);
		do {
			unsigned char c;
			int sta;

			pack.who = 0;
			sta = joe_read(fileno(termin), &c, 1);
			if (sta == 0)
				pack.ch = NO_MORE_DATA;
			else
				pack.ch = c;
			pack.size = 0;
			joe_write(mpxsfd, &pack, sizeof(struct packet) - 1024);
		} while (joe_read(fds[0], &pack, 1) == 1);
		_exit(0);
	}
	close(fds[0]);
	ackkbd = fds[1];
}

/* Kill keyboard task */

static void mpxsusp(void)
{
	if (ackkbd!=-1) {
		kill(kbdpid, 9);
		while (wait(NULL) < 0 && errno == EINTR)
			/* do nothing */;
		close(ackkbd);
	}
}

/* We used to leave the keyboard copy task around during suspend, but
   Cygwin gets confused when two processes are waiting for input and you
   change the tty from raw to cooked (on the call to ttopnn()): the keyboard
   process was stuck in cooked until he got a carriage return- then he
   switched back to raw (he's supposed to switch to raw without waiting for
   the end of line). Probably this should be done for ttshell() as well. */

void ttsusp(void)
{
	int omode;

#ifdef SIGTSTP
	omode = ttymode;
	mpxsusp();
	ttclsn();
	fprintf(stderr, (char *)joe_gettext(_("You have suspended the program.  Type 'fg' to return\n")));
	kill(0, SIGTSTP);
#ifdef junk
	/* Hmmm... this should not have been necessary */
	if (ackkbd != -1)
		kill(kbdpid, SIGCONT);
#endif
	if (omode)
		ttopnn();
	if (ackkbd!= -1)
		mpxresume();
#else
	ttshell(NULL);
#endif
}

/* Stuff for asynchronous I/O multiplexing.  We do not use streams or
   select() because joe needs to work on versions of UNIX which predate
   these calls.  Instead, when there is multiple async sources, we use
   helper processes which packetize data from the sources.  A header on each
   packet indicates the source.  There is no guarentee that packets getting
   written to the same pipe don't get interleaved, but you can reasonable
   rely on it with small packets. */

static void mpxstart(void)
{
	int fds[2];
	pipe(fds);
	mpxfd = fds[0];
	mpxsfd = fds[1];
	mpxresume();
}

static void mpxend(void)
{
	mpxsusp();
	ackkbd = -1;
	close(mpxfd);
	close(mpxsfd);
	if (have)
		havec = pack.ch;
}

/* Get a pty/tty pair.  Returns open pty in 'ptyfd' and returns tty name
 * string in static buffer or NULL if couldn't get a pair.
 */

#ifdef __svr4__
#define USEPTMX 1
#else
#ifdef __CYGWIN__
#define USEPTMX 1
#endif
#endif

#ifdef sgi

/* Newer sgi machines can do it the __svr4__ way, but old ones can't */

extern char *_getpty();

static unsigned char *getpty(int *ptyfd)
{
	return (unsigned char *)_getpty(ptyfd, O_RDWR, 0600, 0);
}

#else
#ifdef USEPTMX

/* Strange streams way */

extern char *ptsname();

static unsigned char *getpty(int *ptyfd)
{
	int fdm;
	*ptyfd = fdm = open("/dev/ptmx", O_RDWR);
	grantpt(fdm);
	unlockpt(fdm);
	return (unsigned char *)ptsname(fdm);
}

#else
#ifdef HAVE_OPENPTY

/* BSD function, present in libc5 and glibc2 */

static unsigned char *getpty(int *ptyfd)
{
	static unsigned char name[32];
	int ttyfd;

        if (openpty(ptyfd, &ttyfd, (char *)name, NULL, NULL) == 0)
           return(name);
        else
	   return (NULL);
}

#else
/* The normal way: for each possible pty/tty pair, try to open the pty and
 * then the corresponding tty.  If both could be opened, close them both and
 * then re-open the pty.  If that succeeded, return with the opened pty and the
 * name of the tty.
 *
 * Logically you should only have to succeed in opening the pty- but the
 * permissions may be set wrong on the tty, so we have to try that too.
 * We close them both and re-open the pty because we want the forked process
 * to open the tty- that way it gets to be the controlling tty for that
 * process and the process gets to be the session leader.
 */

static unsigned char *getpty(int *ptyfd)
{
	int x, fd;
	unsigned char *orgpwd = pwd();
	static unsigned char **ptys = NULL;
	static unsigned char *ttydir;
	static unsigned char *ptydir;
	static unsigned char ttyname[32];

	if (!ptys) {
		ttydir = USTR "/dev/pty/";
		ptydir = USTR "/dev/ptym/";	/* HPUX systems */
		if (chpwd(ptydir) || !(ptys = rexpnd(USTR "pty*")))
			if (!ptys) {
				ttydir = ptydir = USTR "/dev/";	/* Everyone else */
				if (!chpwd(ptydir))
					ptys = rexpnd(USTR "pty*");
			}
	}
	chpwd(orgpwd);

	if (ptys)
		for (fd = 0; ptys[fd]; ++fd) {
			zcpy(ttyname, ptydir);
			zcat(ttyname, ptys[fd]);
			if ((*ptyfd = open((char *)ttyname, O_RDWR)) >= 0) {
				ptys[fd][0] = 't';
				zcpy(ttyname, ttydir);
				zcat(ttyname, ptys[fd]);
				ptys[fd][0] = 'p';
				x = open((char *)ttyname, O_RDWR);
				if (x >= 0) {
					close(x);
					close(*ptyfd);
					zcpy(ttyname, ptydir);
					zcat(ttyname, ptys[fd]);
					*ptyfd = open((char *)ttyname, O_RDWR);
					ptys[fd][0] = 't';
					zcpy(ttyname, ttydir);
					zcat(ttyname, ptys[fd]);
					ptys[fd][0] = 'p';
					return ttyname;
				} else
					close(*ptyfd);
			}
		}
	return NULL;
}

#endif
#endif
#endif

/* Shell dies signal handler.  Puts pty in non-block mode so
 * that read returns with <1 when all data from process has
 * been read. */
int dead = 0;
int death_fd;
static RETSIGTYPE death(int unused)
{
	fcntl(death_fd,F_SETFL,O_NDELAY);
	wait(NULL);
	dead = 1;
}

#ifndef SIGCHLD
#define SIGCHLD SIGCLD
#endif

/* Build a new environment, but replace one variable */

static unsigned char **newenv(unsigned char **old, unsigned char *s)
{
	unsigned char **new;
	int x, y, z;

	for (x = 0; old[x]; ++x) ;
	new = (unsigned char **) joe_malloc((x + 2) * sizeof(unsigned char *));

	for (x = 0, y = 0; old[x]; ++x) {
		for (z = 0; s[z] != '='; ++z)
			if (s[z] != old[x][z])
				break;
		if (s[z] == '=') {
			if (s[z + 1])
				new[y++] = s;
		} else
			new[y++] = old[x];
	}
	if (x == y)
		new[y++] = s;
	new[y] = 0;
	return new;
}

/* Create a shell process */

/* If out_only is set, leave program's stdin attached to JOE's stdin */

MPX *mpxmk(int *ptyfd, unsigned char *cmd, unsigned char **args, void (*func) (/* ??? */), void *object, void (*die) (/* ??? */), void *dieobj, int out_only)
{
	unsigned char buf[80];
	int fds[2];
	int comm[2];
	pid_t pid;
	int x;
	MPX *m = 0;
	unsigned char *name;

	/* Get pty/tty pair */
	if (!(name = getpty(ptyfd)))
		return NULL;

	/* Find free slot */
	for (x = 0; x != NPROC; ++x)
		if (!asyncs[x].func) {
			m = asyncs + x;
			break;
		}
	if (x==NPROC)
		return NULL;

	/* Fixes cygwin console bug: if you fork() with inverse video he assumes you want
	 * ESC [ 0 m to keep it in inverse video from then on. */
	set_attr(maint->t,0);

	/* Flush output */
	ttflsh();

	/* Bump no. current async inputs to joe */
	++nmpx;

	/* Start input multiplexer */
	if (ackkbd == -1)
		mpxstart();

	/* Remember callback function */
	m->func = func;
	m->object = object;
	m->die = die;
	m->dieobj = dieobj;

	/* Acknowledgement pipe */
	pipe(fds);
	m->ackfd = fds[1];

	/* PID number pipe */
	pipe(comm);


	/* Create processes... */
	if (!(m->kpid = fork())) {
		/* This process copies data from shell to joe */
		/* After each packet it sends to joe it waits for
		   an acknowledgement from joe so that it can not get
		   too far ahead with buffering */

		/* Close joe side of pipes */
		close(fds[1]);
		close(comm[0]);

		/* Flag which indicates child died */
		dead = 0;
		death_fd = *ptyfd;
		joe_set_signal(SIGCHLD, death);

		if (!(pid = fork())) {
			/* This process becomes the shell */
			signrm();

			/* Close pty (we only need tty) */
			close(*ptyfd);

			/* All of this stuff is for disassociating ourself from
			   controlling tty (session leader) and starting a new
			   session.  This is the most non-portable part of UNIX- second
			   only to pty/tty pair creation. */
#ifndef HAVE_LOGIN_TTY

#ifdef TIOCNOTTY
			x = open("/dev/tty", O_RDWR);
			ioctl(x, TIOCNOTTY, 0);
#endif

			setsid();	/* I think you do setprgp(0,0) on systems with no setsid() */
#ifndef SETPGRP_VOID
			setpgrp(0, 0);
#else
			setpgrp();
#endif

#endif

			/* Close all fds */
			for (x = (out_only ? 1 : 0); x != 32; ++x)
				close(x);	/* Yes, this is quite a kludge... all in the
						   name of portability */


			/* Open the TTY */
			if ((x = open((char *)name, O_RDWR)) != -1) {	/* Standard input */
				unsigned char **env = newenv(mainenv, USTR "TERM=");


				if (!out_only) {
#ifdef HAVE_LOGIN_TTY
					login_tty(x);

#else
				/* This tells the fd that it's a tty (I think) */
#ifdef __svr4__
					ioctl(x, I_PUSH, "ptem");
					ioctl(x, I_PUSH, "ldterm");
#endif

				/* Open stdout, stderr */
					dup(x);
					dup(x);	/* Standard output, standard error */
					/* (yes, stdin, stdout, and stderr must all be open for reading and
					 * writing.  On some systems the shell assumes this */
#endif

#ifdef HAVE_POSIX_TERMIOS
					tcsetattr(0, TCSADRAIN, &oldterm);
#else
#ifdef HAVE_SYSV_TERMIO
					ioctl(0, TCSETAW, &oldterm);
#else
					ioctl(0, TIOCSETN, &oarg);
					ioctl(0, TIOCSETC, &otarg);
					ioctl(0, TIOCSLTC, &oltarg);
#endif
#endif
					/* We could probably have a special TTY set-up for JOE, but for now
					 * we'll just use the TTY setup for the TTY was was run on */

					/* Execute the shell */
					execve((char *)cmd, (char **)args, (char **)env);

					/* If shell didn't execute */
					joe_snprintf_1(buf,sizeof(buf),joe_gettext(_("Couldn't execute shell '%s'\n")),cmd);
					write(1,(char *)buf,zlen(buf));
					sleep(1);

				} else {
					unsigned char buf[1024];
					int len;
					dup(x); /* Standard error */
					
					for (;;) {
						len = read(0, buf, sizeof(buf));
						if (len > 0)
							write(1, buf, len);
						else
							break;
					}
				}


			}

			_exit(0);
		}

		/* Tell JOE PID of shell */
		joe_write(comm[1], &pid, sizeof(pid));

		/* sigpipe should be ignored here. */

		/* This process copies data from shell to JOE until EOF.  It creates a packet
		   for each data */


		/* We don't really get EOF from a pty- it would just wait forever
		   until someone else writes to the tty.  So: when the shell
		   dies, the child died signal handler death() puts pty in non-block
		   mode.  This allows us to read any remaining data- then
		   read returns 0 and we know we're done. */

	      loop:
		pack.who = m;
		pack.ch = 0;

		/* Read data from process */
		pack.size = joe_read(*ptyfd, pack.data, 1024);

		/* On SUNOS 5.8, the very first read from the pty returns 0 for some reason */
		if (!pack.size)
			pack.size = joe_read(*ptyfd, pack.data, 1024);

		if (pack.size > 0) {
			/* Send data to JOE, wait for ack */
			joe_write(mpxsfd, &pack, sizeof(struct packet) - 1024 + pack.size);

			joe_read(fds[0], &pack, 1);
			goto loop;
		} else {
			/* Shell died: return */
			pack.ch = NO_MORE_DATA;
			pack.size = 0;
			joe_write(mpxsfd, &pack, sizeof(struct packet) - 1024);

			_exit(0);
		}
	}
	joe_read(comm[0], &m->pid, sizeof(m->pid));

	/* We only need comm once */
	close(comm[0]);
	close(comm[1]);

	/* Close other side of copy process pipe */
	close(fds[0]);
	return m;
}

void mpxdied(MPX *m)
{
	if (!--nmpx)
		mpxend();
	while (wait(NULL) < 0 && errno == EINTR)
		/* do nothing */;
	if (m->die)
		m->die(m->dieobj);
	m->func = NULL;
	edupd(1);
}