init.c

sysvinit--linux系统下的init

	while(!got_cont) pause();
	got_cont = 0;
	errno = saved_errno;
}

/*
 *	Set terminal settings to reasonable defaults
 */
void console_stty(void)
{
	struct termios tty;
	int fd;

	if ((fd = console_open(O_RDWR|O_NOCTTY)) < 0) {
		initlog(L_VB, "can't open %s", console_dev);
		return;
	}

	(void) tcgetattr(fd, &tty);

	tty.c_cflag &= CBAUD|CBAUDEX|CSIZE|CSTOPB|PARENB|PARODD;
	tty.c_cflag |= HUPCL|CLOCAL|CREAD;

	tty.c_cc[VINTR]  = 3;	/* ctrl('c') */
	tty.c_cc[VQUIT]  = 28;	/* ctrl('\\') */
	tty.c_cc[VERASE] = 127;
	tty.c_cc[VKILL]  = 24;	/* ctrl('x') */
	tty.c_cc[VEOF]   = 4;	/* ctrl('d') */
	tty.c_cc[VTIME]  = 0;
	tty.c_cc[VMIN]   = 1;
	tty.c_cc[VSTART] = 17;	/* ctrl('q') */
	tty.c_cc[VSTOP]  = 19;	/* ctrl('s') */
	tty.c_cc[VSUSP]  = 26;	/* ctrl('z') */

	/*
	 *	Set pre and post processing
	 */
	tty.c_iflag = IGNPAR|ICRNL|IXON|IXANY;
	tty.c_oflag = OPOST|ONLCR;
	tty.c_lflag = ISIG|ICANON|ECHO|ECHOCTL|ECHOPRT|ECHOKE;

	/*
	 *	Now set the terminal line.
	 *	We don't care about non-transmitted output data
	 *	and non-read input data.
	 */
	(void) tcsetattr(fd, TCSANOW, &tty);
	(void) tcflush(fd, TCIOFLUSH);
	(void) close(fd);
}

/*
 *	Print to the system console
 */
void print(char *s)
{
	int fd;

	if ((fd = console_open(O_WRONLY|O_NOCTTY|O_NDELAY)) >= 0) {
		write(fd, s, strlen(s));
		close(fd);
	}
}

/*
 *	Log something to a logfile and the console.
 */
#ifdef __GNUC__
__attribute__ ((format (printf, 2, 3)))
#endif
void initlog(int loglevel, char *s, ...)
{
	va_list va_alist;
	char buf[256];
	sigset_t nmask, omask;

	va_start(va_alist, s);
	vsnprintf(buf, sizeof(buf), s, va_alist);
	va_end(va_alist);

	if (loglevel & L_SY) {
		/*
		 *	Re-establish connection with syslogd every time.
		 *	Block signals while talking to syslog.
		 */
		sigfillset(&nmask);
		sigprocmask(SIG_BLOCK, &nmask, &omask);
		openlog("init", 0, LOG_DAEMON);
		syslog(LOG_INFO, "%s", buf);
		closelog();
		sigprocmask(SIG_SETMASK, &omask, NULL);
	}

	/*
	 *	And log to the console.
	 */
	if (loglevel & L_CO) {
		print("\rINIT: ");
		print(buf);
		print("\r\n");
	}
}


/*
 *	Build a new environment for execve().
 */
char **init_buildenv(int child)
{
	char		i_lvl[] = "RUNLEVEL=x";
	char		i_prev[] = "PREVLEVEL=x";
	char		i_cons[32];
	char		**e;
	int		n, i;

	for (n = 0; environ[n]; n++)
		;
	n += NR_EXTRA_ENV + 8;
	e = calloc(n, sizeof(char *));

	for (n = 0; environ[n]; n++)
		e[n] = istrdup(environ[n]);

	for (i = 0; i < NR_EXTRA_ENV; i++)
		if (extra_env[i])
			e[n++] = istrdup(extra_env[i]);

	if (child) {
		snprintf(i_cons, sizeof(i_cons), "CONSOLE=%s", console_dev);
		i_lvl[9]   = thislevel;
		i_prev[10] = prevlevel;
		e[n++] = istrdup(i_lvl);
		e[n++] = istrdup(i_prev);
		e[n++] = istrdup(i_cons);
		e[n++] = istrdup(E_VERSION);
	}

	e[n++] = NULL;

	return e;
}


void init_freeenv(char **e)
{
	int		n;

	for (n = 0; e[n]; n++)
		free(e[n]);
	free(e);
}


/*
 *	Fork and execute.
 *
 *	This function is too long and indents too deep.
 *
 */
int spawn(CHILD *ch, int *res)
{
  char *args[16];		/* Argv array */
  char buf[136];		/* Line buffer */
  int f, st, rc;		/* Scratch variables */
  char *ptr;			/* Ditto */
  time_t t;			/* System time */
  int oldAlarm;			/* Previous alarm value */
  char *proc = ch->process;	/* Command line */
  pid_t pid, pgrp;		/* child, console process group. */
  sigset_t nmask, omask;	/* For blocking SIGCHLD */
  struct sigaction sa;

  *res = -1;
  buf[sizeof(buf) - 1] = 0;

  /* Skip '+' if it's there */
  if (proc[0] == '+') proc++;

  ch->flags |= XECUTED;

  if (ch->action == RESPAWN || ch->action == ONDEMAND) {
	/* Is the date stamp from less than 2 minutes ago? */
	time(&t);
	if (ch->tm + TESTTIME > t) {
		ch->count++;
	} else {
		ch->count = 0;
		ch->tm = t;
	}

	/* Do we try to respawn too fast? */
	if (ch->count >= MAXSPAWN) {

	  initlog(L_VB,
		"Id \"%s\" respawning too fast: disabled for %d minutes",
		ch->id, SLEEPTIME / 60);
	  ch->flags &= ~RUNNING;
	  ch->flags |= FAILING;

	  /* Remember the time we stopped */
	  ch->tm = t;

	  /* Try again in 5 minutes */
	  oldAlarm = alarm(0);
	  if (oldAlarm > SLEEPTIME || oldAlarm <= 0) oldAlarm = SLEEPTIME;
	  alarm(oldAlarm);
	  return(-1);
	}
  }

  /* See if there is an "initscript" (except in single user mode). */
  if (access(INITSCRIPT, R_OK) == 0 && runlevel != 'S') {
	/* Build command line using "initscript" */
	args[1] = SHELL;
	args[2] = INITSCRIPT;
	args[3] = ch->id;
	args[4] = ch->rlevel;
	args[5] = "unknown";
	for(f = 0; actions[f].name; f++) {
		if (ch->action == actions[f].act) {
			args[5] = actions[f].name;
			break;
		}
	}
	args[6] = proc;
	args[7] = NULL;
  } else if (strpbrk(proc, "~`!$^&*()=|\\{}[];\"'<>?")) {
  /* See if we need to fire off a shell for this command */
  	/* Give command line to shell */
  	args[1] = SHELL;
  	args[2] = "-c";
  	strcpy(buf, "exec ");
  	strncat(buf, proc, sizeof(buf) - strlen(buf) - 1);
  	args[3] = buf;
  	args[4] = NULL;
  } else {
	/* Split up command line arguments */
	buf[0] = 0;
  	strncat(buf, proc, sizeof(buf) - 1);
  	ptr = buf;
  	for(f = 1; f < 15; f++) {
  		/* Skip white space */
  		while(*ptr == ' ' || *ptr == '\t') ptr++;
  		args[f] = ptr;
  		
		/* May be trailing space.. */
		if (*ptr == 0) break;

  		/* Skip this `word' */
  		while(*ptr && *ptr != ' ' && *ptr != '\t' && *ptr != '#')
  			ptr++;
  		
  		/* If end-of-line, break */	
  		if (*ptr == '#' || *ptr == 0) {
  			f++;
  			*ptr = 0;
  			break;
  		}
  		/* End word with \0 and continue */
  		*ptr++ = 0;
  	}
  	args[f] = NULL;
  }
  args[0] = args[1];
  while(1) {
	/*
	 *	Block sigchild while forking.
	 */
	sigemptyset(&nmask);
	sigaddset(&nmask, SIGCHLD);
	sigprocmask(SIG_BLOCK, &nmask, &omask);

	if ((pid = fork()) == 0) {

		close(0);
		close(1);
		close(2);
		if (pipe_fd >= 0) close(pipe_fd);

  		sigprocmask(SIG_SETMASK, &omask, NULL);

		/*
		 *	In sysinit, boot, bootwait or single user mode:
		 *	for any wait-type subprocess we _force_ the console
		 *	to be its controlling tty.
		 */
  		if (strchr("*#sS", runlevel) && ch->flags & WAITING) {
			/*
			 *	We fork once extra. This is so that we can
			 *	wait and change the process group and session
			 *	of the console after exit of the leader.
			 */
			setsid();
			if ((f = console_open(O_RDWR|O_NOCTTY)) >= 0) {
				/* Take over controlling tty by force */
				(void)ioctl(f, TIOCSCTTY, 1);
  				dup(f);
  				dup(f);
			}
			if ((pid = fork()) < 0) {
  				initlog(L_VB, "cannot fork");
				exit(1);
			}
			if (pid > 0) {
				/*
				 *	Ignore keyboard signals etc.
				 *	Then wait for child to exit.
				 */
				SETSIG(sa, SIGINT, SIG_IGN, SA_RESTART);
				SETSIG(sa, SIGTSTP, SIG_IGN, SA_RESTART);
				SETSIG(sa, SIGQUIT, SIG_IGN, SA_RESTART);
				SETSIG(sa, SIGCHLD, SIG_DFL, SA_RESTART);

				while ((rc = waitpid(pid, &st, 0)) != pid)
					if (rc < 0 && errno == ECHILD)
						break;

				/*
				 *	Small optimization. See if stealing
				 *	controlling tty back is needed.
				 */
				pgrp = tcgetpgrp(f);
				if (pgrp != getpid())
					exit(0);

				/*
				 *	Steal controlling tty away. We do
				 *	this with a temporary process.
				 */
				if ((pid = fork()) < 0) {
  					initlog(L_VB, "cannot fork");
					exit(1);
				}
				if (pid == 0) {
					setsid();
					(void)ioctl(f, TIOCSCTTY, 1);
					exit(0);
				}
				while((rc = waitpid(pid, &st, 0)) != pid)
					if (rc < 0 && errno == ECHILD)
						break;
				exit(0);
			}

			/* Set ioctl settings to default ones */
			console_stty();

  		} else {
			setsid();
			if ((f = console_open(O_RDWR|O_NOCTTY)) < 0) {
				initlog(L_VB, "open(%s): %s", console_dev,
					strerror(errno));
				f = open("/dev/null", O_RDWR);
			}
			dup(f);
			dup(f);
		}

  		/* Reset all the signals, set up environment */
  		for(f = 1; f < NSIG; f++) SETSIG(sa, f, SIG_DFL, SA_RESTART);
		environ = init_buildenv(1);

		/*
		 *	Execute prog. In case of ENOEXEC try again
		 *	as a shell script.
		 */
  		execvp(args[1], args + 1);
		if (errno == ENOEXEC) {
  			args[1] = SHELL;
  			args[2] = "-c";
  			strcpy(buf, "exec ");
  			strncat(buf, proc, sizeof(buf) - strlen(buf) - 1);
  			args[3] = buf;
  			args[4] = NULL;
			execvp(args[1], args + 1);
		}
  		initlog(L_VB, "cannot execute \"%s\"", args[1]);
  		exit(1);
  	}
	*res = pid;
  	sigprocmask(SIG_SETMASK, &omask, NULL);

	INITDBG(L_VB, "Started id %s (pid %d)", ch->id, pid);

	if (pid == -1) {
		initlog(L_VB, "cannot fork, retry..");
		do_sleep(5);
		continue;
	}
	return(pid);
  }
}

/*
 *	Start a child running!
 */
void startup(CHILD *ch)
{
	/*
	 *	See if it's disabled
	 */
	if (ch->flags & FAILING) return;

	switch(ch->action) {

		case SYSINIT:
		case BOOTWAIT:
		case WAIT:
		case POWERWAIT:
		case POWERFAILNOW:
		case POWEROKWAIT:
		case CTRLALTDEL:
			if (!(ch->flags & XECUTED)) ch->flags |= WAITING;
		case KBREQUEST:
		case BOOT:
		case POWERFAIL:
		case ONCE:
			if (ch->flags & XECUTED) break;
		case ONDEMAND:
		case RESPAWN:
  			ch->flags |= RUNNING;
  			if (spawn(ch, &(ch->pid)) < 0) break;
			/*
			 *	Do NOT log if process field starts with '+'
			 *	FIXME: that's for compatibility with *very*
			 *	old getties - probably it can be taken out.
			 */
  			if (ch->process[0] != '+')
				write_utmp_wtmp("", ch->id, ch->pid,
					INIT_PROCESS, "");
  			break;
	}
}


/*
 *	Read the inittab file.
 */
void read_inittab(void)
{
  FILE		*fp;			/* The INITTAB file */
  CHILD		*ch, *old, *i;		/* Pointers to CHILD structure */
  CHILD		*head = NULL;		/* Head of linked list */
#ifdef INITLVL
  struct stat	st;			/* To stat INITLVL */
#endif
  sigset_t	nmask, omask;		/* For blocking SIGCHLD. */
  char		buf[256];		/* Line buffer */
  char		err[64];		/* Error message. */
  char		*id, *rlevel,
		*action, *process;	/* Fields of a line */
  char		*p;
  int		lineNo = 0;		/* Line number in INITTAB file */
  int		actionNo;		/* Decoded action field */
  int		f;			/* Counter */
  int		round;			/* round 0 for SIGTERM, 1 for SIGKILL */
  int		foundOne = 0;		/* No killing no sleep */
  int		talk;			/* Talk to the user */
  int		done = 0;		/* Ready yet? */

#if DEBUG
  if (newFamily != NULL) {
	INITDBG(L_VB, "PANIC newFamily != NULL");
	exit(1);
  }
  INITDBG(L_VB, "Reading inittab");
#endif

  /*
   *	Open INITTAB and real line by line.
   */
  if ((fp = fopen(INITTAB, "r")) == NULL)
	initlog(L_VB, "No inittab file found");

  while(!done) {
	/*
	 *	Add single user shell entry at the end.
	 */
	if (fp == NULL || fgets(buf, sizeof(buf), fp) == NULL) {
		done = 1;
		/*
		 *	See if we have a single user entry.
		 */
		for(old = newFamily; old; old = old->next)
			if (strpbrk(old->rlevel, "S")) break;
		if (old == NULL)
			snprintf(buf, sizeof(buf), "~~:S:wait:%s\n", SULOGIN);
		else
			continue;
	}
	lineNo++;
	/*
	 *	Skip comments and empty lines
	 */
	for(p = buf; *p == ' ' || *p == '\t'; p++)
		;
	if (*p == '#' || *p == '\n') continue;

	/*
	 *	Decode the fields
	 */
	id =      strsep(&p, ":");
	rlevel =  strsep(&p, ":");
	action =  strsep(&p, ":");
	process = strsep(&p, "\n");

	/*
	 *	Check if syntax is OK. Be very verbose here, to
	 *	avoid newbie postings on comp.os.linux.setup :)
	 */
	err[0] = 0;
	if (!id || !*id) strcpy(err, "missing id field");
	if (!rlevel)     strcpy(err, "missing runlevel field");
	if (!process)    strcpy(err, "missing process field");
	if (!action || !*action)
			strcpy(err, "missing action field");
	if (id && strlen(id) > sizeof(utproto.ut_id))
		sprintf(err, "id field too long (max %d characters)",
			(int)sizeof(utproto.ut_id));
	if (rlevel && strlen(rlevel) > 11)
		strcpy(err, "rlevel field too long (max 11 characters)");
	if (process && strlen(process) > 127)
		strcpy(err, "process field too long");
	if (action && strlen(action) > 32)
		strcpy(err, "action field too long");
	if (err[0] != 0) {
		initlog(L_VB, "%s[%d]: %s", INITTAB, lineNo, err);
		INITDBG(L_VB, "%s:%s:%s:%s", id, rlevel, action, process);
		continue;
	}
  
	/*
	 *	Decode the "action" field
	 */
	actionNo = -1;
	for(f = 0; actions[f].name; f++)
		if (strcasecmp(action, actions[f].name) == 0) {
			actionNo = actions[f].act;
			break;
		}
	if (actionNo == -1) {
		initlog(L_VB, "%s[%d]: %s: unknown action field",
			INITTAB, lineNo, action);
		continue;
	}

	/*
	 *	See if the id field is unique
	 */
	for(old = newFamily; old; old = old->next) {
		if(strcmp(old->id, id) == 0 && strcmp(id, "~~")) {
			initlog(L_VB, "%s[%d]: duplicate ID field \"%s\"",
				INITTAB, lineNo, id);
			break;
		}
	}
	if (old) continue;

	/*
	 *	Allocate a CHILD structure
	 */
	ch = imalloc(sizeof(CHILD));

	/*
	 *	And fill it in.
	 */
	ch->action = actionNo;
	strncpy(ch->id, id, sizeof(utproto.ut_id) + 1); /* Hack for different libs. */
	strncpy(ch->process, process, sizeof(ch->process) - 1);
	if (rlevel[0]) {
		for(f = 0; f < sizeof(rlevel) - 1 && rlevel[f]; f++) {
			ch->rlevel[f] = rlevel[f];
			if (ch->rlevel[f] == 's') ch->rlevel[f] = 'S';
		}
		strncpy(ch->rlevel, rlevel, sizeof(ch->rlevel) - 1);
	} else {
		strcpy(ch->rlevel, "0123456789");
		if (ISPOWER(ch->action))
			strcpy(ch->rlevel, "S0123456789");
	}
	/*
	 *	We have the fake runlevel '#' for SYSINIT  and
	 *	'*' for BOOT and BOOTWAIT.
	 */
	if (ch->action == SYSINIT) strcpy(ch->rlevel, "#");
	if (ch->action == BOOT || ch->action == BOOTWAIT)
		strcpy(ch->rlevel, "*");

	/*
	 *	Now add it to the linked list. Special for powerfail.
	 */
	if (ISPOWER(ch->action)) {

		/*
		 *	Disable by default
		 */
		ch->flags |= XECUTED;

		/*
		 *	Tricky: insert at the front of the list..
		 */
		old = NULL;
		for(i = newFamily; i; i = i->next) {
			if (!ISPOWER(i->action)) break;
			old = i;
		}
		/*
		 *	Now add after entry "old"
		 */
		if (old) {
			ch->next = i;
			old->next = ch;
			if (i == NULL) head = ch;
		} else {
			ch->next = newFamily;
			newFamily = ch;
			if (ch->next == NULL) head = ch;
		}
	} else {
		/*
		 *	Just add at end of the list
		 */
		if (ch->action == KBREQUEST) ch->flags |= XECUTED;
		ch->next = NULL;
		if (head)
			head->next = ch;
		else
			newFamily = ch;
		head = ch;
	}

	/*
	 *	Walk through the old list comparing id fields
	 */
	for(old = family; old; old = old->next)
		if (strcmp(old->id, ch->id) == 0) {
			old->new = ch;
			break;
		}
  }
  /*
   *	We're done.
   */
  if (fp) fclose(fp);

  /*
   *	Loop through the list of children, and see if they need to
   *	be killed. 
   */

  INITDBG(L_VB, "Checking for children to kill");
  for(round = 0; round < 2; round++) {
    talk = 1;
    for(ch = family; ch; ch = ch->next) {
	ch->flags &= ~KILLME;

	/*
	 *	Is this line deleted?
	 */
	if (ch->new == NULL) ch->flags |= KILLME;

	/*
	 *	If the entry has changed, kill it anyway. Note that
	 *	we do not check ch->process, only the "action" field.
	 *	This way, you can turn an entry "off" immediately, but
	 *	changes in the command line will only become effective
	 *	after the running version has exited.
	 */
	if (ch->new && ch->action != ch->new->action) ch->flags |= KILLME;