proc.c

早期freebsd实现

    Char **v;
    struct command *t;
{
    register struct process *pp;

    okpcntl();
    ++v;
    do {
	pp = pfind(*v);
	pstart(pp, 0);
    } while (*v && *++v);
}

/*
 * %... & - builtin - put the job into the background
 */
void
/*ARGSUSED*/
dobg1(v, t)
    Char **v;
    struct command *t;
{
    register struct process *pp;

    pp = pfind(v[0]);
    pstart(pp, 0);
}

/*
 * dostop - builtin - stop the job
 */
void
/*ARGSUSED*/
dostop(v, t)
    Char **v;
    struct command *t;
{
    pkill(++v, SIGSTOP);
}

/*
 * dokill - builtin - superset of kill (1)
 */
void
/*ARGSUSED*/
dokill(v, t)
    Char **v;
    struct command *t;
{
    register int signum = SIGTERM;
    register char *name;

    v++;
    if (v[0] && v[0][0] == '-') {
	if (v[0][1] == 'l') {
	    for (signum = 1; signum < NSIG; signum++) {
		(void) fprintf(cshout, "%s ", sys_signame[signum]);
		if (signum == NSIG / 2)
		    (void) fputc('\n', cshout);
	    }
	    (void) fputc('\n', cshout);
	    return;
	}
	if (Isdigit(v[0][1])) {
	    signum = atoi(short2str(v[0] + 1));
	    if (signum < 0 || signum > NSIG)
		stderror(ERR_NAME | ERR_BADSIG);
	}
	else {
	    name = short2str(&v[0][1]);
	    if (!strncasecmp(name, "sig", 3))
		name += 3;

	    for (signum = 1; signum < NSIG; signum++)
		if (!strcasecmp(sys_signame[signum], name))
		    break;

	    if (signum == NSIG) {
		setname(vis_str(&v[0][1]));
		stderror(ERR_NAME | ERR_UNKSIG);
	    }
	}
	v++;
    }
    pkill(v, signum);
}

static void
pkill(v, signum)
    Char  **v;
    int     signum;
{
    register struct process *pp, *np;
    register int jobflags = 0;
    int     pid, err1 = 0;
    sigset_t omask;
    Char   *cp;

    omask = sigmask(SIGCHLD);
    if (setintr)
	omask |= sigmask(SIGINT);
    omask = sigblock(omask) & ~omask;
    gflag = 0, tglob(v);
    if (gflag) {
	v = globall(v);
	if (v == 0)
	    stderror(ERR_NAME | ERR_NOMATCH);
    }
    else {
	v = gargv = saveblk(v);
	trim(v);
    }

    while (v && (cp = *v)) {
	if (*cp == '%') {
	    np = pp = pfind(cp);
	    do
		jobflags |= np->p_flags;
	    while ((np = np->p_friends) != pp);
	    switch (signum) {

	    case SIGSTOP:
	    case SIGTSTP:
	    case SIGTTIN:
	    case SIGTTOU:
		if ((jobflags & PRUNNING) == 0) {
		    (void) fprintf(csherr, "%s: Already suspended\n",
				   vis_str(cp));
		    err1++;
		    goto cont;
		}
		break;
		/*
		 * suspend a process, kill -CONT %, then type jobs; the shell
		 * says it is suspended, but it is running; thanks jaap..
		 */
	    case SIGCONT:
		pstart(pp, 0);
		goto cont;
	    }
	    if (killpg((pid_t) pp->p_jobid, signum) < 0) {
		(void) fprintf(csherr, "%s: %s\n", vis_str(cp),
			       strerror(errno));
		err1++;
	    }
	    if (signum == SIGTERM || signum == SIGHUP)
		(void) killpg((pid_t) pp->p_jobid, SIGCONT);
	}
	else if (!(Isdigit(*cp) || *cp == '-'))
	    stderror(ERR_NAME | ERR_JOBARGS);
	else {
	    pid = atoi(short2str(cp));
	    if (kill((pid_t) pid, signum) < 0) {
		(void) fprintf(csherr, "%d: %s\n", pid, strerror(errno));
		err1++;
		goto cont;
	    }
	    if (signum == SIGTERM || signum == SIGHUP)
		(void) kill((pid_t) pid, SIGCONT);
	}
cont:
	v++;
    }
    if (gargv)
	blkfree(gargv), gargv = 0;
    (void) sigsetmask(omask);
    if (err1)
	stderror(ERR_SILENT);
}

/*
 * pstart - start the job in foreground/background
 */
void
pstart(pp, foregnd)
    register struct process *pp;
    int     foregnd;
{
    register struct process *np;
    sigset_t omask;
    long    jobflags = 0;

    omask = sigblock(sigmask(SIGCHLD));
    np = pp;
    do {
	jobflags |= np->p_flags;
	if (np->p_flags & (PRUNNING | PSTOPPED)) {
	    np->p_flags |= PRUNNING;
	    np->p_flags &= ~PSTOPPED;
	    if (foregnd)
		np->p_flags |= PFOREGND;
	    else
		np->p_flags &= ~PFOREGND;
	}
    } while ((np = np->p_friends) != pp);
    if (!foregnd)
	pclrcurr(pp);
    (void) pprint(pp, foregnd ? NAME | JOBDIR : NUMBER | NAME | AMPERSAND);
    if (foregnd)
	(void) tcsetpgrp(FSHTTY, pp->p_jobid);
    if (jobflags & PSTOPPED)
	(void) killpg((pid_t) pp->p_jobid, SIGCONT);
    (void) sigsetmask(omask);
}

void
panystop(neednl)
    bool    neednl;
{
    register struct process *pp;

    chkstop = 2;
    for (pp = proclist.p_next; pp; pp = pp->p_next)
	if (pp->p_flags & PSTOPPED)
	    stderror(ERR_STOPPED, neednl ? "\n" : "");
}

struct process *
pfind(cp)
    Char   *cp;
{
    register struct process *pp, *np;

    if (cp == 0 || cp[1] == 0 || eq(cp, STRcent2) || eq(cp, STRcentplus)) {
	if (pcurrent == NULL)
	    stderror(ERR_NAME | ERR_JOBCUR);
	return (pcurrent);
    }
    if (eq(cp, STRcentminus) || eq(cp, STRcenthash)) {
	if (pprevious == NULL)
	    stderror(ERR_NAME | ERR_JOBPREV);
	return (pprevious);
    }
    if (Isdigit(cp[1])) {
	int     idx = atoi(short2str(cp + 1));

	for (pp = proclist.p_next; pp; pp = pp->p_next)
	    if (pp->p_index == idx && pp->p_pid == pp->p_jobid)
		return (pp);
	stderror(ERR_NAME | ERR_NOSUCHJOB);
    }
    np = NULL;
    for (pp = proclist.p_next; pp; pp = pp->p_next)
	if (pp->p_pid == pp->p_jobid) {
	    if (cp[1] == '?') {
		register Char *dp;

		for (dp = pp->p_command; *dp; dp++) {
		    if (*dp != cp[2])
			continue;
		    if (prefix(cp + 2, dp))
			goto match;
		}
	    }
	    else if (prefix(cp + 1, pp->p_command)) {
	match:
		if (np)
		    stderror(ERR_NAME | ERR_AMBIG);
		np = pp;
	    }
	}
    if (np)
	return (np);
    stderror(ERR_NAME | cp[1] == '?' ? ERR_JOBPAT : ERR_NOSUCHJOB);
    /* NOTREACHED */
    return (0);
}


/*
 * pgetcurr - find most recent job that is not pp, preferably stopped
 */
static struct process *
pgetcurr(pp)
    register struct process *pp;
{
    register struct process *np;
    register struct process *xp = NULL;

    for (np = proclist.p_next; np; np = np->p_next)
	if (np != pcurrent && np != pp && np->p_pid &&
	    np->p_pid == np->p_jobid) {
	    if (np->p_flags & PSTOPPED)
		return (np);
	    if (xp == NULL)
		xp = np;
	}
    return (xp);
}

/*
 * donotify - flag the job so as to report termination asynchronously
 */
void
/*ARGSUSED*/
donotify(v, t)
    Char **v;
    struct command *t;
{
    register struct process *pp;

    pp = pfind(*++v);
    pp->p_flags |= PNOTIFY;
}

/*
 * Do the fork and whatever should be done in the child side that
 * should not be done if we are not forking at all (like for simple builtin's)
 * Also do everything that needs any signals fiddled with in the parent side
 *
 * Wanttty tells whether process and/or tty pgrps are to be manipulated:
 *	-1:	leave tty alone; inherit pgrp from parent
 *	 0:	already have tty; manipulate process pgrps only
 *	 1:	want to claim tty; manipulate process and tty pgrps
 * It is usually just the value of tpgrp.
 */

int
pfork(t, wanttty)
    struct command *t;		/* command we are forking for */
    int     wanttty;
{
    register int pid;
    bool    ignint = 0;
    int     pgrp;
    sigset_t omask;

    /*
     * A child will be uninterruptible only under very special conditions.
     * Remember that the semantics of '&' is implemented by disconnecting the
     * process from the tty so signals do not need to ignored just for '&'.
     * Thus signals are set to default action for children unless: we have had
     * an "onintr -" (then specifically ignored) we are not playing with
     * signals (inherit action)
     */
    if (setintr)
	ignint = (tpgrp == -1 && (t->t_dflg & F_NOINTERRUPT))
	    || (gointr && eq(gointr, STRminus));
    /*
     * Check for maximum nesting of 16 processes to avoid Forking loops
     */
    if (child == 16)
	stderror(ERR_NESTING, 16);
    /*
     * Hold SIGCHLD until we have the process installed in our table.
     */
    omask = sigblock(sigmask(SIGCHLD));
    while ((pid = fork()) < 0)
	if (setintr == 0)
	    (void) sleep(FORKSLEEP);
	else {
	    (void) sigsetmask(omask);
	    stderror(ERR_NOPROC);
	}
    if (pid == 0) {
	settimes();
	pgrp = pcurrjob ? pcurrjob->p_jobid : getpid();
	pflushall();
	pcurrjob = NULL;
	child++;
	if (setintr) {
	    setintr = 0;	/* until I think otherwise */
	    /*
	     * Children just get blown away on SIGINT, SIGQUIT unless "onintr
	     * -" seen.
	     */
	    (void) signal(SIGINT, ignint ? SIG_IGN : SIG_DFL);
	    (void) signal(SIGQUIT, ignint ? SIG_IGN : SIG_DFL);
	    if (wanttty >= 0) {
		/* make stoppable */
		(void) signal(SIGTSTP, SIG_DFL);
		(void) signal(SIGTTIN, SIG_DFL);
		(void) signal(SIGTTOU, SIG_DFL);
	    }
	    (void) signal(SIGTERM, parterm);
	}
	else if (tpgrp == -1 && (t->t_dflg & F_NOINTERRUPT)) {
	    (void) signal(SIGINT, SIG_IGN);
	    (void) signal(SIGQUIT, SIG_IGN);
	}
	pgetty(wanttty, pgrp);
	/*
	 * Nohup and nice apply only to NODE_COMMAND's but it would be nice
	 * (?!?) if you could say "nohup (foo;bar)" Then the parser would have
	 * to know about nice/nohup/time
	 */
	if (t->t_dflg & F_NOHUP)
	    (void) signal(SIGHUP, SIG_IGN);
	if (t->t_dflg & F_NICE)
	    (void) setpriority(PRIO_PROCESS, 0, t->t_nice);
    }
    else {
	if (wanttty >= 0)
	    (void) setpgid(pid, pcurrjob ? pcurrjob->p_jobid : pid);
	palloc(pid, t);
	(void) sigsetmask(omask);
    }

    return (pid);
}

static void
okpcntl()
{
    if (tpgrp == -1)
	stderror(ERR_JOBCONTROL);
    if (tpgrp == 0)
	stderror(ERR_JOBCTRLSUB);
}

/*
 * if we don't have vfork(), things can still go in the wrong order
 * resulting in the famous 'Stopped (tty output)'. But some systems
 * don't permit the setpgid() call, (these are more recent secure
 * systems such as ibm's aix). Then we'd rather print an error message
 * than hang the shell!
 * I am open to suggestions how to fix that.
 */
void
pgetty(wanttty, pgrp)
    int     wanttty, pgrp;
{
    sigset_t omask = 0;

    /*
     * christos: I am blocking the tty signals till I've set things
     * correctly....
     */
    if (wanttty > 0)
	omask = sigblock(sigmask(SIGTSTP)|sigmask(SIGTTIN)|sigmask(SIGTTOU));
    /*
     * From: Michael Schroeder <[e-mail]>
     * Don't check for tpgrp >= 0 so even non-interactive shells give
     * background jobs process groups Same for the comparison in the other part
     * of the #ifdef
     */
    if (wanttty >= 0)
	if (setpgid(0, pgrp) == -1) {
	    (void) fprintf(csherr, "csh: setpgid error.\n");
	    xexit(0);
	}

    if (wanttty > 0) {
	(void) tcsetpgrp(FSHTTY, pgrp);
	(void) sigsetmask(omask);
    }

    if (tpgrp > 0)
	tpgrp = 0;		/* gave tty away */
}