sem.c

早期freebsd实现

		    else if (tpgrp == -1 &&
			     (t->t_dflg & F_NOINTERRUPT)) {
			(void) signal(SIGINT, SIG_IGN);
			(void) signal(SIGQUIT, SIG_IGN);
		    }

		    pgetty(wanttty, pgrp);
		    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);
		}

	    }
	if (pid != 0) {
	    /*
	     * It would be better if we could wait for the whole job when we
	     * knew the last process had been started.  Pwait, in fact, does
	     * wait for the whole job anyway, but this test doesn't really
	     * express our intentions.
	     */
	    if (didfds == 0 && t->t_dflg & F_PIPEIN) {
		(void) close(pipein[0]);
		(void) close(pipein[1]);
	    }
	    if ((t->t_dflg & F_PIPEOUT) == 0) {
		if (nosigchld) {
		    (void) sigsetmask(csigmask);
		    nosigchld = 0;
		}
		if ((t->t_dflg & F_AMPERSAND) == 0)
		    pwait();
	    }
	    break;
	}
	doio(t, pipein, pipeout);
	if (t->t_dflg & F_PIPEOUT) {
	    (void) close(pipeout[0]);
	    (void) close(pipeout[1]);
	}
	/*
	 * Perform a builtin function. If we are not forked, arrange for
	 * possible stopping
	 */
	if (bifunc) {
	    func(t, bifunc);
	    if (forked)
		exitstat();
	    break;
	}
	if (t->t_dtyp != NODE_PAREN) {
	    doexec(NULL, t);
	    /* NOTREACHED */
	}
	/*
	 * For () commands must put new 0,1,2 in FSH* and recurse
	 */
	OLDSTD = dcopy(0, FOLDSTD);
	SHOUT = dcopy(1, FSHOUT);
	SHERR = dcopy(2, FSHERR);
	(void) close(SHIN);
	SHIN = -1;
	didfds = 0;
	wanttty = -1;
	t->t_dspr->t_dflg |= t->t_dflg & F_NOINTERRUPT;
	execute(t->t_dspr, wanttty, NULL, NULL);
	exitstat();

    case NODE_PIPE:
	t->t_dcar->t_dflg |= F_PIPEOUT |
	    (t->t_dflg & (F_PIPEIN | F_AMPERSAND | F_STDERR | F_NOINTERRUPT));
	execute(t->t_dcar, wanttty, pipein, pv);
	t->t_dcdr->t_dflg |= F_PIPEIN | (t->t_dflg &
			(F_PIPEOUT | F_AMPERSAND | F_NOFORK | F_NOINTERRUPT));
	if (wanttty > 0)
	    wanttty = 0;	/* got tty already */
	execute(t->t_dcdr, wanttty, pv, pipeout);
	break;

    case NODE_LIST:
	if (t->t_dcar) {
	    t->t_dcar->t_dflg |= t->t_dflg & F_NOINTERRUPT;
	    execute(t->t_dcar, wanttty, NULL, NULL);
	    /*
	     * In strange case of A&B make a new job after A
	     */
	    if (t->t_dcar->t_dflg & F_AMPERSAND && t->t_dcdr &&
		(t->t_dcdr->t_dflg & F_AMPERSAND) == 0)
		pendjob();
	}
	if (t->t_dcdr) {
	    t->t_dcdr->t_dflg |= t->t_dflg &
		(F_NOFORK | F_NOINTERRUPT);
	    execute(t->t_dcdr, wanttty, NULL, NULL);
	}
	break;

    case NODE_OR:
    case NODE_AND:
	if (t->t_dcar) {
	    t->t_dcar->t_dflg |= t->t_dflg & F_NOINTERRUPT;
	    execute(t->t_dcar, wanttty, NULL, NULL);
	    if ((getn(value(STRstatus)) == 0) !=
		(t->t_dtyp == NODE_AND))
		return;
	}
	if (t->t_dcdr) {
	    t->t_dcdr->t_dflg |= t->t_dflg &
		(F_NOFORK | F_NOINTERRUPT);
	    execute(t->t_dcdr, wanttty, NULL, NULL);
	}
	break;
    }
    /*
     * Fall through for all breaks from switch
     * 
     * If there will be no more executions of this command, flush all file
     * descriptors. Places that turn on the F_REPEAT bit are responsible for
     * doing donefds after the last re-execution
     */
    if (didfds && !(t->t_dflg & F_REPEAT))
	donefds();
}

static void
vffree(i)
int i;
{
    register Char **v;

    if ((v = gargv) != NULL) {
	gargv = 0;
	xfree((ptr_t) v);
    }
    if ((v = pargv) != NULL) {
	pargv = 0;
	xfree((ptr_t) v);
    }
    _exit(i);
}

/*
 * Expand and glob the words after an i/o redirection.
 * If more than one word is generated, then update the command vector.
 *
 * This is done differently in all the shells:
 * 1. in the bourne shell and ksh globbing is not performed
 * 2. Bash/csh say ambiguous
 * 3. zsh does i/o to/from all the files
 * 4. itcsh concatenates the words.
 *
 * I don't know what is best to do. I think that Ambiguous is better
 * than restructuring the command vector, because the user can get
 * unexpected results. In any case, the command vector restructuring 
 * code is present and the user can choose it by setting noambiguous
 */
static Char *
splicepipe(t, cp)
    register struct command *t;
    Char *cp;	/* word after < or > */
{
    Char *blk[2];

    if (adrof(STRnoambiguous)) {
	Char **pv;

	blk[0] = Dfix1(cp); /* expand $ */
	blk[1] = NULL;

	gflag = 0, tglob(blk);
	if (gflag) {
	    pv = globall(blk);
	    if (pv == NULL) {
		setname(vis_str(blk[0]));
		xfree((ptr_t) blk[0]);
		stderror(ERR_NAME | ERR_NOMATCH);
	    }
	    gargv = NULL;
	    if (pv[1] != NULL) { /* we need to fix the command vector */
		Char **av = blkspl(t->t_dcom, &pv[1]);
		xfree((ptr_t) t->t_dcom);
		t->t_dcom = av;
	    }
	    xfree((ptr_t) blk[0]);
	    blk[0] = pv[0];
	    xfree((ptr_t) pv);
	}
    }
    else {
	blk[0] = globone(blk[1] = Dfix1(cp), G_ERROR);
	xfree((ptr_t) blk[1]);
    }
    return(blk[0]);
}

/*
 * Perform io redirection.
 * We may or maynot be forked here.
 */
static void
doio(t, pipein, pipeout)
    register struct command *t;
    int    *pipein, *pipeout;
{
    register int fd;
    register Char *cp;
    register int flags = t->t_dflg;

    if (didfds || (flags & F_REPEAT))
	return;
    if ((flags & F_READ) == 0) {/* F_READ already done */
	if (t->t_dlef) {
	    char    tmp[MAXPATHLEN+1];

	    /*
	     * so < /dev/std{in,out,err} work
	     */
	    (void) dcopy(SHIN, 0);
	    (void) dcopy(SHOUT, 1);
	    (void) dcopy(SHERR, 2);
	    cp = splicepipe(t, t->t_dlef);
	    (void) strncpy(tmp, short2str(cp), MAXPATHLEN);
	    tmp[MAXPATHLEN] = '\0';
	    xfree((ptr_t) cp);
	    if ((fd = open(tmp, O_RDONLY)) < 0)
		stderror(ERR_SYSTEM, tmp, strerror(errno));
	    (void) dmove(fd, 0);
	}
	else if (flags & F_PIPEIN) {
	    (void) close(0);
	    (void) dup(pipein[0]);
	    (void) close(pipein[0]);
	    (void) close(pipein[1]);
	}
	else if ((flags & F_NOINTERRUPT) && tpgrp == -1) {
	    (void) close(0);
	    (void) open(_PATH_DEVNULL, O_RDONLY);
	}
	else {
	    (void) close(0);
	    (void) dup(OLDSTD);
	    (void) ioctl(0, FIONCLEX, NULL);
	}
    }
    if (t->t_drit) {
	char    tmp[MAXPATHLEN+1];

	cp = splicepipe(t, t->t_drit);
	(void) strncpy(tmp, short2str(cp), MAXPATHLEN);
	tmp[MAXPATHLEN] = '\0';
	xfree((ptr_t) cp);
	/*
	 * so > /dev/std{out,err} work
	 */
	(void) dcopy(SHOUT, 1);
	(void) dcopy(SHERR, 2);
	if ((flags & F_APPEND) &&
#ifdef O_APPEND
	    (fd = open(tmp, O_WRONLY | O_APPEND)) >= 0);
#else
	    (fd = open(tmp, O_WRONLY)) >= 0)
	    (void) lseek(1, (off_t) 0, L_XTND);
#endif
	else {
	    if (!(flags & F_OVERWRITE) && adrof(STRnoclobber)) {
		if (flags & F_APPEND)
		    stderror(ERR_SYSTEM, tmp, strerror(errno));
		chkclob(tmp);
	    }
	    if ((fd = creat(tmp, 0666)) < 0)
		stderror(ERR_SYSTEM, tmp, strerror(errno));
	}
	(void) dmove(fd, 1);
    }
    else if (flags & F_PIPEOUT) {
	(void) close(1);
	(void) dup(pipeout[1]);
    }
    else {
	(void) close(1);
	(void) dup(SHOUT);
	(void) ioctl(1, FIONCLEX, NULL);
    }

    (void) close(2);
    if (flags & F_STDERR) {
	(void) dup(1);
    }
    else {
	(void) dup(SHERR);
	(void) ioctl(2, FIONCLEX, NULL);
    }
    didfds = 1;
}

void
mypipe(pv)
    register int *pv;
{

    if (pipe(pv) < 0)
	goto oops;
    pv[0] = dmove(pv[0], -1);
    pv[1] = dmove(pv[1], -1);
    if (pv[0] >= 0 && pv[1] >= 0)
	return;
oops:
    stderror(ERR_PIPE);
}

static void
chkclob(cp)
    register char *cp;
{
    struct stat stb;

    if (stat(cp, &stb) < 0)
	return;
    if (S_ISCHR(stb.st_mode))
	return;
    stderror(ERR_EXISTS, cp);
}