sem.c

早期freebsd实现

/*-
 * Copyright (c) 1980, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)sem.c	8.1 (Berkeley) 5/31/93";
#endif /* not lint */

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if __STDC__
# include <stdarg.h>
#else
# include <varargs.h>
#endif

#include "csh.h"
#include "proc.h"
#include "extern.h"

static void	 vffree __P((int));
static Char	*splicepipe __P((struct command *t, Char *));
static void	 doio __P((struct command *t, int *, int *));
static void	 chkclob __P((char *));

void
execute(t, wanttty, pipein, pipeout)
    register struct command *t;
    int     wanttty, *pipein, *pipeout;
{
    bool    forked = 0;
    struct biltins *bifunc;
    int     pid = 0;
    int     pv[2];

    static sigset_t csigmask;

    static sigset_t ocsigmask;
    static int onosigchld = 0;
    static int nosigchld = 0;

    UNREGISTER(forked);
    UNREGISTER(bifunc);
    UNREGISTER(wanttty);

    if (t == 0)
	return;

    if (t->t_dflg & F_AMPERSAND)
	wanttty = 0;
    switch (t->t_dtyp) {

    case NODE_COMMAND:
	if ((t->t_dcom[0][0] & (QUOTE | TRIM)) == QUOTE)
	    (void) Strcpy(t->t_dcom[0], t->t_dcom[0] + 1);
	if ((t->t_dflg & F_REPEAT) == 0)
	    Dfix(t);		/* $ " ' \ */
	if (t->t_dcom[0] == 0)
	    return;
	/* fall into... */

    case NODE_PAREN:
	if (t->t_dflg & F_PIPEOUT)
	    mypipe(pipeout);
	/*
	 * Must do << early so parent will know where input pointer should be.
	 * If noexec then this is all we do.
	 */
	if (t->t_dflg & F_READ) {
	    (void) close(0);
	    heredoc(t->t_dlef);
	    if (noexec)
		(void) close(0);
	}

	set(STRstatus, Strsave(STR0));

	/*
	 * This mess is the necessary kludge to handle the prefix builtins:
	 * nice, nohup, time.  These commands can also be used by themselves,
	 * and this is not handled here. This will also work when loops are
	 * parsed.
	 */
	while (t->t_dtyp == NODE_COMMAND)
	    if (eq(t->t_dcom[0], STRnice))
		if (t->t_dcom[1])
		    if (strchr("+-", t->t_dcom[1][0]))
			if (t->t_dcom[2]) {
			    setname("nice");
			    t->t_nice =
				getn(t->t_dcom[1]);
			    lshift(t->t_dcom, 2);
			    t->t_dflg |= F_NICE;
			}
			else
			    break;
		    else {
			t->t_nice = 4;
			lshift(t->t_dcom, 1);
			t->t_dflg |= F_NICE;
		    }
		else
		    break;
	    else if (eq(t->t_dcom[0], STRnohup))
		if (t->t_dcom[1]) {
		    t->t_dflg |= F_NOHUP;
		    lshift(t->t_dcom, 1);
		}
		else
		    break;
	    else if (eq(t->t_dcom[0], STRtime))
		if (t->t_dcom[1]) {
		    t->t_dflg |= F_TIME;
		    lshift(t->t_dcom, 1);
		}
		else
		    break;
	    else
		break;

	/* is it a command */
	if (t->t_dtyp == NODE_COMMAND) {
	    /*
	     * Check if we have a builtin function and remember which one.
	     */
	    bifunc = isbfunc(t);
 	    if (noexec) {
		/*
		 * Continue for builtins that are part of the scripting language
		 */
		if (bifunc->bfunct != dobreak   && bifunc->bfunct != docontin &&
		    bifunc->bfunct != doelse    && bifunc->bfunct != doend    &&
		    bifunc->bfunct != doforeach && bifunc->bfunct != dogoto   &&
		    bifunc->bfunct != doif      && bifunc->bfunct != dorepeat &&
		    bifunc->bfunct != doswbrk   && bifunc->bfunct != doswitch &&
		    bifunc->bfunct != dowhile   && bifunc->bfunct != dozip)
		    break;
	    }
	}
	else {			/* not a command */
	    bifunc = NULL;
	    if (noexec)
		break;
	}

	/*
	 * We fork only if we are timed, or are not the end of a parenthesized
	 * list and not a simple builtin function. Simple meaning one that is
	 * not pipedout, niced, nohupped, or &'d. It would be nice(?) to not
	 * fork in some of these cases.
	 */
	/*
	 * Prevent forking cd, pushd, popd, chdir cause this will cause the
	 * shell not to change dir!
	 */
	if (bifunc && (bifunc->bfunct == dochngd ||
		       bifunc->bfunct == dopushd ||
		       bifunc->bfunct == dopopd))
	    t->t_dflg &= ~(F_NICE);
	if (((t->t_dflg & F_TIME) || ((t->t_dflg & F_NOFORK) == 0 &&
	     (!bifunc || t->t_dflg &
	      (F_PIPEOUT | F_AMPERSAND | F_NICE | F_NOHUP)))) ||
	/*
	 * We have to fork for eval too.
	 */
	    (bifunc && (t->t_dflg & (F_PIPEIN | F_PIPEOUT)) != 0 &&
	     bifunc->bfunct == doeval))
	    if (t->t_dtyp == NODE_PAREN ||
		t->t_dflg & (F_REPEAT | F_AMPERSAND) || bifunc) {
		forked++;
		/*
		 * We need to block SIGCHLD here, so that if the process does
		 * not die before we can set the process group
		 */
		if (wanttty >= 0 && !nosigchld) {
		    csigmask = sigblock(sigmask(SIGCHLD));
		    nosigchld = 1;
		}

		pid = pfork(t, wanttty);
		if (pid == 0 && nosigchld) {
		    (void) sigsetmask(csigmask);
		    nosigchld = 0;
		}
		else if (pid != 0 && (t->t_dflg & F_AMPERSAND))
		    backpid = pid;

	    }
	    else {
		int     ochild, osetintr, ohaderr, odidfds;
		int     oSHIN, oSHOUT, oSHERR, oOLDSTD, otpgrp;
		sigset_t omask;

		/*
		 * Prepare for the vfork by saving everything that the child
		 * corrupts before it exec's. Note that in some signal
		 * implementations which keep the signal info in user space
		 * (e.g. Sun's) it will also be necessary to save and restore
		 * the current sigvec's for the signals the child touches
		 * before it exec's.
		 */
		if (wanttty >= 0 && !nosigchld && !noexec) {
		    csigmask = sigblock(sigmask(SIGCHLD));
		    nosigchld = 1;
		}
		omask = sigblock(sigmask(SIGCHLD) | sigmask(SIGINT));
		ochild = child;
		osetintr = setintr;
		ohaderr = haderr;
		odidfds = didfds;
		oSHIN = SHIN;
		oSHOUT = SHOUT;
		oSHERR = SHERR;
		oOLDSTD = OLDSTD;
		otpgrp = tpgrp;
		ocsigmask = csigmask;
		onosigchld = nosigchld;
		Vsav = Vdp = 0;
		Vexpath = 0;
		Vt = 0;
		pid = vfork();

		if (pid < 0) {
		    (void) sigsetmask(omask);
		    stderror(ERR_NOPROC);
		}
		forked++;
		if (pid) {	/* parent */
		    child = ochild;
		    setintr = osetintr;
		    haderr = ohaderr;
		    didfds = odidfds;
		    SHIN = oSHIN;
		    SHOUT = oSHOUT;
		    SHERR = oSHERR;
		    OLDSTD = oOLDSTD;
		    tpgrp = otpgrp;
		    csigmask = ocsigmask;
		    nosigchld = onosigchld;

		    xfree((ptr_t) Vsav);
		    Vsav = 0;
		    xfree((ptr_t) Vdp);
		    Vdp = 0;
		    xfree((ptr_t) Vexpath);
		    Vexpath = 0;
		    blkfree((Char **) Vt);
		    Vt = 0;
		    /* this is from pfork() */
		    palloc(pid, t);
		    (void) sigsetmask(omask);
		}
		else {		/* child */
		    /* this is from pfork() */
		    int     pgrp;
		    bool    ignint = 0;

		    if (nosigchld) {
			(void) sigsetmask(csigmask);
			nosigchld = 0;
		    }

		    if (setintr)
			ignint =
			    (tpgrp == -1 &&
			     (t->t_dflg & F_NOINTERRUPT))
			    || (gointr && eq(gointr, STRminus));
		    pgrp = pcurrjob ? pcurrjob->p_jobid : getpid();
		    child++;
		    if (setintr) {
			setintr = 0;
			if (ignint) {
			    (void) signal(SIGINT, SIG_IGN);
			    (void) signal(SIGQUIT, SIG_IGN);
			}
			else {
			    (void) signal(SIGINT, vffree);
			    (void) signal(SIGQUIT, SIG_DFL);
			}

			if (wanttty >= 0) {
			    (void) signal(SIGTSTP, SIG_DFL);
			    (void) signal(SIGTTIN, SIG_DFL);
			    (void) signal(SIGTTOU, SIG_DFL);
			}

			(void) signal(SIGTERM, parterm);
		    }