xref: /freebsd/contrib/tcsh/sh.sem.c (revision 6560ac57ce879857203bc456cdc3849808dc0700)

/*
 * sh.sem.c: I/O redirections and job forking. A touchy issue!
 *	     Most stuff with builtins is incorrect
 */
/*-
 * Copyright (c) 1980, 1991 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. 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.
 */
#include "sh.h"
#include "tc.h"
#include "tw.h"
#ifdef WINNT_NATIVE
#include "nt.const.h"
#endif /*WINNT_NATIVE*/

#ifdef CLOSE_ON_EXEC
# ifndef SUNOS4
#  ifndef CLEX_DUPS
#   define CLEX_DUPS
#  endif /* CLEX_DUPS */
# endif /* !SUNOS4 */
#endif /* CLOSE_ON_EXEC */

#if defined(__sparc__) || defined(sparc)
# if !defined(MACH) && SYSVREL == 0 && !defined(Lynx) && !defined(BSD4_4) && !defined(__linux__) && !defined(__GNU__) && !defined(__GLIBC__)
#  include <vfork.h>
# endif /* !MACH && SYSVREL == 0 && !Lynx && !BSD4_4 && !glibc */
#endif /* __sparc__ || sparc */

#ifdef VFORK
static	void		vffree		(int);
#endif
static	Char		*splicepipe	(struct command *, Char *);
static	void		 doio		(struct command *, int *, int *);
static	void		 chkclob	(const char *);

/*
 * C shell
 */

/*
 * For SVR4, there are problems with pipelines having the first process as
 * the group leader.  The problem occurs when the first process exits before
 * the others have a chance to setpgid().  This is because in SVR4 you can't
 * have a zombie as a group leader.  The solution I have used is to reverse
 * the order in which pipelines are started, making the last process the
 * group leader.  (Note I am not using 'pipeline' in the generic sense -- I
 * mean processes connected by '|'.)  I don't know yet if this causes other
 * problems.
 *
 * All the changes for this are in execute(), and are enclosed in
 * '#ifdef BACKPIPE'
 *
 * David Dawes (dawes@physics.su.oz.au) Oct 1991
 */

/*VARARGS 1*/
void
execute(struct command *t, volatile int wanttty, int *pipein, int *pipeout,
    int do_glob)
{
    int    forked = 0;
    const struct biltins * volatile bifunc;
    pid_t pid = 0;
    int     pv[2];
    sigset_t set;
    static sigset_t csigset;
#ifdef VFORK
    static int onosigchld = 0;
#endif /* VFORK */
    static int nosigchld = 0;

    (void) &wanttty;
    (void) &forked;
    (void) &bifunc;

    if (t == 0)
	return;

#ifdef WINNT_NATIVE
    {
        if ((varval(STRNTslowexec) == STRNULL) &&
            !t->t_dcdr && !t->t_dcar && !t->t_dflg && !didfds &&
            (intty || intact) && (t->t_dtyp == NODE_COMMAND) &&
	    !isbfunc(t)) {
	    if ((t->t_dcom[0][0] & (QUOTE | TRIM)) == QUOTE)
		(void) Strcpy(t->t_dcom[0], t->t_dcom[0] + 1);
	    Dfix(t);
            if (nt_try_fast_exec(t) == 0)
                return;
        }
    }
#endif /* WINNT_NATIVE */

    /*
     * Ed hutchins@sgi.com & Dominic dbg@sgi.com
     * Sat Feb 25 03:13:11 PST 1995
     * try implicit cd if we have a 1 word command
     */
    if (implicit_cd && (intty || intact) && t->t_dcom && t->t_dcom[0] &&
	 t->t_dcom[0][0] && (blklen(t->t_dcom) == 1) && !noexec) {
	Char *sCName;
	struct stat stbuf;
	char *pathname;

	sCName = dollar(t->t_dcom[0]);
	if (sCName != NULL && sCName[0] == '~') {
	    struct Strbuf buf = Strbuf_INIT;
	    const Char *name_end;

	    for (name_end = sCName + 1; *name_end != '\0' && *name_end != '/';
		 name_end++)
		continue;
	    if (name_end != sCName + 1) {
		Char *name, *home;

		name = Strnsave(sCName + 1, name_end - (sCName + 1));
		home = gethdir(name);
		if (home != NULL) {
		    Strbuf_append(&buf, home);
		    xfree(home);
		} else
		    Strbuf_append(&buf, name);
		xfree(name);
	    } else
		Strbuf_append(&buf, varval(STRhome));
	    Strbuf_append(&buf, name_end);
	    xfree(sCName);
	    sCName = Strbuf_finish(&buf);
	}

	pathname = short2str(sCName);
	xfree(sCName);
	/* if this is a dir, tack a "cd" on as the first arg */
	if (pathname != NULL &&
	    ((stat(pathname, &stbuf) != -1 && S_ISDIR(stbuf.st_mode))
#ifdef WINNT_NATIVE
	     || (pathname[0] && pathname[1] == ':' && pathname[2] == '\0')
#endif /* WINNT_NATIVE */
	     )) {
	    Char *vCD[2];
	    Char **ot_dcom = t->t_dcom;

	    vCD[0] = Strsave(STRcd);
	    vCD[1] = NULL;
	    t->t_dcom = blkspl(vCD, ot_dcom);
	    xfree(ot_dcom);
	    if (implicit_cd > 1) {
		blkpr(t->t_dcom);
		xputchar( '\n' );
	    }
	}
    }

    /*
     * From: Michael Schroeder <mlschroe@immd4.informatik.uni-erlangen.de>
     * Don't check for wantty > 0...
     */
    if (t->t_dflg & F_AMPERSAND)
	wanttty = 0;
    switch (t->t_dtyp) {

    case NODE_COMMAND:
	if ((t->t_dcom[0][0] & (QUOTE | TRIM)) == QUOTE)
	    memmove(t->t_dcom[0], t->t_dcom[0] + 1,
		    (Strlen(t->t_dcom[0] + 1) + 1) * sizeof (*t->t_dcom[0]));
	if ((t->t_dflg & F_REPEAT) == 0)
	    Dfix(t);		/* $ " ' \ */
	if (t->t_dcom[0] == 0) {
	    return;
	}
	/*FALLTHROUGH*/

    case NODE_PAREN:
#ifdef BACKPIPE
	if (t->t_dflg & F_PIPEIN)
	    mypipe(pipein);
#else /* !BACKPIPE */
	if (t->t_dflg & F_PIPEOUT)
	    mypipe(pipeout);
#endif /* BACKPIPE */
	/*
	 * 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) {
	    int old_pintr_disabled;

	    xclose(0);
	    if (setintr)
		pintr_push_enable(&old_pintr_disabled);
	    heredoc(t->t_dlef);
	    if (setintr)
		cleanup_until(&old_pintr_disabled);
	    if (noexec)
		xclose(0);
	}

	setcopy(STRstatus, STR0, VAR_READWRITE);

	/*
	 * 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 = (unsigned char)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], STRhup)) {
		if (t->t_dcom[1]) {
		    t->t_dflg |= F_HUP;
		    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;
	    }
#ifdef F_VER
	    else if (eq(t->t_dcom[0], STRver))
		if (t->t_dcom[1] && t->t_dcom[2]) {
		    setname("ver");
		    t->t_systype = getv(t->t_dcom[1]);
		    lshift(t->t_dcom, 2);
		    t->t_dflg |= F_VER;
		}
		else
		    break;
#endif  /* F_VER */
	    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 == NULL)
		    break;
		if (bifunc->bfunct != (bfunc_t)dobreak	&&
		    bifunc->bfunct != (bfunc_t)docontin	&&
		    bifunc->bfunct != (bfunc_t)doelse	&&
		    bifunc->bfunct != (bfunc_t)doend	&&
		    bifunc->bfunct != (bfunc_t)doforeach&&
		    bifunc->bfunct != (bfunc_t)dogoto	&&
		    bifunc->bfunct != (bfunc_t)doif	&&
		    bifunc->bfunct != (bfunc_t)dorepeat	&&
		    bifunc->bfunct != (bfunc_t)doswbrk	&&
		    bifunc->bfunct != (bfunc_t)doswitch	&&
		    bifunc->bfunct != (bfunc_t)dowhile	&&
		    bifunc->bfunct != (bfunc_t)dozip)
		    break;
	    }
	}
	else {			/* not a command */
	    bifunc = NULL;
	    if (noexec)
		break;
	}

	/*
	 * GrP Executing a command - run jobcmd hook
	 * Don't run for builtins
	 * Don't run if we're not in a tty
	 * Don't run if we're not really executing
	 */
	/*
	 * CR  -  Charles Ross Aug 2005
	 * added "isoutatty".
	 * The new behavior is that the jobcmd won't be executed
	 * if stdout (SHOUT) isnt attached to a tty.. IE when
	 * redirecting, or using backquotes etc..
	 */
	if (t->t_dtyp == NODE_COMMAND && !bifunc && !noexec && intty && isoutatty) {
	    Char *cmd = unparse(t);

	    cleanup_push(cmd, xfree);
	    job_cmd(cmd);
	    cleanup_until(cmd);
	}

	/*
	 * 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.
	 */
#ifdef BACKPIPE
	/*
	 * Can't have NOFORK for the tail of a pipe - because it is not the
	 * last command spawned (even if it is at the end of a parenthesised
	 * list).
	 */
	if (t->t_dflg & F_PIPEIN)
	    t->t_dflg &= ~(F_NOFORK);
#else
	/*
	 * "command | builtin" may cause major misbehaviour as noted in
	 * in the BUGS file entry
	 * Subject: Redirected input to built-in functions misbehaves badly
	 * forking when the builtin is the end of the pipe corrects the
	 * problem.
	 */
	if (bifunc && (t->t_dflg & F_PIPEIN))
	    t->t_dflg &= ~(F_NOFORK);
#endif /* BACKPIPE */
	/*
	 * Prevent forking cd, pushd, popd, chdir cause this will cause the
	 * shell not to change dir! (XXX: but only for nice?)
	 */
	if (bifunc && (bifunc->bfunct == (bfunc_t)dochngd ||
		       bifunc->bfunct == (bfunc_t)dopushd ||
		       bifunc->bfunct == (bfunc_t)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 | F_HUP)))) ||
	/*
	 * We have to fork for eval too.
	 */
	    (bifunc && (t->t_dflg & F_PIPEIN) != 0 &&
	     bifunc->bfunct == (bfunc_t)doeval)) {
#ifdef VFORK
	    if (t->t_dtyp == NODE_PAREN ||
		t->t_dflg & (F_REPEAT | F_AMPERSAND) || bifunc)
#endif /* VFORK */
	    {
		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) {
		    sigemptyset(&set);
		    sigaddset(&set, SIGCHLD);
		    (void)sigprocmask(SIG_BLOCK, &set, &csigset);

		    nosigchld = 1;
		}

		pid = pfork(t, wanttty);
		if (pid == 0 && nosigchld) {
		    sigprocmask(SIG_SETMASK, &csigset, NULL);
		    nosigchld = 0;
		}
		else if (pid != 0 && (t->t_dflg & F_AMPERSAND))
		    backpid = pid;
	    }

#ifdef VFORK
	    else {
		int     ochild, osetintr, ohaderr, odidfds;
		int     oSHIN, oSHOUT, oSHDIAG, oOLDSTD, otpgrp;
		int     oisoutatty, oisdiagatty;
		sigset_t oset, ocsigset;
# ifndef CLOSE_ON_EXEC
		int     odidcch;
# endif  /* !CLOSE_ON_EXEC */

		/*
		 * 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.
		 */

		/*
		 * Sooooo true... If this is a Sun, save the sigvec's. (Skip
		 * Gilbrech - 11/22/87)
		 */
# ifdef SAVESIGVEC
		struct sigaction savesv[NSIGSAVED];
		sigset_t savesm;

# endif /* SAVESIGVEC */
		if (wanttty >= 0 && !nosigchld && !noexec) {
		    sigemptyset(&set);
		    sigaddset(&set, SIGCHLD);
		    (void)sigprocmask(SIG_BLOCK, &set, &csigset);
		    nosigchld = 1;
		}
		sigemptyset(&set);
		sigaddset(&set, SIGCHLD);
		sigaddset(&set, SIGINT);
		(void)sigprocmask(SIG_BLOCK, &set, &oset);
		ochild = child;
		osetintr = setintr;
		ohaderr = haderr;
		odidfds = didfds;
# ifndef CLOSE_ON_EXEC
		odidcch = didcch;
# endif /* !CLOSE_ON_EXEC */
		oSHIN = SHIN;
		oSHOUT = SHOUT;
		oSHDIAG = SHDIAG;
		oOLDSTD = OLDSTD;
		otpgrp = tpgrp;
		oisoutatty = isoutatty;
		oisdiagatty = isdiagatty;
		ocsigset = csigset;
		onosigchld = nosigchld;
		Vsav = Vdp = 0;
		Vexpath = 0;
		Vt = 0;
# ifdef SAVESIGVEC
		savesigvec(savesv, savesm);
# endif /* SAVESIGVEC */
		if (use_fork)
		    pid = fork();
		else
		    pid = vfork();

		if (pid < 0) {
# ifdef SAVESIGVEC
		    restoresigvec(savesv, savesm);
# endif /* SAVESIGVEC */
		    sigprocmask(SIG_SETMASK, &oset, NULL);
		    stderror(ERR_NOPROC);
		}
		forked++;
		if (pid) {	/* parent */
# ifdef SAVESIGVEC
		    restoresigvec(savesv, savesm);
# endif /* SAVESIGVEC */
		    child = ochild;
		    setintr = osetintr;
		    haderr = ohaderr;
		    didfds = odidfds;
		    SHIN = oSHIN;
# ifndef CLOSE_ON_EXEC
		    didcch = odidcch;
# endif /* !CLOSE_ON_EXEC */
		    SHOUT = oSHOUT;
		    SHDIAG = oSHDIAG;
		    OLDSTD = oOLDSTD;
		    tpgrp = otpgrp;
		    isoutatty = oisoutatty;
		    isdiagatty = oisdiagatty;
		    csigset = ocsigset;
		    nosigchld = onosigchld;

		    xfree(Vsav);
		    Vsav = 0;
		    xfree(Vdp);
		    Vdp = 0;
		    xfree(Vexpath);
		    Vexpath = 0;
		    blk_cleanup(Vt);
		    Vt = 0;
		    /* this is from pfork() */
		    palloc(pid, t);
		    sigprocmask(SIG_SETMASK, &oset, NULL);
		}
		else {		/* child */
		    /* this is from pfork() */
		    pid_t pgrp;
		    int    ignint = 0;
		    if (nosigchld) {
			sigprocmask(SIG_SETMASK, &csigset, NULL);
			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;
/*
 * casts made right for SunOS 4.0 by Douglas C. Schmidt
 * <schmidt%sunshine.ics.uci.edu@ROME.ICS.UCI.EDU>
 * (thanks! -- PWP)
 *
 * ignint ifs cleaned by Johan Widen <mcvax!osiris.sics.se!jw@uunet.UU.NET>
 * (thanks again)
 */
			if (ignint) {
			    (void) signal(SIGINT, SIG_IGN);
			    (void) signal(SIGQUIT, SIG_IGN);
			}
			else {
			    (void) signal(SIGINT, vffree);
			    (void) signal(SIGQUIT, SIG_DFL);
			}
# ifdef BSDJOBS
			if (wanttty >= 0) {
			    (void) signal(SIGTSTP, SIG_DFL);
			    (void) signal(SIGTTIN, SIG_DFL);
			    (void) signal(SIGTTOU, SIG_DFL);
			}
# endif /* BSDJOBS */

			sigaction(SIGTERM, &parterm, NULL);
		    }
		    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_HUP)
			(void) signal(SIGHUP, SIG_DFL);
		    if (t->t_dflg & F_NICE) {
			int nval = SIGN_EXTEND_CHAR(t->t_nice);
# if defined(HAVE_SETPRIORITY) && defined(PRIO_PROCESS)
			if (setpriority(PRIO_PROCESS, 0, nval) == -1 && errno)
				stderror(ERR_SYSTEM, "setpriority",
				    strerror(errno));
# else /* !HAVE_SETPRIORITY || !PRIO_PROCESS */
			(void) nice(nval);
# endif /* HAVE_SETPRIORITY && PRIO_PROCESS */
		    }
# ifdef F_VER
		    if (t->t_dflg & F_VER) {
			tsetenv(STRSYSTYPE, t->t_systype ? STRbsd43 : STRsys53);
			dohash(NULL, NULL);
		    }
# endif /* F_VER */
		}

	    }
#endif /* VFORK */
	}
	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.
	     */
#ifdef BACKPIPE
	    if (didfds == 0 && t->t_dflg & F_PIPEOUT) {
		xclose(pipeout[0]);
		xclose(pipeout[1]);
	    }
	    if ((t->t_dflg & F_PIPEIN) != 0)
		break;
#else /* !BACKPIPE */
	    if (didfds == 0 && t->t_dflg & F_PIPEIN) {
		xclose(pipein[0]);
		xclose(pipein[1]);
	    }
	    if ((t->t_dflg & F_PIPEOUT) != 0)
		break;
#endif /* BACKPIPE */

	    if (nosigchld) {
		sigprocmask(SIG_SETMASK, &csigset, NULL);
		nosigchld = 0;
	    }
	    if ((t->t_dflg & F_AMPERSAND) == 0)
		pwait();
	    break;
	}

	doio(t, pipein, pipeout);
#ifdef BACKPIPE
	if (t->t_dflg & F_PIPEIN) {
	    xclose(pipein[0]);
	    xclose(pipein[1]);
	}
#else /* !BACKPIPE */
	if (t->t_dflg & F_PIPEOUT) {
	    xclose(pipeout[0]);
	    xclose(pipeout[1]);
	}
#endif /* BACKPIPE */
	/*
	 * Perform a builtin function. If we are not forked, arrange for
	 * possible stopping
	 */
	if (bifunc) {
	    if (forked) {
		func(t, bifunc);
		exitstat();
	    } else {
		jmp_buf_t oldexit;
		int ohaderr = haderr;

		getexit(oldexit);
		if (setexit() == 0)
		    func(t, bifunc);
		resexit(oldexit);
		haderr = ohaderr;

		if (adrof(STRprintexitvalue)) {
		    int rv = getn(varval(STRstatus));
		    if (rv != 0)
			xprintf(CGETS(17, 2, "Exit %d\n"), rv);
		}
	    }
	    break;
	}
	if (t->t_dtyp != NODE_PAREN) {
	    doexec(t, do_glob);
	    /* NOTREACHED */
	}
	/*
	 * For () commands must put new 0,1,2 in FSH* and recurse
	 */
	if ((OLDSTD = dcopy(0, FOLDSTD)) >= 0)
	    (void)close_on_exec(OLDSTD, 1);
	if ((SHOUT = dcopy(1, FSHOUT)) >= 0) {
	    (void)close_on_exec(SHOUT, 1);
	    isoutatty = isatty(SHOUT);
	}
	if ((SHDIAG = dcopy(2, FSHDIAG)) >= 0) {
	    (void)close_on_exec(SHDIAG, 1);
	    isdiagatty = isatty(SHDIAG);
    	}
	xclose(SHIN);
	SHIN = -1;
#ifndef CLOSE_ON_EXEC
	didcch = 0;
#else
	(void) close_on_exec(FSHOUT, 1);
	(void) close_on_exec(FSHDIAG, 1);
	(void) close_on_exec(FOLDSTD, 1);
#endif /* !CLOSE_ON_EXEC */
	didfds = 0;
	wanttty = -1;
	t->t_dspr->t_dflg |= t->t_dflg & (F_NOINTERRUPT | F_BACKQ);
	execute(t->t_dspr, wanttty, NULL, NULL, do_glob);
	exitstat();

    case NODE_PIPE:
#ifdef BACKPIPE
	t->t_dcdr->t_dflg |= F_PIPEIN | (t->t_dflg &
	    (F_PIPEOUT | F_AMPERSAND | F_NOFORK | F_NOINTERRUPT | F_BACKQ));
	execute(t->t_dcdr, wanttty, pv, pipeout, do_glob);
	t->t_dcar->t_dflg |= F_PIPEOUT | (t->t_dflg &
	    (F_PIPEIN | F_AMPERSAND | F_STDERR | F_NOINTERRUPT | F_BACKQ));
	execute(t->t_dcar, wanttty, pipein, pv, do_glob);
#else /* !BACKPIPE */
	t->t_dcar->t_dflg |= F_PIPEOUT | (t->t_dflg &
	    (F_PIPEIN | F_AMPERSAND | F_STDERR | F_NOINTERRUPT | F_BACKQ));
	execute(t->t_dcar, wanttty, pipein, pv, do_glob);
	t->t_dcdr->t_dflg |= F_PIPEIN | (t->t_dflg &
	    (F_PIPEOUT | F_AMPERSAND | F_NOFORK | F_NOINTERRUPT | F_BACKQ));
	execute(t->t_dcdr, wanttty, pv, pipeout, do_glob);
#endif /* BACKPIPE */
	break;

    case NODE_LIST:
	if (t->t_dcar) {
	    t->t_dcar->t_dflg |= t->t_dflg & (F_NOINTERRUPT | F_BACKQ);
	    execute(t->t_dcar, wanttty, NULL, NULL, do_glob);
	    /*
	     * 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 | F_BACKQ);
	    execute(t->t_dcdr, wanttty, NULL, NULL, do_glob);
	}
	break;

    case NODE_OR:
    case NODE_AND:
	if (t->t_dcar) {
	    t->t_dcar->t_dflg |= t->t_dflg & (F_NOINTERRUPT | F_BACKQ);
	    execute(t->t_dcar, wanttty, NULL, NULL, do_glob);
	    if ((getn(varval(STRstatus)) == 0) !=
		(t->t_dtyp == NODE_AND)) {
		return;
	    }
	}
	if (t->t_dcdr) {
	    t->t_dcdr->t_dflg |= t->t_dflg &
		(F_NOFORK | F_NOINTERRUPT | F_BACKQ);
	    execute(t->t_dcdr, wanttty, NULL, NULL, do_glob);
	}
	break;

    default:
	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();
}

#ifdef VFORK
static void
/*ARGSUSED*/
vffree(int snum)
{
    USE(snum);

    _exit(1);
}
#endif /* VFORK */

/*
 * 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(struct command *t, Char *cp)
{
    Char *blk[2];

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

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

	gflag = tglob(blk);
	if (gflag) {
	    pv = globall(blk, gflag);
	    if (pv == NULL) {
		setname(short2str(blk[0]));
		xfree(blk[0]);
		stderror(ERR_NAME | ERR_NOMATCH);
	    }
	    if (pv[1] != NULL) { /* we need to fix the command vector */
		Char **av = blkspl(t->t_dcom, &pv[1]);
		xfree(t->t_dcom);
		t->t_dcom = av;
	    }
	    xfree(blk[0]);
	    blk[0] = pv[0];
	    xfree(pv);
	}
    }
    else {
	Char *buf;

	buf = Dfix1(cp);
	cleanup_push(buf, xfree);
	blk[0] = globone(buf, G_ERROR);
	cleanup_until(buf);
    }
    return(blk[0]);
}

/*
 * Perform io redirection.
 * We may or maynot be forked here.
 */
static void
doio(struct command *t, int *pipein, int *pipeout)
{
    int fd;
    Char *cp;
    unsigned long 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;

	    /*
	     * so < /dev/std{in,out,err} work
	     */
	    (void) dcopy(SHIN, 0);
	    (void) dcopy(SHOUT, 1);
	    (void) dcopy(SHDIAG, 2);
	    cp = splicepipe(t, t->t_dlef);
	    tmp = strsave(short2str(cp));
	    xfree(cp);
	    cleanup_push(tmp, xfree);
	    if ((fd = xopen(tmp, O_RDONLY|O_LARGEFILE)) < 0)
		stderror(ERR_SYSTEM, tmp, strerror(errno));
	    cleanup_until(tmp);
	    /* allow input files larger than 2Gb  */
#ifndef WINNT_NATIVE
	    (void) fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_LARGEFILE);
#endif /*!WINNT_NATIVE*/
	    (void) dmove(fd, 0);
	}
	else if (flags & F_PIPEIN) {
	    xclose(0);
	    TCSH_IGNORE(dup(pipein[0]));
	    xclose(pipein[0]);
	    xclose(pipein[1]);
	}
	else if ((flags & F_NOINTERRUPT) && tpgrp == -1) {
	    xclose(0);
	    (void) xopen(_PATH_DEVNULL, O_RDONLY|O_LARGEFILE);
	}
	else {
	    xclose(0);
	    TCSH_IGNORE(dup(OLDSTD));
#if defined(CLOSE_ON_EXEC) && defined(CLEX_DUPS)
	    /*
	     * PWP: Unlike Bezerkeley 4.3, FIONCLEX for Pyramid is preserved
	     * across dup()s, so we have to UNSET it here or else we get a
	     * command with NO stdin, stdout, or stderr at all (a bad thing
	     * indeed)
	     */
	    (void) close_on_exec(0, 0);
#endif /* CLOSE_ON_EXEC && CLEX_DUPS */
	}
    }
    if (t->t_drit) {
	char *tmp;

	cp = splicepipe(t, t->t_drit);
	tmp = strsave(short2str(cp));
	xfree(cp);
	cleanup_push(tmp, xfree);
	/*
	 * so > /dev/std{out,err} work
	 */
	(void) dcopy(SHOUT, 1);
	(void) dcopy(SHDIAG, 2);
	if ((flags & F_APPEND) != 0) {
#ifdef O_APPEND
	    fd = xopen(tmp, O_WRONLY|O_APPEND|O_LARGEFILE);
#else /* !O_APPEND */
	    fd = xopen(tmp, O_WRONLY|O_LARGEFILE);
	    (void) lseek(fd, (off_t) 0, L_XTND);
#endif /* O_APPEND */
	}
	else
	    fd = 0;
	if ((flags & F_APPEND) == 0 || fd == -1) {
	    if (!(flags & F_OVERWRITE) && no_clobber) {
		if (flags & F_APPEND)
		    stderror(ERR_SYSTEM, tmp, strerror(errno));
		chkclob(tmp);
	    }
	    if ((fd = xcreat(tmp, 0666)) < 0)
		stderror(ERR_SYSTEM, tmp, strerror(errno));
	    /* allow input files larger than 2Gb  */
#ifndef WINNT_NATIVE
	    (void) fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) | O_LARGEFILE);
#endif /*!WINNT_NATIVE*/
	}
	cleanup_until(tmp);
	(void) dmove(fd, 1);
	is1atty = isatty(1);
    }
    else if (flags & F_PIPEOUT) {
	xclose(1);
	TCSH_IGNORE(dup(pipeout[1]));
	is1atty = 0;
    }
    else {
	xclose(1);
	TCSH_IGNORE(dup(SHOUT));
	is1atty = isoutatty;
# if defined(CLOSE_ON_EXEC) && defined(CLEX_DUPS)
	(void) close_on_exec(1, 0);
# endif /* CLOSE_ON_EXEC && CLEX_DUPS */
    }

    xclose(2);
    if (flags & F_STDERR) {
	TCSH_IGNORE(dup(1));
	is2atty = is1atty;
    }
    else {
	TCSH_IGNORE(dup(SHDIAG));
	is2atty = isdiagatty;
# if defined(CLOSE_ON_EXEC) && defined(CLEX_DUPS)
	(void) close_on_exec(2, 0);
# endif /* CLOSE_ON_EXEC && CLEX_DUPS */
    }
    didfds = 1;
}

void
mypipe(int *pv)
{

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

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

    if (stat(cp, &stb) < 0)
	return;
    if (S_ISCHR(stb.st_mode))
	return;
    if (no_clobber & NOCLOBBER_NOTEMPTY && stb.st_size == 0)
	return;
    if (no_clobber & NOCLOBBER_ASK) {
	if (getYN(CGETS(22, 15,
	    "Do you really want to overwrite an existing file? [N/y] ")))
	    return;
    }

    stderror(ERR_EXISTS, cp);
}