source: trunk/src/kash/eval.c

/*      $NetBSD: eval.c,v 1.84 2005/06/23 23:05:29 christos Exp $       */

/*-
 * Copyright (c) 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kenneth Almquist.
 *
 * 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.
 */

#if 0
#ifndef lint
static char sccsid[] = "@(#)eval.c      8.9 (Berkeley) 6/8/95";
#else
__RCSID("$NetBSD: eval.c,v 1.84 2005/06/23 23:05:29 christos Exp $");
#endif /* not lint */
#endif

#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#ifdef HAVE_SYSCTL_H
# ifdef __OpenBSD__ /* joyful crap */
#  include <sys/param.h>
#  undef psh
# endif
# include <sys/sysctl.h>
#endif

/*
 * Evaluate a command.
 */

#include "shell.h"
#include "nodes.h"
#include "syntax.h"
#include "expand.h"
#include "parser.h"
#include "jobs.h"
#include "eval.h"
#include "builtins.h"
#include "options.h"
#include "exec.h"
#include "redir.h"
#include "input.h"
#include "output.h"
#include "trap.h"
#include "var.h"
#include "memalloc.h"
#include "error.h"
#include "show.h"
#include "mystring.h"
#include "main.h"
#ifndef SMALL
# include "myhistedit.h"
#endif
#include "shinstance.h"


/* flags in argument to evaltree */
#define EV_EXIT 01              /* exit after evaluating tree */
#define EV_TESTED 02            /* exit status is checked; ignore -e flag */
#define EV_BACKCMD 04           /* command executing within back quotes */

/*int evalskip;*/                       /* set if we are skipping commands */
/*STATIC int skipcount;*/               /* number of levels to skip */
/*MKINIT int loopnest;*/                /* current loop nesting level */
/*int funcnest;*/                       /* depth of function calls */


/*char *commandname;*/
/*struct strlist *cmdenviron;*/
/*int exitstatus;*/                     /* exit status of last command */
/*int back_exitstatus;*/                /* exit status of backquoted command */


STATIC void evalloop(shinstance *, union node *, int);
STATIC void evalfor(shinstance *, union node *, int);
STATIC void evalcase(shinstance *, union node *, int);
STATIC void evalsubshell(shinstance *, union node *, int);
STATIC unsigned expredir(shinstance *, union node *);
STATIC void evalpipe(shinstance *, union node *);
STATIC void evalcommand(shinstance *, union node *, int, struct backcmd *);
STATIC void prehash(shinstance *, union node *);


/*
 * Called to reset things after an exception.
 */

#ifdef mkinit
INCLUDE "eval.h"

RESET {
        psh->evalskip = 0;
        psh->loopnest = 0;
        psh->funcnest = 0;
}

SHELLPROC {
        psh->exitstatus = 0;
}
#endif

static int
sh_pipe(shinstance *psh, int fds[2])
{
        int nfd;

        if (shfile_pipe(&psh->fdtab, fds))
                return -1;

        if (fds[0] < 3) {
                nfd = shfile_fcntl(&psh->fdtab, fds[0], F_DUPFD, 3);
                if (nfd != -1) {
                        shfile_close(&psh->fdtab, fds[0]);
                        fds[0] = nfd;
                }
        }

        if (fds[1] < 3) {
                nfd = shfile_fcntl(&psh->fdtab, fds[1], F_DUPFD, 3);
                if (nfd != -1) {
                        shfile_close(&psh->fdtab, fds[1]);
                        fds[1] = nfd;
                }
        }
        return 0;
}


/*
 * The eval commmand.
 */

int
evalcmd(shinstance *psh, int argc, char **argv)
{
        char *p;
        char *concat;
        char **ap;

        if (argc > 1) {
                p = argv[1];
                if (argc > 2) {
                        STARTSTACKSTR(psh, concat);
                        ap = argv + 2;
                        for (;;) {
                                while (*p)
                                        STPUTC(psh, *p++, concat);
                                if ((p = *ap++) == NULL)
                                        break;
                                STPUTC(psh, ' ', concat);
                        }
                        STPUTC(psh, '\0', concat);
                        p = grabstackstr(psh, concat);
                }
                evalstring(psh, p, EV_TESTED);
        }
        return psh->exitstatus;
}


/*
 * Execute a command or commands contained in a string.
 */

void
evalstring(shinstance *psh, char *s, int flag)
{
        union node *n;
        struct stackmark smark;

        setstackmark(psh, &smark);
        setinputstring(psh, s, 1);

        while ((n = parsecmd(psh, 0)) != NEOF) {
                evaltree(psh, n, flag);
                popstackmark(psh, &smark);
        }
        popfile(psh);
        popstackmark(psh, &smark);
}



/*
 * Evaluate a parse tree.  The value is left in the global variable
 * exitstatus.
 */

void
evaltree(shinstance *psh, union node *n, int flags)
{
        if (n == NULL) {
                TRACE((psh, "evaltree(NULL) called\n"));
                psh->exitstatus = 0;
                goto out;
        }
#ifndef SMALL
        psh->displayhist = 1;   /* show history substitutions done with fc */
#endif
        TRACE((psh, "pid %" SHPID_PRI ", evaltree(%p: %d, %d) called\n",
               sh_getpid(psh), n, n->type, flags));
        switch (n->type) {
        case NSEMI:
                evaltree(psh, n->nbinary.ch1, flags & EV_TESTED);
                if (psh->evalskip)
                        goto out;
                evaltree(psh, n->nbinary.ch2, flags);
                break;
        case NAND:
                evaltree(psh, n->nbinary.ch1, EV_TESTED);
                if (psh->evalskip || psh->exitstatus != 0)
                        goto out;
                evaltree(psh, n->nbinary.ch2, flags);
                break;
        case NOR:
                evaltree(psh, n->nbinary.ch1, EV_TESTED);
                if (psh->evalskip || psh->exitstatus == 0)
                        goto out;
                evaltree(psh, n->nbinary.ch2, flags);
                break;
        case NREDIR: {
                unsigned const oldfnames = expredir(psh, n->nredir.redirect);
                redirect(psh, n->nredir.redirect, REDIR_PUSH);
                evaltree(psh, n->nredir.n, flags);
                popredir(psh);
                expredircleanup(psh, oldfnames);
                break;
        }
        case NSUBSHELL:
                evalsubshell(psh, n, flags);
                break;
        case NBACKGND:
                evalsubshell(psh, n, flags);
                break;
        case NIF: {
                evaltree(psh, n->nif.test, EV_TESTED);
                if (psh->evalskip)
                        goto out;
                if (psh->exitstatus == 0)
                        evaltree(psh, n->nif.ifpart, flags);
                else if (n->nif.elsepart)
                        evaltree(psh, n->nif.elsepart, flags);
                else
                        psh->exitstatus = 0;
                break;
        }
        case NWHILE:
        case NUNTIL:
                evalloop(psh, n, flags);
                break;
        case NFOR:
                evalfor(psh, n, flags);
                break;
        case NCASE:
                evalcase(psh, n, flags);
                break;
        case NDEFUN:
                defun(psh, n->narg.text, n->narg.next);
                psh->exitstatus = 0;
                break;
        case NNOT:
                evaltree(psh, n->nnot.com, EV_TESTED);
                psh->exitstatus = !psh->exitstatus;
                break;
        case NPIPE:
                evalpipe(psh, n);
                break;
        case NCMD:
                evalcommand(psh, n, flags, (struct backcmd *)NULL);
                break;
        default:
                out1fmt(psh, "Node type = %d\n", n->type);
                flushout(&psh->output);
                break;
        }
out:
        if (psh->pendingsigs)
                dotrap(psh);
        if ((flags & EV_EXIT) != 0)
                exitshell(psh, psh->exitstatus);
}


STATIC void
evalloop(shinstance *psh, union node *n, int flags)
{
        int status;

        psh->loopnest++;
        status = 0;
        for (;;) {
                evaltree(psh, n->nbinary.ch1, EV_TESTED);
                if (psh->evalskip) {
skipping:         if (psh->evalskip == SKIPCONT && --psh->skipcount <= 0) {
                                psh->evalskip = 0;
                                continue;
                        }
                        if (psh->evalskip == SKIPBREAK && --psh->skipcount <= 0)
                                psh->evalskip = 0;
                        break;
                }
                if (n->type == NWHILE) {
                        if (psh->exitstatus != 0)
                                break;
                } else {
                        if (psh->exitstatus == 0)
                                break;
                }
                evaltree(psh, n->nbinary.ch2, flags & EV_TESTED);
                status = psh->exitstatus;
                if (psh->evalskip)
                        goto skipping;
        }
        psh->loopnest--;
        psh->exitstatus = status;
}



STATIC void
evalfor(shinstance *psh, union node *n, int flags)
{
        struct arglist arglist;
        union node *argp;
        struct strlist *sp;
        struct stackmark smark;
        int status = 0;

        setstackmark(psh, &smark);
        arglist.lastp = &arglist.list;
        for (argp = n->nfor.args ; argp ; argp = argp->narg.next) {
                expandarg(psh, argp, &arglist, EXP_FULL | EXP_TILDE);
                if (psh->evalskip)
                        goto out;
        }
        *arglist.lastp = NULL;

        psh->loopnest++;
        for (sp = arglist.list ; sp ; sp = sp->next) {
                setvar(psh, n->nfor.var, sp->text, 0);
                evaltree(psh, n->nfor.body, flags & EV_TESTED);
                status = psh->exitstatus;
                if (psh->evalskip) {
                        if (psh->evalskip == SKIPCONT && --psh->skipcount <= 0) {
                                psh->evalskip = 0;
                                continue;
                        }
                        if (psh->evalskip == SKIPBREAK && --psh->skipcount <= 0)
                                psh->evalskip = 0;
                        break;
                }
        }
        psh->loopnest--;
        psh->exitstatus = status;
out:
        popstackmark(psh, &smark);
}



STATIC void
evalcase(shinstance *psh, union node *n, int flags)
{
        union node *cp;
        union node *patp;
        struct arglist arglist;
        struct stackmark smark;
        int status = 0;

        setstackmark(psh, &smark);
        arglist.lastp = &arglist.list;
        expandarg(psh, n->ncase.expr, &arglist, EXP_TILDE);
        for (cp = n->ncase.cases ; cp && psh->evalskip == 0 ; cp = cp->nclist.next) {
                for (patp = cp->nclist.pattern ; patp ; patp = patp->narg.next) {
                        if (casematch(psh, patp, arglist.list->text)) {
                                if (psh->evalskip == 0) {
                                        evaltree(psh, cp->nclist.body, flags);
                                        status = psh->exitstatus;
                                }
                                goto out;
                        }
                }
        }
out:
        psh->exitstatus = status;
        popstackmark(psh, &smark);
}


#ifdef KASH_USE_FORKSHELL2
/*
 * Child of evalsubshell.
 */
struct evalsubshellchild
{
    int flags;
    int backgnd;
};

static int evalsubshell_child(shinstance *psh, union node *n, void *argp)
{
    struct evalsubshellchild args = *(struct evalsubshellchild *)argp;

    INTON;
    if (args.backgnd)
            args.flags &=~ EV_TESTED;
    redirect(psh, n->nredir.redirect, 0);
    /* never returns */
    evaltree(psh, n->nredir.n, args.flags | EV_EXIT);
    /** @todo make us return here. */
    return 0;
}
#endif /* KASH_USE_FORKSHELL2 */


/*
 * Kick off a subshell to evaluate a tree.
 */

STATIC void
evalsubshell(shinstance *psh, union node *n, int flags)
{
        struct job *jp;
        int backgnd = (n->type == NBACKGND);
        unsigned expfnamedepth;

        expfnamedepth = expredir(psh, n->nredir.redirect);
        INTOFF;
        jp = makejob(psh, n, 1);
#ifdef KASH_USE_FORKSHELL2
        {
                struct evalsubshellchild args;
                args.flags = flags;
                args.backgnd = backgnd;
                forkshell2(psh, jp, n, backgnd ? FORK_BG : FORK_FG,
                           evalsubshell_child, n, &args, sizeof(args), NULL);
        }
#else
        if (forkshell(psh, jp, n, backgnd ? FORK_BG : FORK_FG) == 0) {
                INTON;
                if (backgnd)
                        flags &=~ EV_TESTED;
                redirect(psh, n->nredir.redirect, 0);
                /* never returns */
                evaltree(psh, n->nredir.n, flags | EV_EXIT);
        }
#endif
        if (! backgnd)
                psh->exitstatus = waitforjob(psh, jp);
        expredircleanup(psh, expfnamedepth);
        INTON;
}



/*
 * Compute the names of the files in a redirection list.
 */

STATIC unsigned
expredir(shinstance *psh, union node *n)
{
        union node *redir;
        redirexpfnames *expfnames;
        unsigned i;

        /* We typically end up here w/o redirections. */
        if (!n)
            return !(expfnames = psh->expfnames) ? 0 : expfnames->depth + 1;

        /* Prepare a table for the expanded names. */
        i = 0;
        for (redir = n; redir ; redir = redir->nfile.next)
            i++;
        expfnames = stalloc(psh, offsetof(redirexpfnames, names) +  sizeof(expfnames->names[0]) * i);
        expfnames->count = i;
        TRACE2((psh, "expredir: %p: count=%u\n", expfnames, i));

        /* Do the expansion. */
        for (redir = n, i = 0 ; redir ; redir = redir->nfile.next, i++) {
                struct arglist fn;
                fn.lastp = &fn.list;
                switch (redir->type) {
                case NFROMTO:
                case NFROM:
                case NTO:
                case NCLOBBER:
                case NAPPEND:
                        expandarg(psh, redir->nfile.fname, &fn, EXP_TILDE | EXP_REDIR);
                        expfnames->names[i] = fn.list->text;
                        break;
                case NFROMFD:
                case NTOFD:
                        if (redir->ndup.vname) {
                                expandarg(psh, redir->ndup.vname, &fn, EXP_FULL | EXP_TILDE);
                                fixredir(psh, redir, fn.list->text, 1);
                        }
                        expfnames->names[i] = NULL;
                        break;
                default:
                        kHlpAssert(redir->type == NHERE || redir->type == NXHERE);
                        expfnames->names[i] = NULL;
                        break;
                }
        }
        kHlpAssert(i == expfnames->count);

        /* Do the linking at the end, as nesting happens when we expand backtick arguments. */
        expfnames->prev = psh->expfnames;
        psh->expfnames = expfnames;
        return expfnames->depth = psh->expfnames ? psh->expfnames->depth + 1 : 1;
}

STATIC void
expredircleanup(shinstance *psh, unsigned depth)
{
        redirexpfnames *expfnames = psh->expfnames;
        kHlpAssert(expfnames == NULL ? depth == 0 : expfnames->depth == depth || expfnames->depth + 1 == depth);
        while (expfnames && expfnames->depth >= depth)
            expfnames = psh->expfnames = expfnames->prev;
}


#ifdef KASH_USE_FORKSHELL2
/*
 * Child of evalpipe.
 */
struct evalpipechild
{
        int prevfd;
        int pip[2];
};

static int evalpipe_child(shinstance *psh, union node *n, void *argp)
{
        struct evalpipechild args = *(struct evalpipechild *)argp;

        if (args.prevfd > 0) {
                movefd(psh, args.prevfd, 0);
        }
        if (args.pip[1] >= 0) {
                shfile_close(&psh->fdtab, args.pip[0]);
                if (args.pip[1] != 1) {
                        movefd(psh, args.pip[1], 1);
                }
        }
        evaltree(psh, n, EV_EXIT);
        /** @todo make it return thru here. */
        return 0;
}
#endif /* KASH_USE_FORKSHELL2 */

/*
 * Evaluate a pipeline.  All the processes in the pipeline are children
 * of the process creating the pipeline.  (This differs from some versions
 * of the shell, which make the last process in a pipeline the parent
 * of all the rest.)
 */

STATIC void
evalpipe(shinstance *psh, union node *n)
{
        struct job *jp;
        struct nodelist *lp;
        int pipelen;
        int prevfd;
        int pip[2];

        TRACE((psh, "evalpipe(0x%lx) called\n", (long)n));
        pipelen = 0;
        for (lp = n->npipe.cmdlist ; lp ; lp = lp->next)
                pipelen++;
        INTOFF;
        jp = makejob(psh, n, pipelen);
        prevfd = -1;
        for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
                prehash(psh, lp->n);
                pip[1] = -1;
                if (lp->next) {
                        if (sh_pipe(psh, pip) < 0) {
                                shfile_close(&psh->fdtab, prevfd);
                                error(psh, "Pipe call failed");
                        }
                }
#ifdef KASH_USE_FORKSHELL2
                {
                        struct evalpipechild args;
                        args.prevfd = prevfd;
                        args.pip[0] = pip[0];
                        args.pip[1] = pip[1];
                        forkshell2(psh, jp, lp->n, n->npipe.backgnd ? FORK_BG : FORK_FG,
                                   evalpipe_child, lp->n, &args, sizeof(args), NULL);
                }
#else
                if (forkshell(psh, jp, lp->n, n->npipe.backgnd ? FORK_BG : FORK_FG) == 0) {
                        INTON;
                        if (prevfd > 0) {
                                movefd(psh, prevfd, 0);
                        }
                        if (pip[1] >= 0) {
                                shfile_close(&psh->fdtab, pip[0]);
                                if (pip[1] != 1) {
                                        movefd(psh, pip[1], 1);
                                }
                        }
                        evaltree(psh, lp->n, EV_EXIT);
                }
#endif
                if (prevfd >= 0)
                        shfile_close(&psh->fdtab, prevfd);
                prevfd = pip[0];
                shfile_close(&psh->fdtab, pip[1]);
        }
        if (n->npipe.backgnd == 0) {
                psh->exitstatus = waitforjob(psh, jp);
                TRACE((psh, "evalpipe:  job done exit status %d\n", psh->exitstatus));
        }
        INTON;
}

#ifdef KASH_USE_FORKSHELL2
/*
 * evalbackcmd child.
 */
struct evalbackcmdchild
{
        int pip[2];
};

static int evalbackcmd_child(shinstance *psh, union node *n, void *argp)
{
        struct evalbackcmdchild args = *(struct evalbackcmdchild *)argp;

        FORCEINTON;
        shfile_close(&psh->fdtab, args.pip[0]);
        if (args.pip[1] != 1) {
                movefd(psh, args.pip[1], 1);
        }
        eflag(psh) = 0;
        evaltree(psh, n, EV_EXIT);
        /* NOTREACHED */ /** @todo make it return here to simplify thread handling (no need for setjmp). */
        return 0;
}
#endif /* KASH_USE_FORKSHELL2 */

/*
 * Execute a command inside back quotes.  If it's a builtin command, we
 * want to save its output in a block obtained from malloc.  Otherwise
 * we fork off a subprocess and get the output of the command via a pipe.
 * Should be called with interrupts off.
 */

void
evalbackcmd(shinstance *psh, union node *n, struct backcmd *result)
{
        int pip[2];
        struct job *jp;
        struct stackmark smark;         /* unnecessary */

        setstackmark(psh, &smark);
        result->fd = -1;
        result->buf = NULL;
        result->nleft = 0;
        result->jp = NULL;
        if (n == NULL) {
                goto out;
        }
#ifdef notyet
        /*
         * For now we disable executing builtins in the same
         * context as the shell, because we are not keeping
         * enough state to recover from changes that are
         * supposed only to affect subshells. eg. echo "`cd /`"
         */
        if (n->type == NCMD) {
                psh->exitstatus = opsh->exitstatus;
                evalcommand(psh, n, EV_BACKCMD, result);
        } else
#endif
        {
                INTOFF;
                if (sh_pipe(psh, pip) < 0)
                        error(psh, "Pipe call failed");
                jp = makejob(psh, n, 1);
#ifdef KASH_USE_FORKSHELL2
                {
                        struct evalbackcmdchild args;
                        args.pip[0] = pip[0];
                        args.pip[1] = pip[1];
                        forkshell2(psh, jp, n, FORK_NOJOB,
                                   evalbackcmd_child, n, &args, sizeof(args), NULL);
                }
#else
                if (forkshell(psh, jp, n, FORK_NOJOB) == 0) {
                        FORCEINTON;
                        shfile_close(&psh->fdtab, pip[0]);
                        if (pip[1] != 1) {
                                movefd(psh, pip[1], 1);
                        }
                        eflag(psh) = 0;
                        evaltree(psh, n, EV_EXIT);
                        /* NOTREACHED */
                }
#endif
                shfile_close(&psh->fdtab, pip[1]);
                result->fd = pip[0];
                result->jp = jp;
                INTON;
        }
out:
        popstackmark(psh, &smark);
        TRACE((psh, "evalbackcmd done: fd=%d buf=0x%x nleft=%d jp=0x%x\n",
                result->fd, result->buf, result->nleft, result->jp));
}

static const char *
syspath(shinstance *psh)
{
#ifdef CTL_USER
        static char *sys_path = NULL;
        static int mib[] = {CTL_USER, USER_CS_PATH};
#endif
#ifdef PC_PATH_SEP
        static char def_path[] = "PATH=/usr/bin;/bin;/usr/sbin;/sbin";
#else
        static char def_path[] = "PATH=/usr/bin:/bin:/usr/sbin:/sbin";
#endif
#ifdef CTL_USER
        size_t len;

        if (sys_path == NULL) {
                if (sysctl(mib, 2, 0, &len, 0, 0) != -1 &&
                    (sys_path = ckmalloc(psh, len + 5)) != NULL &&
                    sysctl(mib, 2, sys_path + 5, &len, 0, 0) != -1) {
                        memcpy(sys_path, "PATH=", 5);
                } else {
                        ckfree(psh, sys_path);
                        /* something to keep things happy */
                        sys_path = def_path;
                }
        }
        return sys_path;
#else
        return def_path;
#endif
}

static int
parse_command_args(shinstance *psh, int argc, char **argv, int *use_syspath)
{
        int sv_argc = argc;
        char *cp, c;

        *use_syspath = 0;

        for (;;) {
                argv++;
                if (--argc == 0)
                        break;
                cp = *argv;
                if (*cp++ != '-')
                        break;
                if (*cp == '-' && cp[1] == 0) {
                        argv++;
                        argc--;
                        break;
                }
                while ((c = *cp++)) {
                        switch (c) {
                        case 'p':
                                *use_syspath = 1;
                                break;
                        default:
                                /* run 'typecmd' for other options */
                                return 0;
                        }
                }
        }
        return sv_argc - argc;
}


/*
 * The split up evalcommand code:
 *      evalcommand_out, evalcommand_parent, evalcommand_doit, evalcommand_child
 */
/*int vforked = 0; - obsolete */

/* Both child and parent exits thru here. */
STATIC void
evalcommand_out(shinstance *psh, int flags, char *lastarg, unsigned expfnamedepth, struct stackmark *smarkp)
{
        if (lastarg)
                /* dsl: I think this is intended to be used to support
                 * '_' in 'vi' command mode during line editing...
                 * However I implemented that within libedit itself.
                 */
                setvar(psh, "_", lastarg, 0);
        expredircleanup(psh, expfnamedepth);
        popstackmark(psh, smarkp);

        if (eflag(psh) && psh->exitstatus && !(flags & EV_TESTED))
                exitshell(psh, psh->exitstatus);
}


/* Called if we forkshell(). */
STATIC void
evalcommand_parent(shinstance *psh, int flags, char *lastarg, unsigned expfnamedepth, struct stackmark *smarkp,
                   int mode, struct job *jp, int pip[2], struct backcmd *backcmd)
{
        if (mode == FORK_FG) {  /* argument to fork */
                psh->exitstatus = waitforjob(psh, jp);
        } else if (mode == FORK_NOJOB) {
                backcmd->fd = pip[0];
                shfile_close(&psh->fdtab, pip[1]);
                backcmd->jp = jp;
        }
        FORCEINTON;

        evalcommand_out(psh, flags, lastarg, expfnamedepth, smarkp);
}

struct evalcommanddoit
{
        struct stackmark smark;
        unsigned expfnamedepth;

        struct backcmd *backcmd;
        int flags;
        int argc;
        char **argv;
        char *lastarg;
        struct arglist varlist;
        const char *path;
        struct cmdentry cmdentry;

        /* for child stuff only: */
        int pip[2];
};

STATIC void
evalcommand_doit(shinstance *psh, union node *cmd, struct evalcommanddoit *args)
{
        struct jmploc jmploc;
        struct jmploc *volatile savehandler;
        struct localvar *volatile savelocalvars;

        /* This is the child process if a fork occurred. */
        /* Execute the command. */
        switch (args->cmdentry.cmdtype) {
                case CMDFUNCTION: {
                        volatile struct shparam saveparam;
#ifdef DEBUG
                        trputs(psh, "Shell function:  ");  trargs(psh, args->argv);
#endif
                        redirect(psh, cmd->ncmd.redirect, REDIR_PUSH);
                        saveparam = psh->shellparam;
                        psh->shellparam.malloc = 0;
                        psh->shellparam.reset = 1;
                        psh->shellparam.nparam = args->argc - 1;
                        psh->shellparam.p = args->argv + 1;
                        psh->shellparam.optnext = NULL;
                        INTOFF;
                        savelocalvars = psh->localvars;
                        psh->localvars = NULL;
                        INTON;
                        if (setjmp(jmploc.loc)) {
                                if (psh->exception == EXSHELLPROC) {
                                        freeparam(psh, (volatile struct shparam *)
                                                &saveparam);
                                } else {
                                        freeparam(psh, &psh->shellparam);
                                        psh->shellparam = saveparam;
                                }
                                poplocalvars(psh);
                                psh->localvars = savelocalvars;
                                psh->handler = savehandler;
                                longjmp(psh->handler->loc, 1);
                        }
                        savehandler = psh->handler;
                        psh->handler = &jmploc;
                        listmklocal(psh, args->varlist.list, 0);
                        /* stop shell blowing its stack */
                        if (++psh->funcnest > 1000)
                                error(psh, "too many nested function calls");
                        evaltree(psh, args->cmdentry.u.func, args->flags & EV_TESTED);
                        psh->funcnest--;
                        INTOFF;
                        poplocalvars(psh);
                        psh->localvars = savelocalvars;
                        freeparam(psh, &psh->shellparam);
                        psh->shellparam = saveparam;
                        psh->handler = savehandler;
                        popredir(psh);
                        INTON;
                        if (psh->evalskip == SKIPFUNC) {
                                psh->evalskip = 0;
                                psh->skipcount = 0;
                        }
                        if (args->flags & EV_EXIT)
                                exitshell(psh, psh->exitstatus);
                        break;
                }

                case CMDBUILTIN:
                case CMDSPLBLTIN: {
                        volatile int temp_path = 0;
                        char *volatile savecmdname;
                        int volatile savecmdnamemalloc;
                        volatile int e;
                        int mode;
#ifdef DEBUG
                        trputs(psh, "builtin command:  ");  trargs(psh, args->argv);
#endif
                        mode = (args->cmdentry.u.bltin == execcmd) ? 0 : REDIR_PUSH;
                        if (args->flags == EV_BACKCMD) {
                                psh->memout.nleft = 0;
                                psh->memout.nextc = psh->memout.buf;
                                psh->memout.bufsize = 64;
                                mode |= REDIR_BACKQ;
                        }
                        e = -1;
                        savehandler = psh->handler;
                        savecmdname = psh->commandname;
                        savecmdnamemalloc = psh->commandnamemalloc;
                        psh->handler = &jmploc;
                        if (!setjmp(jmploc.loc)) {
                                /* We need to ensure the command hash table isn't
                                 * corruped by temporary PATH assignments.
                                 * However we must ensure the 'local' command works!
                                 */
                                if (args->path != pathval(psh) && (args->cmdentry.u.bltin == hashcmd ||
                                        args->cmdentry.u.bltin == typecmd)) {
                                        savelocalvars = psh->localvars;
                                        psh->localvars = 0;
                                        mklocal(psh, args->path - 5 /* PATH= */, 0);
                                        temp_path = 1;
                                } else
                                        temp_path = 0;
                                redirect(psh, cmd->ncmd.redirect, mode);

                                /* exec is a special builtin, but needs this list... */
                                psh->cmdenviron = args->varlist.list;
                                /* we must check 'readonly' flag for all builtins */
                                listsetvar(psh, args->varlist.list,
                                        args->cmdentry.cmdtype == CMDSPLBLTIN ? 0 : VNOSET);
                                psh->commandnamemalloc = 0;
                                psh->commandname = args->argv[0];
                                /* initialize nextopt */
                                psh->argptr = args->argv + 1;
                                psh->optptr = NULL;
                                /* and getopt */
#if 0 /** @todo fix getop usage! */
#if defined(__FreeBSD__) || defined(__EMX__) || defined(__APPLE__)
                                optreset = 1;
                                optind = 1;
#else
                                optind = 0; /* init */
#endif
#endif

                                psh->exitstatus = args->cmdentry.u.bltin(psh, args->argc, args->argv);
                        } else {
                                e = psh->exception;
                                psh->exitstatus = e == EXINT ? SIGINT + 128 :
                                                e == EXEXEC ? psh->exerrno : 2;
                        }
                        psh->handler = savehandler;
                        output_flushall(psh);
                        psh->out1 = &psh->output;
                        psh->out2 = &psh->errout;
                        freestdout(psh);
                        if (temp_path) {
                                poplocalvars(psh);
                                psh->localvars = savelocalvars;
                        }
                        psh->cmdenviron = NULL;
                        if (e != EXSHELLPROC) {
                                psh->commandname = savecmdname;
                                psh->commandnamemalloc = savecmdnamemalloc;
                                if (args->flags & EV_EXIT)
                                        exitshell(psh, psh->exitstatus);
                        }
                        else if (savecmdnamemalloc)
                                sh_free(psh, savecmdname);
                        if (e != -1) {
                                if ((e != EXERROR && e != EXEXEC)
                                        || args->cmdentry.cmdtype == CMDSPLBLTIN)
                                        exraise(psh, e);
                                FORCEINTON;
                        }
                        if (args->cmdentry.u.bltin != execcmd)
                                popredir(psh);
                        if (args->flags == EV_BACKCMD) {
                                args->backcmd->buf = psh->memout.buf;
                                args->backcmd->nleft = (int)(psh->memout.nextc - psh->memout.buf);
                                psh->memout.buf = NULL;
                        }
                        break;
                }

                default: {
                        struct strlist *sp;
                        char **envp;
#ifdef DEBUG
                        trputs(psh, "normal command:  ");  trargs(psh, args->argv);
#endif
                        clearredir(psh);
                        redirect(psh, cmd->ncmd.redirect, 0);
                        for (sp = args->varlist.list ; sp ; sp = sp->next)
                                setvareq(psh, sp->text, VEXPORT|VSTACK);
                        envp = environment(psh);
                        shellexec(psh, args->argv, envp, args->path,
                                  args->cmdentry.u.n.index, args->cmdentry.u.n.suffix);
                        break;
                }
        }

        evalcommand_out(psh, args->flags, args->lastarg, args->expfnamedepth, &args->smark);
}

/* child callback. */
static int evalcommand_child(shinstance *psh, union node *cmd, void *argp)
{
        struct evalcommanddoit *args = (struct evalcommanddoit *)argp;

        if (args->flags & EV_BACKCMD) {
                FORCEINTON;
                shfile_close(&psh->fdtab, args->pip[0]);
                if (args->pip[1] != 1) {
                        movefd(psh, args->pip[1], 1);
                }
        }
        args->flags |= EV_EXIT;

        evalcommand_doit(psh, cmd, args);
        /* not reached */  /** @todo make it return here */
        return 0;
}

#ifdef KASH_USE_FORKSHELL2
/* Copies data in the argument structure from parent to child. */
static void evalcommand_setup_child(shinstance *pshchild, shinstance *pshparent, void *argp)
{
        struct evalcommanddoit *args = (struct evalcommanddoit *)argp;
        char **argv;
        char **srcargv;
        struct strlist *sp;
        int argc, i;

        setstackmark(pshchild, &args->smark);

        /* copy arguments. */
        srcargv = args->argv;
        argc = args->argc;
        args->argv = argv = stalloc(pshchild, sizeof(char *) * (argc + 1));
        for (i = 0; i < argc; i++)
                argv[i] = stsavestr(pshchild, srcargv[i]);
        argv[argc] = NULL;
        if (args->lastarg)
                args->lastarg = argv[argc - 1];

        /* copy variable list, checking for the 'path'. */
        sp = args->varlist.list;
        args->varlist.list = NULL;
        args->varlist.lastp = &args->varlist.list;
        for (; sp; sp = sp->next) {
                struct strlist *snew = (struct strlist *)stalloc(pshchild, sizeof(*snew));
                char *text;
                snew->next = NULL;
                snew->text = text = stsavestr(pshchild, sp->text);

                if (&text[5] == args->path)
                        args->path = &text[sizeof("PATH=") - 1];

                *args->varlist.lastp = snew;
                args->varlist.lastp = &snew->next;
        }

        if (args->path == pathval(pshparent))
                args->path = pathval(pshchild);

        /* back tick command should be ignored in this codepath
           (flags != EV_BACKCMD as EV_EXIT is ORed in). */

        /* If cmdentry references an internal function, we must duplicates (reference) it's nodes. */
        if (args->cmdentry.cmdtype == CMDFUNCTION)
                args->cmdentry.u.func = copyparsetree(pshchild, args->cmdentry.u.func); /** @todo isn't this duplicated already? */
}
#endif /* KASH_USE_FORKSHELL2 */

/*
 * Execute a simple command.
 */

STATIC void
evalcommand(shinstance *psh, union node *cmd, int flags, struct backcmd *backcmd)
{
        struct evalcommanddoit args;
        char **argv;
        int argc;

        union node *argp;
        int numvars;
        struct arglist arglist;
        struct strlist *sp;
        const char *path = pathval(psh);

        /* First expand the arguments. */
        TRACE((psh, "evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
        setstackmark(psh, &args.smark);
        psh->back_exitstatus = 0;

        arglist.lastp = &arglist.list;
        /* Expand arguments, ignoring the initial 'name=value' ones */
        for (argp = cmd->ncmd.args, numvars = 0 ; argp ; argp = argp->narg.next, numvars++) {
            char *p = argp->narg.text;
            char ch = *p;
            if (is_name(ch)) {
                    do  ch = *++p;
                    while (is_in_name(ch));
                    if (ch == '=')
                            continue;
            }
            break;
        }
        for (/*continue on argp from above. */ ; argp ; argp = argp->narg.next)
                expandarg(psh, argp, &arglist, EXP_FULL | EXP_TILDE);
        *arglist.lastp = NULL;

        args.expfnamedepth = expredir(psh, cmd->ncmd.redirect);

        /* Now do the initial 'name=value' ones we skipped above */
        args.varlist.lastp = &args.varlist.list;
        for (argp = cmd->ncmd.args ; numvars > 0 && argp ; argp = argp->narg.next, numvars--)
                expandarg(psh, argp, &args.varlist, EXP_VARTILDE);
        *args.varlist.lastp = NULL;

        argc = 0;
        for (sp = arglist.list ; sp ; sp = sp->next)
                argc++;
        args.argc = argc;
        args.argv = argv = stalloc(psh, sizeof (char *) * (argc + 1));

        for (sp = arglist.list ; sp ; sp = sp->next) {
                TRACE((psh, "evalcommand arg: %s\n", sp->text));
                *argv++ = sp->text;
        }
        *argv = NULL;
        args.lastarg = NULL;
        if (iflag(psh) && psh->funcnest == 0 && argc > 0)
                args.lastarg = argv[-1];
        argv -= argc;

        /* Print the command if xflag is set. */
        if (xflag(psh)) {
                char sep = 0;
                out2str(psh, ps4val(psh));
                for (sp = args.varlist.list ; sp ; sp = sp->next) {
                        if (sep != 0)
                                outc(sep, &psh->errout);
                        out2str(psh, sp->text);
                        sep = ' ';
                }
                for (sp = arglist.list ; sp ; sp = sp->next) {
                        if (sep != 0)
                                outc(sep, &psh->errout);
                        out2str(psh, sp->text);
                        sep = ' ';
                }
                outc('\n', &psh->errout);
                flushout(&psh->errout);
        }

        /* Now locate the command. */
        if (argc == 0) {
                args.cmdentry.cmdtype = CMDSPLBLTIN;
                args.cmdentry.u.bltin = bltincmd;
        } else {
                static const char PATH[] = "PATH=";
                int cmd_flags = DO_ERR;

                /*
                 * Modify the command lookup path, if a PATH= assignment
                 * is present
                 */
                for (sp = args.varlist.list; sp; sp = sp->next)
                        if (strncmp(sp->text, PATH, sizeof(PATH) - 1) == 0)
                                path = sp->text + sizeof(PATH) - 1;

                do {
                        int argsused, use_syspath;
                        find_command(psh, argv[0], &args.cmdentry, cmd_flags, path);
                        if (args.cmdentry.cmdtype == CMDUNKNOWN) {
                                psh->exitstatus = 127;
                                flushout(&psh->errout);
                                evalcommand_out(psh, flags, args.lastarg, args.expfnamedepth, &args.smark);
                                return;
                        }

                        /* implement the 'command' builtin here */
                        if (args.cmdentry.cmdtype != CMDBUILTIN ||
                            args.cmdentry.u.bltin != bltincmd)
                                break;
                        cmd_flags |= DO_NOFUNC;
                        argsused = parse_command_args(psh, argc, argv, &use_syspath);
                        if (argsused == 0) {
                                /* use 'type' builting to display info */
                                args.cmdentry.u.bltin = typecmd;
                                break;
                        }
                        argc -= argsused;
                        argv += argsused;
                        if (use_syspath)
                                path = syspath(psh) + 5;
                } while (argc != 0);
                if (args.cmdentry.cmdtype == CMDSPLBLTIN && cmd_flags & DO_NOFUNC)
                        /* posix mandates that 'command <splbltin>' act as if
                           <splbltin> was a normal builtin */
                        args.cmdentry.cmdtype = CMDBUILTIN;
        }

        /* Fork off a child process if necessary. */
        if (cmd->ncmd.backgnd
         || (args.cmdentry.cmdtype == CMDNORMAL && (flags & EV_EXIT) == 0)
         || (  (flags & EV_BACKCMD) != 0
            && (  (args.cmdentry.cmdtype != CMDBUILTIN && args.cmdentry.cmdtype != CMDSPLBLTIN)
                   || args.cmdentry.u.bltin == dotcmd
                   || args.cmdentry.u.bltin == evalcmd))) {
                struct job *jp;
                int mode;

                INTOFF;
                jp = makejob(psh, cmd, 1);
                mode = cmd->ncmd.backgnd;
                args.pip[0] = -1;
                args.pip[1] = -1;
                if (flags & EV_BACKCMD) {
                        mode = FORK_NOJOB;
                        if (sh_pipe(psh, args.pip) < 0)
                                error(psh, "Pipe call failed");
                }

                args.backcmd = backcmd;
                args.flags = flags;
                args.path = path;
#ifdef KASH_USE_FORKSHELL2
                forkshell2(psh, jp, cmd, mode, evalcommand_child, cmd,
                           &args, sizeof(args), evalcommand_setup_child);
                evalcommand_parent(psh, flags, args.lastarg, args.expfnamedepth,
                                   &args.smark, mode, jp, args.pip, backcmd);
#else
                if (forkshell(psh, jp, cmd, mode) != 0) {
                        evalcommand_parent(psh, flags, args.lastarg, args.expfnamedepth,
                                           &args.smark, mode, jp, args.pip, backcmd);
                        return; /* at end of routine */
                }
                evalcommand_child(psh, cmd, &args);
#endif
        } else {
                args.backcmd = backcmd;
                args.flags = flags;
                args.path = path;
                evalcommand_doit(psh, cmd, &args);
        }
}


/*
 * Search for a command.  This is called before we fork so that the
 * location of the command will be available in the parent as well as
 * the child.  The check for "goodname" is an overly conservative
 * check that the name will not be subject to expansion.
 */

STATIC void
prehash(shinstance *psh, union node *n)
{
        struct cmdentry entry;

        if (n->type == NCMD && n->ncmd.args)
                if (goodname(n->ncmd.args->narg.text))
                        find_command(psh, n->ncmd.args->narg.text, &entry, 0,
                                         pathval(psh));
}



/*
 * Builtin commands.  Builtin commands whose functions are closely
 * tied to evaluation are implemented here.
 */

/*
 * No command given.
 */

int
bltincmd(shinstance *psh, int argc, char **argv)
{
        /*
         * Preserve psh->exitstatus of a previous possible redirection
         * as POSIX mandates
         */
        return psh->back_exitstatus;
}


/*
 * Handle break and continue commands.  Break, continue, and return are
 * all handled by setting the psh->evalskip flag.  The evaluation routines
 * above all check this flag, and if it is set they start skipping
 * commands rather than executing them.  The variable skipcount is
 * the number of loops to break/continue, or the number of function
 * levels to return.  (The latter is always 1.)  It should probably
 * be an error to break out of more loops than exist, but it isn't
 * in the standard shell so we don't make it one here.
 */

int
breakcmd(shinstance *psh, int argc, char **argv)
{
        int n = argc > 1 ? number(psh, argv[1]) : 1;

        if (n > psh->loopnest)
                n = psh->loopnest;
        if (n > 0) {
                psh->evalskip = (**argv == 'c')? SKIPCONT : SKIPBREAK;
                psh->skipcount = n;
        }
        return 0;
}


/*
 * The return command.
 */

int
returncmd(shinstance *psh, int argc, char **argv)
{
#if 0
        int ret = argc > 1 ? number(psh, argv[1]) : psh->exitstatus;
#else
        int ret;
        if (argc > 1)  {
                /* make return -1 and VSC lite work ... */
                if (argv[1][0] != '-' || !is_number(&argv[1][1]))
                        ret = number(psh, argv[1]);
                else
                        ret = -number(psh, &argv[1][1]) & 255; /* take the bash approach */
        } else {
                ret = psh->exitstatus;
        }
#endif

        if (psh->funcnest) {
                psh->evalskip = SKIPFUNC;
                psh->skipcount = 1;
                return ret;
        }
        else {
                /* Do what ksh does; skip the rest of the file */
                psh->evalskip = SKIPFILE;
                psh->skipcount = 1;
                return ret;
        }
}


int
falsecmd(shinstance *psh, int argc, char **argv)
{
        return 1;
}


int
truecmd(shinstance *psh, int argc, char **argv)
{
        return 0;
}


int
execcmd(shinstance *psh, int argc, char **argv)
{
        if (argc > 1) {
                struct strlist *sp;

                iflag(psh) = 0;         /* exit on error */
                mflag(psh) = 0;
                optschanged(psh);
                for (sp = psh->cmdenviron; sp; sp = sp->next)
                        setvareq(psh, sp->text, VEXPORT|VSTACK);
                shellexec(psh, argv + 1, environment(psh), pathval(psh), 0, -1);
        }
        return 0;
}

static int
conv_time(clock_t ticks, char *seconds, size_t l)
{
        static clock_t tpm = 0;
        clock_t mins;
        size_t i;

        if (!tpm)
                tpm = /*sysconf(_SC_CLK_TCK)*/sh_sysconf_clk_tck() * 60;

        mins = ticks / tpm;
#ifdef _MSC_VER
        {
                char tmp[64];
                sprintf(tmp, "%.4f", (ticks - mins * tpm) * 60.0 / tpm);
                strlcpy(seconds, tmp, l);
        }
#else
        snprintf(seconds, l, "%.4f", (ticks - mins * tpm) * 60.0 / tpm );
#endif

        if (seconds[0] == '6' && seconds[1] == '0') {
                /* 59.99995 got rounded up... */
                mins++;
                strlcpy(seconds, "0.0", l);
                return mins;
        }

        /* suppress trailing zeros */
        i = strlen(seconds) - 1;
        for (; seconds[i] == '0' && seconds[i - 1] != '.'; i--)
                seconds[i] = 0;
        return mins;
}

int
timescmd(shinstance *psh, int argc, char **argv)
{
        shtms tms;
        int u, s, cu, cs;
        char us[8], ss[8], cus[8], css[8];

        nextopt(psh, "");

        sh_times(psh, &tms);

        u = conv_time(tms.tms_utime, us, sizeof(us));
        s = conv_time(tms.tms_stime, ss, sizeof(ss));
        cu = conv_time(tms.tms_cutime, cus, sizeof(cus));
        cs = conv_time(tms.tms_cstime, css, sizeof(css));

        outfmt(psh->out1, "%dm%ss %dm%ss\n%dm%ss %dm%ss\n",
                u, us, s, ss, cu, cus, cs, css);

        return 0;
}