/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 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.
 */

#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <signal.h>
#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>

#include "shell.h"
#if JOBS
#include <termios.h>
#undef CEOF                     /* syntax.h redefines this */
#endif
#include "redir.h"
#include "exec.h"
#include "show.h"
#include "main.h"
#include "parser.h"
#include "nodes.h"
#include "jobs.h"
#include "options.h"
#include "trap.h"
#include "syntax.h"
#include "input.h"
#include "output.h"
#include "memalloc.h"
#include "error.h"
#include "mystring.h"
#include "var.h"
#include "builtins.h"
#include "eval.h"


/*
 * A job structure contains information about a job.  A job is either a
 * single process or a set of processes contained in a pipeline.  In the
 * latter case, pidlist will be non-NULL, and will point to a -1 terminated
 * array of pids.
 */

struct procstat {
        pid_t pid;              /* process id */
        int status;             /* status flags (defined above) */
        char *cmd;              /* text of command being run */
};


/* states */
#define JOBSTOPPED 1            /* all procs are stopped */
#define JOBDONE 2               /* all procs are completed */


struct job {
        struct procstat ps0;    /* status of process */
        struct procstat *ps;    /* status or processes when more than one */
        short nprocs;           /* number of processes */
        pid_t pgrp;             /* process group of this job */
        char state;             /* true if job is finished */
        char used;              /* true if this entry is in use */
        char changed;           /* true if status has changed */
        char foreground;        /* true if running in the foreground */
        char remembered;        /* true if $! referenced */
        char pipefail;          /* pass any non-zero status */
#if JOBS
        char jobctl;            /* job running under job control */
        struct job *next;       /* job used after this one */
#endif
};


static struct job *jobtab;      /* array of jobs */
static int njobs;               /* size of array */
static pid_t backgndpid = -1;   /* pid of last background process */
static struct job *bgjob = NULL; /* last background process */
#if JOBS
static struct job *jobmru;      /* most recently used job list */
static pid_t initialpgrp;       /* pgrp of shell on invocation */
#endif
static int ttyfd = -1;

/* mode flags for dowait */
#define DOWAIT_BLOCK    0x1 /* wait until a child exits */
#define DOWAIT_SIG      0x2 /* if DOWAIT_BLOCK, abort on signal */
#define DOWAIT_SIG_TRAP 0x4 /* if DOWAIT_SIG, abort on trapped signal only */

#if JOBS
static void restartjob(struct job *);
#endif
static void freejob(struct job *);
static int waitcmdloop(struct job *);
static struct job *getjob_nonotfound(const char *);
static struct job *getjob(const char *);
pid_t killjob(const char *, int);
static pid_t dowait(int, struct job *);
static void checkzombies(void);
static void cmdtxt(union node *);
static void cmdputs(const char *);
#if JOBS
static void setcurjob(struct job *);
static void deljob(struct job *);
static struct job *getcurjob(struct job *);
#endif
static int getjobstatus(const struct job *);
static void printjobcmd(struct job *);
static void showjob(struct job *, int);


/*
 * Turn job control on and off.
 */

static int jobctl;

#if JOBS
static void
jobctl_notty(void)
{
        if (ttyfd >= 0) {
                close(ttyfd);
                ttyfd = -1;
        }
        if (!iflag) {
                setsignal(SIGTSTP);
                setsignal(SIGTTOU);
                setsignal(SIGTTIN);
                jobctl = 1;
                return;
        }
        out2fmt_flush("sh: can't access tty; job control turned off\n");
        mflag = 0;
}

void
setjobctl(int on)
{
        int i;

        if (on == jobctl || rootshell == 0)
                return;
        if (on) {
                if (ttyfd != -1)
                        close(ttyfd);
                if ((ttyfd = open(_PATH_TTY, O_RDWR | O_CLOEXEC)) < 0) {
                        i = 0;
                        while (i <= 2 && !isatty(i))
                                i++;
                        if (i > 2 ||
                            (ttyfd = fcntl(i, F_DUPFD_CLOEXEC, 10)) < 0) {
                                jobctl_notty();
                                return;
                        }
                }
                if (ttyfd < 10) {
                        /*
                         * Keep our TTY file descriptor out of the way of
                         * the user's redirections.
                         */
                        if ((i = fcntl(ttyfd, F_DUPFD_CLOEXEC, 10)) < 0) {
                                jobctl_notty();
                                return;
                        }
                        close(ttyfd);
                        ttyfd = i;
                }
                do { /* while we are in the background */
                        initialpgrp = tcgetpgrp(ttyfd);
                        if (initialpgrp < 0) {
                                jobctl_notty();
                                return;
                        }
                        if (initialpgrp != getpgrp()) {
                                if (!iflag) {
                                        initialpgrp = -1;
                                        jobctl_notty();
                                        return;
                                }
                                kill(0, SIGTTIN);
                                continue;
                        }
                } while (0);
                setsignal(SIGTSTP);
                setsignal(SIGTTOU);
                setsignal(SIGTTIN);
                setpgid(0, rootpid);
                tcsetpgrp(ttyfd, rootpid);
        } else { /* turning job control off */
                setpgid(0, initialpgrp);
                if (ttyfd >= 0) {
                        tcsetpgrp(ttyfd, initialpgrp);
                        close(ttyfd);
                        ttyfd = -1;
                }
                setsignal(SIGTSTP);
                setsignal(SIGTTOU);
                setsignal(SIGTTIN);
        }
        jobctl = on;
}
#endif


#if JOBS
int
fgcmd(int argc __unused, char **argv __unused)
{
        struct job *jp;
        pid_t pgrp;
        int status;

        nextopt("");
        jp = getjob(*argptr);
        if (jp->jobctl == 0)
                error("job not created under job control");
        printjobcmd(jp);
        flushout(&output);
        pgrp = jp->ps[0].pid;
        if (ttyfd >= 0)
                tcsetpgrp(ttyfd, pgrp);
        restartjob(jp);
        jp->foreground = 1;
        INTOFF;
        status = waitforjob(jp, (int *)NULL);
        INTON;
        return status;
}


int
bgcmd(int argc __unused, char **argv __unused)
{
        struct job *jp;

        nextopt("");
        do {
                jp = getjob(*argptr);
                if (jp->jobctl == 0)
                        error("job not created under job control");
                if (jp->state == JOBDONE)
                        continue;
                restartjob(jp);
                jp->foreground = 0;
                out1fmt("[%td] ", jp - jobtab + 1);
                printjobcmd(jp);
        } while (*argptr != NULL && *++argptr != NULL);
        return 0;
}


static void
restartjob(struct job *jp)
{
        struct procstat *ps;
        int i;

        if (jp->state == JOBDONE)
                return;
        setcurjob(jp);
        INTOFF;
        kill(-jp->ps[0].pid, SIGCONT);
        for (ps = jp->ps, i = jp->nprocs ; --i >= 0 ; ps++) {
                if (WIFSTOPPED(ps->status)) {
                        ps->status = -1;
                        jp->state = 0;
                }
        }
        INTON;
}
#endif


int
jobscmd(int argc __unused, char *argv[] __unused)
{
        char *id;
        int ch, mode;

        mode = SHOWJOBS_DEFAULT;
        while ((ch = nextopt("lps")) != '\0') {
                switch (ch) {
                case 'l':
                        mode = SHOWJOBS_VERBOSE;
                        break;
                case 'p':
                        mode = SHOWJOBS_PGIDS;
                        break;
                case 's':
                        mode = SHOWJOBS_PIDS;
                        break;
                }
        }

        if (*argptr == NULL)
                showjobs(0, mode);
        else
                while ((id = *argptr++) != NULL)
                        showjob(getjob(id), mode);

        return (0);
}

static int getjobstatus(const struct job *jp)
{
        int i, status;

        if (!jp->pipefail)
                return (jp->ps[jp->nprocs - 1].status);
        for (i = jp->nprocs - 1; i >= 0; i--) {
                status = jp->ps[i].status;
                if (status != 0)
                        return (status);
        }
        return (0);
}

static void
printjobcmd(struct job *jp)
{
        struct procstat *ps;
        int i;

        for (ps = jp->ps, i = jp->nprocs ; --i >= 0 ; ps++) {
                out1str(ps->cmd);
                if (i > 0)
                        out1str(" | ");
        }
        out1c('\n');
}

static void
showjob(struct job *jp, int mode)
{
        char s[64];
        char statebuf[16];
        const char *statestr, *coredump;
        struct procstat *ps;
        struct job *j;
        int col, curr, i, jobno, prev, procno, status;
        char c;

        procno = (mode == SHOWJOBS_PGIDS) ? 1 : jp->nprocs;
        jobno = jp - jobtab + 1;
        curr = prev = 0;
#if JOBS
        if ((j = getcurjob(NULL)) != NULL) {
                curr = j - jobtab + 1;
                if ((j = getcurjob(j)) != NULL)
                        prev = j - jobtab + 1;
        }
#endif
        coredump = "";
        status = getjobstatus(jp);
        if (jp->state == 0) {
                statestr = "Running";
#if JOBS
        } else if (jp->state == JOBSTOPPED) {
                ps = jp->ps + jp->nprocs - 1;
                while (!WIFSTOPPED(ps->status) && ps > jp->ps)
                        ps--;
                if (WIFSTOPPED(ps->status))
                        i = WSTOPSIG(ps->status);
                else
                        i = -1;
                statestr = strsignal(i);
                if (statestr == NULL)
                        statestr = "Suspended";
#endif
        } else if (WIFEXITED(status)) {
                if (WEXITSTATUS(status) == 0)
                        statestr = "Done";
                else {
                        fmtstr(statebuf, sizeof(statebuf), "Done(%d)",
                            WEXITSTATUS(status));
                        statestr = statebuf;
                }
        } else {
                i = WTERMSIG(status);
                statestr = strsignal(i);
                if (statestr == NULL)
                        statestr = "Unknown signal";
                if (WCOREDUMP(status))
                        coredump = " (core dumped)";
        }

        for (ps = jp->ps ; procno > 0 ; ps++, procno--) { /* for each process */
                if (mode == SHOWJOBS_PIDS || mode == SHOWJOBS_PGIDS) {
                        out1fmt("%d\n", (int)ps->pid);
                        continue;
                }
                if (mode != SHOWJOBS_VERBOSE && ps != jp->ps)
                        continue;
                if (jobno == curr && ps == jp->ps)
                        c = '+';
                else if (jobno == prev && ps == jp->ps)
                        c = '-';
                else
                        c = ' ';
                if (ps == jp->ps)
                        fmtstr(s, 64, "[%d] %c ", jobno, c);
                else
                        fmtstr(s, 64, "    %c ", c);
                out1str(s);
                col = strlen(s);
                if (mode == SHOWJOBS_VERBOSE) {
                        fmtstr(s, 64, "%d ", (int)ps->pid);
                        out1str(s);
                        col += strlen(s);
                }
                if (ps == jp->ps) {
                        out1str(statestr);
                        out1str(coredump);
                        col += strlen(statestr) + strlen(coredump);
                }
                do {
                        out1c(' ');
                        col++;
                } while (col < 30);
                if (mode == SHOWJOBS_VERBOSE) {
                        out1str(ps->cmd);
                        out1c('\n');
                } else
                        printjobcmd(jp);
        }
}

/*
 * Print a list of jobs.  If "change" is nonzero, only print jobs whose
 * statuses have changed since the last call to showjobs.
 *
 * If the shell is interrupted in the process of creating a job, the
 * result may be a job structure containing zero processes.  Such structures
 * will be freed here.
 */

void
showjobs(int change, int mode)
{
        int jobno;
        struct job *jp;

        TRACE(("showjobs(%d) called\n", change));
        checkzombies();
        for (jobno = 1, jp = jobtab ; jobno <= njobs ; jobno++, jp++) {
                if (! jp->used)
                        continue;
                if (jp->nprocs == 0) {
                        freejob(jp);
                        continue;
                }
                if (change && ! jp->changed)
                        continue;
                showjob(jp, mode);
                if (mode == SHOWJOBS_DEFAULT || mode == SHOWJOBS_VERBOSE) {
                        jp->changed = 0;
                        /* Hack: discard jobs for which $! has not been
                         * referenced in interactive mode when they terminate.
                         */
                        if (jp->state == JOBDONE && !jp->remembered &&
                                        (iflag || jp != bgjob)) {
                                freejob(jp);
                        }
                }
        }
}


/*
 * Mark a job structure as unused.
 */

static void
freejob(struct job *jp)
{
        struct procstat *ps;
        int i;

        INTOFF;
        if (bgjob == jp)
                bgjob = NULL;
        for (i = jp->nprocs, ps = jp->ps ; --i >= 0 ; ps++) {
                if (ps->cmd != nullstr)
                        ckfree(ps->cmd);
        }
        if (jp->ps != &jp->ps0)
                ckfree(jp->ps);
        jp->used = 0;
#if JOBS
        deljob(jp);
#endif
        INTON;
}



int
waitcmd(int argc __unused, char **argv __unused)
{
        struct job *job;
        int retval;

        nextopt("");
        if (*argptr == NULL)
                return (waitcmdloop(NULL));

        do {
                job = getjob_nonotfound(*argptr);
                if (job == NULL)
                        retval = 127;
                else
                        retval = waitcmdloop(job);
                argptr++;
        } while (*argptr != NULL);

        return (retval);
}

static int
waitcmdloop(struct job *job)
{
        int status, retval, sig;
        struct job *jp;

        /*
         * Loop until a process is terminated or stopped, or a SIGINT is
         * received.
         */

        do {
                if (job != NULL) {
                        if (job->state == JOBDONE) {
                                status = getjobstatus(job);
                                if (WIFEXITED(status))
                                        retval = WEXITSTATUS(status);
                                else
                                        retval = WTERMSIG(status) + 128;
                                if (! iflag || ! job->changed)
                                        freejob(job);
                                else {
                                        job->remembered = 0;
                                        deljob(job);
                                        if (job == bgjob)
                                                bgjob = NULL;
                                }
                                return retval;
                        }
                } else {
                        if (njobs == 0)
                                return 0;
                        for (jp = jobtab ; jp < jobtab + njobs; jp++)
                                if (jp->used && jp->state == JOBDONE) {
                                        if (! iflag || ! jp->changed)
                                                freejob(jp);
                                        else {
                                                jp->remembered = 0;
                                                if (jp == bgjob)
                                                        bgjob = NULL;
                                        }
                                }
                        for (jp = jobtab ; ; jp++) {
                                if (jp >= jobtab + njobs) {     /* no running procs */
                                        return 0;
                                }
                                if (jp->used && jp->state == 0)
                                        break;
                        }
                }
        } while (dowait(DOWAIT_BLOCK | DOWAIT_SIG, job) != -1);

        sig = pendingsig_waitcmd;
        pendingsig_waitcmd = 0;
        return sig + 128;
}



int
jobidcmd(int argc __unused, char **argv __unused)
{
        struct job *jp;
        int i;

        nextopt("");
        jp = getjob(*argptr);
        for (i = 0 ; i < jp->nprocs ; ) {
                out1fmt("%d", (int)jp->ps[i].pid);
                out1c(++i < jp->nprocs? ' ' : '\n');
        }
        return 0;
}



/*
 * Convert a job name to a job structure.
 */

static struct job *
getjob_nonotfound(const char *name)
{
        int jobno;
        struct job *found, *jp;
        size_t namelen;
        pid_t pid;
        int i;

        if (name == NULL) {
#if JOBS
                name = "%+";
#else
                error("No current job");
#endif
        }
        if (name[0] == '%') {
                if (is_digit(name[1])) {
                        jobno = number(name + 1);
                        if (jobno > 0 && jobno <= njobs
                         && jobtab[jobno - 1].used != 0)
                                return &jobtab[jobno - 1];
#if JOBS
                } else if ((name[1] == '%' || name[1] == '+') &&
                    name[2] == '\0') {
                        if ((jp = getcurjob(NULL)) == NULL)
                                error("No current job");
                        return (jp);
                } else if (name[1] == '-' && name[2] == '\0') {
                        if ((jp = getcurjob(NULL)) == NULL ||
                            (jp = getcurjob(jp)) == NULL)
                                error("No previous job");
                        return (jp);
#endif
                } else if (name[1] == '?') {
                        found = NULL;
                        for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) {
                                if (jp->used && jp->nprocs > 0
                                 && strstr(jp->ps[0].cmd, name + 2) != NULL) {
                                        if (found)
                                                error("%s: ambiguous", name);
                                        found = jp;
                                }
                        }
                        if (found != NULL)
                                return (found);
                } else {
                        namelen = strlen(name);
                        found = NULL;
                        for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) {
                                if (jp->used && jp->nprocs > 0
                                 && strncmp(jp->ps[0].cmd, name + 1,
                                 namelen - 1) == 0) {
                                        if (found)
                                                error("%s: ambiguous", name);
                                        found = jp;
                                }
                        }
                        if (found)
                                return found;
                }
        } else if (is_number(name)) {
                pid = (pid_t)number(name);
                for (jp = jobtab, i = njobs ; --i >= 0 ; jp++) {
                        if (jp->used && jp->nprocs > 0
                         && jp->ps[jp->nprocs - 1].pid == pid)
                                return jp;
                }
        }
        return NULL;
}


static struct job *
getjob(const char *name)
{
        struct job *jp;

        jp = getjob_nonotfound(name);
        if (jp == NULL)
                error("No such job: %s", name);
        return (jp);
}


int
killjob(const char *name, int sig)
{
        struct job *jp;
        int i, ret;

        jp = getjob(name);
        if (jp->state == JOBDONE)
                return 0;
        if (jp->jobctl)
                return kill(-jp->ps[0].pid, sig);
        ret = -1;
        errno = ESRCH;
        for (i = 0; i < jp->nprocs; i++)
                if (jp->ps[i].status == -1 || WIFSTOPPED(jp->ps[i].status)) {
                        if (kill(jp->ps[i].pid, sig) == 0)
                                ret = 0;
                } else
                        ret = 0;
        return ret;
}

/*
 * Return a new job structure,
 */

struct job *
makejob(union node *node __unused, int nprocs)
{
        int i;
        struct job *jp;

        for (i = njobs, jp = jobtab ; ; jp++) {
                if (--i < 0) {
                        INTOFF;
                        if (njobs == 0) {
                                jobtab = ckmalloc(4 * sizeof jobtab[0]);
#if JOBS
                                jobmru = NULL;
#endif
                        } else {
                                jp = ckmalloc((njobs + 4) * sizeof jobtab[0]);
                                memcpy(jp, jobtab, njobs * sizeof jp[0]);
#if JOBS
                                /* Relocate `next' pointers and list head */
                                if (jobmru != NULL)
                                        jobmru = &jp[jobmru - jobtab];
                                for (i = 0; i < njobs; i++)
                                        if (jp[i].next != NULL)
                                                jp[i].next = &jp[jp[i].next -
                                                    jobtab];
#endif
                                if (bgjob != NULL)
                                        bgjob = &jp[bgjob - jobtab];
                                /* Relocate `ps' pointers */
                                for (i = 0; i < njobs; i++)
                                        if (jp[i].ps == &jobtab[i].ps0)
                                                jp[i].ps = &jp[i].ps0;
                                ckfree(jobtab);
                                jobtab = jp;
                        }
                        jp = jobtab + njobs;
                        for (i = 4 ; --i >= 0 ; jobtab[njobs++].used = 0)
                                ;
                        INTON;
                        break;
                }
                if (jp->used == 0)
                        break;
        }
        INTOFF;
        jp->state = 0;
        jp->used = 1;
        jp->changed = 0;
        jp->nprocs = 0;
        jp->foreground = 0;
        jp->remembered = 0;
        jp->pipefail = pipefailflag;
#if JOBS
        jp->jobctl = jobctl;
        jp->next = NULL;
#endif
        if (nprocs > 1) {
                jp->ps = ckmalloc(nprocs * sizeof (struct procstat));
        } else {
                jp->ps = &jp->ps0;
        }
        INTON;
        TRACE(("makejob(%p, %d) returns %%%td\n", (void *)node, nprocs,
            jp - jobtab + 1));
        return jp;
}

#if JOBS
static void
setcurjob(struct job *cj)
{
        struct job *jp, *prev;

        for (prev = NULL, jp = jobmru; jp != NULL; prev = jp, jp = jp->next) {
                if (jp == cj) {
                        if (prev != NULL)
                                prev->next = jp->next;
                        else
                                jobmru = jp->next;
                        jp->next = jobmru;
                        jobmru = cj;
                        return;
                }
        }
        cj->next = jobmru;
        jobmru = cj;
}

static void
deljob(struct job *j)
{
        struct job *jp, *prev;

        for (prev = NULL, jp = jobmru; jp != NULL; prev = jp, jp = jp->next) {
                if (jp == j) {
                        if (prev != NULL)
                                prev->next = jp->next;
                        else
                                jobmru = jp->next;
                        return;
                }
        }
}

/*
 * Return the most recently used job that isn't `nj', and preferably one
 * that is stopped.
 */
static struct job *
getcurjob(struct job *nj)
{
        struct job *jp;

        /* Try to find a stopped one.. */
        for (jp = jobmru; jp != NULL; jp = jp->next)
                if (jp->used && jp != nj && jp->state == JOBSTOPPED)
                        return (jp);
        /* Otherwise the most recently used job that isn't `nj' */
        for (jp = jobmru; jp != NULL; jp = jp->next)
                if (jp->used && jp != nj)
                        return (jp);

        return (NULL);
}

#endif

/*
 * Fork of a subshell.  If we are doing job control, give the subshell its
 * own process group.  Jp is a job structure that the job is to be added to.
 * N is the command that will be evaluated by the child.  Both jp and n may
 * be NULL.  The mode parameter can be one of the following:
 *      FORK_FG - Fork off a foreground process.
 *      FORK_BG - Fork off a background process.
 *      FORK_NOJOB - Like FORK_FG, but don't give the process its own
 *                   process group even if job control is on.
 *
 * When job control is turned off, background processes have their standard
 * input redirected to /dev/null (except for the second and later processes
 * in a pipeline).
 */

pid_t
forkshell(struct job *jp, union node *n, int mode)
{
        pid_t pid;
        pid_t pgrp;

        TRACE(("forkshell(%%%td, %p, %d) called\n", jp - jobtab, (void *)n,
            mode));
        INTOFF;
        if (mode == FORK_BG && (jp == NULL || jp->nprocs == 0))
                checkzombies();
        flushall();
        pid = fork();
        if (pid == -1) {
                TRACE(("Fork failed, errno=%d\n", errno));
                INTON;
                error("Cannot fork: %s", strerror(errno));
        }
        if (pid == 0) {
                struct job *p;
                int wasroot;
                int i;

                TRACE(("Child shell %d\n", (int)getpid()));
                wasroot = rootshell;
                rootshell = 0;
                handler = &main_handler;
                closescript();
                INTON;
                forcelocal = 0;
                clear_traps();
#if JOBS
                jobctl = 0;             /* do job control only in root shell */
                if (wasroot && mode != FORK_NOJOB && mflag) {
                        if (jp == NULL || jp->nprocs == 0)
                                pgrp = getpid();
                        else
                                pgrp = jp->ps[0].pid;
                        if (setpgid(0, pgrp) == 0 && mode == FORK_FG &&
                            ttyfd >= 0) {
                                /*
                                 * Each process in a pipeline must have the tty
                                 * pgrp set before running its code.
                                 * Only for pipelines of three or more processes
                                 * could this be reduced to two calls.
                                 */
                                if (tcsetpgrp(ttyfd, pgrp) < 0)
                                        error("tcsetpgrp failed, errno=%d", errno);
                        }
                        setsignal(SIGTSTP);
                        setsignal(SIGTTOU);
                } else if (mode == FORK_BG) {
                        ignoresig(SIGINT);
                        ignoresig(SIGQUIT);
                        if ((jp == NULL || jp->nprocs == 0) &&
                            ! fd0_redirected_p ()) {
                                close(0);
                                if (open(_PATH_DEVNULL, O_RDONLY) != 0)
                                        error("cannot open %s: %s",
                                            _PATH_DEVNULL, strerror(errno));
                        }
                }
#else
                if (mode == FORK_BG) {
                        ignoresig(SIGINT);
                        ignoresig(SIGQUIT);
                        if ((jp == NULL || jp->nprocs == 0) &&
                            ! fd0_redirected_p ()) {
                                close(0);
                                if (open(_PATH_DEVNULL, O_RDONLY) != 0)
                                        error("cannot open %s: %s",
                                            _PATH_DEVNULL, strerror(errno));
                        }
                }
#endif
                INTOFF;
                for (i = njobs, p = jobtab ; --i >= 0 ; p++)
                        if (p->used)
                                freejob(p);
                INTON;
                if (wasroot && iflag) {
                        setsignal(SIGINT);
                        setsignal(SIGQUIT);
                        setsignal(SIGTERM);
                }
                return pid;
        }
        if (rootshell && mode != FORK_NOJOB && mflag) {
                if (jp == NULL || jp->nprocs == 0)
                        pgrp = pid;
                else
                        pgrp = jp->ps[0].pid;
                setpgid(pid, pgrp);
        }
        if (mode == FORK_BG) {
                if (bgjob != NULL && bgjob->state == JOBDONE &&
                    !bgjob->remembered && !iflag)
                        freejob(bgjob);
                backgndpid = pid;               /* set $! */
                bgjob = jp;
        }
        if (jp) {
                struct procstat *ps = &jp->ps[jp->nprocs++];
                ps->pid = pid;
                ps->status = -1;
                ps->cmd = nullstr;
                if (iflag && rootshell && n)
                        ps->cmd = commandtext(n);
                jp->foreground = mode == FORK_FG;
#if JOBS
                setcurjob(jp);
#endif
        }
        INTON;
        TRACE(("In parent shell:  child = %d\n", (int)pid));
        return pid;
}


pid_t
vforkexecshell(struct job *jp, char **argv, char **envp, const char *path, int idx, int pip[2])
{
        pid_t pid;
        struct jmploc jmploc;
        struct jmploc *savehandler;
        int inton;

        TRACE(("vforkexecshell(%%%td, %s, %p) called\n", jp - jobtab, argv[0],
            (void *)pip));
        inton = is_int_on();
        INTOFF;
        flushall();
        savehandler = handler;
        pid = vfork();
        if (pid == -1) {
                TRACE(("Vfork failed, errno=%d\n", errno));
                INTON;
                error("Cannot fork: %s", strerror(errno));
        }
        if (pid == 0) {
                TRACE(("Child shell %d\n", (int)getpid()));
                if (setjmp(jmploc.loc))
                        _exit(exitstatus);
                if (pip != NULL) {
                        close(pip[0]);
                        if (pip[1] != 1) {
                                dup2(pip[1], 1);
                                close(pip[1]);
                        }
                }
                handler = &jmploc;
                shellexec(argv, envp, path, idx);
        }
        handler = savehandler;
        if (jp) {
                struct procstat *ps = &jp->ps[jp->nprocs++];
                ps->pid = pid;
                ps->status = -1;
                ps->cmd = nullstr;
                jp->foreground = 1;
#if JOBS
                setcurjob(jp);
#endif
        }
        SETINTON(inton);
        TRACE(("In parent shell:  child = %d\n", (int)pid));
        return pid;
}


/*
 * Wait for job to finish.
 *
 * Under job control we have the problem that while a child process is
 * running interrupts generated by the user are sent to the child but not
 * to the shell.  This means that an infinite loop started by an inter-
 * active user may be hard to kill.  With job control turned off, an
 * interactive user may place an interactive program inside a loop.  If
 * the interactive program catches interrupts, the user doesn't want
 * these interrupts to also abort the loop.  The approach we take here
 * is to have the shell ignore interrupt signals while waiting for a
 * foreground process to terminate, and then send itself an interrupt
 * signal if the child process was terminated by an interrupt signal.
 * Unfortunately, some programs want to do a bit of cleanup and then
 * exit on interrupt; unless these processes terminate themselves by
 * sending a signal to themselves (instead of calling exit) they will
 * confuse this approach.
 */

int
waitforjob(struct job *jp, int *signaled)
{
#if JOBS
        int propagate_int = jp->jobctl && jp->foreground;
#endif
        int jobindex;
        int status;
        int st;

        INTOFF;
        TRACE(("waitforjob(%%%td) called\n", jp - jobtab + 1));
        while (jp->state == 0)
                if (dowait(DOWAIT_BLOCK | (Tflag ? DOWAIT_SIG |
                    DOWAIT_SIG_TRAP : 0), jp) == -1) {
                        jobindex = jp - jobtab;
                        dotrap();
                        jp = jobtab + jobindex;
                }
#if JOBS
        if (jp->jobctl) {
                if (ttyfd >= 0 && tcsetpgrp(ttyfd, rootpid) < 0)
                        error("tcsetpgrp failed, errno=%d\n", errno);
        }
        if (jp->state == JOBSTOPPED)
                setcurjob(jp);
#endif
        status = getjobstatus(jp);
        if (signaled != NULL)
                *signaled = WIFSIGNALED(status);
        /* convert to 8 bits */
        if (WIFEXITED(status))
                st = WEXITSTATUS(status);
#if JOBS
        else if (WIFSTOPPED(status))
                st = WSTOPSIG(status) + 128;
#endif
        else
                st = WTERMSIG(status) + 128;
        if (! JOBS || jp->state == JOBDONE)
                freejob(jp);
        if (int_pending()) {
                if (!WIFSIGNALED(status) || WTERMSIG(status) != SIGINT)
                        CLEAR_PENDING_INT;
        }
#if JOBS
        else if (rootshell && propagate_int &&
                        WIFSIGNALED(status) && WTERMSIG(status) == SIGINT)
                kill(getpid(), SIGINT);
#endif
        INTON;
        return st;
}


static void
dummy_handler(int sig __unused)
{
}

/*
 * Wait for a process to terminate.
 */

static pid_t
dowait(int mode, struct job *job)
{
        struct sigaction sa, osa;
        sigset_t mask, omask;
        pid_t pid;
        int status;
        struct procstat *sp;
        struct job *jp;
        struct job *thisjob;
        const char *sigstr;
        int done;
        int stopped;
        int sig;
        int coredump;
        int wflags;
        int restore_sigchld;

        TRACE(("dowait(%d, %p) called\n", mode, job));
        restore_sigchld = 0;
        if ((mode & DOWAIT_SIG) != 0) {
                sigfillset(&mask);
                sigprocmask(SIG_BLOCK, &mask, &omask);
                INTOFF;
                if (!issigchldtrapped()) {
                        restore_sigchld = 1;
                        sa.sa_handler = dummy_handler;
                        sa.sa_flags = 0;
                        sigemptyset(&sa.sa_mask);
                        sigaction(SIGCHLD, &sa, &osa);
                }
        }
        do {
#if JOBS
                if (iflag)
                        wflags = WUNTRACED | WCONTINUED;
                else
#endif
                        wflags = 0;
                if ((mode & (DOWAIT_BLOCK | DOWAIT_SIG)) != DOWAIT_BLOCK)
                        wflags |= WNOHANG;
                pid = wait3(&status, wflags, (struct rusage *)NULL);
                TRACE(("wait returns %d, status=%d\n", (int)pid, status));
                if (pid == 0 && (mode & DOWAIT_SIG) != 0) {
                        pid = -1;
                        if (((mode & DOWAIT_SIG_TRAP) != 0 ?
                            pendingsig : pendingsig_waitcmd) != 0) {
                                errno = EINTR;
                                break;
                        }
                        sigsuspend(&omask);
                        if (int_pending())
                                break;
                }
        } while (pid == -1 && errno == EINTR);
        if (pid == -1 && errno == ECHILD && job != NULL)
                job->state = JOBDONE;
        if ((mode & DOWAIT_SIG) != 0) {
                if (restore_sigchld)
                        sigaction(SIGCHLD, &osa, NULL);
                sigprocmask(SIG_SETMASK, &omask, NULL);
                INTON;
        }
        if (pid <= 0)
                return pid;
        INTOFF;
        thisjob = NULL;
        for (jp = jobtab ; jp < jobtab + njobs ; jp++) {
                if (jp->used && jp->nprocs > 0) {
                        done = 1;
                        stopped = 1;
                        for (sp = jp->ps ; sp < jp->ps + jp->nprocs ; sp++) {
                                if (sp->pid == -1)
                                        continue;
                                if (sp->pid == pid && (sp->status == -1 ||
                                    WIFSTOPPED(sp->status))) {
                                        TRACE(("Changing status of proc %d from 0x%x to 0x%x\n",
                                                   (int)pid, sp->status,
                                                   status));
                                        if (WIFCONTINUED(status)) {
                                                sp->status = -1;
                                                jp->state = 0;
                                        } else
                                                sp->status = status;
                                        thisjob = jp;
                                }
                                if (sp->status == -1)
                                        stopped = 0;
                                else if (WIFSTOPPED(sp->status))
                                        done = 0;
                        }
                        if (stopped) {          /* stopped or done */
                                int state = done? JOBDONE : JOBSTOPPED;
                                if (jp->state != state) {
                                        TRACE(("Job %td: changing state from %d to %d\n", jp - jobtab + 1, jp->state, state));
                                        jp->state = state;
                                        if (jp != job) {
                                                if (done && !jp->remembered &&
                                                    !iflag && jp != bgjob)
                                                        freejob(jp);
#if JOBS
                                                else if (done)
                                                        deljob(jp);
#endif
                                        }
                                }
                        }
                }
        }
        INTON;
        if (!thisjob || thisjob->state == 0)
                ;
        else if ((!rootshell || !iflag || thisjob == job) &&
            thisjob->foreground && thisjob->state != JOBSTOPPED) {
                sig = 0;
                coredump = 0;
                for (sp = thisjob->ps; sp < thisjob->ps + thisjob->nprocs; sp++)
                        if (WIFSIGNALED(sp->status)) {
                                sig = WTERMSIG(sp->status);
                                coredump = WCOREDUMP(sp->status);
                        }
                if (sig > 0 && sig != SIGINT && sig != SIGPIPE) {
                        sigstr = strsignal(sig);
                        if (sigstr != NULL)
                                out2str(sigstr);
                        else
                                out2str("Unknown signal");
                        if (coredump)
                                out2str(" (core dumped)");
                        out2c('\n');
                        flushout(out2);
                }
        } else {
                TRACE(("Not printing status, rootshell=%d, job=%p\n", rootshell, job));
                thisjob->changed = 1;
        }
        return pid;
}



/*
 * return 1 if there are stopped jobs, otherwise 0
 */
int job_warning = 0;
int
stoppedjobs(void)
{
        int jobno;
        struct job *jp;

        if (job_warning)
                return (0);
        for (jobno = 1, jp = jobtab; jobno <= njobs; jobno++, jp++) {
                if (jp->used == 0)
                        continue;
                if (jp->state == JOBSTOPPED) {
                        out2fmt_flush("You have stopped jobs.\n");
                        job_warning = 2;
                        return (1);
                }
        }

        return (0);
}


static void
checkzombies(void)
{
        while (njobs > 0 && dowait(0, NULL) > 0)
                ;
}


int
backgndpidset(void)
{
        return backgndpid != -1;
}


pid_t
backgndpidval(void)
{
        if (bgjob != NULL && !forcelocal)
                bgjob->remembered = 1;
        return backgndpid;
}

/*
 * Return a string identifying a command (to be printed by the
 * jobs command.
 */

static char *cmdnextc;
static int cmdnleft;
#define MAXCMDTEXT      200

char *
commandtext(union node *n)
{
        char *name;

        cmdnextc = name = ckmalloc(MAXCMDTEXT);
        cmdnleft = MAXCMDTEXT - 4;
        cmdtxt(n);
        *cmdnextc = '\0';
        return name;
}


static void
cmdtxtdogroup(union node *n)
{
        cmdputs("; do ");
        cmdtxt(n);
        cmdputs("; done");
}


static void
cmdtxtredir(union node *n, const char *op, int deffd)
{
        char s[2];

        if (n->nfile.fd != deffd) {
                s[0] = n->nfile.fd + '0';
                s[1] = '\0';
                cmdputs(s);
        }
        cmdputs(op);
        if (n->type == NTOFD || n->type == NFROMFD) {
                if (n->ndup.dupfd >= 0)
                        s[0] = n->ndup.dupfd + '0';
                else
                        s[0] = '-';
                s[1] = '\0';
                cmdputs(s);
        } else {
                cmdtxt(n->nfile.fname);
        }
}


static void
cmdtxt(union node *n)
{
        union node *np;
        struct nodelist *lp;

        if (n == NULL)
                return;
        switch (n->type) {
        case NSEMI:
                cmdtxt(n->nbinary.ch1);
                cmdputs("; ");
                cmdtxt(n->nbinary.ch2);
                break;
        case NAND:
                cmdtxt(n->nbinary.ch1);
                cmdputs(" && ");
                cmdtxt(n->nbinary.ch2);
                break;
        case NOR:
                cmdtxt(n->nbinary.ch1);
                cmdputs(" || ");
                cmdtxt(n->nbinary.ch2);
                break;
        case NPIPE:
                for (lp = n->npipe.cmdlist ; lp ; lp = lp->next) {
                        cmdtxt(lp->n);
                        if (lp->next)
                                cmdputs(" | ");
                }
                break;
        case NSUBSHELL:
                cmdputs("(");
                cmdtxt(n->nredir.n);
                cmdputs(")");
                break;
        case NREDIR:
        case NBACKGND:
                cmdtxt(n->nredir.n);
                break;
        case NIF:
                cmdputs("if ");
                cmdtxt(n->nif.test);
                cmdputs("; then ");
                cmdtxt(n->nif.ifpart);
                cmdputs("...");
                break;
        case NWHILE:
                cmdputs("while ");
                cmdtxt(n->nbinary.ch1);
                cmdtxtdogroup(n->nbinary.ch2);
                break;
        case NUNTIL:
                cmdputs("until ");
                cmdtxt(n->nbinary.ch1);
                cmdtxtdogroup(n->nbinary.ch2);
                break;
        case NFOR:
                cmdputs("for ");
                cmdputs(n->nfor.var);
                cmdputs(" in ...");
                break;
        case NCASE:
                cmdputs("case ");
                cmdputs(n->ncase.expr->narg.text);
                cmdputs(" in ...");
                break;
        case NDEFUN:
                cmdputs(n->narg.text);
                cmdputs("() ...");
                break;
        case NNOT:
                cmdputs("! ");
                cmdtxt(n->nnot.com);
                break;
        case NCMD:
                for (np = n->ncmd.args ; np ; np = np->narg.next) {
                        cmdtxt(np);
                        if (np->narg.next)
                                cmdputs(" ");
                }
                for (np = n->ncmd.redirect ; np ; np = np->nfile.next) {
                        cmdputs(" ");
                        cmdtxt(np);
                }
                break;
        case NARG:
                cmdputs(n->narg.text);
                break;
        case NTO:
                cmdtxtredir(n, ">", 1);
                break;
        case NAPPEND:
                cmdtxtredir(n, ">>", 1);
                break;
        case NTOFD:
                cmdtxtredir(n, ">&", 1);
                break;
        case NCLOBBER:
                cmdtxtredir(n, ">|", 1);
                break;
        case NFROM:
                cmdtxtredir(n, "<", 0);
                break;
        case NFROMTO:
                cmdtxtredir(n, "<>", 0);
                break;
        case NFROMFD:
                cmdtxtredir(n, "<&", 0);
                break;
        case NHERE:
        case NXHERE:
                cmdputs("<<...");
                break;
        default:
                cmdputs("???");
                break;
        }
}



static void
cmdputs(const char *s)
{
        const char *p;
        char *q;
        char c;
        int subtype = 0;

        if (cmdnleft <= 0)
                return;
        p = s;
        q = cmdnextc;
        while ((c = *p++) != '\0') {
                if (c == CTLESC)
                        *q++ = *p++;
                else if (c == CTLVAR) {
                        *q++ = '$';
                        if (--cmdnleft > 0)
                                *q++ = '{';
                        subtype = *p++;
                        if ((subtype & VSTYPE) == VSLENGTH && --cmdnleft > 0)
                                *q++ = '#';
                } else if (c == '=' && subtype != 0) {
                        *q = "}-+?=##%%\0X"[(subtype & VSTYPE) - VSNORMAL];
                        if (*q)
                                q++;
                        else
                                cmdnleft++;
                        if (((subtype & VSTYPE) == VSTRIMLEFTMAX ||
                            (subtype & VSTYPE) == VSTRIMRIGHTMAX) &&
                            --cmdnleft > 0)
                                *q = q[-1], q++;
                        subtype = 0;
                } else if (c == CTLENDVAR) {
                        *q++ = '}';
                } else if (c == CTLBACKQ || c == CTLBACKQ+CTLQUOTE) {
                        cmdnleft -= 5;
                        if (cmdnleft > 0) {
                                *q++ = '$';
                                *q++ = '(';
                                *q++ = '.';
                                *q++ = '.';
                                *q++ = '.';
                                *q++ = ')';
                        }
                } else if (c == CTLARI) {
                        cmdnleft -= 2;
                        if (cmdnleft > 0) {
                                *q++ = '$';
                                *q++ = '(';
                                *q++ = '(';
                        }
                        p++;
                } else if (c == CTLENDARI) {
                        if (--cmdnleft > 0) {
                                *q++ = ')';
                                *q++ = ')';
                        }
                } else if (c == CTLQUOTEMARK || c == CTLQUOTEEND)
                        cmdnleft++; /* ignore */
                else
                        *q++ = c;
                if (--cmdnleft <= 0) {
                        *q++ = '.';
                        *q++ = '.';
                        *q++ = '.';
                        break;
                }
        }
        cmdnextc = q;
}