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-rw-r--r--bin/1sh/jobs.c1552
1 files changed, 1552 insertions, 0 deletions
diff --git a/bin/1sh/jobs.c b/bin/1sh/jobs.c
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+++ b/bin/1sh/jobs.c
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+/*-
+ * 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.
+ */
+
+#ifndef lint
+#if 0
+static char sccsid[] = "@(#)jobs.c	8.5 (Berkeley) 5/4/95";
+#endif
+#endif /* not lint */
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD: releng/12.0/bin/sh/jobs.c 328818 2018-02-02 22:53:58Z jilles $");
+
+#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"
+
+
+/*
+ * 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 used */
+	char changed;		/* true if status has changed */
+	char foreground;	/* true if running in the foreground */
+	char remembered;	/* true if $! referenced */
+#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 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 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 = jp->ps[jp->nprocs - 1].status;
+	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 = job->ps[job->nprocs - 1].status;
+				if (WIFEXITED(status))
+					retval = WEXITSTATUS(status);
+				else
+					retval = WTERMSIG(status) + 128;
+				if (! iflag || ! job->changed)
+					freejob(job);
+				else {
+					job->remembered = 0;
+					if (job == bgjob)
+						bgjob = NULL;
+				}
+				return retval;
+			}
+		} else {
+			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, (struct job *)NULL) != -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;
+#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) {
+				/*** this causes superfluous TIOCSPGRPS ***/
+				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;
+
+	TRACE(("vforkexecshell(%%%td, %s, %p) called\n", jp - jobtab, argv[0],
+	    (void *)pip));
+	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(exception == EXEXEC ? exerrno : 2);
+		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
+	}
+	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 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)
+			dotrap();
+#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 = jp->ps[jp->nprocs - 1].status;
+	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;
+}