usr/src/sys/kern/kern_proc.c

/*
 * Copyright (c) 1982, 1986, 1989, 1991 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)kern_proc.c 7.16 (Berkeley) 6/28/91
 */

#include "param.h"
#include "systm.h"
#include "map.h"
#include "kernel.h"
#include "proc.h"
#include "buf.h"
#include "seg.h"
#include "acct.h"
#include "wait.h"
#include "file.h"
#include "../ufs/quota.h"
#include "uio.h"
#include "malloc.h"
#include "mbuf.h"
#include "ioctl.h"
#include "tty.h"

/*
 * Is p an inferior of the current process?
 */
inferior(p)
        register struct proc *p;
{

        for (; p != curproc; p = p->p_pptr)
                if (p->p_pid == 0)
                        return (0);
        return (1);
}

/*
 * Locate a process by number
 */
struct proc *
pfind(pid)
        register pid;
{
        register struct proc *p = pidhash[PIDHASH(pid)];

        for (; p; p = p->p_hash)
                if (p->p_pid == pid)
                        return (p);
        return ((struct proc *)0);
}

/*
 * Locate a process group by number
 */
struct pgrp *
pgfind(pgid)
        register pid_t pgid;
{
        register struct pgrp *pgrp = pgrphash[PIDHASH(pgid)];

        for (; pgrp; pgrp = pgrp->pg_hforw)
                if (pgrp->pg_id == pgid)
                        return (pgrp);
        return ((struct pgrp *)0);
}

/*
 * Move p to a new or existing process group (and session)
 */
enterpgrp(p, pgid, mksess)
        register struct proc *p;
        pid_t pgid;
{
        register struct pgrp *pgrp = pgfind(pgid);
        register struct proc **pp;
        register struct proc *cp;
        int n;

#ifdef DIAGNOSTIC
        if (pgrp && mksess)     /* firewalls */
                panic("enterpgrp: setsid into non-empty pgrp");
        if (SESS_LEADER(p))
                panic("enterpgrp: session leader attempted setpgrp");
#endif
        if (pgrp == NULL) {
                /*
                 * new process group
                 */
#ifdef DIAGNOSTIC
                if (p->p_pid != pgid)
                        panic("enterpgrp: new pgrp and pid != pgid");
#endif
                MALLOC(pgrp, struct pgrp *, sizeof(struct pgrp), M_PGRP,
                       M_WAITOK);
                if (mksess) {
                        register struct session *sess;

                        /*
                         * new session
                         */
                        MALLOC(sess, struct session *, sizeof(struct session),
                                M_SESSION, M_WAITOK);
                        sess->s_leader = p;
                        sess->s_count = 1;
                        sess->s_ttyvp = NULL;
                        sess->s_ttyp = NULL;
                        bcopy(p->p_session->s_login, sess->s_login,
                            sizeof(sess->s_login));
                        p->p_flag &= ~SCTTY;
                        pgrp->pg_session = sess;
#ifdef DIAGNOSTIC
                        if (p != curproc)
                                panic("enterpgrp: mksession and p != curproc");
#endif
                } else {
                        pgrp->pg_session = p->p_session;
                        pgrp->pg_session->s_count++;
                }
                pgrp->pg_id = pgid;
                pgrp->pg_hforw = pgrphash[n = PIDHASH(pgid)];
                pgrphash[n] = pgrp;
                pgrp->pg_jobc = 0;
                pgrp->pg_mem = NULL;
        } else if (pgrp == p->p_pgrp)
                return;

        /*
         * Adjust eligibility of affected pgrps to participate in job control.
         * Increment eligibility counts before decrementing, otherwise we
         * could reach 0 spuriously during the first call.
         */
        fixjobc(p, pgrp, 1);
        fixjobc(p, p->p_pgrp, 0);

        /*
         * unlink p from old process group
         */
        for (pp = &p->p_pgrp->pg_mem; *pp; pp = &(*pp)->p_pgrpnxt)
                if (*pp == p) {
                        *pp = p->p_pgrpnxt;
                        goto done;
                }
        panic("enterpgrp: can't find p on old pgrp");
done:
        /*
         * delete old if empty
         */
        if (p->p_pgrp->pg_mem == 0)
                pgdelete(p->p_pgrp);
        /*
         * link into new one
         */
        p->p_pgrp = pgrp;
        p->p_pgrpnxt = pgrp->pg_mem;
        pgrp->pg_mem = p;
}

/*
 * remove process from process group
 */
leavepgrp(p)
        register struct proc *p;
{
        register struct proc **pp = &p->p_pgrp->pg_mem;

        for (; *pp; pp = &(*pp)->p_pgrpnxt)
                if (*pp == p) {
                        *pp = p->p_pgrpnxt;
                        goto done;
                }
        panic("leavepgrp: can't find p in pgrp");
done:
        if (!p->p_pgrp->pg_mem)
                pgdelete(p->p_pgrp);
        p->p_pgrp = 0;
}

/*
 * delete a process group
 */
pgdelete(pgrp)
        register struct pgrp *pgrp;
{
        register struct pgrp **pgp = &pgrphash[PIDHASH(pgrp->pg_id)];

        if (pgrp->pg_session->s_ttyp != NULL &&
            pgrp->pg_session->s_ttyp->t_pgrp == pgrp)
                pgrp->pg_session->s_ttyp->t_pgrp = NULL;
        for (; *pgp; pgp = &(*pgp)->pg_hforw)
                if (*pgp == pgrp) {
                        *pgp = pgrp->pg_hforw;
                        goto done;
                }
        panic("pgdelete: can't find pgrp on hash chain");
done:
        if (--pgrp->pg_session->s_count == 0)
                FREE(pgrp->pg_session, M_SESSION);
        FREE(pgrp, M_PGRP);
}

static orphanpg();

/*
 * Adjust pgrp jobc counters when specified process changes process group.
 * We count the number of processes in each process group that "qualify"
 * the group for terminal job control (those with a parent in a different
 * process group of the same session).  If that count reaches zero, the
 * process group becomes orphaned.  Check both the specified process'
 * process group and that of its children.
 * entering == 0 => p is leaving specified group.
 * entering == 1 => p is entering specified group.
 */
fixjobc(p, pgrp, entering)
        register struct proc *p;
        register struct pgrp *pgrp;
        int entering;
{
        register struct pgrp *hispgrp;
        register struct session *mysession = pgrp->pg_session;

        /*
         * Check p's parent to see whether p qualifies its own process
         * group; if so, adjust count for p's process group.
         */
        if ((hispgrp = p->p_pptr->p_pgrp) != pgrp &&
            hispgrp->pg_session == mysession)
                if (entering)
                        pgrp->pg_jobc++;
                else if (--pgrp->pg_jobc == 0)
                        orphanpg(pgrp);

        /*
         * Check this process' children to see whether they qualify
         * their process groups; if so, adjust counts for children's
         * process groups.
         */
        for (p = p->p_cptr; p; p = p->p_osptr)
                if ((hispgrp = p->p_pgrp) != pgrp &&
                    hispgrp->pg_session == mysession &&
                    p->p_stat != SZOMB)
                        if (entering)
                                hispgrp->pg_jobc++;
                        else if (--hispgrp->pg_jobc == 0)
                                orphanpg(hispgrp);
}

/*
 * A process group has become orphaned;
 * if there are any stopped processes in the group,
 * hang-up all process in that group.
 */
static
orphanpg(pg)
        struct pgrp *pg;
{
        register struct proc *p;

        for (p = pg->pg_mem; p; p = p->p_pgrpnxt) {
                if (p->p_stat == SSTOP) {
                        for (p = pg->pg_mem; p; p = p->p_pgrpnxt) {
                                psignal(p, SIGHUP);
                                psignal(p, SIGCONT);
                        }
                        return;
                }
        }
}

#ifdef debug
/* DEBUG */
pgrpdump()
{
        register struct pgrp *pgrp;
        register struct proc *p;
        register i;

        for (i=0; i<PIDHSZ; i++) {
                if (pgrphash[i]) {
                  printf("\tindx %d\n", i);
                  for (pgrp=pgrphash[i]; pgrp; pgrp=pgrp->pg_hforw) {
                    printf("\tpgrp %x, pgid %d, sess %x, sesscnt %d, mem %x\n",
                        pgrp, pgrp->pg_id, pgrp->pg_session,
                        pgrp->pg_session->s_count, pgrp->pg_mem);
                    for (p=pgrp->pg_mem; p; p=p->p_pgrpnxt) {
                        printf("\t\tpid %d addr %x pgrp %x\n",
                                p->p_pid, p, p->p_pgrp);
                    }
                  }

                }
        }
}
#endif /* debug */