+/*
+ * 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 "kernel.h"
+#include "proc.h"
+#include "buf.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 */
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