clean up event handling so that events that do longjmp's don't turn

[unix-history] / usr / src / sys / kern / kern_proc.c

/*      kern_proc.c     4.34    82/08/22        */

#include "../h/param.h"
#include "../h/systm.h"
#include "../h/map.h"
#include "../h/mtpr.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/proc.h"
#include "../h/buf.h"
#include "../h/reg.h"
#include "../h/inode.h"
#include "../h/seg.h"
#include "../h/acct.h"
#include "/usr/include/wait.h"
#include "../h/pte.h"
#include "../h/vm.h"
#include "../h/text.h"
#include "../h/psl.h"
#include "../h/vlimit.h"
#include "../h/file.h"
#include "../h/quota.h"
#include "../h/descrip.h"
#include "../h/uio.h"

/*
* exec system call, with and without environments.
*/
struct execa {
       char    *fname;
       char    **argp;
       char    **envp;
};

exec()
{
       ((struct execa *)u.u_ap)->envp = NULL;
       exece();
}

exece()
{
       register nc;
       register char *cp;
       register struct buf *bp;
       register struct execa *uap;
       int na, ne, ucp, ap, c;
       int indir, uid, gid;
       char *sharg;
       struct inode *ip;
       swblk_t bno;
       char cfname[MAXNAMLEN + 1];
       char cfarg[SHSIZE];
       int resid;

       if ((ip = namei(uchar, 0, 1)) == NULL)
               return;
       bno = 0;
       bp = 0;
       indir = 0;
       uid = u.u_uid;
       gid = u.u_gid;
       if (ip->i_mode & ISUID)
               uid = ip->i_uid;
       if (ip->i_mode & ISGID)
               gid = ip->i_gid;

 again:
       if (access(ip, IEXEC))
               goto bad;
       if ((u.u_procp->p_flag&STRC) && access(ip, IREAD))
               goto bad;
       if ((ip->i_mode & IFMT) != IFREG ||
          (ip->i_mode & (IEXEC|(IEXEC>>3)|(IEXEC>>6))) == 0) {
               u.u_error = EACCES;
               goto bad;
       }

       /*
        * Read in first few bytes of file for segment sizes, ux_mag:
        *      407 = plain executable
        *      410 = RO text
        *      413 = demand paged RO text
        * Also an ASCII line beginning with #! is
        * the file name of a ``shell'' and arguments may be prepended
        * to the argument list if given here.
        *
        * SHELL NAMES ARE LIMITED IN LENGTH.
        *
        * ONLY ONE ARGUMENT MAY BE PASSED TO THE SHELL FROM
        * THE ASCII LINE.
        */
       u.u_error = rdwri(UIO_READ, ip, (caddr_t)&u.u_exdata, sizeof (u.u_exdata),
           0, 1, &resid);
       if (u.u_error)
               goto bad;
       u.u_count = resid;
#ifndef lint
       if (u.u_count > sizeof(u.u_exdata) - sizeof(u.u_exdata.Ux_A) &&
           u.u_exdata.ux_shell[0] != '#') {
               u.u_error = ENOEXEC;
               goto bad;
       }
#endif
       switch (u.u_exdata.ux_mag) {

       case 0407:
               u.u_exdata.ux_dsize += u.u_exdata.ux_tsize;
               u.u_exdata.ux_tsize = 0;
               break;

       case 0413:
       case 0410:
               if (u.u_exdata.ux_tsize == 0) {
                       u.u_error = ENOEXEC;
                       goto bad;
               }
               break;

       default:
               if (u.u_exdata.ux_shell[0] != '#' ||
                   u.u_exdata.ux_shell[1] != '!' ||
                   indir) {
                       u.u_error = ENOEXEC;
                       goto bad;
               }
               cp = &u.u_exdata.ux_shell[2];           /* skip "#!" */
               while (cp < &u.u_exdata.ux_shell[SHSIZE]) {
                       if (*cp == '\t')
                               *cp = ' ';
                       else if (*cp == '\n') {
                               *cp = '\0';
                               break;
                       }
                       cp++;
               }
               if (*cp != '\0') {
                       u.u_error = ENOEXEC;
                       goto bad;
               }
               cp = &u.u_exdata.ux_shell[2];
               while (*cp == ' ')
                       cp++;
               u.u_dirp = cp;
               while (*cp && *cp != ' ')
                       cp++;
               sharg = NULL;
               if (*cp) {
                       *cp++ = '\0';
                       while (*cp == ' ')
                               cp++;
                       if (*cp) {
                               bcopy((caddr_t)cp, (caddr_t)cfarg, SHSIZE);
                               sharg = cfarg;
                       }
               }
               bcopy((caddr_t)u.u_dent.d_name, (caddr_t)cfname,
                   (unsigned)(u.u_dent.d_namlen + 1));
               indir = 1;
               iput(ip);
               ip = namei(schar, 0, 1);
               if (ip == NULL)
                       return;
               goto again;
       }

       /*
        * Collect arguments on "file" in swap space.
        */
       na = 0;
       ne = 0;
       nc = 0;
       uap = (struct execa *)u.u_ap;
       if ((bno = rmalloc(argmap, ctod(clrnd((int) btoc(NCARGS))))) == 0) {
               swkill(u.u_procp, "exece");
               goto bad;
       }
       if (bno % CLSIZE)
               panic("execa rmalloc");
       if (uap->argp) for (;;) {
               ap = NULL;
               if (indir && (na == 1 || na == 2 && sharg))
                       ap = (int)uap->fname;
               else if (uap->argp) {
                       ap = fuword((caddr_t)uap->argp);
                       uap->argp++;
               }
               if (ap==NULL && uap->envp) {
                       uap->argp = NULL;
                       if ((ap = fuword((caddr_t)uap->envp)) == NULL)
                               break;
                       uap->envp++;
                       ne++;
               }
               if (ap == NULL)
                       break;
               na++;
               if (ap == -1)
                       u.u_error = EFAULT;
               do {
                       if (nc >= NCARGS-1)
                               u.u_error = E2BIG;
                       if (indir && na == 2 && sharg != NULL)
                               c = *sharg++ & 0377;
                       else if ((c = fubyte((caddr_t)ap++)) < 0)
                               u.u_error = EFAULT;
                       if (u.u_error) {
                               if (bp)
                                       brelse(bp);
                               bp = 0;
                               goto badarg;
                       }
                       if (nc % (CLSIZE*NBPG) == 0) {
                               if (bp)
                                       bdwrite(bp);
                               bp = getblk(argdev, bno + nc / NBPG,
                                   CLSIZE*NBPG);
                               cp = bp->b_un.b_addr;
                       }
                       nc++;
                       *cp++ = c;
               } while (c > 0);
       }
       if (bp)
               bdwrite(bp);
       bp = 0;
       nc = (nc + NBPW-1) & ~(NBPW-1);
       if (indir) {
               u.u_dent.d_namlen = strlen(cfname);
               bcopy((caddr_t)cfname, (caddr_t)u.u_dent.d_name,
                   (unsigned)(u.u_dent.d_namlen + 1));
       }
       getxfile(ip, nc + (na+4)*NBPW, uid, gid);
       if (u.u_error) {
badarg:
               for (c = 0; c < nc; c += CLSIZE*NBPG)
                       if (bp = baddr(argdev, bno + c / NBPG, CLSIZE*NBPG)) {
                               bp->b_flags |= B_AGE;           /* throw away */
                               bp->b_flags &= ~B_DELWRI;       /* cancel io */
                               brelse(bp);
                               bp = 0;
                       }
               goto bad;
       }

       /*
        * copy back arglist
        */
       ucp = USRSTACK - nc - NBPW;
       ap = ucp - na*NBPW - 3*NBPW;
       u.u_ar0[SP] = ap;
       (void) suword((caddr_t)ap, na-ne);
       nc = 0;
       for (;;) {
               ap += NBPW;
               if (na==ne) {
                       (void) suword((caddr_t)ap, 0);
                       ap += NBPW;
               }
               if (--na < 0)
                       break;
               (void) suword((caddr_t)ap, ucp);
               do {
                       if (nc % (CLSIZE*NBPG) == 0) {
                               if (bp)
                                       brelse(bp);
                               bp = bread(argdev, bno + nc / NBPG,
                                   CLSIZE*NBPG);
                               bp->b_flags |= B_AGE;           /* throw away */
                               bp->b_flags &= ~B_DELWRI;       /* cancel io */
                               cp = bp->b_un.b_addr;
                       }
                       (void) subyte((caddr_t)ucp++, (c = *cp++));
                       nc++;
               } while(c&0377);
       }
       (void) suword((caddr_t)ap, 0);
       (void) suword((caddr_t)ucp, 0);
       setregs();
bad:
       if (bp)
               brelse(bp);
       if (bno)
               rmfree(argmap, ctod(clrnd((int) btoc(NCARGS))), bno);
       iput(ip);
}

/*
* Read in and set up memory for executed file.
*/
getxfile(ip, nargc, uid, gid)
register struct inode *ip;
{
       register size_t ts, ds, ss;
       int pagi;

       if (u.u_exdata.ux_mag == 0413)
               pagi = SPAGI;
       else
               pagi = 0;
       if (u.u_exdata.ux_tsize!=0 && (ip->i_flag&ITEXT)==0 &&
           ip->i_count!=1) {
               register struct file *fp;

               for (fp = file; fp < fileNFILE; fp++) {
                       if (fp->f_type == DTYPE_FILE &&
                           fp->f_inode == ip && (fp->f_flag&FWRITE)) {
                               u.u_error = ETXTBSY;
                               goto bad;
                       }
               }
       }

       /*
        * Compute text and data sizes and make sure not too large.
        */
       ts = clrnd(btoc(u.u_exdata.ux_tsize));
       ds = clrnd(btoc((u.u_exdata.ux_dsize+u.u_exdata.ux_bsize)));
       ss = clrnd(SSIZE + btoc(nargc));
       if (chksize(ts, ds, ss))
               goto bad;

       /*
        * Make sure enough space to start process.
        */
       u.u_cdmap = zdmap;
       u.u_csmap = zdmap;
       if (swpexpand(ds, ss, &u.u_cdmap, &u.u_csmap) == NULL)
               goto bad;

       /*
        * At this point, committed to the new image!
        * Release virtual memory resources of old process, and
        * initialize the virtual memory of the new process.
        * If we resulted from vfork(), instead wakeup our
        * parent who will set SVFDONE when he has taken back
        * our resources.
        */
       u.u_prof.pr_scale = 0;
       if ((u.u_procp->p_flag & SVFORK) == 0)
               vrelvm();
       else {
               u.u_procp->p_flag &= ~SVFORK;
               u.u_procp->p_flag |= SKEEP;
               wakeup((caddr_t)u.u_procp);
               while ((u.u_procp->p_flag & SVFDONE) == 0)
                       sleep((caddr_t)u.u_procp, PZERO - 1);
               u.u_procp->p_flag &= ~(SVFDONE|SKEEP);
       }
       u.u_procp->p_flag &= ~(SPAGI|SSEQL|SUANOM|SNUSIG);
       u.u_procp->p_flag |= pagi;
       u.u_dmap = u.u_cdmap;
       u.u_smap = u.u_csmap;
       vgetvm(ts, ds, ss);

       if (pagi == 0)
               u.u_error =
                   rdwri(UIO_READ, ip,
                       (char*)ctob(ts), (int)u.u_exdata.ux_dsize,
                       (int)(sizeof(u.u_exdata)+u.u_exdata.ux_tsize),
                       0, (int *)0);
       xalloc(ip, pagi);
       if (pagi && u.u_procp->p_textp)
               vinifod((struct fpte *)dptopte(u.u_procp, 0),
                   PG_FTEXT, u.u_procp->p_textp->x_iptr,
                   1 + ts/CLSIZE, (int)btoc(u.u_exdata.ux_dsize));

       /* THIS SHOULD BE DONE AT A LOWER LEVEL, IF AT ALL */
       mtpr(TBIA, 0);

       if (u.u_error)
               swkill(u.u_procp, "i/o error mapping pages");
       /*
        * set SUID/SGID protections, if no tracing
        */
       if ((u.u_procp->p_flag&STRC)==0) {
               u.u_uid = uid;
               u.u_procp->p_uid = uid;
               u.u_gid = gid;
               u.u_grps[gid/(sizeof(int)*8)] |= 1 << (gid%(sizeof(int)*8));
       } else
               psignal(u.u_procp, SIGTRAP);
       u.u_tsize = ts;
       u.u_dsize = ds;
       u.u_ssize = ss;
bad:
       return;
}

/*
* Clear registers on exec
*/
setregs()
{
       register int (**rp)();
       register i;
       long sigmask;

       for (rp = &u.u_signal[1], sigmask = 1L; rp < &u.u_signal[NSIG];
           sigmask <<= 1, rp++) {
               switch (*rp) {

               case SIG_IGN:
               case SIG_DFL:
               case SIG_HOLD:
                       continue;

               default:
                       /*
                        * Normal or deferring catch; revert to default.
                        */
                       (void) spl6();
                       *rp = SIG_DFL;
                       if ((int)*rp & 1)
                               u.u_procp->p_siga0 |= sigmask;
                       else
                               u.u_procp->p_siga0 &= ~sigmask;
                       if ((int)*rp & 2)
                               u.u_procp->p_siga1 |= sigmask;
                       else
                               u.u_procp->p_siga1 &= ~sigmask;
                       (void) spl0();
                       continue;
               }
       }
/*
       for (rp = &u.u_ar0[0]; rp < &u.u_ar0[16];)
               *rp++ = 0;
*/
       u.u_ar0[PC] = u.u_exdata.ux_entloc + 2; /* skip over entry mask */
       for (i=0; i<NOFILE; i++) {
               if (u.u_pofile[i]&EXCLOSE) {
                       closef(u.u_ofile[i], 1, u.u_pofile[i]);
                       u.u_ofile[i] = NULL;
                       u.u_pofile[i] = 0;
               }
       }

       /*
        * Remember file name for accounting.
        */
       u.u_acflag &= ~AFORK;
       bcopy((caddr_t)u.u_dent.d_name, (caddr_t)u.u_comm,
           (unsigned)(u.u_dent.d_namlen + 1));
}

/*
* Exit system call: pass back caller's arg
*/
rexit()
{
       register struct a {
               int     rval;
       } *uap;

       uap = (struct a *)u.u_ap;
       exit((uap->rval & 0377) << 8);
}

/*
* Release resources.
* Save u. area for parent to look at.
* Enter zombie state.
* Wake up parent and init processes,
* and dispose of children.
*/
exit(rv)
{
       register int i;
       register struct proc *p, *q;
       register int x;

#ifdef PGINPROF
       vmsizmon();
#endif
       p = u.u_procp;
       p->p_flag &= ~(STRC|SULOCK);
       p->p_flag |= SWEXIT;
       p->p_clktim = 0;
       (void) spl6();
       if ((int)SIG_IGN & 1)
               p->p_siga0 = ~0;
       else
               p->p_siga0 = 0;
       if ((int)SIG_IGN & 2)
               p->p_siga1 = ~0;
       else
               p->p_siga1 = 0;
       (void) spl0();
       p->p_cpticks = 0;
       p->p_pctcpu = 0;
       for (i=0; i<NSIG; i++)
               u.u_signal[i] = SIG_IGN;
       /*
        * Release virtual memory.  If we resulted from
        * a vfork(), instead give the resources back to
        * the parent.
        */
       if ((p->p_flag & SVFORK) == 0)
               vrelvm();
       else {
               p->p_flag &= ~SVFORK;
               wakeup((caddr_t)p);
               while ((p->p_flag & SVFDONE) == 0)
                       sleep((caddr_t)p, PZERO - 1);
               p->p_flag &= ~SVFDONE;
       }
       for (i = 0; i < NOFILE; i++) {
#ifdef notdef
               /* why was this like this? */
               f = u.u_ofile[i];
               u.u_ofile[i] = NULL;
               closef(f, 1);
#else
               closef(u.u_ofile[i], 1, u.u_pofile[i]);
               u.u_ofile[i] = NULL;
               u.u_pofile[i] = 0;
#endif
       }
       ilock(u.u_cdir);
       iput(u.u_cdir);
       if (u.u_rdir) {
               ilock(u.u_rdir);
               iput(u.u_rdir);
       }
       u.u_limit[LIM_FSIZE] = INFINITY;
       acct();
#ifdef QUOTA
       qclean();
#endif
       vrelpt(u.u_procp);
       vrelu(u.u_procp, 0);
       (void) spl5();          /* hack for mem alloc race XXX */
       multprog--;
       p->p_stat = SZOMB;
       noproc = 1;
       i = PIDHASH(p->p_pid);
       x = p - proc;
       if (pidhash[i] == x)
               pidhash[i] = p->p_idhash;
       else {
               for (i = pidhash[i]; i != 0; i = proc[i].p_idhash)
                       if (proc[i].p_idhash == x) {
                               proc[i].p_idhash = p->p_idhash;
                               goto done;
                       }
               panic("exit");
       }
       if (p->p_pid == 1)
               panic("init died");
done:
       ((struct xproc *)p)->xp_xstat = rv;             /* overlay */
       ((struct xproc *)p)->xp_vm = u.u_vm;            /* overlay */
       vmsadd(&((struct xproc *)p)->xp_vm, &u.u_cvm);
       for (q = proc; q < procNPROC; q++)
               if (q->p_pptr == p) {
                       if (q->p_osptr)
                               q->p_osptr->p_ysptr = q->p_ysptr;
                       if (q->p_ysptr)
                               q->p_ysptr->p_osptr = q->p_osptr;
                       if (proc[1].p_cptr)
                               proc[1].p_cptr->p_ysptr = q;
                       q->p_osptr = proc[1].p_cptr;
                       q->p_ysptr = NULL;
                       proc[1].p_cptr = q;

                       q->p_pptr = &proc[1];
                       q->p_ppid = 1;
                       wakeup((caddr_t)&proc[1]);
                       /*
                        * Traced processes are killed
                        * since their existence means someone is screwing up.
                        * Stopped processes are sent a hangup and a continue.
                        * This is designed to be ``safe'' for setuid
                        * processes since they must be willing to tolerate
                        * hangups anyways.
                        */
                       if (q->p_flag&STRC) {
                               q->p_flag &= ~STRC;
                               psignal(q, SIGKILL);
                       } else if (q->p_stat == SSTOP) {
                               psignal(q, SIGHUP);
                               psignal(q, SIGCONT);
                       }
                       /*
                        * Protect this process from future
                        * tty signals, clear TSTP/TTIN/TTOU if pending.
                        */
                       (void) spgrp(q, -1);
               }
       psignal(p->p_pptr, SIGCHLD);
       wakeup((caddr_t)p->p_pptr);
       swtch();
}

wait()
{
       struct vtimes vm;
       struct vtimes *vp;

       if ((u.u_ar0[PS] & PSL_ALLCC) != PSL_ALLCC) {
               wait1(0, (struct vtimes *)0);
               return;
       }
       vp = (struct vtimes *)u.u_ar0[R1];
       wait1(u.u_ar0[R0], &vm);
       if (u.u_error)
               return;
       (void) copyout((caddr_t)&vm, (caddr_t)vp, sizeof (struct vtimes));
}

/*
* Wait system call.
* Search for a terminated (zombie) child,
* finally lay it to rest, and collect its status.
* Look also for stopped (traced) children,
* and pass back status from them.
*/
wait1(options, vp)
       register options;
       struct vtimes *vp;
{
       register f;
       register struct proc *p, *q;

       f = 0;
loop:
       for (p = proc; p < procNPROC; p++)
       if (p->p_pptr == u.u_procp) {
               f++;
               if (p->p_stat == SZOMB) {
                       u.u_r.r_val1 = p->p_pid;
                       u.u_r.r_val2 = ((struct xproc *)p)->xp_xstat;
                       ((struct xproc *)p)->xp_xstat = 0;
                       if (vp)
                               *vp = ((struct xproc *)p)->xp_vm;
                       vmsadd(&u.u_cvm, &((struct xproc *)p)->xp_vm);
                       ((struct xproc *)p)->xp_vm = zvms;
                       p->p_stat = NULL;
                       p->p_pid = 0;
                       p->p_ppid = 0;
                       if (q = p->p_ysptr)
                               q->p_osptr = p->p_osptr;
                       if (q = p->p_osptr)
                               q->p_ysptr = p->p_ysptr;
                       if ((q = p->p_pptr)->p_cptr == p)
                               q->p_cptr = p->p_osptr;
                       p->p_pptr = 0;
                       p->p_ysptr = 0;
                       p->p_osptr = 0;
                       p->p_cptr = 0;
                       p->p_sig = 0;
                       p->p_siga0 = 0;
                       p->p_siga1 = 0;
                       p->p_pgrp = 0;
                       p->p_flag = 0;
                       p->p_wchan = 0;
                       p->p_cursig = 0;
                       return;
               }
               if (p->p_stat == SSTOP && (p->p_flag&SWTED)==0 &&
                   (p->p_flag&STRC || options&WUNTRACED)) {
                       p->p_flag |= SWTED;
                       u.u_r.r_val1 = p->p_pid;
                       u.u_r.r_val2 = (p->p_cursig<<8) | WSTOPPED;
                       return;
               }
       }
       if (f==0) {
               u.u_error = ECHILD;
               return;
       }
       if (options&WNOHANG) {
               u.u_r.r_val1 = 0;
               return;
       }
       if ((u.u_procp->p_flag&SNUSIG) && setjmp(u.u_qsav)) {
               u.u_eosys = RESTARTSYS;
               return;
       }
       sleep((caddr_t)u.u_procp, PWAIT);
       goto loop;
}

/*
* fork system call.
*/
fork()
{

       u.u_cdmap = zdmap;
       u.u_csmap = zdmap;
       if (swpexpand(u.u_dsize, u.u_ssize, &u.u_cdmap, &u.u_csmap) == 0) {
               u.u_r.r_val2 = 0;
               return;
       }
       fork1(0);
}

fork1(isvfork)
{
       register struct proc *p1, *p2;
#ifndef QUOTA
       register a;

       a = 0;
#else
       if (u.u_quota != NOQUOT && u.u_quota->q_plim &&
           u.u_quota->q_cnt >= u.u_quota->q_plim) {
               u.u_error = EPROCLIM;
               return;
       }
#endif
       p2 = NULL;
       for (p1 = proc; p1 < procNPROC; p1++) {
#ifdef QUOTA
               if (p1->p_stat == NULL) {
                       p2 = p1;
                       break;
               }
#else
               if (p1->p_stat==NULL && p2==NULL)
                       p2 = p1;
               else {
                       if (p1->p_uid==u.u_uid && p1->p_stat!=NULL)
                               a++;
               }
#endif
       }
       /*
        * Disallow if
        *  No processes at all;
        *  not su and too many procs owned; or
        *  not su and would take last slot.
        */
       if (p2==NULL)
               tablefull("proc");
#ifdef QUOTA
       if (p2==NULL || (u.u_uid!=0 && p2==procNPROC-1)) {
#else
       if (p2==NULL || (u.u_uid!=0 && (p2==procNPROC-1 || a>MAXUPRC))) {
#endif
               u.u_error = EAGAIN;
               if (!isvfork) {
                       (void) vsexpand(0, &u.u_cdmap, 1);
                       (void) vsexpand(0, &u.u_csmap, 1);
               }
               goto out;
       }
       p1 = u.u_procp;
       if (newproc(isvfork)) {
               u.u_r.r_val1 = p1->p_pid;
               u.u_r.r_val2 = 1;  /* child */
               u.u_start = time;
               u.u_acflag = AFORK;
#ifdef QUOTA
               u.u_qflags &= ~QUF_LOGIN;
#endif
               return;
       }
       u.u_r.r_val1 = p2->p_pid;

out:
       u.u_r.r_val2 = 0;
}

spgrp(top, npgrp)
register struct proc *top;
{
       register struct proc *pp, *p;
       int f = 0;

       for (p = top; npgrp == -1 || u.u_uid == p->p_uid ||
           !u.u_uid || inferior(p); p = pp) {
               if (npgrp == -1) {
#define bit(a)  (1<<(a-1))
                       p->p_sig &= ~(bit(SIGTSTP)|bit(SIGTTIN)|bit(SIGTTOU));
               } else
                       p->p_pgrp = npgrp;
               f++;
               /*
                * Search for children.
                */
               for (pp = proc; pp < procNPROC; pp++)
                       if (pp->p_pptr == p)
                               goto cont;
               /*
                * Search for siblings.
                */
               for (; p != top; p = p->p_pptr)
                       for (pp = p + 1; pp < procNPROC; pp++)
                               if (pp->p_pptr == p->p_pptr)
                                       goto cont;
               break;
       cont:
               ;
       }
       return (f);
}

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

       for (; p != u.u_procp; p = p->p_pptr)
               if (p->p_ppid == 0)
                       return (0);
       return (1);
}

struct proc *
pfind(pid)
       int pid;
{
       register struct proc *p;

       for (p = &proc[pidhash[PIDHASH(pid)]]; p != &proc[0]; p = &proc[p->p_idhash])
               if (p->p_pid == pid)
                       return (p);
       return ((struct proc *)0);
}