xref: /original-bsd/sys/kern/kern_proc.c (revision fbed46ce) 
1 /*	kern_proc.c	4.26	82/04/19	*/
2 
3 #include "../h/param.h"
4 #include "../h/systm.h"
5 #include "../h/map.h"
6 #include "../h/mtpr.h"
7 #include "../h/dir.h"
8 #include "../h/user.h"
9 #include "../h/proc.h"
10 #include "../h/buf.h"
11 #include "../h/reg.h"
12 #include "../h/inode.h"
13 #include "../h/seg.h"
14 #include "../h/acct.h"
15 #include "/usr/include/wait.h"
16 #include "../h/pte.h"
17 #include "../h/vm.h"
18 #include "../h/text.h"
19 #include "../h/psl.h"
20 #include "../h/vlimit.h"
21 #include "../h/file.h"
22 
23 /*
24  * exec system call, with and without environments.
25  */
26 struct execa {
27 	char	*fname;
28 	char	**argp;
29 	char	**envp;
30 };
31 
32 exec()
33 {
34 	((struct execa *)u.u_ap)->envp = NULL;
35 	exece();
36 }
37 
38 exece()
39 {
40 	register nc;
41 	register char *cp;
42 	register struct buf *bp;
43 	register struct execa *uap;
44 	int na, ne, ucp, ap, c;
45 	int indir, uid, gid;
46 	char *sharg;
47 	struct inode *ip;
48 	swblk_t bno;
49 	char cfname[MAXNAMLEN + 1];
50 	char cfarg[SHSIZE];
51 
52 	if ((ip = namei(uchar, 0, 1)) == NULL)
53 		return;
54 	bno = 0;
55 	bp = 0;
56 	indir = 0;
57 	uid = u.u_uid;
58 	gid = u.u_gid;
59 	if (ip->i_mode & ISUID)
60 		uid = ip->i_uid;
61 	if (ip->i_mode & ISGID)
62 		gid = ip->i_gid;
63 
64   again:
65 	if (access(ip, IEXEC))
66 		goto bad;
67 	if ((u.u_procp->p_flag&STRC) && access(ip, IREAD))
68 		goto bad;
69 	if ((ip->i_mode & IFMT) != IFREG ||
70 	   (ip->i_mode & (IEXEC|(IEXEC>>3)|(IEXEC>>6))) == 0) {
71 		u.u_error = EACCES;
72 		goto bad;
73 	}
74 
75 	/*
76 	 * Read in first few bytes of file for segment sizes, ux_mag:
77 	 *	407 = plain executable
78 	 *	410 = RO text
79 	 *	413 = demand paged RO text
80 	 * Also an ASCII line beginning with #! is
81 	 * the file name of a ``shell'' and arguments may be prepended
82 	 * to the argument list if given here.
83 	 *
84 	 * SHELL NAMES ARE LIMITED IN LENGTH.
85 	 *
86 	 * ONLY ONE ARGUMENT MAY BE PASSED TO THE SHELL FROM
87 	 * THE ASCII LINE.
88 	 */
89 	u.u_base = (caddr_t)&u.u_exdata;
90 	u.u_count = sizeof(u.u_exdata);
91 	u.u_offset = 0;
92 	u.u_segflg = 1;
93 	readi(ip);
94 	u.u_segflg = 0;
95 	if (u.u_error)
96 		goto bad;
97 	if (u.u_count > sizeof(u.u_exdata) - sizeof(u.u_exdata.Ux_A) &&
98 	    u.u_exdata.ux_shell[0] != '#') {
99 		u.u_error = ENOEXEC;
100 		goto bad;
101 	}
102 	switch (u.u_exdata.ux_mag) {
103 
104 	case 0407:
105 		u.u_exdata.ux_dsize += u.u_exdata.ux_tsize;
106 		u.u_exdata.ux_tsize = 0;
107 		break;
108 
109 	case 0413:
110 	case 0410:
111 		if (u.u_exdata.ux_tsize == 0) {
112 			u.u_error = ENOEXEC;
113 			goto bad;
114 		}
115 		break;
116 
117 	default:
118 		if (u.u_exdata.ux_shell[0] != '#' ||
119 		    u.u_exdata.ux_shell[1] != '!' ||
120 		    indir) {
121 			u.u_error = ENOEXEC;
122 			goto bad;
123 		}
124 		cp = &u.u_exdata.ux_shell[2];		/* skip "#!" */
125 		while (cp < &u.u_exdata.ux_shell[SHSIZE]) {
126 			if (*cp == '\t')
127 				*cp = ' ';
128 			else if (*cp == '\n') {
129 				*cp = '\0';
130 				break;
131 			}
132 			cp++;
133 		}
134 		if (*cp != '\0') {
135 			u.u_error = ENOEXEC;
136 			goto bad;
137 		}
138 		cp = &u.u_exdata.ux_shell[2];
139 		while (*cp == ' ')
140 			cp++;
141 		u.u_dirp = cp;
142 		while (*cp && *cp != ' ')
143 			cp++;
144 		sharg = NULL;
145 		if (*cp) {
146 			*cp++ = '\0';
147 			while (*cp == ' ')
148 				cp++;
149 			if (*cp) {
150 				bcopy((caddr_t)cp, (caddr_t)cfarg, SHSIZE);
151 				sharg = cfarg;
152 			}
153 		}
154 		bcopy((caddr_t)u.u_dent.d_name, (caddr_t)cfname,
155 		    u.u_dent.d_namlen + 1);
156 		indir = 1;
157 		iput(ip);
158 		ip = namei(schar, 0, 1);
159 		if (ip == NULL)
160 			return;
161 		goto again;
162 	}
163 
164 	/*
165 	 * Collect arguments on "file" in swap space.
166 	 */
167 	na = 0;
168 	ne = 0;
169 	nc = 0;
170 	uap = (struct execa *)u.u_ap;
171 	if ((bno = rmalloc(argmap, ctod(clrnd((int) btoc(NCARGS))))) == 0) {
172 		swkill(u.u_procp, "exece");
173 		goto bad;
174 	}
175 	if (bno % CLSIZE)
176 		panic("execa rmalloc");
177 	if (uap->argp) for (;;) {
178 		ap = NULL;
179 		if (indir && (na == 1 || na == 2 && sharg))
180 			ap = (int)uap->fname;
181 		else if (uap->argp) {
182 			ap = fuword((caddr_t)uap->argp);
183 			uap->argp++;
184 		}
185 		if (ap==NULL && uap->envp) {
186 			uap->argp = NULL;
187 			if ((ap = fuword((caddr_t)uap->envp)) == NULL)
188 				break;
189 			uap->envp++;
190 			ne++;
191 		}
192 		if (ap == NULL)
193 			break;
194 		na++;
195 		if (ap == -1)
196 			u.u_error = EFAULT;
197 		do {
198 			if (nc >= NCARGS-1)
199 				u.u_error = E2BIG;
200 			if (indir && na == 2 && sharg != NULL)
201 				c = *sharg++ & 0377;
202 			else if ((c = fubyte((caddr_t)ap++)) < 0)
203 				u.u_error = EFAULT;
204 			if (u.u_error) {
205 				if (bp)
206 					brelse(bp);
207 				bp = 0;
208 				goto badarg;
209 			}
210 			if (nc % (CLSIZE*NBPG) == 0) {
211 				if (bp)
212 					bdwrite(bp);
213 				bp = getblk(argdev, bno + nc / NBPG,
214 				    CLSIZE*NBPG);
215 				cp = bp->b_un.b_addr;
216 			}
217 			nc++;
218 			*cp++ = c;
219 		} while (c > 0);
220 	}
221 	if (bp)
222 		bdwrite(bp);
223 	bp = 0;
224 	nc = (nc + NBPW-1) & ~(NBPW-1);
225 	if (indir) {
226 		u.u_dent.d_namlen = strlen(cfname);
227 		bcopy((caddr_t)cfname, (caddr_t)u.u_dent.d_name,
228 		    u.u_dent.d_namlen + 1);
229 	}
230 	getxfile(ip, nc + (na+4)*NBPW, uid, gid);
231 	if (u.u_error) {
232 badarg:
233 		for (c = 0; c < nc; c += CLSIZE*NBPG)
234 			if (bp = baddr(argdev, bno + c / NBPG, CLSIZE*NBPG)) {
235 				bp->b_flags |= B_AGE;		/* throw away */
236 				bp->b_flags &= ~B_DELWRI;	/* cancel io */
237 				brelse(bp);
238 				bp = 0;
239 			}
240 		goto bad;
241 	}
242 
243 	/*
244 	 * copy back arglist
245 	 */
246 	ucp = USRSTACK - nc - NBPW;
247 	ap = ucp - na*NBPW - 3*NBPW;
248 	u.u_ar0[SP] = ap;
249 	(void) suword((caddr_t)ap, na-ne);
250 	nc = 0;
251 	for (;;) {
252 		ap += NBPW;
253 		if (na==ne) {
254 			(void) suword((caddr_t)ap, 0);
255 			ap += NBPW;
256 		}
257 		if (--na < 0)
258 			break;
259 		(void) suword((caddr_t)ap, ucp);
260 		do {
261 			if (nc % (CLSIZE*NBPG) == 0) {
262 				if (bp)
263 					brelse(bp);
264 				bp = bread(argdev, bno + nc / NBPG,
265 				    CLSIZE*NBPG);
266 				bp->b_flags |= B_AGE;		/* throw away */
267 				bp->b_flags &= ~B_DELWRI;	/* cancel io */
268 				cp = bp->b_un.b_addr;
269 			}
270 			(void) subyte((caddr_t)ucp++, (c = *cp++));
271 			nc++;
272 		} while(c&0377);
273 	}
274 	(void) suword((caddr_t)ap, 0);
275 	(void) suword((caddr_t)ucp, 0);
276 	setregs();
277 bad:
278 	if (bp)
279 		brelse(bp);
280 	if (bno)
281 		rmfree(argmap, ctod(clrnd((int) btoc(NCARGS))), bno);
282 	iput(ip);
283 }
284 
285 /*
286  * Read in and set up memory for executed file.
287  */
288 getxfile(ip, nargc, uid, gid)
289 register struct inode *ip;
290 {
291 	register size_t ts, ds, ss;
292 	int pagi;
293 
294 	if (u.u_exdata.ux_mag == 0413)
295 		pagi = SPAGI;
296 	else
297 		pagi = 0;
298 	if (u.u_exdata.ux_tsize!=0 && (ip->i_flag&ITEXT)==0 &&
299 	    ip->i_count!=1) {
300 		register struct file *fp;
301 
302 		for (fp = file; fp < fileNFILE; fp++) {
303 			if (fp->f_flag & FSOCKET)
304 				continue;
305 			if (fp->f_inode == ip && (fp->f_flag&FWRITE)) {
306 				u.u_error = ETXTBSY;
307 				goto bad;
308 			}
309 		}
310 	}
311 
312 	/*
313 	 * Compute text and data sizes and make sure not too large.
314 	 */
315 	ts = clrnd(btoc(u.u_exdata.ux_tsize));
316 	ds = clrnd(btoc((u.u_exdata.ux_dsize+u.u_exdata.ux_bsize)));
317 	ss = clrnd(SSIZE + btoc(nargc));
318 	if (chksize(ts, ds, ss))
319 		goto bad;
320 
321 	/*
322 	 * Make sure enough space to start process.
323 	 */
324 	u.u_cdmap = zdmap;
325 	u.u_csmap = zdmap;
326 	if (swpexpand(ds, ss, &u.u_cdmap, &u.u_csmap) == NULL)
327 		goto bad;
328 
329 	/*
330 	 * At this point, committed to the new image!
331 	 * Release virtual memory resources of old process, and
332 	 * initialize the virtual memory of the new process.
333 	 * If we resulted from vfork(), instead wakeup our
334 	 * parent who will set SVFDONE when he has taken back
335 	 * our resources.
336 	 */
337 	u.u_prof.pr_scale = 0;
338 	if ((u.u_procp->p_flag & SVFORK) == 0)
339 		vrelvm();
340 	else {
341 		u.u_procp->p_flag &= ~SVFORK;
342 		u.u_procp->p_flag |= SKEEP;
343 		wakeup((caddr_t)u.u_procp);
344 		while ((u.u_procp->p_flag & SVFDONE) == 0)
345 			sleep((caddr_t)u.u_procp, PZERO - 1);
346 		u.u_procp->p_flag &= ~(SVFDONE|SKEEP);
347 	}
348 	u.u_procp->p_flag &= ~(SPAGI|SSEQL|SUANOM|SNUSIG);
349 	u.u_procp->p_flag |= pagi;
350 	u.u_dmap = u.u_cdmap;
351 	u.u_smap = u.u_csmap;
352 	vgetvm(ts, ds, ss);
353 
354 	if (pagi == 0) {
355 		/*
356 		 * Read in data segment.
357 		 */
358 		u.u_base = (char *)ctob(ts);
359 		u.u_offset = sizeof(u.u_exdata)+u.u_exdata.ux_tsize;
360 		u.u_count = u.u_exdata.ux_dsize;
361 		readi(ip);
362 	}
363 	xalloc(ip, pagi);
364 	if (pagi && u.u_procp->p_textp)
365 		vinifod((struct fpte *)dptopte(u.u_procp, 0),
366 		    PG_FTEXT, u.u_procp->p_textp->x_iptr,
367 		    1 + ts/CLSIZE, (int)btoc(u.u_exdata.ux_dsize));
368 
369 	/* THIS SHOULD BE DONE AT A LOWER LEVEL, IF AT ALL */
370 	mtpr(TBIA, 0);
371 
372 	/*
373 	 * set SUID/SGID protections, if no tracing
374 	 */
375 	if ((u.u_procp->p_flag&STRC)==0) {
376 		u.u_uid = uid;
377 		u.u_procp->p_uid = uid;
378 		u.u_gid = gid;
379 		u.u_grps[gid/(sizeof(int)*8)] |= 1 << (gid%(sizeof(int)*8));
380 	} else
381 		psignal(u.u_procp, SIGTRAP);
382 	u.u_tsize = ts;
383 	u.u_dsize = ds;
384 	u.u_ssize = ss;
385 bad:
386 	return;
387 }
388 
389 /*
390  * Clear registers on exec
391  */
392 setregs()
393 {
394 	register int (**rp)();
395 	register i;
396 	long sigmask;
397 
398 	for (rp = &u.u_signal[1], sigmask = 1L; rp < &u.u_signal[NSIG];
399 	    sigmask <<= 1, rp++) {
400 		switch (*rp) {
401 
402 		case SIG_IGN:
403 		case SIG_DFL:
404 		case SIG_HOLD:
405 			continue;
406 
407 		default:
408 			/*
409 			 * Normal or deferring catch; revert to default.
410 			 */
411 			(void) spl6();
412 			*rp = SIG_DFL;
413 			if ((int)*rp & 1)
414 				u.u_procp->p_siga0 |= sigmask;
415 			else
416 				u.u_procp->p_siga0 &= ~sigmask;
417 			if ((int)*rp & 2)
418 				u.u_procp->p_siga1 |= sigmask;
419 			else
420 				u.u_procp->p_siga1 &= ~sigmask;
421 			(void) spl0();
422 			continue;
423 		}
424 	}
425 /*
426 	for (rp = &u.u_ar0[0]; rp < &u.u_ar0[16];)
427 		*rp++ = 0;
428 */
429 	u.u_ar0[PC] = u.u_exdata.ux_entloc + 2; /* skip over entry mask */
430 	for (i=0; i<NOFILE; i++) {
431 		if (u.u_pofile[i]&EXCLOSE) {
432 			closef(u.u_ofile[i], 1);
433 			u.u_ofile[i] = NULL;
434 			u.u_pofile[i] &= ~EXCLOSE;
435 		}
436 	}
437 
438 	/*
439 	 * Remember file name for accounting.
440 	 */
441 	u.u_acflag &= ~AFORK;
442 	bcopy((caddr_t)u.u_dent.d_name, (caddr_t)u.u_comm,
443 	    u.u_dent.d_namlen + 1);
444 }
445 
446 /*
447  * Exit system call: pass back caller's arg
448  */
449 rexit()
450 {
451 	register struct a {
452 		int	rval;
453 	} *uap;
454 
455 	uap = (struct a *)u.u_ap;
456 	exit((uap->rval & 0377) << 8);
457 }
458 
459 /*
460  * Release resources.
461  * Save u. area for parent to look at.
462  * Enter zombie state.
463  * Wake up parent and init processes,
464  * and dispose of children.
465  */
466 exit(rv)
467 {
468 	register int i;
469 	register struct proc *p, *q;
470 	register struct file *f;
471 	register int x;
472 
473 #ifdef PGINPROF
474 	vmsizmon();
475 #endif
476 	p = u.u_procp;
477 	p->p_flag &= ~(STRC|SULOCK);
478 	p->p_flag |= SWEXIT;
479 	p->p_clktim = 0;
480 	(void) spl6();
481 	if ((int)SIG_IGN & 1)
482 		p->p_siga0 = ~0;
483 	else
484 		p->p_siga0 = 0;
485 	if ((int)SIG_IGN & 2)
486 		p->p_siga1 = ~0;
487 	else
488 		p->p_siga1 = 0;
489 	(void) spl0();
490 	p->p_cpticks = 0;
491 	p->p_pctcpu = 0;
492 	for (i=0; i<NSIG; i++)
493 		u.u_signal[i] = SIG_IGN;
494 	/*
495 	 * Release virtual memory.  If we resulted from
496 	 * a vfork(), instead give the resources back to
497 	 * the parent.
498 	 */
499 	if ((p->p_flag & SVFORK) == 0)
500 		vrelvm();
501 	else {
502 		p->p_flag &= ~SVFORK;
503 		wakeup((caddr_t)p);
504 		while ((p->p_flag & SVFDONE) == 0)
505 			sleep((caddr_t)p, PZERO - 1);
506 		p->p_flag &= ~SVFDONE;
507 	}
508 	for (i=0; i<NOFILE; i++) {
509 		f = u.u_ofile[i];
510 		u.u_ofile[i] = NULL;
511 		closef(f, 1);
512 	}
513 	ilock(u.u_cdir);
514 	iput(u.u_cdir);
515 	if (u.u_rdir) {
516 		ilock(u.u_rdir);
517 		iput(u.u_rdir);
518 	}
519 	u.u_limit[LIM_FSIZE] = INFINITY;
520 	acct();
521 	vrelpt(u.u_procp);
522 	vrelu(u.u_procp, 0);
523 	(void) spl5();		/* hack for mem alloc race XXX */
524 	multprog--;
525 	p->p_stat = SZOMB;
526 	noproc = 1;
527 	i = PIDHASH(p->p_pid);
528 	x = p - proc;
529 	if (pidhash[i] == x)
530 		pidhash[i] = p->p_idhash;
531 	else {
532 		for (i = pidhash[i]; i != 0; i = proc[i].p_idhash)
533 			if (proc[i].p_idhash == x) {
534 				proc[i].p_idhash = p->p_idhash;
535 				goto done;
536 			}
537 		panic("exit");
538 	}
539 	if (p->p_pid == 1)
540 		panic("init died");
541 done:
542 	((struct xproc *)p)->xp_xstat = rv;		/* overlay */
543 	((struct xproc *)p)->xp_vm = u.u_vm;		/* overlay */
544 	vmsadd(&((struct xproc *)p)->xp_vm, &u.u_cvm);
545 	for (q = proc; q < procNPROC; q++)
546 		if (q->p_pptr == p) {
547 			q->p_pptr = &proc[1];
548 			q->p_ppid = 1;
549 			wakeup((caddr_t)&proc[1]);
550 			/*
551 			 * Traced processes are killed
552 			 * since their existence means someone is screwing up.
553 			 * Stopped processes are sent a hangup and a continue.
554 			 * This is designed to be ``safe'' for setuid
555 			 * processes since they must be willing to tolerate
556 			 * hangups anyways.
557 			 */
558 			if (q->p_flag&STRC) {
559 				q->p_flag &= ~STRC;
560 				psignal(q, SIGKILL);
561 			} else if (q->p_stat == SSTOP) {
562 				psignal(q, SIGHUP);
563 				psignal(q, SIGCONT);
564 			}
565 			/*
566 			 * Protect this process from future
567 			 * tty signals, clear TSTP/TTIN/TTOU if pending.
568 			 */
569 			(void) spgrp(q, -1);
570 		}
571 	psignal(p->p_pptr, SIGCHLD);
572 	wakeup((caddr_t)p->p_pptr);
573 	swtch();
574 }
575 
576 wait()
577 {
578 	struct vtimes vm;
579 	struct vtimes *vp;
580 
581 	if ((u.u_ar0[PS] & PSL_ALLCC) != PSL_ALLCC) {
582 		wait1(0, (struct vtimes *)0);
583 		return;
584 	}
585 	vp = (struct vtimes *)u.u_ar0[R1];
586 	wait1(u.u_ar0[R0], &vm);
587 	if (u.u_error)
588 		return;
589 	(void) copyout((caddr_t)&vm, (caddr_t)vp, sizeof (struct vtimes));
590 }
591 
592 /*
593  * Wait system call.
594  * Search for a terminated (zombie) child,
595  * finally lay it to rest, and collect its status.
596  * Look also for stopped (traced) children,
597  * and pass back status from them.
598  */
599 wait1(options, vp)
600 	register options;
601 	struct vtimes *vp;
602 {
603 	register f;
604 	register struct proc *p;
605 
606 	f = 0;
607 loop:
608 	for (p = proc; p < procNPROC; p++)
609 	if (p->p_pptr == u.u_procp) {
610 		f++;
611 		if (p->p_stat == SZOMB) {
612 			u.u_r.r_val1 = p->p_pid;
613 			u.u_r.r_val2 = ((struct xproc *)p)->xp_xstat;
614 			((struct xproc *)p)->xp_xstat = 0;
615 			if (vp)
616 				*vp = ((struct xproc *)p)->xp_vm;
617 			vmsadd(&u.u_cvm, &((struct xproc *)p)->xp_vm);
618 			((struct xproc *)p)->xp_vm = zvms;
619 			p->p_stat = NULL;
620 			p->p_pid = 0;
621 			p->p_ppid = 0;
622 			p->p_pptr = 0;
623 			p->p_sig = 0;
624 			p->p_siga0 = 0;
625 			p->p_siga1 = 0;
626 			p->p_pgrp = 0;
627 			p->p_flag = 0;
628 			p->p_wchan = 0;
629 			p->p_cursig = 0;
630 			return;
631 		}
632 		if (p->p_stat == SSTOP && (p->p_flag&SWTED)==0 &&
633 		    (p->p_flag&STRC || options&WUNTRACED)) {
634 			p->p_flag |= SWTED;
635 			u.u_r.r_val1 = p->p_pid;
636 			u.u_r.r_val2 = (p->p_cursig<<8) | WSTOPPED;
637 			return;
638 		}
639 	}
640 	if (f==0) {
641 		u.u_error = ECHILD;
642 		return;
643 	}
644 	if (options&WNOHANG) {
645 		u.u_r.r_val1 = 0;
646 		return;
647 	}
648 	if ((u.u_procp->p_flag&SNUSIG) && setjmp(u.u_qsav)) {
649 		u.u_eosys = RESTARTSYS;
650 		return;
651 	}
652 	sleep((caddr_t)u.u_procp, PWAIT);
653 	goto loop;
654 }
655 
656 /*
657  * fork system call.
658  */
659 fork()
660 {
661 
662 	u.u_cdmap = zdmap;
663 	u.u_csmap = zdmap;
664 	if (swpexpand(u.u_dsize, u.u_ssize, &u.u_cdmap, &u.u_csmap) == 0) {
665 		u.u_r.r_val2 = 0;
666 		return;
667 	}
668 	fork1(0);
669 }
670 
671 fork1(isvfork)
672 {
673 	register struct proc *p1, *p2;
674 	register a;
675 
676 	a = 0;
677 	p2 = NULL;
678 	for (p1 = proc; p1 < procNPROC; p1++) {
679 		if (p1->p_stat==NULL && p2==NULL)
680 			p2 = p1;
681 		else {
682 			if (p1->p_uid==u.u_uid && p1->p_stat!=NULL)
683 				a++;
684 		}
685 	}
686 	/*
687 	 * Disallow if
688 	 *  No processes at all;
689 	 *  not su and too many procs owned; or
690 	 *  not su and would take last slot.
691 	 */
692 	if (p2==NULL)
693 		tablefull("proc");
694 	if (p2==NULL || (u.u_uid!=0 && (p2==procNPROC-1 || a>MAXUPRC))) {
695 		u.u_error = EAGAIN;
696 		if (!isvfork) {
697 			(void) vsexpand(0, &u.u_cdmap, 1);
698 			(void) vsexpand(0, &u.u_csmap, 1);
699 		}
700 		goto out;
701 	}
702 	p1 = u.u_procp;
703 	if (newproc(isvfork)) {
704 		u.u_r.r_val1 = p1->p_pid;
705 		u.u_r.r_val2 = 1;  /* child */
706 		u.u_start = time;
707 		u.u_acflag = AFORK;
708 		return;
709 	}
710 	u.u_r.r_val1 = p2->p_pid;
711 
712 out:
713 	u.u_r.r_val2 = 0;
714 }
715 
716 /*
717  * break system call.
718  *  -- bad planning: "break" is a dirty word in C.
719  */
720 sbreak()
721 {
722 	struct a {
723 		char	*nsiz;
724 	};
725 	register int n, d;
726 
727 	/*
728 	 * set n to new data size
729 	 * set d to new-old
730 	 */
731 
732 	n = btoc(((struct a *)u.u_ap)->nsiz);
733 	if (!u.u_sep)
734 		n -= ctos(u.u_tsize) * stoc(1);
735 	if (n < 0)
736 		n = 0;
737 	d = clrnd(n - u.u_dsize);
738 	if (ctob(u.u_dsize+d) > u.u_limit[LIM_DATA]) {
739 		u.u_error = ENOMEM;
740 		return;
741 	}
742 	if (chksize(u.u_tsize, u.u_dsize+d, u.u_ssize))
743 		return;
744 	if (swpexpand(u.u_dsize+d, u.u_ssize, &u.u_dmap, &u.u_smap)==0)
745 		return;
746 	expand(d, P0BR);
747 }
748