xref: /netbsd-src/bin/csh/set.c (revision 1ca5c1b28139779176bd5c13ad7c5f25c0bcd5f8)
1 /* $NetBSD: set.c,v 1.17 2001/11/03 13:35:40 lukem Exp $ */
2 
3 /*-
4  * Copyright (c) 1980, 1991, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 #ifndef lint
38 #if 0
39 static char sccsid[] = "@(#)set.c	8.1 (Berkeley) 5/31/93";
40 #else
41 __RCSID("$NetBSD: set.c,v 1.17 2001/11/03 13:35:40 lukem Exp $");
42 #endif
43 #endif /* not lint */
44 
45 #include <sys/types.h>
46 
47 #include <stdlib.h>
48 
49 #ifndef SHORT_STRINGS
50 #include <string.h>
51 #endif /* SHORT_STRINGS */
52 
53 #if __STDC__
54 # include <stdarg.h>
55 #else
56 # include <varargs.h>
57 #endif
58 
59 #include "csh.h"
60 #include "extern.h"
61 
62 static Char *getinx(Char *, int *);
63 static void asx(Char *, int, Char *);
64 static struct varent *getvx(Char *, int);
65 static Char *xset(Char *, Char ***);
66 static Char *operate(int, Char *, Char *);
67 static void putn1(int);
68 static struct varent *madrof(Char *, struct varent *);
69 static void unsetv1(struct varent *);
70 static void exportpath(Char **);
71 static void balance(struct varent *, int, int);
72 
73 /*
74  * C Shell
75  */
76 
77 void
78 /*ARGSUSED*/
79 doset(Char **v, struct command *t)
80 {
81     Char op, *p, **vecp, *vp;
82     int subscr;
83     bool hadsub;
84 
85     v++;
86     p = *v++;
87     if (p == 0) {
88 	prvars();
89 	return;
90     }
91     do {
92 	hadsub = 0;
93 	vp = p;
94 	if (letter(*p))
95 	    for (; alnum(*p); p++)
96 		continue;
97 	if (vp == p || !letter(*vp))
98 	    stderror(ERR_NAME | ERR_VARBEGIN);
99 	if ((p - vp) > MAXVARLEN)
100 	    stderror(ERR_NAME | ERR_VARTOOLONG);
101 	if (*p == '[') {
102 	    hadsub++;
103 	    p = getinx(p, &subscr);
104 	}
105 	if ((op = *p) != '\0') {
106 	    *p++ = 0;
107 	    if (*p == 0 && *v && **v == '(')
108 		p = *v++;
109 	}
110 	else if (*v && eq(*v, STRequal)) {
111 	    op = '=', v++;
112 	    if (*v)
113 		p = *v++;
114 	}
115 	if (op && op != '=')
116 	    stderror(ERR_NAME | ERR_SYNTAX);
117 	if (eq(p, STRLparen)) {
118 	    Char **e = v;
119 
120 	    if (hadsub)
121 		stderror(ERR_NAME | ERR_SYNTAX);
122 	    for (;;) {
123 		if (!*e)
124 		    stderror(ERR_NAME | ERR_MISSING, ')');
125 		if (**e == ')')
126 		    break;
127 		e++;
128 	    }
129 	    p = *e;
130 	    *e = 0;
131 	    vecp = saveblk(v);
132 	    set1(vp, vecp, &shvhed);
133 	    *e = p;
134 	    v = e + 1;
135 	}
136 	else if (hadsub)
137 	    asx(vp, subscr, Strsave(p));
138 	else
139 	    set(vp, Strsave(p));
140 	if (eq(vp, STRpath)) {
141 	    exportpath(adrof(STRpath)->vec);
142 	    dohash(NULL, NULL);
143 	}
144 	else if (eq(vp, STRhistchars)) {
145 	    Char *pn = value(STRhistchars);
146 
147 	    HIST = *pn++;
148 	    HISTSUB = *pn;
149 	}
150 	else if (eq(vp, STRuser)) {
151 	    Setenv(STRUSER, value(vp));
152 	    Setenv(STRLOGNAME, value(vp));
153 	}
154 	else if (eq(vp, STRwordchars)) {
155 	    word_chars = value(vp);
156 	}
157 	else if (eq(vp, STRterm))
158 	    Setenv(STRTERM, value(vp));
159 	else if (eq(vp, STRhome)) {
160 	    Char *cp;
161 
162 	    cp = Strsave(value(vp));	/* get the old value back */
163 
164 	    /*
165 	     * convert to cononical pathname (possibly resolving symlinks)
166 	     */
167 	    cp = dcanon(cp, cp);
168 
169 	    set(vp, Strsave(cp));	/* have to save the new val */
170 
171 	    /* and now mirror home with HOME */
172 	    Setenv(STRHOME, cp);
173 	    /* fix directory stack for new tilde home */
174 	    dtilde();
175 	    xfree((ptr_t)cp);
176 	}
177 #ifdef FILEC
178 	else if (eq(vp, STRfilec))
179 	    filec = 1;
180 #endif
181     } while ((p = *v++) != NULL);
182 }
183 
184 static Char *
185 getinx(Char *cp, int *ip)
186 {
187     *ip = 0;
188     *cp++ = 0;
189     while (*cp && Isdigit(*cp))
190 	*ip = *ip * 10 + *cp++ - '0';
191     if (*cp++ != ']')
192 	stderror(ERR_NAME | ERR_SUBSCRIPT);
193     return (cp);
194 }
195 
196 static void
197 asx(Char *vp, int subscr, Char *p)
198 {
199     struct varent *v;
200 
201     v = getvx(vp, subscr);
202     xfree((ptr_t) v->vec[subscr - 1]);
203     v->vec[subscr - 1] = globone(p, G_APPEND);
204 }
205 
206 static struct varent *
207 getvx(Char *vp, int subscr)
208 {
209     struct varent *v;
210 
211     v = adrof(vp);
212     if (v == 0)
213 	udvar(vp);
214     if (subscr < 1 || subscr > blklen(v->vec))
215 	stderror(ERR_NAME | ERR_RANGE);
216     return (v);
217 }
218 
219 void
220 /*ARGSUSED*/
221 dolet(Char **v, struct command *t)
222 {
223     Char c, op, *p, *vp;
224     int subscr;
225     bool hadsub;
226 
227     v++;
228     p = *v++;
229     if (p == 0) {
230 	prvars();
231 	return;
232     }
233     do {
234 	hadsub = 0;
235 	vp = p;
236 	if (letter(*p))
237 	    for (; alnum(*p); p++)
238 		continue;
239 	if (vp == p || !letter(*vp))
240 	    stderror(ERR_NAME | ERR_VARBEGIN);
241 	if ((p - vp) > MAXVARLEN)
242 	    stderror(ERR_NAME | ERR_VARTOOLONG);
243 	if (*p == '[') {
244 	    hadsub++;
245 	    p = getinx(p, &subscr);
246 	}
247 	if (*p == 0 && *v)
248 	    p = *v++;
249 	if ((op = *p) != '\0')
250 	    *p++ = 0;
251 	else
252 	    stderror(ERR_NAME | ERR_ASSIGN);
253 
254 	if (*p == '\0' && *v == NULL)
255 	    stderror(ERR_NAME | ERR_ASSIGN);
256 
257 	vp = Strsave(vp);
258 	if (op == '=') {
259 	    c = '=';
260 	    p = xset(p, &v);
261 	}
262 	else {
263 	    c = *p++;
264 	    if (any("+-", c)) {
265 		if (c != op || *p)
266 		    stderror(ERR_NAME | ERR_UNKNOWNOP);
267 		p = Strsave(STR1);
268 	    }
269 	    else {
270 		if (any("<>", op)) {
271 		    if (c != op)
272 			stderror(ERR_NAME | ERR_UNKNOWNOP);
273 		    c = *p++;
274 		    stderror(ERR_NAME | ERR_SYNTAX);
275 		}
276 		if (c != '=')
277 		    stderror(ERR_NAME | ERR_UNKNOWNOP);
278 		p = xset(p, &v);
279 	    }
280 	}
281 	if (op == '=') {
282 	    if (hadsub)
283 		asx(vp, subscr, p);
284 	    else
285 		set(vp, p);
286 	} else if (hadsub) {
287 	    struct varent *gv = getvx(vp, subscr);
288 
289 	    asx(vp, subscr, operate(op, gv->vec[subscr - 1], p));
290 	}
291 	else
292 	    set(vp, operate(op, value(vp), p));
293 	if (eq(vp, STRpath)) {
294 	    exportpath(adrof(STRpath)->vec);
295 	    dohash(NULL, NULL);
296 	}
297 	xfree((ptr_t) vp);
298 	if (c != '=')
299 	    xfree((ptr_t) p);
300     } while ((p = *v++) != NULL);
301 }
302 
303 static Char *
304 xset(Char *cp, Char ***vp)
305 {
306     Char *dp;
307 
308     if (*cp) {
309 	dp = Strsave(cp);
310 	--(*vp);
311 	xfree((ptr_t) ** vp);
312 	**vp = dp;
313     }
314     return (putn(expr(vp)));
315 }
316 
317 static Char *
318 operate(int op, Char *vp, Char *p)
319 {
320     Char opr[2], **v, *vec[5], **vecp;
321     int i;
322 
323     v = vec;
324     vecp = v;
325     if (op != '=') {
326 	if (*vp)
327 	    *v++ = vp;
328 	opr[0] = op;
329 	opr[1] = 0;
330 	*v++ = opr;
331 	if (op == '<' || op == '>')
332 	    *v++ = opr;
333     }
334     *v++ = p;
335     *v++ = 0;
336     i = expr(&vecp);
337     if (*vecp)
338 	stderror(ERR_NAME | ERR_EXPRESSION);
339     return (putn(i));
340 }
341 
342 static Char *putp;
343 
344 Char *
345 putn(int n)
346 {
347     static Char numbers[15];
348     int num;
349 
350     putp = numbers;
351     if (n < 0) {
352 	n = -n;
353 	*putp++ = '-';
354     }
355     num = 2;			/* confuse lint */
356     if (sizeof(int) == num && ((unsigned int) n) == 0x8000) {
357 	*putp++ = '3';
358 	n = 2768;
359 #ifdef pdp11
360     }
361 #else
362     }
363     else {
364 	num = 4;		/* confuse lint */
365 	if (sizeof(int) == num && ((unsigned int) n) == 0x80000000) {
366 	    *putp++ = '2';
367 	    n = 147483648;
368 	}
369     }
370 #endif
371     putn1(n);
372     *putp = 0;
373     return (Strsave(numbers));
374 }
375 
376 static void
377 putn1(int n)
378 {
379     if (n > 9)
380 	putn1(n / 10);
381     *putp++ = n % 10 + '0';
382 }
383 
384 int
385 getn(Char *cp)
386 {
387     int n, sign;
388 
389     sign = 0;
390     if (cp[0] == '+' && cp[1])
391 	cp++;
392     if (*cp == '-') {
393 	sign++;
394 	cp++;
395 	if (!Isdigit(*cp))
396 	    stderror(ERR_NAME | ERR_BADNUM);
397     }
398     n = 0;
399     while (Isdigit(*cp))
400 	n = n * 10 + *cp++ - '0';
401     if (*cp)
402 	stderror(ERR_NAME | ERR_BADNUM);
403     return (sign ? -n : n);
404 }
405 
406 Char *
407 value1(Char *var, struct varent *head)
408 {
409     struct varent *vp;
410 
411     vp = adrof1(var, head);
412     return (vp == 0 || vp->vec[0] == 0 ? STRNULL : vp->vec[0]);
413 }
414 
415 static struct varent *
416 madrof(Char *pat, struct varent *vp)
417 {
418     struct varent *vp1;
419 
420     for (; vp; vp = vp->v_right) {
421 	if (vp->v_left && (vp1 = madrof(pat, vp->v_left)))
422 	    return vp1;
423 	if (Gmatch(vp->v_name, pat))
424 	    return vp;
425     }
426     return vp;
427 }
428 
429 struct varent *
430 adrof1(Char *name, struct varent *v)
431 {
432     int cmp;
433 
434     v = v->v_left;
435     while (v && ((cmp = *name - *v->v_name) ||
436 		 (cmp = Strcmp(name, v->v_name))))
437 	if (cmp < 0)
438 	    v = v->v_left;
439 	else
440 	    v = v->v_right;
441     return v;
442 }
443 
444 /*
445  * The caller is responsible for putting value in a safe place
446  */
447 void
448 set(Char *var, Char *val)
449 {
450     Char **vec;
451 
452     vec = (Char **)xmalloc((size_t)(2 * sizeof(Char **)));
453     vec[0] = val;
454     vec[1] = 0;
455     set1(var, vec, &shvhed);
456 }
457 
458 void
459 set1(Char *var, Char **vec, struct varent *head)
460 {
461     Char **oldv;
462 
463     oldv = vec;
464     gflag = 0;
465     tglob(oldv);
466     if (gflag) {
467 	vec = globall(oldv);
468 	if (vec == 0) {
469 	    blkfree(oldv);
470 	    stderror(ERR_NAME | ERR_NOMATCH);
471 	}
472 	blkfree(oldv);
473 	gargv = 0;
474     }
475     setq(var, vec, head);
476 }
477 
478 void
479 setq(Char *name, Char **vec, struct varent *p)
480 {
481     struct varent *c;
482     int f;
483 
484     f = 0;			/* tree hangs off the header's left link */
485     while ((c = p->v_link[f]) != NULL) {
486 	if ((f = *name - *c->v_name) == 0 &&
487 	    (f = Strcmp(name, c->v_name)) == 0) {
488 	    blkfree(c->vec);
489 	    goto found;
490 	}
491 	p = c;
492 	f = f > 0;
493     }
494     p->v_link[f] = c = (struct varent *)xmalloc((size_t)sizeof(struct varent));
495     c->v_name = Strsave(name);
496     c->v_bal = 0;
497     c->v_left = c->v_right = 0;
498     c->v_parent = p;
499     balance(p, f, 0);
500 found:
501     trim(c->vec = vec);
502 }
503 
504 void
505 /*ARGSUSED*/
506 unset(Char **v, struct command *t)
507 {
508     unset1(v, &shvhed);
509 #ifdef FILEC
510     if (adrof(STRfilec) == 0)
511 	filec = 0;
512 #endif
513     if (adrof(STRhistchars) == 0) {
514 	HIST = '!';
515 	HISTSUB = '^';
516     }
517     if (adrof(STRwordchars) == 0)
518 	word_chars = STR_WORD_CHARS;
519 }
520 
521 void
522 unset1(Char *v[], struct varent *head)
523 {
524     struct varent *vp;
525     int cnt;
526 
527     while (*++v) {
528 	cnt = 0;
529 	while ((vp = madrof(*v, head->v_left)) != NULL)
530 	    unsetv1(vp), cnt++;
531 	if (cnt == 0)
532 	    setname(vis_str(*v));
533     }
534 }
535 
536 void
537 unsetv(Char *var)
538 {
539     struct varent *vp;
540 
541     if ((vp = adrof1(var, &shvhed)) == 0)
542 	udvar(var);
543     unsetv1(vp);
544 }
545 
546 static void
547 unsetv1(struct varent *p)
548 {
549     struct varent *c, *pp;
550     int f;
551 
552     /*
553      * Free associated memory first to avoid complications.
554      */
555     blkfree(p->vec);
556     xfree((ptr_t) p->v_name);
557     /*
558      * If p is missing one child, then we can move the other into where p is.
559      * Otherwise, we find the predecessor of p, which is guaranteed to have no
560      * right child, copy it into p, and move it's left child into it.
561      */
562     if (p->v_right == 0)
563 	c = p->v_left;
564     else if (p->v_left == 0)
565 	c = p->v_right;
566     else {
567 	for (c = p->v_left; c->v_right; c = c->v_right)
568 	    continue;
569 	p->v_name = c->v_name;
570 	p->vec = c->vec;
571 	p = c;
572 	c = p->v_left;
573     }
574     /*
575      * Move c into where p is.
576      */
577     pp = p->v_parent;
578     f = pp->v_right == p;
579     if ((pp->v_link[f] = c) != NULL)
580 	c->v_parent = pp;
581     /*
582      * Free the deleted node, and rebalance.
583      */
584     xfree((ptr_t) p);
585     balance(pp, f, 1);
586 }
587 
588 void
589 setNS(Char *cp)
590 {
591     set(cp, Strsave(STRNULL));
592 }
593 
594 void
595 /*ARGSUSED*/
596 shift(Char **v, struct command *t)
597 {
598     struct varent *argv;
599     Char *name;
600 
601     v++;
602     name = *v;
603     if (name == 0)
604 	name = STRargv;
605     else
606 	(void) strip(name);
607     argv = adrof(name);
608     if (argv == 0)
609 	udvar(name);
610     if (argv->vec[0] == 0)
611 	stderror(ERR_NAME | ERR_NOMORE);
612     lshift(argv->vec, 1);
613 }
614 
615 static void
616 exportpath(Char **val)
617 {
618     Char exppath[BUFSIZE];
619 
620     exppath[0] = 0;
621     if (val)
622 	while (*val) {
623 	    if (Strlen(*val) + Strlen(exppath) + 2 > BUFSIZE) {
624 		(void)fprintf(csherr,
625 			       "Warning: ridiculously long PATH truncated\n");
626 		break;
627 	    }
628 	    (void)Strcat(exppath, *val++);
629 	    if (*val == 0 || eq(*val, STRRparen))
630 		break;
631 	    (void)Strcat(exppath, STRcolon);
632 	}
633     Setenv(STRPATH, exppath);
634 }
635 
636 #ifndef lint
637  /*
638   * Lint thinks these have null effect
639   */
640  /* macros to do single rotations on node p */
641 #define rright(p) (\
642 	t = (p)->v_left,\
643 	(t)->v_parent = (p)->v_parent,\
644 	((p)->v_left = t->v_right) ? (t->v_right->v_parent = (p)) : 0,\
645 	(t->v_right = (p))->v_parent = t,\
646 	(p) = t)
647 #define rleft(p) (\
648 	t = (p)->v_right,\
649 	(t)->v_parent = (p)->v_parent,\
650 	((p)->v_right = t->v_left) ? (t->v_left->v_parent = (p)) : 0,\
651 	(t->v_left = (p))->v_parent = t,\
652 	(p) = t)
653 #else
654 struct varent *
655 rleft(struct varent *p)
656 {
657     return (p);
658 }
659 struct varent *
660 rright(struct varent *p)
661 {
662     return (p);
663 }
664 #endif				/* ! lint */
665 
666 
667 /*
668  * Rebalance a tree, starting at p and up.
669  * F == 0 means we've come from p's left child.
670  * D == 1 means we've just done a delete, otherwise an insert.
671  */
672 static void
673 balance(struct varent *p, int f, int d)
674 {
675     struct varent *pp;
676 
677 #ifndef lint
678     struct varent *t;	/* used by the rotate macros */
679 
680 #endif
681     int ff;
682 
683     /*
684      * Ok, from here on, p is the node we're operating on; pp is it's parent; f
685      * is the branch of p from which we have come; ff is the branch of pp which
686      * is p.
687      */
688     for (; (pp = p->v_parent) != NULL; p = pp, f = ff) {
689 	ff = pp->v_right == p;
690 	if (f ^ d) {		/* right heavy */
691 	    switch (p->v_bal) {
692 	    case -1:		/* was left heavy */
693 		p->v_bal = 0;
694 		break;
695 	    case 0:		/* was balanced */
696 		p->v_bal = 1;
697 		break;
698 	    case 1:		/* was already right heavy */
699 		switch (p->v_right->v_bal) {
700 		case 1:	/* sigle rotate */
701 		    pp->v_link[ff] = rleft(p);
702 		    p->v_left->v_bal = 0;
703 		    p->v_bal = 0;
704 		    break;
705 		case 0:	/* single rotate */
706 		    pp->v_link[ff] = rleft(p);
707 		    p->v_left->v_bal = 1;
708 		    p->v_bal = -1;
709 		    break;
710 		case -1:	/* double rotate */
711 		    (void) rright(p->v_right);
712 		    pp->v_link[ff] = rleft(p);
713 		    p->v_left->v_bal =
714 			p->v_bal < 1 ? 0 : -1;
715 		    p->v_right->v_bal =
716 			p->v_bal > -1 ? 0 : 1;
717 		    p->v_bal = 0;
718 		    break;
719 		}
720 		break;
721 	    }
722 	}
723 	else {			/* left heavy */
724 	    switch (p->v_bal) {
725 	    case 1:		/* was right heavy */
726 		p->v_bal = 0;
727 		break;
728 	    case 0:		/* was balanced */
729 		p->v_bal = -1;
730 		break;
731 	    case -1:		/* was already left heavy */
732 		switch (p->v_left->v_bal) {
733 		case -1:	/* single rotate */
734 		    pp->v_link[ff] = rright(p);
735 		    p->v_right->v_bal = 0;
736 		    p->v_bal = 0;
737 		    break;
738 		case 0:	/* signle rotate */
739 		    pp->v_link[ff] = rright(p);
740 		    p->v_right->v_bal = -1;
741 		    p->v_bal = 1;
742 		    break;
743 		case 1:	/* double rotate */
744 		    (void) rleft(p->v_left);
745 		    pp->v_link[ff] = rright(p);
746 		    p->v_left->v_bal =
747 			p->v_bal < 1 ? 0 : -1;
748 		    p->v_right->v_bal =
749 			p->v_bal > -1 ? 0 : 1;
750 		    p->v_bal = 0;
751 		    break;
752 		}
753 		break;
754 	    }
755 	}
756 	/*
757 	 * If from insert, then we terminate when p is balanced. If from
758 	 * delete, then we terminate when p is unbalanced.
759 	 */
760 	if ((p->v_bal == 0) ^ d)
761 	    break;
762     }
763 }
764 
765 void
766 plist(struct varent *p)
767 {
768     struct varent *c;
769     sigset_t sigset;
770     int len;
771 
772     if (setintr) {
773 	sigemptyset(&sigset);
774 	(void)sigaddset(&sigset, SIGINT);
775 	(void)sigprocmask(SIG_UNBLOCK, &sigset, NULL);
776     }
777 
778     for (;;) {
779 	while (p->v_left)
780 	    p = p->v_left;
781 x:
782 	if (p->v_parent == 0)	/* is it the header? */
783 	    return;
784 	len = blklen(p->vec);
785 	(void)fprintf(cshout, "%s\t", short2str(p->v_name));
786 	if (len != 1)
787 	    (void)fputc('(', cshout);
788 	blkpr(cshout, p->vec);
789 	if (len != 1)
790 	    (void)fputc(')', cshout);
791 	(void)fputc('\n', cshout);
792 	if (p->v_right) {
793 	    p = p->v_right;
794 	    continue;
795 	}
796 	do {
797 	    c = p;
798 	    p = p->v_parent;
799 	} while (p->v_right == c);
800 	goto x;
801     }
802 }
803