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set.c revision 1.39 
      1 /* $NetBSD: set.c,v 1.39 2022/09/14 16:15:51 christos 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #ifndef lint
     34 #if 0
     35 static char sccsid[] = "@(#)set.c	8.1 (Berkeley) 5/31/93";
     36 #else
     37 __RCSID("$NetBSD: set.c,v 1.39 2022/09/14 16:15:51 christos Exp $");
     38 #endif
     39 #endif /* not lint */
     40 
     41 #include <sys/types.h>
     42 
     43 #include <stdarg.h>
     44 #include <stdlib.h>
     45 
     46 #include <string.h>
     47 
     48 #include "csh.h"
     49 #include "extern.h"
     50 
     51 static Char *getinx(Char *, int *);
     52 static void asx(Char *, int, Char *);
     53 static struct varent *getvx(Char *, int);
     54 static Char *xset(Char *, Char ***);
     55 static Char *operate(int, Char *, Char *);
     56 static void putn1(int);
     57 static struct varent *madrof(Char *, struct varent *);
     58 static void unsetv1(struct varent *);
     59 static void exportpath(Char **);
     60 static void balance(struct varent *, int, int);
     61 
     62 static int wantediting;
     63 
     64 #ifdef EDIT
     65 static const char *
     66 alias_text(void *dummy __unused, const char *name)
     67 {
     68 	static char *buf;
     69 	struct varent *vp;
     70 	Char **av;
     71 	char *p;
     72 	size_t len;
     73 
     74 	vp = adrof1(str2short(name), &aliases);
     75 	if (vp == NULL)
     76 	    return NULL;
     77 
     78 	len = 0;
     79 	for (av = vp->vec; *av; av++) {
     80 	    len += strlen(vis_str(*av));
     81 	    if (av[1])
     82 		len++;
     83 	}
     84 	len++;
     85 	free(buf);
     86 	p = buf = xmalloc(len);
     87 	for (av = vp->vec; *av; av++) {
     88 	    const char *s = vis_str(*av);
     89 	    while ((*p++ = *s++) != '\0')
     90 		continue;
     91 	    if (av[1])
     92 		*p++ = ' ';
     93 	}
     94 	*p = '\0';
     95 	return buf;
     96 }
     97 #endif
     98 
     99 /*
    100  * C Shell
    101  */
    102 
    103 static void
    104 update_vars(Char *vp)
    105 {
    106     if (eq(vp, STRpath)) {
    107 	struct varent *pt = adrof(STRpath);
    108 	if (pt == NULL)
    109 	    stderror(ERR_NAME | ERR_UNDVAR);
    110 	else {
    111 	    exportpath(pt->vec);
    112 	    dohash(NULL, NULL);
    113 	}
    114     }
    115     else if (eq(vp, STRhistchars)) {
    116 	Char *pn = value(STRhistchars);
    117 
    118 	HIST = *pn++;
    119 	HISTSUB = *pn;
    120     }
    121     else if (eq(vp, STRuser)) {
    122 	Setenv(STRUSER, value(vp));
    123 	Setenv(STRLOGNAME, value(vp));
    124     }
    125     else if (eq(vp, STRwordchars)) {
    126 	word_chars = value(vp);
    127     }
    128     else if (eq(vp, STRterm))
    129 	Setenv(STRTERM, value(vp));
    130     else if (eq(vp, STRhome)) {
    131 	Char *cp;
    132 
    133 	cp = Strsave(value(vp));	/* get the old value back */
    134 
    135 	/*
    136 	 * convert to canonical pathname (possibly resolving symlinks)
    137 	 */
    138 	cp = dcanon(cp, cp);
    139 
    140 	set(vp, Strsave(cp));	/* have to save the new val */
    141 
    142 	/* and now mirror home with HOME */
    143 	Setenv(STRHOME, cp);
    144 	/* fix directory stack for new tilde home */
    145 	dtilde();
    146 	free(cp);
    147     }
    148 #ifdef FILEC
    149     else if (eq(vp, STRfilec))
    150 	filec = 1;
    151 #endif
    152 #ifdef EDIT
    153     else if (eq(vp, STRedit))
    154 	wantediting = 1;
    155 #endif
    156 }
    157 
    158 void
    159 /*ARGSUSED*/
    160 doset(Char **v, struct command *t)
    161 {
    162     Char op, *p, **vecp, *vp;
    163     int subscr = 0;	/* XXX: GCC */
    164     int hadsub;
    165 
    166     v++;
    167     p = *v++;
    168     if (p == 0) {
    169 	prvars();
    170 	return;
    171     }
    172     do {
    173 	hadsub = 0;
    174 	vp = p;
    175 	if (letter(*p))
    176 	    for (; alnum(*p); p++)
    177 		continue;
    178 	if (vp == p || !letter(*vp))
    179 	    stderror(ERR_NAME | ERR_VARBEGIN);
    180 	if ((p - vp) > MAXVARLEN)
    181 	    stderror(ERR_NAME | ERR_VARTOOLONG);
    182 	if (*p == '[') {
    183 	    hadsub++;
    184 	    p = getinx(p, &subscr);
    185 	}
    186 	if ((op = *p) != '\0') {
    187 	    *p++ = 0;
    188 	    if (*p == 0 && *v && **v == '(')
    189 		p = *v++;
    190 	}
    191 	else if (*v && eq(*v, STRequal)) {
    192 	    op = '=', v++;
    193 	    if (*v)
    194 		p = *v++;
    195 	}
    196 	if (op && op != '=')
    197 	    stderror(ERR_NAME | ERR_SYNTAX);
    198 	if (eq(p, STRLparen)) {
    199 	    Char **e = v;
    200 
    201 	    if (hadsub)
    202 		stderror(ERR_NAME | ERR_SYNTAX);
    203 	    for (;;) {
    204 		if (!*e)
    205 		    stderror(ERR_NAME | ERR_MISSING, ')');
    206 		if (**e == ')')
    207 		    break;
    208 		e++;
    209 	    }
    210 	    p = *e;
    211 	    *e = 0;
    212 	    vecp = saveblk(v);
    213 	    set1(vp, vecp, &shvhed);
    214 	    *e = p;
    215 	    v = e + 1;
    216 	}
    217 	else if (hadsub)
    218 	    asx(vp, subscr, Strsave(p));
    219 	else
    220 	    set(vp, Strsave(p));
    221 	update_vars(vp);
    222     } while ((p = *v++) != NULL);
    223 }
    224 
    225 static Char *
    226 getinx(Char *cp, int *ip)
    227 {
    228     *ip = 0;
    229     *cp++ = 0;
    230     while (*cp && Isdigit(*cp))
    231 	*ip = *ip * 10 + *cp++ - '0';
    232     if (*cp++ != ']')
    233 	stderror(ERR_NAME | ERR_SUBSCRIPT);
    234     return (cp);
    235 }
    236 
    237 static void
    238 asx(Char *vp, int subscr, Char *p)
    239 {
    240     struct varent *v;
    241 
    242     v = getvx(vp, subscr);
    243     free(v->vec[subscr - 1]);
    244     v->vec[subscr - 1] = globone(p, G_APPEND);
    245 }
    246 
    247 static struct varent *
    248 getvx(Char *vp, int subscr)
    249 {
    250     struct varent *v;
    251 
    252     v = adrof(vp);
    253     if (v == 0)
    254 	udvar(vp);
    255     if (subscr < 1 || subscr > blklen(v->vec))
    256 	stderror(ERR_NAME | ERR_RANGE);
    257     return (v);
    258 }
    259 
    260 void
    261 /*ARGSUSED*/
    262 dolet(Char **v, struct command *t)
    263 {
    264     Char c, op, *p, *vp;
    265     int subscr = 0;	/* XXX: GCC */
    266     int hadsub;
    267 
    268     v++;
    269     p = *v++;
    270     if (p == 0) {
    271 	prvars();
    272 	return;
    273     }
    274     do {
    275 	hadsub = 0;
    276 	vp = p;
    277 	if (letter(*p))
    278 	    for (; alnum(*p); p++)
    279 		continue;
    280 	if (vp == p || !letter(*vp))
    281 	    stderror(ERR_NAME | ERR_VARBEGIN);
    282 	if ((p - vp) > MAXVARLEN)
    283 	    stderror(ERR_NAME | ERR_VARTOOLONG);
    284 	if (*p == '[') {
    285 	    hadsub++;
    286 	    p = getinx(p, &subscr);
    287 	}
    288 	if (*p == 0 && *v)
    289 	    p = *v++;
    290 	if ((op = *p) != '\0')
    291 	    *p++ = 0;
    292 	else
    293 	    stderror(ERR_NAME | ERR_ASSIGN);
    294 
    295 	if (*p == '\0' && *v == NULL)
    296 	    stderror(ERR_NAME | ERR_ASSIGN);
    297 
    298 	vp = Strsave(vp);
    299 	if (op == '=') {
    300 	    c = '=';
    301 	    p = xset(p, &v);
    302 	}
    303 	else {
    304 	    c = *p++;
    305 	    if (any("+-", c)) {
    306 		if (c != op || *p)
    307 		    stderror(ERR_NAME | ERR_UNKNOWNOP);
    308 		p = Strsave(STR1);
    309 	    }
    310 	    else {
    311 		if (any("<>", op)) {
    312 		    if (c != op)
    313 			stderror(ERR_NAME | ERR_UNKNOWNOP);
    314 		    c = *p++;
    315 		    stderror(ERR_NAME | ERR_SYNTAX);
    316 		}
    317 		if (c != '=')
    318 		    stderror(ERR_NAME | ERR_UNKNOWNOP);
    319 		p = xset(p, &v);
    320 	    }
    321 	}
    322 	if (op == '=') {
    323 	    if (hadsub)
    324 		asx(vp, subscr, p);
    325 	    else
    326 		set(vp, p);
    327 	} else if (hadsub) {
    328 	    struct varent *gv = getvx(vp, subscr);
    329 
    330 	    asx(vp, subscr, operate(op, gv->vec[subscr - 1], p));
    331 	}
    332 	else
    333 	    set(vp, operate(op, value(vp), p));
    334 	if (eq(vp, STRpath)) {
    335 	    struct varent *pt = adrof(STRpath);
    336 	    if (pt == NULL)
    337 		stderror(ERR_NAME | ERR_UNDVAR);
    338 	    else {
    339 		exportpath(pt->vec);
    340 		dohash(NULL, NULL);
    341 	    }
    342 	}
    343 	free(vp);
    344 	if (c != '=')
    345 	    free(p);
    346     } while ((p = *v++) != NULL);
    347 }
    348 
    349 static Char *
    350 xset(Char *cp, Char ***vp)
    351 {
    352     Char *dp;
    353 
    354     if (*cp) {
    355 	dp = Strsave(cp);
    356 	--(*vp);
    357 	free(** vp);
    358 	**vp = dp;
    359     }
    360     return (putn(expr(vp)));
    361 }
    362 
    363 static Char *
    364 operate(int op, Char *vp, Char *p)
    365 {
    366     Char opr[2], **v, *vec[5], **vecp;
    367     int i;
    368 
    369     v = vec;
    370     vecp = v;
    371     if (op != '=') {
    372 	if (*vp)
    373 	    *v++ = vp;
    374 	opr[0] = (Char)op;
    375 	opr[1] = 0;
    376 	*v++ = opr;
    377 	if (op == '<' || op == '>')
    378 	    *v++ = opr;
    379     }
    380     *v++ = p;
    381     *v++ = 0;
    382     i = expr(&vecp);
    383     if (*vecp)
    384 	stderror(ERR_NAME | ERR_EXPRESSION);
    385     return (putn(i));
    386 }
    387 
    388 static Char *putp;
    389 
    390 Char *
    391 putn(int n)
    392 {
    393     static Char numbers[15];
    394 
    395     putp = numbers;
    396     if (n < 0) {
    397 	n = -n;
    398 	*putp++ = '-';
    399     }
    400     if ((unsigned int)n == 0x80000000U) {
    401 	*putp++ = '2';
    402 	n = 147483648;
    403     }
    404     putn1(n);
    405     *putp = 0;
    406     return (Strsave(numbers));
    407 }
    408 
    409 static void
    410 putn1(int n)
    411 {
    412     if (n > 9)
    413 	putn1(n / 10);
    414     *putp++ = (Char)(n % 10 + '0');
    415 }
    416 
    417 int
    418 getn(Char *cp)
    419 {
    420     int n, sign;
    421 
    422     sign = 0;
    423     if (cp[0] == '+' && cp[1])
    424 	cp++;
    425     if (*cp == '-') {
    426 	sign++;
    427 	cp++;
    428 	if (!Isdigit(*cp))
    429 	    stderror(ERR_NAME | ERR_BADNUM);
    430     }
    431     n = 0;
    432     while (Isdigit(*cp))
    433 	n = n * 10 + *cp++ - '0';
    434     if (*cp)
    435 	stderror(ERR_NAME | ERR_BADNUM);
    436     return (sign ? -n : n);
    437 }
    438 
    439 Char *
    440 value1(Char *var, struct varent *head)
    441 {
    442     struct varent *vp;
    443 
    444     vp = adrof1(var, head);
    445     return (vp == 0 || vp->vec[0] == 0 ? STRNULL : vp->vec[0]);
    446 }
    447 
    448 static struct varent *
    449 madrof(Char *pat, struct varent *vp)
    450 {
    451     struct varent *vp1;
    452 
    453     for (; vp; vp = vp->v_right) {
    454 	if (vp->v_left && (vp1 = madrof(pat, vp->v_left)))
    455 	    return vp1;
    456 	if (Gmatch(vp->v_name, pat))
    457 	    return vp;
    458     }
    459     return vp;
    460 }
    461 
    462 struct varent *
    463 adrof1(Char *name, struct varent *v)
    464 {
    465     int cmp;
    466 
    467     v = v->v_left;
    468     while (v && ((cmp = *name - *v->v_name) ||
    469 		 (cmp = Strcmp(name, v->v_name))))
    470 	if (cmp < 0)
    471 	    v = v->v_left;
    472 	else
    473 	    v = v->v_right;
    474     return v;
    475 }
    476 
    477 /*
    478  * The caller is responsible for putting value in a safe place
    479  */
    480 void
    481 set(Char *var, Char *val)
    482 {
    483     Char **vec;
    484 
    485     vec = xmalloc(2 * sizeof(*vec));
    486     vec[0] = val;
    487     vec[1] = 0;
    488     set1(var, vec, &shvhed);
    489 }
    490 
    491 void
    492 set1(Char *var, Char **vec, struct varent *head)
    493 {
    494     Char **oldv;
    495 
    496     oldv = vec;
    497     gflag = 0;
    498     tglob(oldv);
    499     if (gflag) {
    500 	vec = globall(oldv);
    501 	if (vec == 0) {
    502 	    blkfree(oldv);
    503 	    stderror(ERR_NAME | ERR_NOMATCH);
    504 	}
    505 	blkfree(oldv);
    506 	gargv = 0;
    507     }
    508     setq(var, vec, head);
    509 }
    510 
    511 void
    512 setq(Char *name, Char **vec, struct varent *p)
    513 {
    514     struct varent *c;
    515     int f;
    516 
    517     f = 0;			/* tree hangs off the header's left link */
    518     while ((c = p->v_link[f]) != NULL) {
    519 	if ((f = *name - *c->v_name) == 0 &&
    520 	    (f = Strcmp(name, c->v_name)) == 0) {
    521 	    blkfree(c->vec);
    522 	    goto found;
    523 	}
    524 	p = c;
    525 	f = f > 0;
    526     }
    527     p->v_link[f] = c = xmalloc(sizeof(*c));
    528     c->v_name = Strsave(name);
    529     c->v_bal = 0;
    530     c->v_left = c->v_right = 0;
    531     c->v_parent = p;
    532     balance(p, f, 0);
    533 found:
    534     trim(c->vec = vec);
    535 }
    536 
    537 void
    538 /*ARGSUSED*/
    539 unset(Char **v, struct command *t)
    540 {
    541     unset1(v, &shvhed);
    542     if (adrof(STRhistchars) == 0) {
    543 	HIST = '!';
    544 	HISTSUB = '^';
    545     }
    546     if (adrof(STRwordchars) == 0)
    547 	word_chars = STR_WORD_CHARS;
    548 #ifdef FILEC
    549     if (adrof(STRfilec) == 0)
    550 	filec = 0;
    551 #endif
    552 #ifdef EDIT
    553     if (adrof(STRedit) == 0)
    554 	wantediting = 0;
    555 #endif
    556 }
    557 
    558 extern int insource;
    559 void
    560 updateediting(void)
    561 {
    562     if (insource || wantediting == editing)
    563 	return;
    564 
    565     if (wantediting) {
    566 	HistEvent ev;
    567 	Char *vn = value(STRhistchars);
    568 
    569 	el = el_init_fd(getprogname(), cshin, cshout, csherr,
    570 	    SHIN, SHOUT, SHERR);
    571 	el_set(el, EL_EDITOR, *vn ? short2str(vn) : "emacs");
    572 	el_set(el, EL_PROMPT, printpromptstr);
    573 	el_set(el, EL_ALIAS_TEXT, alias_text, NULL);
    574 	el_set(el, EL_SAFEREAD, 1);
    575 	el_set(el, EL_ADDFN, "rl-complete",
    576 	    "ReadLine compatible completion function", _el_fn_complete);
    577 	el_set(el, EL_BIND, "^I", adrof(STRfilec) ? "rl-complete" : "ed-insert",
    578 	    NULL);
    579 	hi = history_init();
    580 	history(hi, &ev, H_SETSIZE, getn(value(STRhistory)));
    581 	loadhist(Histlist.Hnext);
    582 	el_set(el, EL_HIST, history, hi);
    583     } else {
    584 	if (el)
    585 	    el_end(el);
    586 	if (hi)
    587 	    history_end(hi);
    588 	el = NULL;
    589 	hi = NULL;
    590     }
    591     editing = wantediting;
    592 }
    593 
    594 void
    595 unset1(Char *v[], struct varent *head)
    596 {
    597     struct varent *vp;
    598     int cnt;
    599 
    600     while (*++v) {
    601 	cnt = 0;
    602 	while ((vp = madrof(*v, head->v_left)) != NULL)
    603 	    unsetv1(vp), cnt++;
    604 	if (cnt == 0)
    605 	    setname(vis_str(*v));
    606     }
    607 }
    608 
    609 void
    610 unsetv(Char *var)
    611 {
    612     struct varent *vp;
    613 
    614     if ((vp = adrof1(var, &shvhed)) == 0)
    615 	udvar(var);
    616     unsetv1(vp);
    617 }
    618 
    619 static void
    620 unsetv1(struct varent *p)
    621 {
    622     struct varent *c, *pp;
    623     int f;
    624 
    625     /*
    626      * Free associated memory first to avoid complications.
    627      */
    628     blkfree(p->vec);
    629     free(p->v_name);
    630     /*
    631      * If p is missing one child, then we can move the other into where p is.
    632      * Otherwise, we find the predecessor of p, which is guaranteed to have no
    633      * right child, copy it into p, and move its left child into it.
    634      */
    635     if (p->v_right == 0)
    636 	c = p->v_left;
    637     else if (p->v_left == 0)
    638 	c = p->v_right;
    639     else {
    640 	for (c = p->v_left; c->v_right; c = c->v_right)
    641 	    continue;
    642 	p->v_name = c->v_name;
    643 	p->vec = c->vec;
    644 	p = c;
    645 	c = p->v_left;
    646     }
    647     /*
    648      * Move c into where p is.
    649      */
    650     pp = p->v_parent;
    651     f = pp->v_right == p;
    652     if ((pp->v_link[f] = c) != NULL)
    653 	c->v_parent = pp;
    654     /*
    655      * Free the deleted node, and rebalance.
    656      */
    657     free(p);
    658     balance(pp, f, 1);
    659 }
    660 
    661 void
    662 setNS(Char *cp)
    663 {
    664     set(cp, Strsave(STRNULL));
    665 }
    666 
    667 void
    668 /*ARGSUSED*/
    669 shift(Char **v, struct command *t)
    670 {
    671     struct varent *argv;
    672     Char *name;
    673 
    674     v++;
    675     name = *v;
    676     if (name == 0)
    677 	name = STRargv;
    678     else
    679 	(void) strip(name);
    680     argv = adrof(name);
    681     if (argv == 0)
    682 	udvar(name);
    683     if (argv->vec[0] == 0)
    684 	stderror(ERR_NAME | ERR_NOMORE);
    685     lshift(argv->vec, 1);
    686     update_vars(name);
    687 }
    688 
    689 static void
    690 exportpath(Char **val)
    691 {
    692     Char exppath[BUFSIZE];
    693 
    694     exppath[0] = 0;
    695     if (val)
    696 	while (*val) {
    697 	    if (Strlen(*val) + Strlen(exppath) + 2 > BUFSIZE) {
    698 		(void)fprintf(csherr,
    699 			       "Warning: ridiculously long PATH truncated\n");
    700 		break;
    701 	    }
    702 	    (void)Strcat(exppath, *val++);
    703 	    if (*val == 0 || eq(*val, STRRparen))
    704 		break;
    705 	    (void)Strcat(exppath, STRcolon);
    706 	}
    707     Setenv(STRPATH, exppath);
    708 }
    709 
    710 #ifndef lint
    711  /*
    712   * Lint thinks these have null effect
    713   */
    714  /* macros to do single rotations on node p */
    715 #define rright(p) (\
    716 	t = (p)->v_left,\
    717 	(t)->v_parent = (p)->v_parent,\
    718 	((p)->v_left = t->v_right) ? (t->v_right->v_parent = (p)) : 0,\
    719 	(t->v_right = (p))->v_parent = t,\
    720 	(p) = t)
    721 #define rleft(p) (\
    722 	t = (p)->v_right,\
    723 	(t)->v_parent = (p)->v_parent,\
    724 	((p)->v_right = t->v_left) ? (t->v_left->v_parent = (p)) : 0,\
    725 	(t->v_left = (p))->v_parent = t,\
    726 	(p) = t)
    727 #else
    728 struct varent *
    729 rleft(struct varent *p)
    730 {
    731     return (p);
    732 }
    733 struct varent *
    734 rright(struct varent *p)
    735 {
    736     return (p);
    737 }
    738 #endif				/* ! lint */
    739 
    740 
    741 /*
    742  * Rebalance a tree, starting at p and up.
    743  * F == 0 means we've come from p's left child.
    744  * D == 1 means we've just done a delete, otherwise an insert.
    745  */
    746 static void
    747 balance(struct varent *p, int f, int d)
    748 {
    749     struct varent *pp;
    750 
    751 #ifndef lint
    752     struct varent *t;	/* used by the rotate macros */
    753 
    754 #endif
    755     int ff;
    756 
    757     /*
    758      * Ok, from here on, p is the node we're operating on; pp is its parent; f
    759      * is the branch of p from which we have come; ff is the branch of pp which
    760      * is p.
    761      */
    762     for (; (pp = p->v_parent) != NULL; p = pp, f = ff) {
    763 	ff = pp->v_right == p;
    764 	if (f ^ d) {		/* right heavy */
    765 	    switch (p->v_bal) {
    766 	    case -1:		/* was left heavy */
    767 		p->v_bal = 0;
    768 		break;
    769 	    case 0:		/* was balanced */
    770 		p->v_bal = 1;
    771 		break;
    772 	    case 1:		/* was already right heavy */
    773 		switch (p->v_right->v_bal) {
    774 		case 1:	/* single rotate */
    775 		    pp->v_link[ff] = rleft(p);
    776 		    p->v_left->v_bal = 0;
    777 		    p->v_bal = 0;
    778 		    break;
    779 		case 0:	/* single rotate */
    780 		    pp->v_link[ff] = rleft(p);
    781 		    p->v_left->v_bal = 1;
    782 		    p->v_bal = -1;
    783 		    break;
    784 		case -1:	/* double rotate */
    785 		    (void) rright(p->v_right);
    786 		    pp->v_link[ff] = rleft(p);
    787 		    p->v_left->v_bal =
    788 			p->v_bal < 1 ? 0 : -1;
    789 		    p->v_right->v_bal =
    790 			p->v_bal > -1 ? 0 : 1;
    791 		    p->v_bal = 0;
    792 		    break;
    793 		}
    794 		break;
    795 	    }
    796 	}
    797 	else {			/* left heavy */
    798 	    switch (p->v_bal) {
    799 	    case 1:		/* was right heavy */
    800 		p->v_bal = 0;
    801 		break;
    802 	    case 0:		/* was balanced */
    803 		p->v_bal = -1;
    804 		break;
    805 	    case -1:		/* was already left heavy */
    806 		switch (p->v_left->v_bal) {
    807 		case -1:	/* single rotate */
    808 		    pp->v_link[ff] = rright(p);
    809 		    p->v_right->v_bal = 0;
    810 		    p->v_bal = 0;
    811 		    break;
    812 		case 0:	/* single rotate */
    813 		    pp->v_link[ff] = rright(p);
    814 		    p->v_right->v_bal = -1;
    815 		    p->v_bal = 1;
    816 		    break;
    817 		case 1:	/* double rotate */
    818 		    (void) rleft(p->v_left);
    819 		    pp->v_link[ff] = rright(p);
    820 		    p->v_left->v_bal =
    821 			p->v_bal < 1 ? 0 : -1;
    822 		    p->v_right->v_bal =
    823 			p->v_bal > -1 ? 0 : 1;
    824 		    p->v_bal = 0;
    825 		    break;
    826 		}
    827 		break;
    828 	    }
    829 	}
    830 	/*
    831 	 * If from insert, then we terminate when p is balanced. If from
    832 	 * delete, then we terminate when p is unbalanced.
    833 	 */
    834 	if ((p->v_bal == 0) ^ d)
    835 	    break;
    836     }
    837 }
    838 
    839 void
    840 plist(struct varent *p)
    841 {
    842     struct varent *c;
    843     sigset_t nsigset;
    844     int len;
    845 
    846     if (setintr) {
    847 	sigemptyset(&nsigset);
    848 	(void)sigaddset(&nsigset, SIGINT);
    849 	(void)sigprocmask(SIG_UNBLOCK, &nsigset, NULL);
    850     }
    851 
    852     for (;;) {
    853 	while (p->v_left)
    854 	    p = p->v_left;
    855 x:
    856 	if (p->v_parent == 0)	/* is it the header? */
    857 	    return;
    858 	len = blklen(p->vec);
    859 	(void)fprintf(cshout, "%s\t", short2str(p->v_name));
    860 	if (len != 1)
    861 	    (void)fputc('(', cshout);
    862 	blkpr(cshout, p->vec);
    863 	if (len != 1)
    864 	    (void)fputc(')', cshout);
    865 	(void)fputc('\n', cshout);
    866 	if (p->v_right) {
    867 	    p = p->v_right;
    868 	    continue;
    869 	}
    870 	do {
    871 	    c = p;
    872 	    p = p->v_parent;
    873 	} while (p->v_right == c);
    874 	goto x;
    875     }
    876 }
    877