xref: /plan9/sys/src/ape/cmd/pdksh/var.c (revision ec59a3ddbfceee0efe34584c2c9981a5e5ff1ec4) 
1 #include "sh.h"
2 #include "ksh_time.h"
3 #include "ksh_limval.h"
4 #include "ksh_stat.h"
5 #include <ctype.h>
6 
7 /*
8  * Variables
9  *
10  * WARNING: unreadable code, needs a rewrite
11  *
12  * if (flag&INTEGER), val.i contains integer value, and type contains base.
13  * otherwise, (val.s + type) contains string value.
14  * if (flag&EXPORT), val.s contains "name=value" for E-Z exporting.
15  */
16 static	struct tbl vtemp;
17 static	struct table specials;
18 static char	*formatstr	ARGS((struct tbl *vp, const char *s));
19 static void	export		ARGS((struct tbl *vp, const char *val));
20 static int	special		ARGS((const char *name));
21 static void	unspecial	ARGS((const char *name));
22 static void	getspec		ARGS((struct tbl *vp));
23 static void	setspec		ARGS((struct tbl *vp));
24 static void	unsetspec	ARGS((struct tbl *vp));
25 static struct tbl *arraysearch  ARGS((struct tbl *, int));
26 
27 /*
28  * create a new block for function calls and simple commands
29  * assume caller has allocated and set up e->loc
30  */
31 void
32 newblock()
33 {
34 	register struct block *l;
35 	static char *const empty[] = {null};
36 
37 	l = (struct block *) alloc(sizeof(struct block), ATEMP);
38 	l->flags = 0;
39 	ainit(&l->area); /* todo: could use e->area (l->area => l->areap) */
40 	if (!e->loc) {
41 		l->argc = 0;
42 		l->argv = (char **) empty;
43 	} else {
44 		l->argc = e->loc->argc;
45 		l->argv = e->loc->argv;
46 	}
47 	l->exit = l->error = NULL;
48 	tinit(&l->vars, &l->area, 0);
49 	tinit(&l->funs, &l->area, 0);
50 	l->next = e->loc;
51 	e->loc = l;
52 }
53 
54 /*
55  * pop a block handling special variables
56  */
57 void
58 popblock()
59 {
60 	register struct block *l = e->loc;
61 	register struct tbl *vp, **vpp = l->vars.tbls, *vq;
62 	register int i;
63 
64 	e->loc = l->next;	/* pop block */
65 	for (i = l->vars.size; --i >= 0; )
66 		if ((vp = *vpp++) != NULL && (vp->flag&SPECIAL))
67 			if ((vq = global(vp->name))->flag & ISSET)
68 				setspec(vq);
69 			else
70 				unsetspec(vq);
71 	if (l->flags & BF_DOGETOPTS)
72 		user_opt = l->getopts_state;
73 	afreeall(&l->area);
74 	afree(l, ATEMP);
75 }
76 
77 /* called by main() to initialize variable data structures */
78 void
79 initvar()
80 {
81 	static const struct {
82 		const char *name;
83 		int v;
84 	} names[] = {
85 			{ "COLUMNS",		V_COLUMNS },
86 			{ "IFS",		V_IFS },
87 			{ "OPTIND",		V_OPTIND },
88 			{ "PATH",		V_PATH },
89 			{ "POSIXLY_CORRECT",	V_POSIXLY_CORRECT },
90 			{ "TMPDIR",		V_TMPDIR },
91 #ifdef HISTORY
92 			{ "HISTFILE",		V_HISTFILE },
93 			{ "HISTSIZE",		V_HISTSIZE },
94 #endif /* HISTORY */
95 #ifdef EDIT
96 			{ "EDITOR",		V_EDITOR },
97 			{ "VISUAL",		V_VISUAL },
98 #endif /* EDIT */
99 #ifdef KSH
100 			{ "MAIL",		V_MAIL },
101 			{ "MAILCHECK",		V_MAILCHECK },
102 			{ "MAILPATH",		V_MAILPATH },
103 			{ "RANDOM",		V_RANDOM },
104 			{ "SECONDS",		V_SECONDS },
105 			{ "TMOUT",		V_TMOUT },
106 #endif /* KSH */
107 			{ "LINENO",		V_LINENO },
108 			{ (char *) 0,	0 }
109 		};
110 	int i;
111 	struct tbl *tp;
112 
113 	tinit(&specials, APERM, 32); /* must be 2^n (currently 17 specials) */
114 	for (i = 0; names[i].name; i++) {
115 		tp = tenter(&specials, names[i].name, hash(names[i].name));
116 		tp->flag = DEFINED|ISSET;
117 		tp->type = names[i].v;
118 	}
119 }
120 
121 /* Used to calculate an array index for global()/local().  Sets *arrayp to
122  * non-zero if this is an array, sets *valp to the array index, returns
123  * the basename of the array.
124  */
125 const char *
126 array_index_calc(const char *n, bool_t *arrayp, int *valp)
127 {
128 	const char *p;
129 	int len;
130 
131 	*arrayp = FALSE;
132 	p = skip_varname(n, FALSE);
133 	if (p != n && *p == '[' && (len = array_ref_len(p))) {
134 		char *sub, *tmp;
135 		long rval;
136 
137 		/* Calculate the value of the subscript */
138 		*arrayp = TRUE;
139 		tmp = str_nsave(p+1, len-2, ATEMP);
140 		sub = substitute(tmp, 0);
141 		afree(tmp, ATEMP);
142 		n = str_nsave(n, p - n, ATEMP);
143 		evaluate(sub, &rval, KSH_UNWIND_ERROR);
144 		if (rval < 0 || rval > ARRAYMAX)
145 			errorf("%s: subscript out of range", n);
146 		*valp = rval;
147 		afree(sub, ATEMP);
148 	}
149 	return n;
150 }
151 
152 /*
153  * Search for variable, if not found create globally.
154  */
155 struct tbl *
156 global(n)
157 	register const char *n;
158 {
159 	register struct block *l = e->loc;
160 	register struct tbl *vp;
161 	register int c;
162 	unsigned h;
163 	bool_t	 array;
164 	int	 val;
165 
166 	/* Check to see if this is an array */
167 	n = array_index_calc(n, &array, &val);
168 	h = hash(n);
169 	c = n[0];
170 	if (!letter(c)) {
171 		if (array)
172 			errorf("bad substitution");
173 		vp = &vtemp;
174 		vp->flag = DEFINED;
175 		vp->type = 0;
176 		vp->areap = ATEMP;
177 		*vp->name = c;
178 		if (digit(c)) {
179 			for (c = 0; digit(*n); n++)
180 				c = c*10 + *n-'0';
181 			if (c <= l->argc)
182 				/* setstr can't fail here */
183 				setstr(vp, l->argv[c], KSH_RETURN_ERROR);
184 			vp->flag |= RDONLY;
185 			return vp;
186 		}
187 		vp->flag |= RDONLY;
188 		if (n[1] != '\0')
189 			return vp;
190 		vp->flag |= ISSET|INTEGER;
191 		switch (c) {
192 		  case '$':
193 			vp->val.i = kshpid;
194 			break;
195 		  case '!':
196 			/* If no job, expand to nothing */
197 			if ((vp->val.i = j_async()) == 0)
198 				vp->flag &= ~(ISSET|INTEGER);
199 			break;
200 		  case '?':
201 			vp->val.i = exstat;
202 			break;
203 		  case '#':
204 			vp->val.i = l->argc;
205 			break;
206 		  case '-':
207 			vp->flag &= ~INTEGER;
208 			vp->val.s = getoptions();
209 			break;
210 		  default:
211 			vp->flag &= ~(ISSET|INTEGER);
212 		}
213 		return vp;
214 	}
215 	for (l = e->loc; ; l = l->next) {
216 		vp = tsearch(&l->vars, n, h);
217 		if (vp != NULL)
218 			if (array)
219 				return arraysearch(vp, val);
220 			else
221 				return vp;
222 		if (l->next == NULL)
223 			break;
224 	}
225 	vp = tenter(&l->vars, n, h);
226 	if (array)
227 		vp = arraysearch(vp, val);
228 	vp->flag |= DEFINED;
229 	if (special(n))
230 		vp->flag |= SPECIAL;
231 	return vp;
232 }
233 
234 /*
235  * Search for local variable, if not found create locally.
236  */
237 struct tbl *
238 local(n, copy)
239 	register const char *n;
240 	bool_t copy;
241 {
242 	register struct block *l = e->loc;
243 	register struct tbl *vp;
244 	unsigned h;
245 	bool_t	 array;
246 	int	 val;
247 
248 	/* Check to see if this is an array */
249 	n = array_index_calc(n, &array, &val);
250 	h = hash(n);
251 	if (!letter(*n)) {
252 		vp = &vtemp;
253 		vp->flag = DEFINED|RDONLY;
254 		vp->type = 0;
255 		vp->areap = ATEMP;
256 		return vp;
257 	}
258 	vp = tenter(&l->vars, n, h);
259 	if (copy && !(vp->flag & DEFINED)) {
260 		struct block *ll = l;
261 		struct tbl *vq = (struct tbl *) 0;
262 
263 		while ((ll = ll->next) && !(vq = tsearch(&ll->vars, n, h)))
264 			;
265 		if (vq) {
266 			vp->flag |= vq->flag & (EXPORT|INTEGER|RDONLY
267 						|LJUST|RJUST|ZEROFIL
268 						|LCASEV|UCASEV_AL|INT_U|INT_L);
269 			if (vq->flag & INTEGER)
270 				vp->type = vq->type;
271 			vp->u2.field = vq->u2.field;
272 		}
273 	}
274 	if (array)
275 		vp = arraysearch(vp, val);
276 	vp->flag |= DEFINED;
277 	if (special(n))
278 		vp->flag |= SPECIAL;
279 	return vp;
280 }
281 
282 /* get variable string value */
283 char *
284 str_val(vp)
285 	register struct tbl *vp;
286 {
287 	char *s;
288 
289 	if ((vp->flag&SPECIAL))
290 		getspec(vp);
291 	if (!(vp->flag&ISSET))
292 		s = null;		/* special to dollar() */
293 	else if (!(vp->flag&INTEGER))	/* string source */
294 		s = vp->val.s + vp->type;
295 	else {				/* integer source */
296 		/* worst case number length is when base=2, so use BITS(long) */
297 			     /* minus base #     number    null */
298 		static char strbuf[1 + 2 + 1 + BITS(long) + 1];
299 		const char *digits = (vp->flag & UCASEV_AL) ?
300 				  "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
301 				: "0123456789abcdefghijklmnopqrstuvwxyz";
302 		register unsigned long n;
303 		register int base;
304 
305 		s = strbuf + sizeof(strbuf);
306 		if (vp->flag & INT_U)
307 			n = (unsigned long) vp->val.i;
308 		else
309 			n = (vp->val.i < 0) ? -vp->val.i : vp->val.i;
310 		base = (vp->type == 0) ? 10 : vp->type;
311 
312 		*--s = '\0';
313 		do {
314 			*--s = digits[n % base];
315 			n /= base;
316 		} while (n != 0);
317 		if (base != 10) {
318 			*--s = '#';
319 			*--s = digits[base % 10];
320 			if (base >= 10)
321 				*--s = digits[base / 10];
322 		}
323 		if (!(vp->flag & INT_U) && vp->val.i < 0)
324 			*--s = '-';
325 		if (vp->flag & (RJUST|LJUST)) /* case already dealt with */
326 			s = formatstr(vp, s);
327 	}
328 	return s;
329 }
330 
331 /* get variable integer value, with error checking */
332 long
333 intval(vp)
334 	register struct tbl *vp;
335 {
336 	long num;
337 	int base;
338 
339 	base = getint(vp, &num);
340 	if (base == -1)
341 		/* XXX check calls - is error here ok by POSIX? */
342 		errorf("%s: bad number", str_val(vp));
343 	return num;
344 }
345 
346 /* set variable to string value */
347 int
348 setstr(vq, s, error_ok)
349 	register struct tbl *vq;
350 	const char *s;
351 	int error_ok;
352 {
353 	if (vq->flag & RDONLY) {
354 		warningf(TRUE, "%s: is read only", vq->name);
355 		if (!error_ok)
356 			errorf(null);
357 		return 0;
358 	}
359 	if (!(vq->flag&INTEGER)) { /* string dest */
360 		if ((vq->flag&ALLOC)) {
361 			/* debugging */
362 			if (s >= vq->val.s
363 			    && s <= vq->val.s + strlen(vq->val.s))
364 				internal_errorf(TRUE,
365 				    "setstr: %s=%s: assigning to self",
366 				    vq->name, s);
367 			afree((void*)vq->val.s, vq->areap);
368 		}
369 		vq->flag &= ~(ISSET|ALLOC);
370 		vq->type = 0;
371 		if (s && (vq->flag & (UCASEV_AL|LCASEV|LJUST|RJUST)))
372 			s = formatstr(vq, s);
373 		if ((vq->flag&EXPORT))
374 			export(vq, s);
375 		else {
376 			vq->val.s = str_save(s, vq->areap);
377 			if (vq->val.s)		/* <sjg> don't lie */
378 				vq->flag |= ALLOC;
379 		}
380 	} else			/* integer dest */
381 		if (!v_evaluate(vq, s, error_ok))
382 			return 0;
383 	vq->flag |= ISSET;
384 	if ((vq->flag&SPECIAL))
385 		setspec(vq);
386 	return 1;
387 }
388 
389 /* set variable to integer */
390 void
391 setint(vq, n)
392 	register struct tbl *vq;
393 	long n;
394 {
395 	if (!(vq->flag&INTEGER)) {
396 		register struct tbl *vp = &vtemp;
397 		vp->flag = (ISSET|INTEGER);
398 		vp->type = 0;
399 		vp->areap = ATEMP;
400 		vp->val.i = n;
401 		/* setstr can't fail here */
402 		setstr(vq, str_val(vp), KSH_RETURN_ERROR);
403 	} else
404 		vq->val.i = n;
405 	vq->flag |= ISSET;
406 	if ((vq->flag&SPECIAL))
407 		setspec(vq);
408 }
409 
410 int
411 getint(vp, nump)
412 	struct tbl *vp;
413 	long *nump;
414 {
415 	register char *s;
416 	register int c;
417 	int base, neg;
418 	int have_base = 0;
419 	long num;
420 
421 	if (vp->flag&SPECIAL)
422 		getspec(vp);
423 	/* XXX is it possible for ISSET to be set and val.s to be 0? */
424 	if (!(vp->flag&ISSET) || (!(vp->flag&INTEGER) && vp->val.s == NULL))
425 		return -1;
426 	if (vp->flag&INTEGER) {
427 		*nump = vp->val.i;
428 		return vp->type;
429 	}
430 	s = vp->val.s + vp->type;
431 	if (s == NULL)	/* redundent given initial test */
432 		s = null;
433 	base = 10;
434 	num = 0;
435 	neg = 0;
436 	for (c = *s++; c ; c = *s++) {
437 		if (c == '-') {
438 			neg++;
439 		} else if (c == '#') {
440 			base = (int) num;
441 			if (have_base || base < 2 || base > 36)
442 				return -1;
443 			num = 0;
444 			have_base = 1;
445 		} else if (letnum(c)) {
446 			if (isdigit(c))
447 				c -= '0';
448 			else if (islower(c))
449 				c -= 'a' - 10; /* todo: assumes ascii */
450 			else if (isupper(c))
451 				c -= 'A' - 10; /* todo: assumes ascii */
452 			else
453 				c = -1; /* _: force error */
454 			if (c < 0 || c >= base)
455 				return -1;
456 			num = num * base + c;
457 		} else
458 			return -1;
459 	}
460 	if (neg)
461 		num = -num;
462 	*nump = num;
463 	return base;
464 }
465 
466 /* convert variable vq to integer variable, setting its value from vp
467  * (vq and vp may be the same)
468  */
469 struct tbl *
470 setint_v(vq, vp)
471 	register struct tbl *vq, *vp;
472 {
473 	int base;
474 	long num;
475 
476 	if ((base = getint(vp, &num)) == -1)
477 		return NULL;
478 	if (!(vq->flag & INTEGER) && (vq->flag & ALLOC)) {
479 		vq->flag &= ~ALLOC;
480 		afree(vq->val.s, vq->areap);
481 	}
482 	vq->val.i = num;
483 	if (vq->type == 0) /* default base */
484 		vq->type = base;
485 	vq->flag |= ISSET|INTEGER;
486 	if (vq->flag&SPECIAL)
487 		setspec(vq);
488 	return vq;
489 }
490 
491 static char *
492 formatstr(vp, s)
493 	struct tbl *vp;
494 	const char *s;
495 {
496 	int olen, nlen;
497 	char *p, *q;
498 
499 	olen = strlen(s);
500 
501 	if (vp->flag & (RJUST|LJUST)) {
502 		if (!vp->u2.field)	/* default field width */
503 			vp->u2.field = olen;
504 		nlen = vp->u2.field;
505 	} else
506 		nlen = olen;
507 
508 	p = (char *) alloc(nlen + 1, ATEMP);
509 	if (vp->flag & (RJUST|LJUST)) {
510 		int slen;
511 
512 		if (vp->flag & RJUST) {
513 			const char *q = s + olen;
514 			/* strip trailing spaces (at&t ksh uses q[-1] == ' ') */
515 			while (q > s && isspace(q[-1]))
516 				--q;
517 			slen = q - s;
518 			if (slen > vp->u2.field) {
519 				s += slen - vp->u2.field;
520 				slen = vp->u2.field;
521 			}
522 			shf_snprintf(p, nlen + 1,
523 				((vp->flag & ZEROFIL) && digit(*s)) ?
524 					  "%0*s%.*s" : "%*s%.*s",
525 				vp->u2.field - slen, null, slen, s);
526 		} else {
527 			/* strip leading spaces/zeros */
528 			while (isspace(*s))
529 				s++;
530 			if (vp->flag & ZEROFIL)
531 				while (*s == '0')
532 					s++;
533 			shf_snprintf(p, nlen + 1, "%-*.*s",
534 				vp->u2.field, vp->u2.field, s);
535 		}
536 	} else
537 		memcpy(p, s, olen + 1);
538 
539 	if (vp->flag & UCASEV_AL) {
540 		for (q = p; *q; q++)
541 			if (islower(*q))
542 				*q = toupper(*q);
543 	} else if (vp->flag & LCASEV) {
544 		for (q = p; *q; q++)
545 			if (isupper(*q))
546 				*q = tolower(*q);
547 	}
548 
549 	return p;
550 }
551 
552 /*
553  * make vp->val.s be "name=value" for quick exporting.
554  */
555 static void
556 export(vp, val)
557 	register struct tbl *vp;
558 	const char *val;
559 {
560 	register char *xp;
561 	char *op = (vp->flag&ALLOC) ? vp->val.s : NULL;
562 	int namelen = strlen(vp->name);
563 	int vallen = strlen(val) + 1;
564 
565 	vp->flag |= ALLOC;
566 	xp = (char*)alloc(namelen + 1 + vallen, vp->areap);
567 	memcpy(vp->val.s = xp, vp->name, namelen);
568 	xp += namelen;
569 	*xp++ = '=';
570 	vp->type = xp - vp->val.s; /* offset to value */
571 	memcpy(xp, val, vallen);
572 	if (op != NULL)
573 		afree((void*)op, vp->areap);
574 }
575 
576 /*
577  * lookup variable (according to (set&LOCAL)),
578  * set its attributes (INTEGER, RDONLY, EXPORT, TRACE, LJUST, RJUST, ZEROFIL,
579  * LCASEV, UCASEV_AL), and optionally set its value if an assignment.
580  */
581 struct tbl *
582 typeset(var, set, clr, field, base)
583 	register const char *var;
584 	Tflag clr, set;
585 	int field, base;
586 {
587 	register struct tbl *vp;
588 	struct tbl *vpbase, *t;
589 	char *tvar;
590 	const char *val;
591 
592 	/* check for valid variable name, search for value */
593 	val = skip_varname(var, FALSE);
594 	if (val == var)
595 		return NULL;
596 	if (*val == '[') {
597 		int len;
598 
599 		len = array_ref_len(val);
600 		if (len == 0)
601 			return NULL;
602 		/* IMPORT is only used when the shell starts up and is
603 		 * setting up its environment.  Allow only simple array
604 		 * references at this time since parameter/command substitution
605 		 * is preformed on the [expression], which would be a major
606 		 * security hole.
607 		 */
608 		if (set & IMPORT) {
609 			int i;
610 			for (i = 1; i < len - 1; i++)
611 				if (!digit(val[i]))
612 					return NULL;
613 		}
614 		val += len;
615 	}
616 	if (*val == '=')
617 		tvar = str_nsave(var, val++ - var, ATEMP);
618 	else {
619 		/* Importing from original envirnment: must have an = */
620 		if (set & IMPORT)
621 			return NULL;
622 		tvar = (char *) var;
623 		val = NULL;
624 	}
625 
626 	/* Prevent typeset from creating a local PATH/ENV/SHELL */
627 	if (Flag(FRESTRICTED) && (strcmp(tvar, "PATH") == 0
628 				  || strcmp(tvar, "ENV") == 0
629 				  || strcmp(tvar, "SHELL") == 0))
630 		errorf("%s: restricted", tvar);
631 
632 	vp = (set&LOCAL) ? local(tvar, (set & LOCAL_COPY) ? TRUE : FALSE)
633 		: global(tvar);
634 	set &= ~(LOCAL|LOCAL_COPY);
635 
636 	vpbase = (vp->flag & ARRAY) ? global(arrayname(var)) : vp;
637 
638 	/* only allow export flag to be set.  at&t ksh allows any attribute to
639 	 * be changed, which means it can be truncated or modified
640 	 * (-L/-R/-Z/-i).
641 	 */
642 	if ((vpbase->flag&RDONLY)
643 	    && (val || clr || (set & ~EXPORT)))
644 		/* XXX check calls - is error here ok by POSIX? */
645 		errorf("%s: is read only", tvar);
646 	if (val)
647 		afree(tvar, ATEMP);
648 
649 	/* most calls are with set/clr == 0 */
650 	if (set | clr) {
651 		int ok = 1;
652 		/* XXX if x[0] isn't set, there will be problems: need to have
653 		 * one copy of attributes for arrays...
654 		 */
655 		for (t = vpbase; t; t = t->u.array) {
656 			int fake_assign;
657 			char UNINITIALIZED(*s);
658 			char UNINITIALIZED(*free_me);
659 
660 			fake_assign = (t->flag & ISSET) && (!val || t != vp)
661 				      && ((set & (UCASEV_AL|LCASEV|LJUST|RJUST|ZEROFIL))
662 					  || ((t->flag & INTEGER) && (clr & INTEGER))
663 					  || (!(t->flag & INTEGER) && (set & INTEGER)));
664 			if (fake_assign) {
665 				if (t->flag & INTEGER) {
666 					s = str_val(t);
667 					free_me = (char *) 0;
668 				} else {
669 					s = t->val.s + t->type;
670 					free_me = (t->flag & ALLOC) ? t->val.s
671 								  : (char *) 0;
672 				}
673 				t->flag &= ~ALLOC;
674 			}
675 			if (!(t->flag & INTEGER) && (set & INTEGER)) {
676 				t->type = 0;
677 				t->flag &= ~ALLOC;
678 			}
679 			t->flag = (t->flag | set) & ~clr;
680 			/* Don't change base if assignment is to be done,
681 			 * in case assignment fails.
682 			 */
683 			if ((set & INTEGER) && base > 0 && (!val || t != vp))
684 				t->type = base;
685 			if (set & (LJUST|RJUST|ZEROFIL))
686 				t->u2.field = field;
687 			if (fake_assign) {
688 				if (!setstr(t, s, KSH_RETURN_ERROR)) {
689 					/* Somewhat arbitrary action here:
690 					 * zap contents of varibale, but keep
691 					 * the flag settings.
692 					 */
693 					ok = 0;
694 					if (t->flag & INTEGER)
695 						t->flag &= ~ISSET;
696 					else {
697 						if (t->flag & ALLOC)
698 							afree((void*) t->val.s,
699 							      t->areap);
700 						t->flag &= ~(ISSET|ALLOC);
701 						t->type = 0;
702 					}
703 				}
704 				if (free_me)
705 					afree((void *) free_me, t->areap);
706 			}
707 		}
708 		if (!ok)
709 		    errorf(null);
710 	}
711 
712 	if (val != NULL) {
713 		if (vp->flag&INTEGER) {
714 			/* do not zero base before assignment */
715 			setstr(vp, val, KSH_UNWIND_ERROR);
716 			/* Done after assignment to override default */
717 			if (base > 0)
718 				vp->type = base;
719 		} else
720 			/* setstr can't fail (readonly check already done) */
721 			setstr(vp, val, KSH_RETURN_ERROR);
722 	}
723 
724 	/* only x[0] is ever exported, so use vpbase */
725 	if ((vpbase->flag&EXPORT) && !(vpbase->flag&INTEGER)
726 	    && vpbase->type == 0)
727 		export(vpbase, (vpbase->flag&ISSET) ? vpbase->val.s : null);
728 
729 	return vp;
730 }
731 
732 /* Unset a variable.  array_ref is set if there was an array reference in
733  * the name lookup (eg, x[2]).
734  */
735 void
736 unset(vp, array_ref)
737 	register struct tbl *vp;
738 	int array_ref;
739 {
740 	if (vp->flag & ALLOC)
741 		afree((void*)vp->val.s, vp->areap);
742 	if ((vp->flag & ARRAY) && !array_ref) {
743 		struct tbl *a, *tmp;
744 
745 		/* Free up entire array */
746 		for (a = vp->u.array; a; ) {
747 			tmp = a;
748 			a = a->u.array;
749 			if (tmp->flag & ALLOC)
750 				afree((void *) tmp->val.s, tmp->areap);
751 			afree(tmp, tmp->areap);
752 		}
753 		vp->u.array = (struct tbl *) 0;
754 	}
755 	/* If foo[0] is being unset, the remainder of the array is kept... */
756 	vp->flag &= SPECIAL | (array_ref ? ARRAY|DEFINED : 0);
757 	if (vp->flag & SPECIAL)
758 		unsetspec(vp);	/* responsible for `unspecial'ing var */
759 }
760 
761 /* return a pointer to the first char past a legal variable name (returns the
762  * argument if there is no legal name, returns * a pointer to the terminating
763  * null if whole string is legal).
764  */
765 char *
766 skip_varname(s, aok)
767 	const char *s;
768 	int aok;
769 {
770 	int alen;
771 
772 	if (s && letter(*s)) {
773 		while (*++s && letnum(*s))
774 			;
775 		if (aok && *s == '[' && (alen = array_ref_len(s)))
776 			s += alen;
777 	}
778 	return (char *) s;
779 }
780 
781 /* Return a pointer to the first character past any legal variable name.  */
782 char *
783 skip_wdvarname(s, aok)
784 	const char *s;
785 	int aok;	/* skip array de-reference? */
786 {
787 	if (s[0] == CHAR && letter(s[1])) {
788 		do
789 			s += 2;
790 		while (s[0] == CHAR && letnum(s[1]));
791 		if (aok && s[0] == CHAR && s[1] == '[') {
792 			/* skip possible array de-reference */
793 			const char *p = s;
794 			char c;
795 			int depth = 0;
796 
797 			while (1) {
798 				if (p[0] != CHAR)
799 					break;
800 				c = p[1];
801 				p += 2;
802 				if (c == '[')
803 					depth++;
804 				else if (c == ']' && --depth == 0) {
805 					s = p;
806 					break;
807 				}
808 			}
809 		}
810 	}
811 	return (char *) s;
812 }
813 
814 /* Check if coded string s is a variable name */
815 int
816 is_wdvarname(s, aok)
817 	const char *s;
818 	int aok;
819 {
820 	char *p = skip_wdvarname(s, aok);
821 
822 	return p != s && p[0] == EOS;
823 }
824 
825 /* Check if coded string s is a variable assignment */
826 int
827 is_wdvarassign(s)
828 	const char *s;
829 {
830 	char *p = skip_wdvarname(s, TRUE);
831 
832 	return p != s && p[0] == CHAR && p[1] == '=';
833 }
834 
835 /*
836  * Make the exported environment from the exported names in the dictionary.
837  */
838 char **
839 makenv()
840 {
841 	struct block *l = e->loc;
842 	XPtrV env;
843 	register struct tbl *vp, **vpp;
844 	register int i;
845 
846 	XPinit(env, 64);
847 	for (l = e->loc; l != NULL; l = l->next)
848 		for (vpp = l->vars.tbls, i = l->vars.size; --i >= 0; )
849 			if ((vp = *vpp++) != NULL
850 			    && (vp->flag&(ISSET|EXPORT)) == (ISSET|EXPORT)) {
851 				register struct block *l2;
852 				register struct tbl *vp2;
853 				unsigned h = hash(vp->name);
854 
855 				/* unexport any redefined instances */
856 				for (l2 = l->next; l2 != NULL; l2 = l2->next) {
857 					vp2 = tsearch(&l2->vars, vp->name, h);
858 					if (vp2 != NULL)
859 						vp2->flag &= ~EXPORT;
860 				}
861 				if ((vp->flag&INTEGER)) {
862 					/* integer to string */
863 					char *val;
864 					val = str_val(vp);
865 					vp->flag &= ~(INTEGER|RDONLY);
866 					/* setstr can't fail here */
867 					setstr(vp, val, KSH_RETURN_ERROR);
868 				}
869 				XPput(env, vp->val.s);
870 			}
871 	XPput(env, NULL);
872 	return (char **) XPclose(env);
873 }
874 
875 /*
876  * Called after a fork in parent to bump the random number generator.
877  * Done to ensure children will not get the same random number sequence
878  * if the parent doesn't use $RANDOM.
879  */
880 void
881 change_random()
882 {
883     rand();
884 }
885 
886 /*
887  * handle special variables with side effects - PATH, SECONDS.
888  */
889 
890 /* Test if name is a special parameter */
891 static int
892 special(name)
893 	register const char * name;
894 {
895 	register struct tbl *tp;
896 
897 	tp = tsearch(&specials, name, hash(name));
898 	return tp && (tp->flag & ISSET) ? tp->type : V_NONE;
899 }
900 
901 /* Make a variable non-special */
902 static void
903 unspecial(name)
904 	register const char * name;
905 {
906 	register struct tbl *tp;
907 
908 	tp = tsearch(&specials, name, hash(name));
909 	if (tp)
910 		tdelete(tp);
911 }
912 
913 #ifdef KSH
914 static	time_t	seconds;		/* time SECONDS last set */
915 #endif /* KSH */
916 static	int	user_lineno;		/* what user set $LINENO to */
917 
918 static void
919 getspec(vp)
920 	register struct tbl *vp;
921 {
922 	switch (special(vp->name)) {
923 #ifdef KSH
924 	  case V_SECONDS:
925 		vp->flag &= ~SPECIAL;
926 		/* On start up the value of SECONDS is used before seconds
927 		 * has been set - don't do anything in this case
928 		 * (see initcoms[] in main.c).
929 		 */
930 		if (vp->flag & ISSET)
931 			setint(vp, (long) (time((time_t *)0) - seconds));
932 		vp->flag |= SPECIAL;
933 		break;
934 	  case V_RANDOM:
935 		vp->flag &= ~SPECIAL;
936 		setint(vp, (long) (rand() & 0x7fff));
937 		vp->flag |= SPECIAL;
938 		break;
939 #endif /* KSH */
940 #ifdef HISTORY
941 	  case V_HISTSIZE:
942 		vp->flag &= ~SPECIAL;
943 		setint(vp, (long) histsize);
944 		vp->flag |= SPECIAL;
945 		break;
946 #endif /* HISTORY */
947 	  case V_OPTIND:
948 		vp->flag &= ~SPECIAL;
949 		setint(vp, (long) user_opt.uoptind);
950 		vp->flag |= SPECIAL;
951 		break;
952 	  case V_LINENO:
953 		vp->flag &= ~SPECIAL;
954 		setint(vp, (long) current_lineno + user_lineno);
955 		vp->flag |= SPECIAL;
956 		break;
957 	}
958 }
959 
960 static void
961 setspec(vp)
962 	register struct tbl *vp;
963 {
964 	char *s;
965 
966 	switch (special(vp->name)) {
967 	  case V_PATH:
968 		if (path)
969 			afree(path, APERM);
970 		path = str_save(str_val(vp), APERM);
971 		flushcom(1);	/* clear tracked aliases */
972 		break;
973 	  case V_IFS:
974 		setctypes(s = str_val(vp), C_IFS);
975 		ifs0 = *s;
976 		break;
977 	  case V_OPTIND:
978 		vp->flag &= ~SPECIAL;
979 		getopts_reset((int) intval(vp));
980 		vp->flag |= SPECIAL;
981 		break;
982 	  case V_POSIXLY_CORRECT:
983 		change_flag(FPOSIX, OF_SPECIAL, 1);
984 		break;
985 	  case V_TMPDIR:
986 		if (tmpdir) {
987 			afree(tmpdir, APERM);
988 			tmpdir = (char *) 0;
989 		}
990 		/* Use tmpdir iff it is an absolute path, is writable and
991 		 * searchable and is a directory...
992 		 */
993 		{
994 			struct stat statb;
995 			s = str_val(vp);
996 			if (ISABSPATH(s) && eaccess(s, W_OK|X_OK) == 0
997 			    && stat(s, &statb) == 0 && S_ISDIR(statb.st_mode))
998 				tmpdir = str_save(s, APERM);
999 		}
1000 		break;
1001 #ifdef HISTORY
1002 	  case V_HISTSIZE:
1003 		vp->flag &= ~SPECIAL;
1004 		sethistsize((int) intval(vp));
1005 		vp->flag |= SPECIAL;
1006 		break;
1007 	  case V_HISTFILE:
1008 		sethistfile(str_val(vp));
1009 		break;
1010 #endif /* HISTORY */
1011 #ifdef EDIT
1012 	  case V_VISUAL:
1013 		set_editmode(str_val(vp));
1014 		break;
1015 	  case V_EDITOR:
1016 		if (!(global("VISUAL")->flag & ISSET))
1017 			set_editmode(str_val(vp));
1018 		break;
1019 	  case V_COLUMNS:
1020 		if ((x_cols = intval(vp)) <= MIN_COLS)
1021 			x_cols = MIN_COLS;
1022 		break;
1023 #endif /* EDIT */
1024 #ifdef KSH
1025 	  case V_MAIL:
1026 		mbset(str_val(vp));
1027 		break;
1028 	  case V_MAILPATH:
1029 		mpset(str_val(vp));
1030 		break;
1031 	  case V_MAILCHECK:
1032 		vp->flag &= ~SPECIAL;
1033 		mcset(intval(vp));
1034 		vp->flag |= SPECIAL;
1035 		break;
1036 	  case V_RANDOM:
1037 		vp->flag &= ~SPECIAL;
1038 		srand((unsigned int)intval(vp));
1039 		vp->flag |= SPECIAL;
1040 		break;
1041 	  case V_SECONDS:
1042 		vp->flag &= ~SPECIAL;
1043 		seconds = time((time_t*) 0) - intval(vp);
1044 		vp->flag |= SPECIAL;
1045 		break;
1046 	  case V_TMOUT:
1047 		/* at&t ksh seems to do this (only listen if integer) */
1048 		if (vp->flag & INTEGER)
1049 			ksh_tmout = vp->val.i >= 0 ? vp->val.i : 0;
1050 		break;
1051 #endif /* KSH */
1052 	  case V_LINENO:
1053 		vp->flag &= ~SPECIAL;
1054 		/* The -1 is because line numbering starts at 1. */
1055 		user_lineno = (unsigned int) intval(vp) - current_lineno - 1;
1056 		vp->flag |= SPECIAL;
1057 		break;
1058 	}
1059 }
1060 
1061 static void
1062 unsetspec(vp)
1063 	register struct tbl *vp;
1064 {
1065 	switch (special(vp->name)) {
1066 	  case V_PATH:
1067 		if (path)
1068 			afree(path, APERM);
1069 		path = str_save(def_path, APERM);
1070 		flushcom(1);	/* clear tracked aliases */
1071 		break;
1072 	  case V_IFS:
1073 		setctypes(" \t\n", C_IFS);
1074 		ifs0 = ' ';
1075 		break;
1076 	  case V_TMPDIR:
1077 		/* should not become unspecial */
1078 		if (tmpdir) {
1079 			afree(tmpdir, APERM);
1080 			tmpdir = (char *) 0;
1081 		}
1082 		break;
1083 #ifdef KSH
1084 	  case V_MAIL:
1085 		mbset((char *) 0);
1086 		break;
1087 	  case V_MAILPATH:
1088 		mpset((char *) 0);
1089 		break;
1090 #endif /* KSH */
1091 
1092 	  case V_LINENO:
1093 #ifdef KSH
1094 	  case V_MAILCHECK:	/* at&t ksh leaves previous value in place */
1095 	  case V_RANDOM:
1096 	  case V_SECONDS:
1097 	  case V_TMOUT:		/* at&t ksh leaves previous value in place */
1098 #endif /* KSH */
1099 		unspecial(vp->name);
1100 		break;
1101 
1102 	  /* at&t ksh man page says OPTIND, OPTARG and _ lose special meaning,
1103 	   * but OPTARG does not (still set by getopts) and _ is also still
1104 	   * set in various places.
1105 	   * Don't know what at&t does for:
1106 	   *		MAIL, MAILPATH, HISTSIZE, HISTFILE,
1107 	   * Unsetting these in at&t ksh does not loose the `specialness':
1108 	   *    no effect: IFS, COLUMNS, PATH, TMPDIR,
1109 	   *		VISUAL, EDITOR,
1110 	   * pdkshisms: no effect:
1111 	   *		POSIXLY_CORRECT (use set +o posix instead)
1112 	   */
1113 	}
1114 }
1115 
1116 /*
1117  * Search for (and possibly create) a table entry starting with
1118  * vp, indexed by val.
1119  */
1120 static struct tbl *
1121 arraysearch(vp, val)
1122 	struct tbl *vp;
1123 	int val;
1124 {
1125 	struct tbl *prev, *curr, *new;
1126 
1127 	vp->flag |= ARRAY|DEFINED;
1128 
1129 	/* The table entry is always [0] */
1130 	if (val == 0) {
1131 		vp->index = 0;
1132 		return vp;
1133 	}
1134 	prev = vp;
1135 	curr = vp->u.array;
1136 	while (curr && curr->index < val) {
1137 		prev = curr;
1138 		curr = curr->u.array;
1139 	}
1140 	if (curr && curr->index == val) {
1141 		if (curr->flag&ISSET)
1142 			return curr;
1143 		else
1144 			new = curr;
1145 	} else
1146 		new = (struct tbl *)alloc(sizeof(struct tbl)+strlen(vp->name)+1, vp->areap);
1147 	strcpy(new->name, vp->name);
1148 	new->flag = vp->flag & ~(ALLOC|DEFINED|ISSET|SPECIAL);
1149 	new->type = vp->type;
1150 	new->areap = vp->areap;
1151 	new->u2.field = vp->u2.field;
1152 	new->index = val;
1153 	if (curr != new) {		/* not reusing old array entry */
1154 		prev->u.array = new;
1155 		new->u.array = curr;
1156 	}
1157 	return new;
1158 }
1159 
1160 /* Return the length of an array reference (eg, [1+2]) - cp is assumed
1161  * to point to the open bracket.  Returns 0 if there is no matching closing
1162  * bracket.
1163  */
1164 int
1165 array_ref_len(cp)
1166 	const char *cp;
1167 {
1168 	const char *s = cp;
1169 	int c;
1170 	int depth = 0;
1171 
1172 	while ((c = *s++) && (c != ']' || --depth))
1173 		if (c == '[')
1174 			depth++;
1175 	if (!c)
1176 		return 0;
1177 	return s - cp;
1178 }
1179 
1180 /*
1181  * Make a copy of the base of an array name
1182  */
1183 char *
1184 arrayname(str)
1185 	const char *str;
1186 {
1187 	const char *p;
1188 
1189 	if ((p = strchr(str, '[')) == 0)
1190 		/* Shouldn't happen, but why worry? */
1191 		return (char *) str;
1192 
1193 	return str_nsave(str, p - str, ATEMP);
1194 }
1195 
1196 /* Set (or overwrite, if !reset) the array variable var to the values in vals.
1197  */
1198 void
1199 set_array(var, reset, vals)
1200 	const char *var;
1201 	int reset;
1202 	char **vals;
1203 {
1204 	struct tbl *vp, *vq;
1205 	int i;
1206 
1207 	/* to get local array, use "typeset foo; set -A foo" */
1208 	vp = global(var);
1209 
1210 	/* Note: at&t ksh allows set -A but not set +A of a read-only var */
1211 	if ((vp->flag&RDONLY))
1212 		errorf("%s: is read only", var);
1213 	/* This code is quite non-optimal */
1214 	if (reset > 0)
1215 		/* trash existing values and attributes */
1216 		unset(vp, 0);
1217 	/* todo: would be nice for assignment to completely succeed or
1218 	 * completely fail.  Only really effects integer arrays:
1219 	 * evaluation of some of vals[] may fail...
1220 	 */
1221 	for (i = 0; vals[i]; i++) {
1222 		vq = arraysearch(vp, i);
1223 		/* would be nice to deal with errors here... (see above) */
1224 		setstr(vq, vals[i], KSH_RETURN_ERROR);
1225 	}
1226 }
1227