1/*	$OpenBSD: var.c,v 1.73 2023/07/23 23:42:03 kn Exp $	*/
2
3#include <sys/stat.h>
4#include <sys/time.h>
5
6#include <ctype.h>
7#include <errno.h>
8#include <inttypes.h>
9#include <limits.h>
10#include <stdlib.h>
11#include <string.h>
12#include <time.h>
13#include <unistd.h>
14#ifndef SMALL
15# include <term.h>
16# include <curses.h>
17#endif
18
19#include "sh.h"
20
21/*
22 * Variables
23 *
24 * WARNING: unreadable code, needs a rewrite
25 *
26 * if (flag&INTEGER), val.i contains integer value, and type contains base.
27 * otherwise, (val.s + type) contains string value.
28 * if (flag&EXPORT), val.s contains "name=value" for E-Z exporting.
29 */
30static	struct tbl vtemp;
31static	struct table specials;
32static char	*formatstr(struct tbl *, const char *);
33static void	export(struct tbl *, const char *);
34static int	special(const char *);
35static void	unspecial(const char *);
36static void	getspec(struct tbl *);
37static void	setspec(struct tbl *);
38static void	unsetspec(struct tbl *);
39static struct tbl *arraysearch(struct tbl *, int);
40
41/*
42 * create a new block for function calls and simple commands
43 * assume caller has allocated and set up genv->loc
44 */
45void
46newblock(void)
47{
48	struct block *l;
49	static char *const empty[] = {null};
50
51	l = alloc(sizeof(struct block), ATEMP);
52	l->flags = 0;
53	ainit(&l->area); /* todo: could use genv->area (l->area => l->areap) */
54	if (!genv->loc) {
55		l->argc = 0;
56		l->argv = (char **) empty;
57	} else {
58		l->argc = genv->loc->argc;
59		l->argv = genv->loc->argv;
60	}
61	l->exit = l->error = NULL;
62	ktinit(&l->vars, &l->area, 0);
63	ktinit(&l->funs, &l->area, 0);
64	l->next = genv->loc;
65	genv->loc = l;
66}
67
68/*
69 * pop a block handling special variables
70 */
71void
72popblock(void)
73{
74	struct block *l = genv->loc;
75	struct tbl *vp, **vpp = l->vars.tbls, *vq;
76	int i;
77
78	genv->loc = l->next;	/* pop block */
79	for (i = l->vars.size; --i >= 0; )
80		if ((vp = *vpp++) != NULL && (vp->flag&SPECIAL)) {
81			if ((vq = global(vp->name))->flag & ISSET)
82				setspec(vq);
83			else
84				unsetspec(vq);
85		}
86	if (l->flags & BF_DOGETOPTS)
87		user_opt = l->getopts_state;
88	afreeall(&l->area);
89	afree(l, ATEMP);
90}
91
92/* called by main() to initialize variable data structures */
93void
94initvar(void)
95{
96	static const struct {
97		const char *name;
98		int v;
99	} names[] = {
100		{ "COLUMNS",		V_COLUMNS },
101		{ "IFS",		V_IFS },
102		{ "OPTIND",		V_OPTIND },
103		{ "PATH",		V_PATH },
104		{ "POSIXLY_CORRECT",	V_POSIXLY_CORRECT },
105		{ "TMPDIR",		V_TMPDIR },
106		{ "HISTCONTROL",	V_HISTCONTROL },
107		{ "HISTFILE",		V_HISTFILE },
108		{ "HISTSIZE",		V_HISTSIZE },
109		{ "EDITOR",		V_EDITOR },
110		{ "VISUAL",		V_VISUAL },
111#ifndef SMALL
112		{ "MAIL",		V_MAIL },
113		{ "MAILCHECK",		V_MAILCHECK },
114		{ "MAILPATH",		V_MAILPATH },
115#endif /* SMALL */
116		{ "RANDOM",		V_RANDOM },
117		{ "SECONDS",		V_SECONDS },
118		{ "TMOUT",		V_TMOUT },
119		{ "LINENO",		V_LINENO },
120		{ "TERM",		V_TERM },
121		{ NULL,	0 }
122	};
123	int i;
124	struct tbl *tp;
125
126	ktinit(&specials, APERM, 32); /* must be 2^n (currently 19 specials) */
127	for (i = 0; names[i].name; i++) {
128		tp = ktenter(&specials, names[i].name, hash(names[i].name));
129		tp->flag = DEFINED|ISSET;
130		tp->type = names[i].v;
131	}
132}
133
134/* Used to calculate an array index for global()/local().  Sets *arrayp to
135 * non-zero if this is an array, sets *valp to the array index, returns
136 * the basename of the array.
137 */
138static const char *
139array_index_calc(const char *n, bool *arrayp, int *valp)
140{
141	const char *p;
142	int len;
143
144	*arrayp = false;
145	p = skip_varname(n, false);
146	if (p != n && *p == '[' && (len = array_ref_len(p))) {
147		char *sub, *tmp;
148		int64_t rval;
149
150		/* Calculate the value of the subscript */
151		*arrayp = true;
152		tmp = str_nsave(p+1, len-2, ATEMP);
153		sub = substitute(tmp, 0);
154		afree(tmp, ATEMP);
155		n = str_nsave(n, p - n, ATEMP);
156		evaluate(sub, &rval, KSH_UNWIND_ERROR, true);
157		if (rval < 0 || rval > INT_MAX)
158			errorf("%s: subscript %" PRIi64 " out of range",
159			    n, rval);
160		*valp = rval;
161		afree(sub, ATEMP);
162	}
163	return n;
164}
165
166/*
167 * Search for variable, if not found create globally.
168 */
169struct tbl *
170global(const char *n)
171{
172	struct block *l = genv->loc;
173	struct tbl *vp;
174	long	 num;
175	int c;
176	unsigned int h;
177	bool	 array;
178	int	 val;
179
180	/* Check to see if this is an array */
181	n = array_index_calc(n, &array, &val);
182	h = hash(n);
183	c = (unsigned char)n[0];
184	if (!letter(c)) {
185		if (array)
186			errorf("bad substitution");
187		vp = &vtemp;
188		vp->flag = DEFINED;
189		vp->type = 0;
190		vp->areap = ATEMP;
191		*vp->name = c;
192		if (digit(c)) {
193			errno = 0;
194			num = strtol(n, NULL, 10);
195			if (errno == 0 && num <= l->argc)
196				/* setstr can't fail here */
197				setstr(vp, l->argv[num], KSH_RETURN_ERROR);
198			vp->flag |= RDONLY;
199			return vp;
200		}
201		vp->flag |= RDONLY;
202		if (n[1] != '\0')
203			return vp;
204		vp->flag |= ISSET|INTEGER;
205		switch (c) {
206		case '$':
207			vp->val.i = kshpid;
208			break;
209		case '!':
210			/* If no job, expand to nothing */
211			if ((vp->val.i = j_async()) == 0)
212				vp->flag &= ~(ISSET|INTEGER);
213			break;
214		case '?':
215			vp->val.i = exstat;
216			break;
217		case '#':
218			vp->val.i = l->argc;
219			break;
220		case '-':
221			vp->flag &= ~INTEGER;
222			vp->val.s = getoptions();
223			break;
224		default:
225			vp->flag &= ~(ISSET|INTEGER);
226		}
227		return vp;
228	}
229	for (l = genv->loc; ; l = l->next) {
230		vp = ktsearch(&l->vars, n, h);
231		if (vp != NULL) {
232			if (array)
233				return arraysearch(vp, val);
234			else
235				return vp;
236		}
237		if (l->next == NULL)
238			break;
239	}
240	vp = ktenter(&l->vars, n, h);
241	if (array)
242		vp = arraysearch(vp, val);
243	vp->flag |= DEFINED;
244	if (special(n))
245		vp->flag |= SPECIAL;
246	return vp;
247}
248
249/*
250 * Search for local variable, if not found create locally.
251 */
252struct tbl *
253local(const char *n, bool copy)
254{
255	struct block *l = genv->loc;
256	struct tbl *vp;
257	unsigned int h;
258	bool	 array;
259	int	 val;
260
261	/* Check to see if this is an array */
262	n = array_index_calc(n, &array, &val);
263	h = hash(n);
264	if (!letter(*n)) {
265		vp = &vtemp;
266		vp->flag = DEFINED|RDONLY;
267		vp->type = 0;
268		vp->areap = ATEMP;
269		return vp;
270	}
271	vp = ktenter(&l->vars, n, h);
272	if (copy && !(vp->flag & DEFINED)) {
273		struct block *ll = l;
274		struct tbl *vq = NULL;
275
276		while ((ll = ll->next) && !(vq = ktsearch(&ll->vars, n, h)))
277			;
278		if (vq) {
279			vp->flag |= vq->flag &
280			    (EXPORT | INTEGER | RDONLY | LJUST | RJUST |
281			    ZEROFIL | LCASEV | UCASEV_AL | INT_U | INT_L);
282			if (vq->flag & INTEGER)
283				vp->type = vq->type;
284			vp->u2.field = vq->u2.field;
285		}
286	}
287	if (array)
288		vp = arraysearch(vp, val);
289	vp->flag |= DEFINED;
290	if (special(n))
291		vp->flag |= SPECIAL;
292	return vp;
293}
294
295/* get variable string value */
296char *
297str_val(struct tbl *vp)
298{
299	char *s;
300
301	if ((vp->flag&SPECIAL))
302		getspec(vp);
303	if (!(vp->flag&ISSET))
304		s = null;		/* special to dollar() */
305	else if (!(vp->flag&INTEGER))	/* string source */
306		s = vp->val.s + vp->type;
307	else {				/* integer source */
308		/* worst case number length is when base=2, so use
309		 * minus base # number BITS(int64_t) NUL */
310		char strbuf[1 + 2 + 1 + BITS(int64_t) + 1];
311		const char *digits = (vp->flag & UCASEV_AL) ?
312		    "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" :
313		    "0123456789abcdefghijklmnopqrstuvwxyz";
314		uint64_t n;
315		unsigned int base;
316
317		s = strbuf + sizeof(strbuf);
318		if (vp->flag & INT_U)
319			n = (uint64_t) vp->val.i;
320		else
321			n = (vp->val.i < 0) ? -vp->val.i : vp->val.i;
322		base = (vp->type == 0) ? 10 : vp->type;
323		if (base < 2 || base > strlen(digits))
324			base = 10;
325
326		*--s = '\0';
327		do {
328			*--s = digits[n % base];
329			n /= base;
330		} while (n != 0);
331		if (base != 10) {
332			*--s = '#';
333			*--s = digits[base % 10];
334			if (base >= 10)
335				*--s = digits[base / 10];
336		}
337		if (!(vp->flag & INT_U) && vp->val.i < 0)
338			*--s = '-';
339		if (vp->flag & (RJUST|LJUST)) /* case already dealt with */
340			s = formatstr(vp, s);
341		else
342			s = str_save(s, ATEMP);
343	}
344	return s;
345}
346
347/* get variable integer value, with error checking */
348int64_t
349intval(struct tbl *vp)
350{
351	int64_t num;
352	int base;
353
354	base = getint(vp, &num, false);
355	if (base == -1)
356		/* XXX check calls - is error here ok by POSIX? */
357		errorf("%s: bad number", str_val(vp));
358	return num;
359}
360
361/* set variable to string value */
362int
363setstr(struct tbl *vq, const char *s, int error_ok)
364{
365	const char *fs = NULL;
366	int no_ro_check = error_ok & KSH_IGNORE_RDONLY;
367	error_ok &= ~KSH_IGNORE_RDONLY;
368	if ((vq->flag & RDONLY) && !no_ro_check) {
369		warningf(true, "%s: is read only", vq->name);
370		if (!error_ok)
371			errorf(NULL);
372		return 0;
373	}
374	if (!(vq->flag&INTEGER)) { /* string dest */
375		if ((vq->flag&ALLOC)) {
376			/* debugging */
377			if (s >= vq->val.s &&
378			    s <= vq->val.s + strlen(vq->val.s))
379				internal_errorf("%s: %s=%s: assigning to self",
380				    __func__, vq->name, s);
381			afree(vq->val.s, vq->areap);
382		}
383		vq->flag &= ~(ISSET|ALLOC);
384		vq->type = 0;
385		if (s && (vq->flag & (UCASEV_AL|LCASEV|LJUST|RJUST)))
386			fs = s = formatstr(vq, s);
387		if ((vq->flag&EXPORT))
388			export(vq, s);
389		else {
390			vq->val.s = str_save(s, vq->areap);
391			vq->flag |= ALLOC;
392		}
393	} else {		/* integer dest */
394		if (!v_evaluate(vq, s, error_ok, true))
395			return 0;
396	}
397	vq->flag |= ISSET;
398	if ((vq->flag&SPECIAL))
399		setspec(vq);
400	afree((void *)fs, ATEMP);
401	return 1;
402}
403
404/* set variable to integer */
405void
406setint(struct tbl *vq, int64_t n)
407{
408	if (!(vq->flag&INTEGER)) {
409		struct tbl *vp = &vtemp;
410		vp->flag = (ISSET|INTEGER);
411		vp->type = 0;
412		vp->areap = ATEMP;
413		vp->val.i = n;
414		/* setstr can't fail here */
415		setstr(vq, str_val(vp), KSH_RETURN_ERROR);
416	} else
417		vq->val.i = n;
418	vq->flag |= ISSET;
419	if ((vq->flag&SPECIAL))
420		setspec(vq);
421}
422
423int
424getint(struct tbl *vp, int64_t *nump, bool arith)
425{
426	char *s;
427	int c;
428	int base, neg;
429	int have_base = 0;
430	int64_t num;
431
432	if (vp->flag&SPECIAL)
433		getspec(vp);
434	/* XXX is it possible for ISSET to be set and val.s to be 0? */
435	if (!(vp->flag&ISSET) || (!(vp->flag&INTEGER) && vp->val.s == NULL))
436		return -1;
437	if (vp->flag&INTEGER) {
438		*nump = vp->val.i;
439		return vp->type;
440	}
441	s = vp->val.s + vp->type;
442	if (s == NULL)	/* redundant given initial test */
443		s = null;
444	base = 10;
445	num = 0;
446	neg = 0;
447	if (arith && *s == '0' && *(s+1)) {
448		s++;
449		if (*s == 'x' || *s == 'X') {
450			s++;
451			base = 16;
452		} else if (vp->flag & ZEROFIL) {
453			while (*s == '0')
454				s++;
455		} else
456			base = 8;
457		have_base++;
458	}
459	for (c = (unsigned char)*s++; c ; c = (unsigned char)*s++) {
460		if (c == '-') {
461			neg++;
462		} else if (c == '#') {
463			base = (int) num;
464			if (have_base || base < 2 || base > 36)
465				return -1;
466			num = 0;
467			have_base = 1;
468		} else if (letnum(c)) {
469			if (isdigit(c))
470				c -= '0';
471			else if (islower(c))
472				c -= 'a' - 10; /* todo: assumes ascii */
473			else if (isupper(c))
474				c -= 'A' - 10; /* todo: assumes ascii */
475			else
476				c = -1; /* _: force error */
477			if (c < 0 || c >= base)
478				return -1;
479			num = num * base + c;
480		} else
481			return -1;
482	}
483	if (neg)
484		num = -num;
485	*nump = num;
486	return base;
487}
488
489/* convert variable vq to integer variable, setting its value from vp
490 * (vq and vp may be the same)
491 */
492struct tbl *
493setint_v(struct tbl *vq, struct tbl *vp, bool arith)
494{
495	int base;
496	int64_t num;
497
498	if ((base = getint(vp, &num, arith)) == -1)
499		return NULL;
500	if (!(vq->flag & INTEGER) && (vq->flag & ALLOC)) {
501		vq->flag &= ~ALLOC;
502		afree(vq->val.s, vq->areap);
503	}
504	vq->val.i = num;
505	if (vq->type == 0) /* default base */
506		vq->type = base;
507	vq->flag |= ISSET|INTEGER;
508	if (vq->flag&SPECIAL)
509		setspec(vq);
510	return vq;
511}
512
513static char *
514formatstr(struct tbl *vp, const char *s)
515{
516	int olen, nlen;
517	char *p, *q;
518
519	olen = strlen(s);
520
521	if (vp->flag & (RJUST|LJUST)) {
522		if (!vp->u2.field)	/* default field width */
523			vp->u2.field = olen;
524		nlen = vp->u2.field;
525	} else
526		nlen = olen;
527
528	p = alloc(nlen + 1, ATEMP);
529	if (vp->flag & (RJUST|LJUST)) {
530		int slen;
531
532		if (vp->flag & RJUST) {
533			const char *r = s + olen;
534			/* strip trailing spaces (at&t ksh uses r[-1] == ' ') */
535			while (r > s && isspace((unsigned char)r[-1]))
536				--r;
537			slen = r - s;
538			if (slen > vp->u2.field) {
539				s += slen - vp->u2.field;
540				slen = vp->u2.field;
541			}
542			shf_snprintf(p, nlen + 1,
543				((vp->flag & ZEROFIL) && digit(*s)) ?
544					  "%0*s%.*s" : "%*s%.*s",
545				vp->u2.field - slen, null, slen, s);
546		} else {
547			/* strip leading spaces/zeros */
548			while (isspace((unsigned char)*s))
549				s++;
550			if (vp->flag & ZEROFIL)
551				while (*s == '0')
552					s++;
553			shf_snprintf(p, nlen + 1, "%-*.*s",
554				vp->u2.field, vp->u2.field, s);
555		}
556	} else
557		memcpy(p, s, olen + 1);
558
559	if (vp->flag & UCASEV_AL) {
560		for (q = p; *q; q++)
561			if (islower((unsigned char)*q))
562				*q = toupper((unsigned char)*q);
563	} else if (vp->flag & LCASEV) {
564		for (q = p; *q; q++)
565			if (isupper((unsigned char)*q))
566				*q = tolower((unsigned char)*q);
567	}
568
569	return p;
570}
571
572/*
573 * make vp->val.s be "name=value" for quick exporting.
574 */
575static void
576export(struct tbl *vp, const char *val)
577{
578	char *xp;
579	char *op = (vp->flag&ALLOC) ? vp->val.s : NULL;
580	int namelen = strlen(vp->name);
581	int vallen = strlen(val) + 1;
582
583	vp->flag |= ALLOC;
584	xp = alloc(namelen + 1 + vallen, vp->areap);
585	memcpy(vp->val.s = xp, vp->name, namelen);
586	xp += namelen;
587	*xp++ = '=';
588	vp->type = xp - vp->val.s; /* offset to value */
589	memcpy(xp, val, vallen);
590	afree(op, vp->areap);
591}
592
593/*
594 * lookup variable (according to (set&LOCAL)),
595 * set its attributes (INTEGER, RDONLY, EXPORT, TRACE, LJUST, RJUST, ZEROFIL,
596 * LCASEV, UCASEV_AL), and optionally set its value if an assignment.
597 */
598struct tbl *
599typeset(const char *var, int set, int clr, int field, int base)
600{
601	struct tbl *vp;
602	struct tbl *vpbase, *t;
603	char *tvar;
604	const char *val;
605
606	/* check for valid variable name, search for value */
607	val = skip_varname(var, false);
608	if (val == var)
609		return NULL;
610	if (*val == '[') {
611		int len;
612
613		len = array_ref_len(val);
614		if (len == 0)
615			return NULL;
616		/* IMPORT is only used when the shell starts up and is
617		 * setting up its environment.  Allow only simple array
618		 * references at this time since parameter/command substitution
619		 * is preformed on the [expression], which would be a major
620		 * security hole.
621		 */
622		if (set & IMPORT) {
623			int i;
624			for (i = 1; i < len - 1; i++)
625				if (!digit(val[i]))
626					return NULL;
627		}
628		val += len;
629	}
630	if (*val == '=')
631		tvar = str_nsave(var, val++ - var, ATEMP);
632	else {
633		/* Importing from original environment: must have an = */
634		if (set & IMPORT)
635			return NULL;
636		tvar = (char *) var;
637		val = NULL;
638	}
639
640	/* Prevent typeset from creating a local PATH/ENV/SHELL */
641	if (Flag(FRESTRICTED) && (strcmp(tvar, "PATH") == 0 ||
642	    strcmp(tvar, "ENV") == 0 || strcmp(tvar, "SHELL") == 0))
643		errorf("%s: restricted", tvar);
644
645	vp = (set&LOCAL) ? local(tvar, (set & LOCAL_COPY) ? true : false) :
646	    global(tvar);
647	set &= ~(LOCAL|LOCAL_COPY);
648
649	vpbase = (vp->flag & ARRAY) ? global(arrayname(tvar)) : vp;
650
651	/* only allow export flag to be set.  at&t ksh allows any attribute to
652	 * be changed, which means it can be truncated or modified
653	 * (-L/-R/-Z/-i).
654	 */
655	if ((vpbase->flag&RDONLY) &&
656	    (val || clr || (set & ~EXPORT)))
657		/* XXX check calls - is error here ok by POSIX? */
658		errorf("%s: is read only", tvar);
659	if (val)
660		afree(tvar, ATEMP);
661
662	/* most calls are with set/clr == 0 */
663	if (set | clr) {
664		int ok = 1;
665		/* XXX if x[0] isn't set, there will be problems: need to have
666		 * one copy of attributes for arrays...
667		 */
668		for (t = vpbase; t; t = t->u.array) {
669			int fake_assign;
670			int error_ok = KSH_RETURN_ERROR;
671			char *s = NULL;
672			char *free_me = NULL;
673
674			fake_assign = (t->flag & ISSET) && (!val || t != vp) &&
675			    ((set & (UCASEV_AL|LCASEV|LJUST|RJUST|ZEROFIL)) ||
676			    ((t->flag & INTEGER) && (clr & INTEGER)) ||
677			    (!(t->flag & INTEGER) && (set & INTEGER)));
678			if (fake_assign) {
679				if (t->flag & INTEGER) {
680					s = str_val(t);
681					free_me = NULL;
682				} else {
683					s = t->val.s + t->type;
684					free_me = (t->flag & ALLOC) ? t->val.s :
685					    NULL;
686				}
687				t->flag &= ~ALLOC;
688			}
689			if (!(t->flag & INTEGER) && (set & INTEGER)) {
690				t->type = 0;
691				t->flag &= ~ALLOC;
692			}
693			if (!(t->flag & RDONLY) && (set & RDONLY)) {
694				/* allow var to be initialized read-only */
695				error_ok |= KSH_IGNORE_RDONLY;
696			}
697			t->flag = (t->flag | set) & ~clr;
698			/* Don't change base if assignment is to be done,
699			 * in case assignment fails.
700			 */
701			if ((set & INTEGER) && base > 0 && (!val || t != vp))
702				t->type = base;
703			if (set & (LJUST|RJUST|ZEROFIL))
704				t->u2.field = field;
705			if (fake_assign) {
706				if (!setstr(t, s, error_ok)) {
707					/* Somewhat arbitrary action here:
708					 * zap contents of variable, but keep
709					 * the flag settings.
710					 */
711					ok = 0;
712					if (t->flag & INTEGER)
713						t->flag &= ~ISSET;
714					else {
715						if (t->flag & ALLOC)
716							afree(t->val.s, t->areap);
717						t->flag &= ~(ISSET|ALLOC);
718						t->type = 0;
719					}
720				}
721				afree(free_me, t->areap);
722			}
723		}
724		if (!ok)
725		    errorf(NULL);
726	}
727
728	if (val != NULL) {
729		if (vp->flag&INTEGER) {
730			/* do not zero base before assignment */
731			setstr(vp, val, KSH_UNWIND_ERROR | KSH_IGNORE_RDONLY);
732			/* Done after assignment to override default */
733			if (base > 0)
734				vp->type = base;
735		} else
736			/* setstr can't fail (readonly check already done) */
737			setstr(vp, val, KSH_RETURN_ERROR | KSH_IGNORE_RDONLY);
738	}
739
740	/* only x[0] is ever exported, so use vpbase */
741	if ((vpbase->flag&EXPORT) && !(vpbase->flag&INTEGER) &&
742	    vpbase->type == 0)
743		export(vpbase, (vpbase->flag&ISSET) ? vpbase->val.s : null);
744
745	return vp;
746}
747
748/* Unset a variable.  array_ref is set if there was an array reference in
749 * the name lookup (eg, x[2]).
750 */
751void
752unset(struct tbl *vp, int array_ref)
753{
754	if (vp->flag & ALLOC)
755		afree(vp->val.s, vp->areap);
756	if ((vp->flag & ARRAY) && !array_ref) {
757		struct tbl *a, *tmp;
758
759		/* Free up entire array */
760		for (a = vp->u.array; a; ) {
761			tmp = a;
762			a = a->u.array;
763			if (tmp->flag & ALLOC)
764				afree(tmp->val.s, tmp->areap);
765			afree(tmp, tmp->areap);
766		}
767		vp->u.array = NULL;
768	}
769	/* If foo[0] is being unset, the remainder of the array is kept... */
770	vp->flag &= SPECIAL | (array_ref ? ARRAY|DEFINED : 0);
771	if (vp->flag & SPECIAL)
772		unsetspec(vp);	/* responsible for `unspecial'ing var */
773}
774
775/* return a pointer to the first char past a legal variable name (returns the
776 * argument if there is no legal name, returns * a pointer to the terminating
777 * null if whole string is legal).
778 */
779char *
780skip_varname(const char *s, int aok)
781{
782	int alen;
783
784	if (s && letter(*s)) {
785		while (*++s && letnum(*s))
786			;
787		if (aok && *s == '[' && (alen = array_ref_len(s)))
788			s += alen;
789	}
790	return (char *) s;
791}
792
793/* Return a pointer to the first character past any legal variable name.  */
794char *
795skip_wdvarname(const char *s,
796    int aok)				/* skip array de-reference? */
797{
798	if (s[0] == CHAR && letter(s[1])) {
799		do {
800			s += 2;
801		} while (s[0] == CHAR && letnum(s[1]));
802		if (aok && s[0] == CHAR && s[1] == '[') {
803			/* skip possible array de-reference */
804			const char *p = s;
805			char c;
806			int depth = 0;
807
808			while (1) {
809				if (p[0] != CHAR)
810					break;
811				c = p[1];
812				p += 2;
813				if (c == '[')
814					depth++;
815				else if (c == ']' && --depth == 0) {
816					s = p;
817					break;
818				}
819			}
820		}
821	}
822	return (char *) s;
823}
824
825/* Check if coded string s is a variable name */
826int
827is_wdvarname(const char *s, int aok)
828{
829	char *p = skip_wdvarname(s, aok);
830
831	return p != s && p[0] == EOS;
832}
833
834/* Check if coded string s is a variable assignment */
835int
836is_wdvarassign(const char *s)
837{
838	char *p = skip_wdvarname(s, true);
839
840	return p != s && p[0] == CHAR && p[1] == '=';
841}
842
843/*
844 * Make the exported environment from the exported names in the dictionary.
845 */
846char **
847makenv(void)
848{
849	struct block *l;
850	XPtrV env;
851	struct tbl *vp, **vpp;
852	int i;
853
854	XPinit(env, 64);
855	for (l = genv->loc; l != NULL; l = l->next)
856		for (vpp = l->vars.tbls, i = l->vars.size; --i >= 0; )
857			if ((vp = *vpp++) != NULL &&
858			    (vp->flag&(ISSET|EXPORT)) == (ISSET|EXPORT)) {
859				struct block *l2;
860				struct tbl *vp2;
861				unsigned int h = hash(vp->name);
862
863				/* unexport any redefined instances */
864				for (l2 = l->next; l2 != NULL; l2 = l2->next) {
865					vp2 = ktsearch(&l2->vars, vp->name, h);
866					if (vp2 != NULL)
867						vp2->flag &= ~EXPORT;
868				}
869				if ((vp->flag&INTEGER)) {
870					/* integer to string */
871					char *val;
872					val = str_val(vp);
873					vp->flag &= ~(INTEGER|RDONLY);
874					/* setstr can't fail here */
875					setstr(vp, val, KSH_RETURN_ERROR);
876				}
877				XPput(env, vp->val.s);
878			}
879	XPput(env, NULL);
880	return (char **) XPclose(env);
881}
882
883/*
884 * Called after a fork in parent to bump the random number generator.
885 * Done to ensure children will not get the same random number sequence
886 * if the parent doesn't use $RANDOM.
887 */
888void
889change_random(void)
890{
891	rand();
892}
893
894/*
895 * handle special variables with side effects - PATH, SECONDS.
896 */
897
898/* Test if name is a special parameter */
899static int
900special(const char *name)
901{
902	struct tbl *tp;
903
904	tp = ktsearch(&specials, name, hash(name));
905	return tp && (tp->flag & ISSET) ? tp->type : V_NONE;
906}
907
908/* Make a variable non-special */
909static void
910unspecial(const char *name)
911{
912	struct tbl *tp;
913
914	tp = ktsearch(&specials, name, hash(name));
915	if (tp)
916		ktdelete(tp);
917}
918
919static	struct	timespec seconds;	/* time SECONDS last set */
920static	int	user_lineno;		/* what user set $LINENO to */
921
922static void
923getspec(struct tbl *vp)
924{
925	switch (special(vp->name)) {
926	case V_SECONDS:
927		vp->flag &= ~SPECIAL;
928		/* On start up the value of SECONDS is used before seconds
929		 * has been set - don't do anything in this case
930		 * (see initcoms[] in main.c).
931		 */
932		if (vp->flag & ISSET) {
933			struct timespec difference, now;
934
935			clock_gettime(CLOCK_MONOTONIC, &now);
936			timespecsub(&now, &seconds, &difference);
937			setint(vp, (int64_t)difference.tv_sec);
938		}
939		vp->flag |= SPECIAL;
940		break;
941	case V_RANDOM:
942		vp->flag &= ~SPECIAL;
943		setint(vp, (int64_t) (rand() & 0x7fff));
944		vp->flag |= SPECIAL;
945		break;
946	case V_HISTSIZE:
947		vp->flag &= ~SPECIAL;
948		setint(vp, (int64_t) histsize);
949		vp->flag |= SPECIAL;
950		break;
951	case V_OPTIND:
952		vp->flag &= ~SPECIAL;
953		setint(vp, (int64_t) user_opt.uoptind);
954		vp->flag |= SPECIAL;
955		break;
956	case V_LINENO:
957		vp->flag &= ~SPECIAL;
958		setint(vp, (int64_t) current_lineno + user_lineno);
959		vp->flag |= SPECIAL;
960		break;
961	}
962}
963
964static void
965setspec(struct tbl *vp)
966{
967	char *s;
968
969	switch (special(vp->name)) {
970	case V_PATH:
971		afree(search_path, APERM);
972		search_path = str_save(str_val(vp), APERM);
973		flushcom(1);	/* clear tracked aliases */
974		break;
975	case V_IFS:
976		setctypes(s = str_val(vp), C_IFS);
977		ifs0 = *s;
978		break;
979	case V_OPTIND:
980		vp->flag &= ~SPECIAL;
981		getopts_reset((int) intval(vp));
982		vp->flag |= SPECIAL;
983		break;
984	case V_POSIXLY_CORRECT:
985		change_flag(FPOSIX, OF_SPECIAL, 1);
986		break;
987	case V_TMPDIR:
988		afree(tmpdir, APERM);
989		tmpdir = NULL;
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
996			s = str_val(vp);
997			if (s[0] == '/' && access(s, W_OK|X_OK) == 0 &&
998			    stat(s, &statb) == 0 && S_ISDIR(statb.st_mode))
999				tmpdir = str_save(s, APERM);
1000		}
1001		break;
1002	case V_HISTCONTROL:
1003		sethistcontrol(str_val(vp));
1004		break;
1005	case V_HISTSIZE:
1006		vp->flag &= ~SPECIAL;
1007		sethistsize((int) intval(vp));
1008		vp->flag |= SPECIAL;
1009		break;
1010	case V_HISTFILE:
1011		sethistfile(str_val(vp));
1012		break;
1013	case V_VISUAL:
1014		set_editmode(str_val(vp));
1015		break;
1016	case V_EDITOR:
1017		if (!(global("VISUAL")->flag & ISSET))
1018			set_editmode(str_val(vp));
1019		break;
1020	case V_COLUMNS:
1021		{
1022			int64_t l;
1023
1024			if (getint(vp, &l, false) == -1) {
1025				x_cols = MIN_COLS;
1026				break;
1027			}
1028			if (l <= MIN_COLS || l > INT_MAX)
1029				x_cols = MIN_COLS;
1030			else
1031				x_cols = l;
1032		}
1033		break;
1034#ifndef SMALL
1035	case V_MAIL:
1036		mbset(str_val(vp));
1037		break;
1038	case V_MAILPATH:
1039		mpset(str_val(vp));
1040		break;
1041	case V_MAILCHECK:
1042		vp->flag &= ~SPECIAL;
1043		mcset(intval(vp));
1044		vp->flag |= SPECIAL;
1045		break;
1046#endif /* SMALL */
1047	case V_RANDOM:
1048		vp->flag &= ~SPECIAL;
1049		srand_deterministic((unsigned int)intval(vp));
1050		vp->flag |= SPECIAL;
1051		break;
1052	case V_SECONDS:
1053		vp->flag &= ~SPECIAL;
1054		clock_gettime(CLOCK_MONOTONIC, &seconds);
1055		seconds.tv_sec -= intval(vp);
1056		vp->flag |= SPECIAL;
1057		break;
1058	case V_TMOUT:
1059		/* Enforce integer to avoid command execution from initcoms[] */
1060		vp->flag &= ~SPECIAL;
1061		intval(vp);
1062		vp->flag |= SPECIAL;
1063		/* at&t ksh seems to do this (only listen if integer) */
1064		if (vp->flag & INTEGER)
1065			ksh_tmout = vp->val.i >= 0 ? vp->val.i : 0;
1066		break;
1067	case V_LINENO:
1068		vp->flag &= ~SPECIAL;
1069		/* The -1 is because line numbering starts at 1. */
1070		user_lineno = (unsigned int) intval(vp) - current_lineno - 1;
1071		vp->flag |= SPECIAL;
1072		break;
1073	case V_TERM:
1074#ifndef SMALL
1075		{
1076			int ret;
1077
1078			vp->flag &= ~SPECIAL;
1079			if (setupterm(str_val(vp), shl_out->fd, &ret) == ERR)
1080				del_curterm(cur_term);
1081			vp->flag |= SPECIAL;
1082		}
1083#endif
1084		break;
1085	}
1086}
1087
1088static void
1089unsetspec(struct tbl *vp)
1090{
1091	switch (special(vp->name)) {
1092	case V_PATH:
1093		afree(search_path, APERM);
1094		search_path = str_save(def_path, APERM);
1095		flushcom(1);	/* clear tracked aliases */
1096		break;
1097	case V_IFS:
1098		setctypes(" \t\n", C_IFS);
1099		ifs0 = ' ';
1100		break;
1101	case V_TMPDIR:
1102		/* should not become unspecial */
1103		afree(tmpdir, APERM);
1104		tmpdir = NULL;
1105		break;
1106#ifndef SMALL
1107	case V_MAIL:
1108		mbset(NULL);
1109		break;
1110	case V_MAILPATH:
1111		mpset(NULL);
1112		break;
1113#endif /* SMALL */
1114	case V_HISTCONTROL:
1115		sethistcontrol(NULL);
1116		break;
1117	case V_LINENO:
1118#ifndef SMALL
1119	case V_MAILCHECK:	/* at&t ksh leaves previous value in place */
1120#endif /* SMALL */
1121	case V_RANDOM:
1122	case V_SECONDS:
1123	case V_TMOUT:		/* at&t ksh leaves previous value in place */
1124		unspecial(vp->name);
1125		break;
1126
1127	  /* at&t ksh man page says OPTIND, OPTARG and _ lose special meaning,
1128	   * but OPTARG does not (still set by getopts) and _ is also still
1129	   * set in various places.
1130	   * Don't know what at&t does for:
1131	   *		MAIL, MAILPATH, HISTSIZE, HISTFILE,
1132	   * Unsetting these in at&t ksh does not loose the `specialness':
1133	   *    no effect: IFS, COLUMNS, PATH, TMPDIR,
1134	   *		VISUAL, EDITOR,
1135	   * pdkshisms: no effect:
1136	   *		POSIXLY_CORRECT (use set +o posix instead)
1137	   */
1138	}
1139}
1140
1141/*
1142 * Search for (and possibly create) a table entry starting with
1143 * vp, indexed by val.
1144 */
1145static struct tbl *
1146arraysearch(struct tbl *vp, int val)
1147{
1148	struct tbl *prev, *curr, *new;
1149	size_t namelen = strlen(vp->name) + 1;
1150
1151	vp->flag |= ARRAY|DEFINED;
1152	vp->index = 0;
1153	/* The table entry is always [0] */
1154	if (val == 0)
1155		return vp;
1156	prev = vp;
1157	curr = vp->u.array;
1158	while (curr && curr->index < val) {
1159		prev = curr;
1160		curr = curr->u.array;
1161	}
1162	if (curr && curr->index == val) {
1163		if (curr->flag&ISSET)
1164			return curr;
1165		else
1166			new = curr;
1167	} else
1168		new = alloc(sizeof(struct tbl) + namelen,
1169		    vp->areap);
1170	strlcpy(new->name, vp->name, namelen);
1171	new->flag = vp->flag & ~(ALLOC|DEFINED|ISSET|SPECIAL);
1172	new->type = vp->type;
1173	new->areap = vp->areap;
1174	new->u2.field = vp->u2.field;
1175	new->index = val;
1176	if (curr != new) {		/* not reusing old array entry */
1177		prev->u.array = new;
1178		new->u.array = curr;
1179	}
1180	return new;
1181}
1182
1183/* Return the length of an array reference (eg, [1+2]) - cp is assumed
1184 * to point to the open bracket.  Returns 0 if there is no matching closing
1185 * bracket.
1186 */
1187int
1188array_ref_len(const char *cp)
1189{
1190	const char *s = cp;
1191	int c;
1192	int depth = 0;
1193
1194	while ((c = *s++) && (c != ']' || --depth))
1195		if (c == '[')
1196			depth++;
1197	if (!c)
1198		return 0;
1199	return s - cp;
1200}
1201
1202/*
1203 * Make a copy of the base of an array name
1204 */
1205char *
1206arrayname(const char *str)
1207{
1208	const char *p;
1209
1210	if ((p = strchr(str, '[')) == 0)
1211		/* Shouldn't happen, but why worry? */
1212		return (char *) str;
1213
1214	return str_nsave(str, p - str, ATEMP);
1215}
1216
1217/* Set (or overwrite, if !reset) the array variable var to the values in vals.
1218 */
1219void
1220set_array(const char *var, int reset, char **vals)
1221{
1222	struct tbl *vp, *vq;
1223	int i;
1224
1225	/* to get local array, use "typeset foo; set -A foo" */
1226	vp = global(var);
1227
1228	/* Note: at&t ksh allows set -A but not set +A of a read-only var */
1229	if ((vp->flag&RDONLY))
1230		errorf("%s: is read only", var);
1231	/* This code is quite non-optimal */
1232	if (reset > 0)
1233		/* trash existing values and attributes */
1234		unset(vp, 0);
1235	/* todo: would be nice for assignment to completely succeed or
1236	 * completely fail.  Only really effects integer arrays:
1237	 * evaluation of some of vals[] may fail...
1238	 */
1239	for (i = 0; vals[i]; i++) {
1240		vq = arraysearch(vp, i);
1241		/* would be nice to deal with errors here... (see above) */
1242		setstr(vq, vals[i], KSH_RETURN_ERROR);
1243	}
1244}
1245