Add mksh from CVS 2010/08/24 as system/core/mksh module

Both shells (ash from system/core/sh, and mksh) are built by
default but only the one where $(TARGET_SHELL) is set to is
actually installed (the shell and the mkshrc configuration
file are tagged shell_mksh for this to work).

Signed-off-by: Thorsten Glaser <tg@mirbsd.org>
diff --git a/mksh/src/var.c b/mksh/src/var.c
new file mode 100644
index 0000000..4e9729e
--- /dev/null
+++ b/mksh/src/var.c
@@ -0,0 +1,1490 @@
+/*	$OpenBSD: var.c,v 1.34 2007/10/15 02:16:35 deraadt Exp $	*/
+
+/*-
+ * Copyright (c) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+ *	Thorsten Glaser <tg@mirbsd.org>
+ *
+ * Provided that these terms and disclaimer and all copyright notices
+ * are retained or reproduced in an accompanying document, permission
+ * is granted to deal in this work without restriction, including un-
+ * limited rights to use, publicly perform, distribute, sell, modify,
+ * merge, give away, or sublicence.
+ *
+ * This work is provided "AS IS" and WITHOUT WARRANTY of any kind, to
+ * the utmost extent permitted by applicable law, neither express nor
+ * implied; without malicious intent or gross negligence. In no event
+ * may a licensor, author or contributor be held liable for indirect,
+ * direct, other damage, loss, or other issues arising in any way out
+ * of dealing in the work, even if advised of the possibility of such
+ * damage or existence of a defect, except proven that it results out
+ * of said person's immediate fault when using the work as intended.
+ */
+
+#include "sh.h"
+
+#if defined(__OpenBSD__)
+#include <sys/sysctl.h>
+#endif
+
+__RCSID("$MirOS: src/bin/mksh/var.c,v 1.110 2010/07/25 11:35:43 tg Exp $");
+
+/*
+ * Variables
+ *
+ * WARNING: unreadable code, needs a rewrite
+ *
+ * if (flag&INTEGER), val.i contains integer value, and type contains base.
+ * otherwise, (val.s + type) contains string value.
+ * if (flag&EXPORT), val.s contains "name=value" for E-Z exporting.
+ */
+static struct tbl vtemp;
+static struct table specials;
+static char *formatstr(struct tbl *, const char *);
+static void exportprep(struct tbl *, const char *);
+static int special(const char *);
+static void unspecial(const char *);
+static void getspec(struct tbl *);
+static void setspec(struct tbl *);
+static void unsetspec(struct tbl *);
+static int getint(struct tbl *, mksh_ari_t *, bool);
+static mksh_ari_t intval(struct tbl *);
+static struct tbl *arraysearch(struct tbl *, uint32_t);
+static const char *array_index_calc(const char *, bool *, uint32_t *);
+static uint32_t oaathash_update(register uint32_t, register const uint8_t *,
+    register size_t);
+static uint32_t oaathash_finalise(register uint32_t);
+
+uint8_t set_refflag = 0;
+
+/*
+ * create a new block for function calls and simple commands
+ * assume caller has allocated and set up e->loc
+ */
+void
+newblock(void)
+{
+	struct block *l;
+	static const char *empty[] = { null };
+
+	l = alloc(sizeof(struct block), ATEMP);
+	l->flags = 0;
+	ainit(&l->area); /* todo: could use e->area (l->area => l->areap) */
+	if (!e->loc) {
+		l->argc = 0;
+		l->argv = empty;
+	} else {
+		l->argc = e->loc->argc;
+		l->argv = e->loc->argv;
+	}
+	l->exit = l->error = NULL;
+	ktinit(&l->vars, &l->area, 0);
+	ktinit(&l->funs, &l->area, 0);
+	l->next = e->loc;
+	e->loc = l;
+}
+
+/*
+ * pop a block handling special variables
+ */
+void
+popblock(void)
+{
+	struct block *l = e->loc;
+	struct tbl *vp, **vpp = l->vars.tbls, *vq;
+	int i;
+
+	e->loc = l->next;	/* pop block */
+	for (i = l->vars.size; --i >= 0; )
+		if ((vp = *vpp++) != NULL && (vp->flag&SPECIAL)) {
+			if ((vq = global(vp->name))->flag & ISSET)
+				setspec(vq);
+			else
+				unsetspec(vq);
+		}
+	if (l->flags & BF_DOGETOPTS)
+		user_opt = l->getopts_state;
+	afreeall(&l->area);
+	afree(l, ATEMP);
+}
+
+/* called by main() to initialise variable data structures */
+#define VARSPEC_DEFNS
+#include "var_spec.h"
+
+enum var_specs {
+#define VARSPEC_ENUMS
+#include "var_spec.h"
+	V_MAX
+};
+
+static const char * const initvar_names[] = {
+#define VARSPEC_ITEMS
+#include "var_spec.h"
+};
+
+void
+initvar(void)
+{
+	int i = 0;
+	struct tbl *tp;
+
+	ktinit(&specials, APERM,
+	    /* must be 80% of 2^n (currently 12 specials) */ 16);
+	while (i < V_MAX - 1) {
+		tp = ktenter(&specials, initvar_names[i],
+		    hash(initvar_names[i]));
+		tp->flag = DEFINED|ISSET;
+		tp->type = ++i;
+	}
+}
+
+/* Used to calculate an array index for global()/local(). Sets *arrayp to
+ * true if this is an array, sets *valp to the array index, returns
+ * the basename of the array.
+ */
+static const char *
+array_index_calc(const char *n, bool *arrayp, uint32_t *valp)
+{
+	const char *p;
+	int len;
+	char *ap = NULL;
+
+	*arrayp = false;
+ redo_from_ref:
+	p = skip_varname(n, false);
+	if (!set_refflag && (p != n) && ksh_isalphx(n[0])) {
+		struct block *l = e->loc;
+		struct tbl *vp;
+		char *vn;
+		uint32_t h;
+
+		strndupx(vn, n, p - n, ATEMP);
+		h = hash(vn);
+		/* check if this is a reference */
+		do {
+			vp = ktsearch(&l->vars, vn, h);
+		} while (!vp && (l = l->next));
+		afree(vn, ATEMP);
+		if (vp && (vp->flag & (DEFINED|ASSOC|ARRAY)) ==
+		    (DEFINED|ASSOC)) {
+			char *cp;
+
+			/* gotcha! */
+			cp = shf_smprintf("%s%s", str_val(vp), p);
+			afree(ap, ATEMP);
+			n = ap = cp;
+			goto redo_from_ref;
+		}
+	}
+
+	if (p != n && *p == '[' && (len = array_ref_len(p))) {
+		char *sub, *tmp;
+		mksh_ari_t rval;
+
+		/* Calculate the value of the subscript */
+		*arrayp = true;
+		strndupx(tmp, p + 1, len - 2, ATEMP);
+		sub = substitute(tmp, 0);
+		afree(tmp, ATEMP);
+		strndupx(n, n, p - n, ATEMP);
+		evaluate(sub, &rval, KSH_UNWIND_ERROR, true);
+		*valp = (uint32_t)rval;
+		afree(sub, ATEMP);
+	}
+	return (n);
+}
+
+/*
+ * Search for variable, if not found create globally.
+ */
+struct tbl *
+global(const char *n)
+{
+	struct block *l = e->loc;
+	struct tbl *vp;
+	int c;
+	bool array;
+	uint32_t h, val;
+
+	/* Check to see if this is an array */
+	n = array_index_calc(n, &array, &val);
+	h = hash(n);
+	c = n[0];
+	if (!ksh_isalphx(c)) {
+		if (array)
+			errorf("bad substitution");
+		vp = &vtemp;
+		vp->flag = DEFINED;
+		vp->type = 0;
+		vp->areap = ATEMP;
+		*vp->name = c;
+		if (ksh_isdigit(c)) {
+			for (c = 0; ksh_isdigit(*n); n++)
+				c = c*10 + *n-'0';
+			if (c <= l->argc)
+				/* setstr can't fail here */
+				setstr(vp, l->argv[c], KSH_RETURN_ERROR);
+			vp->flag |= RDONLY;
+			return (vp);
+		}
+		vp->flag |= RDONLY;
+		if (n[1] != '\0')
+			return (vp);
+		vp->flag |= ISSET|INTEGER;
+		switch (c) {
+		case '$':
+			vp->val.i = kshpid;
+			break;
+		case '!':
+			/* If no job, expand to nothing */
+			if ((vp->val.i = j_async()) == 0)
+				vp->flag &= ~(ISSET|INTEGER);
+			break;
+		case '?':
+			vp->val.i = exstat;
+			break;
+		case '#':
+			vp->val.i = l->argc;
+			break;
+		case '-':
+			vp->flag &= ~INTEGER;
+			vp->val.s = getoptions();
+			break;
+		default:
+			vp->flag &= ~(ISSET|INTEGER);
+		}
+		return (vp);
+	}
+	for (l = e->loc; ; l = l->next) {
+		vp = ktsearch(&l->vars, n, h);
+		if (vp != NULL) {
+			if (array)
+				return (arraysearch(vp, val));
+			else
+				return (vp);
+		}
+		if (l->next == NULL)
+			break;
+	}
+	vp = ktenter(&l->vars, n, h);
+	if (array)
+		vp = arraysearch(vp, val);
+	vp->flag |= DEFINED;
+	if (special(n))
+		vp->flag |= SPECIAL;
+	return (vp);
+}
+
+/*
+ * Search for local variable, if not found create locally.
+ */
+struct tbl *
+local(const char *n, bool copy)
+{
+	struct block *l = e->loc;
+	struct tbl *vp;
+	bool array;
+	uint32_t h, val;
+
+	/* Check to see if this is an array */
+	n = array_index_calc(n, &array, &val);
+	h = hash(n);
+	if (!ksh_isalphx(*n)) {
+		vp = &vtemp;
+		vp->flag = DEFINED|RDONLY;
+		vp->type = 0;
+		vp->areap = ATEMP;
+		return (vp);
+	}
+	vp = ktenter(&l->vars, n, h);
+	if (copy && !(vp->flag & DEFINED)) {
+		struct block *ll = l;
+		struct tbl *vq = NULL;
+
+		while ((ll = ll->next) && !(vq = ktsearch(&ll->vars, n, h)))
+			;
+		if (vq) {
+			vp->flag |= vq->flag &
+			    (EXPORT | INTEGER | RDONLY | LJUST | RJUST |
+			    ZEROFIL | LCASEV | UCASEV_AL | INT_U | INT_L);
+			if (vq->flag & INTEGER)
+				vp->type = vq->type;
+			vp->u2.field = vq->u2.field;
+		}
+	}
+	if (array)
+		vp = arraysearch(vp, val);
+	vp->flag |= DEFINED;
+	if (special(n))
+		vp->flag |= SPECIAL;
+	return (vp);
+}
+
+/* get variable string value */
+char *
+str_val(struct tbl *vp)
+{
+	char *s;
+
+	if ((vp->flag&SPECIAL))
+		getspec(vp);
+	if (!(vp->flag&ISSET))
+		s = null;		/* special to dollar() */
+	else if (!(vp->flag&INTEGER))	/* string source */
+		s = vp->val.s + vp->type;
+	else {				/* integer source */
+		/* worst case number length is when base=2 */
+		/* 1 (minus) + 2 (base, up to 36) + 1 ('#') + number of bits
+		 * in the mksh_uari_t + 1 (NUL) */
+		char strbuf[1 + 2 + 1 + 8 * sizeof(mksh_uari_t) + 1];
+		const char *digits = (vp->flag & UCASEV_AL) ?
+		    digits_uc : digits_lc;
+		mksh_uari_t n;
+		int base;
+
+		s = strbuf + sizeof(strbuf);
+		if (vp->flag & INT_U)
+			n = vp->val.u;
+		else
+			n = (vp->val.i < 0) ? -vp->val.i : vp->val.i;
+		base = (vp->type == 0) ? 10 : vp->type;
+
+		if (base == 1) {
+			size_t sz = 1;
+
+			*(s = strbuf) = '1';
+			s[1] = '#';
+			if (!UTFMODE || ((n & 0xFF80) == 0xEF80))
+				/* OPTU-16 -> raw octet */
+				s[2] = n & 0xFF;
+			else
+				sz = utf_wctomb(s + 2, n);
+			s[2 + sz] = '\0';
+		} else {
+			*--s = '\0';
+			do {
+				*--s = digits[n % base];
+				n /= base;
+			} while (n != 0);
+			if (base != 10) {
+				*--s = '#';
+				*--s = digits[base % 10];
+				if (base >= 10)
+					*--s = digits[base / 10];
+			}
+			if (!(vp->flag & INT_U) && vp->val.i < 0)
+				*--s = '-';
+		}
+		if (vp->flag & (RJUST|LJUST)) /* case already dealt with */
+			s = formatstr(vp, s);
+		else
+			strdupx(s, s, ATEMP);
+	}
+	return (s);
+}
+
+/* get variable integer value, with error checking */
+static mksh_ari_t
+intval(struct tbl *vp)
+{
+	mksh_ari_t num;
+	int base;
+
+	base = getint(vp, &num, false);
+	if (base == -1)
+		/* XXX check calls - is error here ok by POSIX? */
+		errorf("%s: bad number", str_val(vp));
+	return (num);
+}
+
+/* set variable to string value */
+int
+setstr(struct tbl *vq, const char *s, int error_ok)
+{
+	char *salloc = NULL;
+	int no_ro_check = error_ok & 0x4;
+
+	error_ok &= ~0x4;
+	if ((vq->flag & RDONLY) && !no_ro_check) {
+		warningf(true, "%s: is read only", vq->name);
+		if (!error_ok)
+			errorfz();
+		return (0);
+	}
+	if (!(vq->flag&INTEGER)) { /* string dest */
+		if ((vq->flag&ALLOC)) {
+			/* debugging */
+			if (s >= vq->val.s &&
+			    s <= vq->val.s + strlen(vq->val.s))
+				internal_errorf(
+				    "setstr: %s=%s: assigning to self",
+				    vq->name, s);
+			afree(vq->val.s, vq->areap);
+		}
+		vq->flag &= ~(ISSET|ALLOC);
+		vq->type = 0;
+		if (s && (vq->flag & (UCASEV_AL|LCASEV|LJUST|RJUST)))
+			s = salloc = formatstr(vq, s);
+		if ((vq->flag&EXPORT))
+			exportprep(vq, s);
+		else {
+			strdupx(vq->val.s, s, vq->areap);
+			vq->flag |= ALLOC;
+		}
+	} else {		/* integer dest */
+		if (!v_evaluate(vq, s, error_ok, true))
+			return (0);
+	}
+	vq->flag |= ISSET;
+	if ((vq->flag&SPECIAL))
+		setspec(vq);
+	afree(salloc, ATEMP);
+	return (1);
+}
+
+/* set variable to integer */
+void
+setint(struct tbl *vq, mksh_ari_t n)
+{
+	if (!(vq->flag&INTEGER)) {
+		struct tbl *vp = &vtemp;
+		vp->flag = (ISSET|INTEGER);
+		vp->type = 0;
+		vp->areap = ATEMP;
+		vp->val.i = n;
+		/* setstr can't fail here */
+		setstr(vq, str_val(vp), KSH_RETURN_ERROR);
+	} else
+		vq->val.i = n;
+	vq->flag |= ISSET;
+	if ((vq->flag&SPECIAL))
+		setspec(vq);
+}
+
+static int
+getint(struct tbl *vp, mksh_ari_t *nump, bool arith)
+{
+	char *s;
+	int c, base, neg;
+	bool have_base = false;
+	mksh_ari_t num;
+
+	if (vp->flag&SPECIAL)
+		getspec(vp);
+	/* XXX is it possible for ISSET to be set and val.s to be 0? */
+	if (!(vp->flag&ISSET) || (!(vp->flag&INTEGER) && vp->val.s == NULL))
+		return (-1);
+	if (vp->flag&INTEGER) {
+		*nump = vp->val.i;
+		return (vp->type);
+	}
+	s = vp->val.s + vp->type;
+	if (s == NULL)	/* redundant given initial test */
+		s = null;
+	base = 10;
+	num = 0;
+	neg = 0;
+	if (arith && *s == '0' && *(s+1)) {
+		s++;
+		if (*s == 'x' || *s == 'X') {
+			s++;
+			base = 16;
+		} else if (vp->flag & ZEROFIL) {
+			while (*s == '0')
+				s++;
+		} else
+			base = 8;
+		have_base = true;
+	}
+	for (c = *s++; c ; c = *s++) {
+		if (c == '-') {
+			neg++;
+			continue;
+		} else if (c == '#') {
+			base = (int)num;
+			if (have_base || base < 1 || base > 36)
+				return (-1);
+			if (base == 1) {
+				unsigned int wc;
+
+				if (!UTFMODE)
+					wc = *(unsigned char *)s;
+				else if (utf_mbtowc(&wc, s) == (size_t)-1)
+					/* OPTU-8 -> OPTU-16 */
+					/*
+					 * (with a twist: 1#\uEF80 converts
+					 * the same as 1#\x80 does, thus is
+					 * not round-tripping correctly XXX)
+					 */
+					wc = 0xEF00 + *(unsigned char *)s;
+				*nump = (mksh_ari_t)wc;
+				return (1);
+			}
+			num = 0;
+			have_base = true;
+			continue;
+		} else if (ksh_isdigit(c))
+			c -= '0';
+		else if (ksh_islower(c))
+			c -= 'a' - 10;
+		else if (ksh_isupper(c))
+			c -= 'A' - 10;
+		else
+			return (-1);
+		if (c < 0 || c >= base)
+			return (-1);
+		num = num * base + c;
+	}
+	if (neg)
+		num = -num;
+	*nump = num;
+	return (base);
+}
+
+/* convert variable vq to integer variable, setting its value from vp
+ * (vq and vp may be the same)
+ */
+struct tbl *
+setint_v(struct tbl *vq, struct tbl *vp, bool arith)
+{
+	int base;
+	mksh_ari_t num;
+
+	if ((base = getint(vp, &num, arith)) == -1)
+		return (NULL);
+	if (!(vq->flag & INTEGER) && (vq->flag & ALLOC)) {
+		vq->flag &= ~ALLOC;
+		afree(vq->val.s, vq->areap);
+	}
+	vq->val.i = num;
+	if (vq->type == 0) /* default base */
+		vq->type = base;
+	vq->flag |= ISSET|INTEGER;
+	if (vq->flag&SPECIAL)
+		setspec(vq);
+	return (vq);
+}
+
+static char *
+formatstr(struct tbl *vp, const char *s)
+{
+	int olen, nlen;
+	char *p, *q;
+	size_t psiz;
+
+	olen = utf_mbswidth(s);
+
+	if (vp->flag & (RJUST|LJUST)) {
+		if (!vp->u2.field)	/* default field width */
+			vp->u2.field = olen;
+		nlen = vp->u2.field;
+	} else
+		nlen = olen;
+
+	p = alloc((psiz = nlen * /* MB_LEN_MAX */ 3 + 1), ATEMP);
+	if (vp->flag & (RJUST|LJUST)) {
+		int slen = olen, i = 0;
+
+		if (vp->flag & RJUST) {
+			const char *qq = s;
+			int n = 0;
+
+			while (i < slen)
+				i += utf_widthadj(qq, &qq);
+			/* strip trailing spaces (AT&T uses qq[-1] == ' ') */
+			while (qq > s && ksh_isspace(qq[-1])) {
+				--qq;
+				--slen;
+			}
+			if (vp->flag & ZEROFIL && vp->flag & INTEGER) {
+				if (s[1] == '#')
+					n = 2;
+				else if (s[2] == '#')
+					n = 3;
+				if (vp->u2.field <= n)
+					n = 0;
+			}
+			if (n) {
+				memcpy(p, s, n);
+				s += n;
+			}
+			while (slen > vp->u2.field)
+				slen -= utf_widthadj(s, &s);
+			if (vp->u2.field - slen)
+				memset(p + n, (vp->flag & ZEROFIL) ? '0' : ' ',
+				    vp->u2.field - slen);
+			slen -= n;
+			shf_snprintf(p + vp->u2.field - slen,
+			    psiz - (vp->u2.field - slen),
+			    "%.*s", slen, s);
+		} else {
+			/* strip leading spaces/zeros */
+			while (ksh_isspace(*s))
+				s++;
+			if (vp->flag & ZEROFIL)
+				while (*s == '0')
+					s++;
+			shf_snprintf(p, nlen + 1, "%-*.*s",
+				vp->u2.field, vp->u2.field, s);
+		}
+	} else
+		memcpy(p, s, strlen(s) + 1);
+
+	if (vp->flag & UCASEV_AL) {
+		for (q = p; *q; q++)
+			*q = ksh_toupper(*q);
+	} else if (vp->flag & LCASEV) {
+		for (q = p; *q; q++)
+			*q = ksh_tolower(*q);
+	}
+
+	return (p);
+}
+
+/*
+ * make vp->val.s be "name=value" for quick exporting.
+ */
+static void
+exportprep(struct tbl *vp, const char *val)
+{
+	char *xp;
+	char *op = (vp->flag&ALLOC) ? vp->val.s : NULL;
+	int namelen = strlen(vp->name);
+	int vallen = strlen(val) + 1;
+
+	vp->flag |= ALLOC;
+	xp = alloc(namelen + 1 + vallen, vp->areap);
+	memcpy(vp->val.s = xp, vp->name, namelen);
+	xp += namelen;
+	*xp++ = '=';
+	vp->type = xp - vp->val.s; /* offset to value */
+	memcpy(xp, val, vallen);
+	if (op != NULL)
+		afree(op, vp->areap);
+}
+
+/*
+ * lookup variable (according to (set&LOCAL)),
+ * set its attributes (INTEGER, RDONLY, EXPORT, TRACE, LJUST, RJUST, ZEROFIL,
+ * LCASEV, UCASEV_AL), and optionally set its value if an assignment.
+ */
+struct tbl *
+typeset(const char *var, Tflag set, Tflag clr, int field, int base)
+{
+	struct tbl *vp;
+	struct tbl *vpbase, *t;
+	char *tvar;
+	const char *val;
+	int len;
+
+	/* check for valid variable name, search for value */
+	val = skip_varname(var, false);
+	if (val == var)
+		return (NULL);
+	mkssert(var != NULL);
+	mkssert(*var != 0);
+	if (*val == '[') {
+		if (set_refflag)
+			errorf("%s: reference variable cannot be an array",
+			    var);
+		len = array_ref_len(val);
+		if (len == 0)
+			return (NULL);
+		/* IMPORT is only used when the shell starts up and is
+		 * setting up its environment. Allow only simple array
+		 * references at this time since parameter/command substitution
+		 * is preformed on the [expression] which would be a major
+		 * security hole.
+		 */
+		if (set & IMPORT) {
+			int i;
+			for (i = 1; i < len - 1; i++)
+				if (!ksh_isdigit(val[i]))
+					return (NULL);
+		}
+		val += len;
+	}
+	if (*val == '=')
+		strndupx(tvar, var, val++ - var, ATEMP);
+	else {
+		/* Importing from original environment: must have an = */
+		if (set & IMPORT)
+			return (NULL);
+		strdupx(tvar, var, ATEMP);
+		val = NULL;
+		/* handle foo[*] ⇒ foo (whole array) mapping for R39b */
+		len = strlen(tvar);
+		if (len > 3 && tvar[len-3] == '[' && tvar[len-2] == '*' &&
+		    tvar[len-1] == ']')
+			tvar[len-3] = '\0';
+	}
+
+	/* Prevent typeset from creating a local PATH/ENV/SHELL */
+	if (Flag(FRESTRICTED) && (strcmp(tvar, "PATH") == 0 ||
+	    strcmp(tvar, "ENV") == 0 || strcmp(tvar, "SHELL") == 0))
+		errorf("%s: restricted", tvar);
+
+	vp = (set&LOCAL) ? local(tvar, (set & LOCAL_COPY) ? true : false) :
+	    global(tvar);
+	if (set_refflag == 2 && (vp->flag & (ARRAY|ASSOC)) == ASSOC)
+		vp->flag &= ~ASSOC;
+	else if (set_refflag == 1) {
+		if (vp->flag & ARRAY) {
+			struct tbl *a, *tmp;
+
+			/* Free up entire array */
+			for (a = vp->u.array; a; ) {
+				tmp = a;
+				a = a->u.array;
+				if (tmp->flag & ALLOC)
+					afree(tmp->val.s, tmp->areap);
+				afree(tmp, tmp->areap);
+			}
+			vp->u.array = NULL;
+			vp->flag &= ~ARRAY;
+		}
+		vp->flag |= ASSOC;
+	}
+
+	set &= ~(LOCAL|LOCAL_COPY);
+
+	vpbase = (vp->flag & ARRAY) ? global(arrayname(var)) : vp;
+
+	/* only allow export flag to be set. AT&T ksh allows any attribute to
+	 * be changed which means it can be truncated or modified (-L/-R/-Z/-i)
+	 */
+	if ((vpbase->flag&RDONLY) &&
+	    (val || clr || (set & ~EXPORT)))
+		/* XXX check calls - is error here ok by POSIX? */
+		errorf("%s: is read only", tvar);
+	afree(tvar, ATEMP);
+
+	/* most calls are with set/clr == 0 */
+	if (set | clr) {
+		bool ok = true;
+
+		/* XXX if x[0] isn't set, there will be problems: need to have
+		 * one copy of attributes for arrays...
+		 */
+		for (t = vpbase; t; t = t->u.array) {
+			bool fake_assign;
+			char *s = NULL;
+			char *free_me = NULL;
+
+			fake_assign = (t->flag & ISSET) && (!val || t != vp) &&
+			    ((set & (UCASEV_AL|LCASEV|LJUST|RJUST|ZEROFIL)) ||
+			    ((t->flag & INTEGER) && (clr & INTEGER)) ||
+			    (!(t->flag & INTEGER) && (set & INTEGER)));
+			if (fake_assign) {
+				if (t->flag & INTEGER) {
+					s = str_val(t);
+					free_me = NULL;
+				} else {
+					s = t->val.s + t->type;
+					free_me = (t->flag & ALLOC) ? t->val.s :
+					    NULL;
+				}
+				t->flag &= ~ALLOC;
+			}
+			if (!(t->flag & INTEGER) && (set & INTEGER)) {
+				t->type = 0;
+				t->flag &= ~ALLOC;
+			}
+			t->flag = (t->flag | set) & ~clr;
+			/* Don't change base if assignment is to be done,
+			 * in case assignment fails.
+			 */
+			if ((set & INTEGER) && base > 0 && (!val || t != vp))
+				t->type = base;
+			if (set & (LJUST|RJUST|ZEROFIL))
+				t->u2.field = field;
+			if (fake_assign) {
+				if (!setstr(t, s, KSH_RETURN_ERROR)) {
+					/* Somewhat arbitrary action here:
+					 * zap contents of variable, but keep
+					 * the flag settings.
+					 */
+					ok = false;
+					if (t->flag & INTEGER)
+						t->flag &= ~ISSET;
+					else {
+						if (t->flag & ALLOC)
+							afree(t->val.s, t->areap);
+						t->flag &= ~(ISSET|ALLOC);
+						t->type = 0;
+					}
+				}
+				if (free_me)
+					afree(free_me, t->areap);
+			}
+		}
+		if (!ok)
+			errorfz();
+	}
+
+	if (val != NULL) {
+		if (vp->flag&INTEGER) {
+			/* do not zero base before assignment */
+			setstr(vp, val, KSH_UNWIND_ERROR | 0x4);
+			/* Done after assignment to override default */
+			if (base > 0)
+				vp->type = base;
+		} else
+			/* setstr can't fail (readonly check already done) */
+			setstr(vp, val, KSH_RETURN_ERROR | 0x4);
+	}
+
+	/* only x[0] is ever exported, so use vpbase */
+	if ((vpbase->flag&EXPORT) && !(vpbase->flag&INTEGER) &&
+	    vpbase->type == 0)
+		exportprep(vpbase, (vpbase->flag&ISSET) ? vpbase->val.s : null);
+
+	return (vp);
+}
+
+/**
+ * Unset a variable. The flags can be:
+ * |1	= tear down entire array
+ * |2	= keep attributes, only unset content
+ */
+void
+unset(struct tbl *vp, int flags)
+{
+	if (vp->flag & ALLOC)
+		afree(vp->val.s, vp->areap);
+	if ((vp->flag & ARRAY) && (flags & 1)) {
+		struct tbl *a, *tmp;
+
+		/* Free up entire array */
+		for (a = vp->u.array; a; ) {
+			tmp = a;
+			a = a->u.array;
+			if (tmp->flag & ALLOC)
+				afree(tmp->val.s, tmp->areap);
+			afree(tmp, tmp->areap);
+		}
+		vp->u.array = NULL;
+	}
+	if (flags & 2) {
+		vp->flag &= ~(ALLOC|ISSET);
+		return;
+	}
+	/* If foo[0] is being unset, the remainder of the array is kept... */
+	vp->flag &= SPECIAL | ((flags & 1) ? 0 : ARRAY|DEFINED);
+	if (vp->flag & SPECIAL)
+		unsetspec(vp);	/* responsible for 'unspecial'ing var */
+}
+
+/* return a pointer to the first char past a legal variable name (returns the
+ * argument if there is no legal name, returns a pointer to the terminating
+ * NUL if whole string is legal).
+ */
+const char *
+skip_varname(const char *s, int aok)
+{
+	int alen;
+
+	if (s && ksh_isalphx(*s)) {
+		while (*++s && ksh_isalnux(*s))
+			;
+		if (aok && *s == '[' && (alen = array_ref_len(s)))
+			s += alen;
+	}
+	return (s);
+}
+
+/* Return a pointer to the first character past any legal variable name */
+const char *
+skip_wdvarname(const char *s,
+    int aok)				/* skip array de-reference? */
+{
+	if (s[0] == CHAR && ksh_isalphx(s[1])) {
+		do {
+			s += 2;
+		} while (s[0] == CHAR && ksh_isalnux(s[1]));
+		if (aok && s[0] == CHAR && s[1] == '[') {
+			/* skip possible array de-reference */
+			const char *p = s;
+			char c;
+			int depth = 0;
+
+			while (1) {
+				if (p[0] != CHAR)
+					break;
+				c = p[1];
+				p += 2;
+				if (c == '[')
+					depth++;
+				else if (c == ']' && --depth == 0) {
+					s = p;
+					break;
+				}
+			}
+		}
+	}
+	return (s);
+}
+
+/* Check if coded string s is a variable name */
+int
+is_wdvarname(const char *s, int aok)
+{
+	const char *p = skip_wdvarname(s, aok);
+
+	return (p != s && p[0] == EOS);
+}
+
+/* Check if coded string s is a variable assignment */
+int
+is_wdvarassign(const char *s)
+{
+	const char *p = skip_wdvarname(s, true);
+
+	return (p != s && p[0] == CHAR && p[1] == '=');
+}
+
+/*
+ * Make the exported environment from the exported names in the dictionary.
+ */
+char **
+makenv(void)
+{
+	struct block *l;
+	XPtrV denv;
+	struct tbl *vp, **vpp;
+	int i;
+
+	XPinit(denv, 64);
+	for (l = e->loc; l != NULL; l = l->next)
+		for (vpp = l->vars.tbls, i = l->vars.size; --i >= 0; )
+			if ((vp = *vpp++) != NULL &&
+			    (vp->flag&(ISSET|EXPORT)) == (ISSET|EXPORT)) {
+				struct block *l2;
+				struct tbl *vp2;
+				uint32_t h = hash(vp->name);
+
+				/* unexport any redefined instances */
+				for (l2 = l->next; l2 != NULL; l2 = l2->next) {
+					vp2 = ktsearch(&l2->vars, vp->name, h);
+					if (vp2 != NULL)
+						vp2->flag &= ~EXPORT;
+				}
+				if ((vp->flag&INTEGER)) {
+					/* integer to string */
+					char *val;
+					val = str_val(vp);
+					vp->flag &= ~(INTEGER|RDONLY|SPECIAL);
+					/* setstr can't fail here */
+					setstr(vp, val, KSH_RETURN_ERROR);
+				}
+				XPput(denv, vp->val.s);
+			}
+	XPput(denv, NULL);
+	return ((char **)XPclose(denv));
+}
+
+/* Bob Jenkins' one-at-a-time hash */
+static uint32_t
+oaathash_update(register uint32_t h, register const uint8_t *cp,
+    register size_t n)
+{
+	while (n--) {
+		h += *cp++;
+		h += h << 10;
+		h ^= h >> 6;
+	}
+
+	return (h);
+}
+
+static uint32_t
+oaathash_finalise(register uint32_t h)
+{
+	h += h << 3;
+	h ^= h >> 11;
+	h += h << 15;
+
+	return (h);
+}
+
+uint32_t
+oaathash_full(register const uint8_t *bp)
+{
+	register uint32_t h = 0;
+	register uint8_t c;
+
+	while ((c = *bp++)) {
+		h += c;
+		h += h << 10;
+		h ^= h >> 6;
+	}
+
+	return (oaathash_finalise(h));
+}
+
+void
+change_random(const void *vp, size_t n)
+{
+	register uint32_t h = 0x100;
+#if defined(__OpenBSD__)
+	int mib[2];
+	uint8_t k[3];
+	size_t klen;
+#endif
+
+	kshstate_v.cr_dp = vp;
+	kshstate_v.cr_dsz = n;
+	gettimeofday(&kshstate_v.cr_tv, NULL);
+	h = oaathash_update(oaathash_update(h, (void *)&kshstate_v,
+	    sizeof(kshstate_v)), vp, n);
+	kshstate_v.lcg_state_ = oaathash_finalise(h);
+
+#if defined(__OpenBSD__)
+	/* OpenBSD, MirBSD: proper kernel entropy comes at zero cost */
+
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_ARND;
+	klen = sizeof(k);
+	sysctl(mib, 2, k, &klen, &kshstate_v.lcg_state_,
+	    sizeof(kshstate_v.lcg_state_));
+	/* we ignore failures and take in k anyway */
+	h = oaathash_update(h, k, sizeof(k));
+	kshstate_v.lcg_state_ = oaathash_finalise(h);
+#elif defined(MKSH_A4PB)
+	/* forced by the user to use arc4random_pushb(3) • Cygwin? */
+	{
+		uint32_t prv;
+
+		prv = arc4random_pushb(&kshstate_v.lcg_state_,
+		    sizeof(kshstate_v.lcg_state_));
+		h = oaathash_update(h, &prv, sizeof(prv));
+	}
+	kshstate_v.lcg_state_ = oaathash_finalise(h);
+#endif
+}
+
+/*
+ * handle special variables with side effects - PATH, SECONDS.
+ */
+
+/* Test if name is a special parameter */
+static int
+special(const char *name)
+{
+	struct tbl *tp;
+
+	tp = ktsearch(&specials, name, hash(name));
+	return (tp && (tp->flag & ISSET) ? tp->type : V_NONE);
+}
+
+/* Make a variable non-special */
+static void
+unspecial(const char *name)
+{
+	struct tbl *tp;
+
+	tp = ktsearch(&specials, name, hash(name));
+	if (tp)
+		ktdelete(tp);
+}
+
+static time_t seconds;		/* time SECONDS last set */
+static int user_lineno;		/* what user set $LINENO to */
+
+static void
+getspec(struct tbl *vp)
+{
+	register mksh_ari_t i;
+	int st;
+
+	switch ((st = special(vp->name))) {
+	case V_SECONDS:
+		/*
+		 * On start up the value of SECONDS is used before
+		 * it has been set - don't do anything in this case
+		 * (see initcoms[] in main.c).
+		 */
+		if (vp->flag & ISSET) {
+			struct timeval tv;
+
+			gettimeofday(&tv, NULL);
+			i = tv.tv_sec - seconds;
+		} else
+			return;
+		break;
+	case V_RANDOM:
+		/*
+		 * this is the same Linear Congruential PRNG as Borland
+		 * C/C++ allegedly uses in its built-in rand() function
+		 */
+		i = ((kshstate_v.lcg_state_ =
+		    22695477 * kshstate_v.lcg_state_ + 1) >> 16) & 0x7FFF;
+		break;
+	case V_HISTSIZE:
+		i = histsize;
+		break;
+	case V_OPTIND:
+		i = user_opt.uoptind;
+		break;
+	case V_LINENO:
+		i = current_lineno + user_lineno;
+		break;
+	case V_COLUMNS:
+	case V_LINES:
+		/*
+		 * Do NOT export COLUMNS/LINES. Many applications
+		 * check COLUMNS/LINES before checking ws.ws_col/row,
+		 * so if the app is started with C/L in the environ
+		 * and the window is then resized, the app won't
+		 * see the change cause the environ doesn't change.
+		 */
+		change_winsz();
+		i = st == V_COLUMNS ? x_cols : x_lins;
+		break;
+	default:
+		/* do nothing, do not touch vp at all */
+		return;
+	}
+	vp->flag &= ~SPECIAL;
+	setint(vp, i);
+	vp->flag |= SPECIAL;
+}
+
+static void
+setspec(struct tbl *vp)
+{
+	mksh_ari_t i;
+	char *s;
+	int st;
+
+	switch ((st = special(vp->name))) {
+	case V_PATH:
+		if (path)
+			afree(path, APERM);
+		s = str_val(vp);
+		strdupx(path, s, APERM);
+		flushcom(1);	/* clear tracked aliases */
+		return;
+	case V_IFS:
+		setctypes(s = str_val(vp), C_IFS);
+		ifs0 = *s;
+		return;
+	case V_TMPDIR:
+		if (tmpdir) {
+			afree(tmpdir, APERM);
+			tmpdir = NULL;
+		}
+		/* Use tmpdir iff it is an absolute path, is writable and
+		 * searchable and is a directory...
+		 */
+		{
+			struct stat statb;
+
+			s = str_val(vp);
+			if (s[0] == '/' && access(s, W_OK|X_OK) == 0 &&
+			    stat(s, &statb) == 0 && S_ISDIR(statb.st_mode))
+				strdupx(tmpdir, s, APERM);
+		}
+		break;
+#if HAVE_PERSISTENT_HISTORY
+	case V_HISTFILE:
+		sethistfile(str_val(vp));
+		break;
+#endif
+	case V_TMOUT:
+		/* AT&T ksh seems to do this (only listen if integer) */
+		if (vp->flag & INTEGER)
+			ksh_tmout = vp->val.i >= 0 ? vp->val.i : 0;
+		break;
+
+	/* common sub-cases */
+	case V_OPTIND:
+	case V_HISTSIZE:
+	case V_COLUMNS:
+	case V_LINES:
+	case V_RANDOM:
+	case V_SECONDS:
+	case V_LINENO:
+		vp->flag &= ~SPECIAL;
+		i = intval(vp);
+		vp->flag |= SPECIAL;
+		break;
+	default:
+		/* do nothing, do not touch vp at all */
+		return;
+	}
+
+	/* process the singular parts of the common cases */
+
+	switch (st) {
+	case V_OPTIND:
+		getopts_reset((int)i);
+		break;
+	case V_HISTSIZE:
+		sethistsize((int)i);
+		break;
+	case V_COLUMNS:
+		if (i >= MIN_COLS)
+			x_cols = i;
+		break;
+	case V_LINES:
+		if (i >= MIN_LINS)
+			x_lins = i;
+		break;
+	case V_RANDOM:
+		/*
+		 * mksh R39d+ no longer has the traditional repeatability
+		 * of $RANDOM sequences, but always retains state
+		 */
+		change_random(&i, sizeof(i));
+		break;
+	case V_SECONDS:
+		{
+			struct timeval tv;
+
+			gettimeofday(&tv, NULL);
+			seconds = tv.tv_sec - i;
+		}
+		break;
+	case V_LINENO:
+		/* The -1 is because line numbering starts at 1. */
+		user_lineno = (unsigned int)i - current_lineno - 1;
+		break;
+	}
+}
+
+static void
+unsetspec(struct tbl *vp)
+{
+	switch (special(vp->name)) {
+	case V_PATH:
+		if (path)
+			afree(path, APERM);
+		strdupx(path, def_path, APERM);
+		flushcom(1);	/* clear tracked aliases */
+		break;
+	case V_IFS:
+		setctypes(" \t\n", C_IFS);
+		ifs0 = ' ';
+		break;
+	case V_TMPDIR:
+		/* should not become unspecial */
+		if (tmpdir) {
+			afree(tmpdir, APERM);
+			tmpdir = NULL;
+		}
+		break;
+	case V_LINENO:
+	case V_RANDOM:
+	case V_SECONDS:
+	case V_TMOUT:		/* AT&T ksh leaves previous value in place */
+		unspecial(vp->name);
+		break;
+
+	/*
+	 * AT&T ksh man page says OPTIND, OPTARG and _ lose special
+	 * meaning, but OPTARG does not (still set by getopts) and _ is
+	 * also still set in various places. Don't know what AT&T does
+	 * for HISTSIZE, HISTFILE. Unsetting these in AT&T ksh does not
+	 * loose the 'specialness': IFS, COLUMNS, PATH, TMPDIR
+	 */
+	}
+}
+
+/*
+ * Search for (and possibly create) a table entry starting with
+ * vp, indexed by val.
+ */
+static struct tbl *
+arraysearch(struct tbl *vp, uint32_t val)
+{
+	struct tbl *prev, *curr, *news;
+	size_t len;
+
+	vp->flag = (vp->flag | (ARRAY|DEFINED)) & ~ASSOC;
+	/* The table entry is always [0] */
+	if (val == 0)
+		return (vp);
+	prev = vp;
+	curr = vp->u.array;
+	while (curr && curr->ua.index < val) {
+		prev = curr;
+		curr = curr->u.array;
+	}
+	if (curr && curr->ua.index == val) {
+		if (curr->flag&ISSET)
+			return (curr);
+		news = curr;
+	} else
+		news = NULL;
+	len = strlen(vp->name) + 1;
+	if (!news) {
+		news = alloc(offsetof(struct tbl, name[0]) + len, vp->areap);
+		memcpy(news->name, vp->name, len);
+	}
+	news->flag = (vp->flag & ~(ALLOC|DEFINED|ISSET|SPECIAL)) | AINDEX;
+	news->type = vp->type;
+	news->areap = vp->areap;
+	news->u2.field = vp->u2.field;
+	news->ua.index = val;
+
+	if (curr != news) {		/* not reusing old array entry */
+		prev->u.array = news;
+		news->u.array = curr;
+	}
+	return (news);
+}
+
+/* Return the length of an array reference (eg, [1+2]) - cp is assumed
+ * to point to the open bracket. Returns 0 if there is no matching closing
+ * bracket.
+ */
+int
+array_ref_len(const char *cp)
+{
+	const char *s = cp;
+	int c;
+	int depth = 0;
+
+	while ((c = *s++) && (c != ']' || --depth))
+		if (c == '[')
+			depth++;
+	if (!c)
+		return (0);
+	return (s - cp);
+}
+
+/*
+ * Make a copy of the base of an array name
+ */
+char *
+arrayname(const char *str)
+{
+	const char *p;
+	char *rv;
+
+	if ((p = cstrchr(str, '[')) == 0)
+		/* Shouldn't happen, but why worry? */
+		strdupx(rv, str, ATEMP);
+	else
+		strndupx(rv, str, p - str, ATEMP);
+
+	return (rv);
+}
+
+/* set (or overwrite, if reset) the array variable var to the values in vals */
+mksh_uari_t
+set_array(const char *var, bool reset, const char **vals)
+{
+	struct tbl *vp, *vq;
+	mksh_uari_t i;
+	const char *ccp;
+#ifndef MKSH_SMALL
+	char *cp;
+	mksh_uari_t j;
+#endif
+
+	/* to get local array, use "typeset foo; set -A foo" */
+	vp = global(var);
+
+	/* Note: AT&T ksh allows set -A but not set +A of a read-only var */
+	if ((vp->flag&RDONLY))
+		errorf("%s: is read only", var);
+	/* This code is quite non-optimal */
+	if (reset)
+		/* trash existing values and attributes */
+		unset(vp, 1);
+	/* todo: would be nice for assignment to completely succeed or
+	 * completely fail. Only really effects integer arrays:
+	 * evaluation of some of vals[] may fail...
+	 */
+	i = 0;
+#ifndef MKSH_SMALL
+	j = 0;
+#else
+#define j i
+#endif
+	while ((ccp = vals[i])) {
+#ifndef MKSH_SMALL
+		if (*ccp == '[') {
+			int level = 0;
+
+			while (*ccp) {
+				if (*ccp == ']' && --level == 0)
+					break;
+				if (*ccp == '[')
+					++level;
+				++ccp;
+			}
+			if (*ccp == ']' && level == 0 && ccp[1] == '=') {
+				strndupx(cp, vals[i] + 1, ccp - (vals[i] + 1),
+				    ATEMP);
+				evaluate(substitute(cp, 0), (mksh_ari_t *)&j,
+				    KSH_UNWIND_ERROR, true);
+				afree(cp, ATEMP);
+				ccp += 2;
+			} else
+				ccp = vals[i];
+		}
+#endif
+
+		vq = arraysearch(vp, j);
+		/* would be nice to deal with errors here... (see above) */
+		setstr(vq, ccp, KSH_RETURN_ERROR);
+		i++;
+#ifndef MKSH_SMALL
+		j++;
+#endif
+	}
+
+	return (i);
+}
+
+void
+change_winsz(void)
+{
+	if (x_lins < 0) {
+		/* first time initialisation */
+#ifdef TIOCGWINSZ
+		if (tty_fd < 0)
+			/* non-FTALKING, try to get an fd anyway */
+			tty_init(false, false);
+#endif
+		x_cols = -1;
+	}
+
+#ifdef TIOCGWINSZ
+	/* check if window size has changed */
+	if (tty_fd >= 0) {
+		struct winsize ws;
+
+		if (ioctl(tty_fd, TIOCGWINSZ, &ws) >= 0) {
+			if (ws.ws_col)
+				x_cols = ws.ws_col;
+			if (ws.ws_row)
+				x_lins = ws.ws_row;
+		}
+	}
+#endif
+
+	/* bounds check for sane values, use defaults otherwise */
+	if (x_cols < MIN_COLS)
+		x_cols = 80;
+	if (x_lins < MIN_LINS)
+		x_lins = 24;
+
+#ifdef SIGWINCH
+	got_winch = 0;
+#endif
+}
+
+uint32_t
+evilhash(const char *s)
+{
+	register uint32_t h = 0x100;
+
+	h = oaathash_update(h, (void *)&kshstate_f, sizeof(kshstate_f));
+	kshstate_f.h = oaathash_full((const uint8_t *)s);
+	return (oaathash_finalise(oaathash_update(h,
+	    (void *)&kshstate_f.h, sizeof(kshstate_f.h))));
+}