From a59d14b56593058e17638602d9fe0908928080bb Mon Sep 17 00:00:00 2001
From: tg <tg@mirbsd.org>
Date: Sat, 26 Sep 2009 03:40:03 +0000
Subject: [PATCH] further optimise and simplify the handling of $RANDOM, reads
 and writes to it are now either arc4random or rand/srand, but srand retains
 the old state; set +o arc4random is no longer possible, but if it's there we
 use arc4random(3), if not, we use rand(3) for $RANDOM reads; optimise special
 variable handling too and fix a few consts and other minor things

---
 check.t    |   8 +--
 funcs.c    |   6 +-
 jobs.c     |   6 +-
 main.c     |  84 +++++++++++------------
 mksh.1     |  26 +++-----
 sh.h       |  30 +++------
 sh_flags.h |   7 +-
 syn.c      |   4 +-
 var.c      | 190 ++++++++++++++---------------------------------------
 var_spec.h |  39 +++++++++++
 10 files changed, 158 insertions(+), 242 deletions(-)
 create mode 100644 var_spec.h

diff --git a/check.t b/check.t
index 0c2e5e0..0e561f4 100644
--- a/check.t
+++ b/check.t
@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.310 2009/09/24 17:15:29 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.311 2009/09/26 03:39:57 tg Exp $
 # $OpenBSD: bksl-nl.t,v 1.2 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: history.t,v 1.5 2001/01/28 23:04:56 niklas Exp $
 # $OpenBSD: read.t,v 1.3 2003/03/10 03:48:16 david Exp $
@@ -25,7 +25,7 @@
 # http://www.research.att.com/~gsf/public/ifs.sh
 
 expected-stdout:
-	@(#)MIRBSD KSH R39 2009/09/24
+	@(#)MIRBSD KSH R39 2009/09/25
 description:
 	Check version of shell.
 stdin:
@@ -4042,8 +4042,8 @@ description:
 	isn't exec-ed
 stdin:
 	sortprog=$(whence -p sort) || sortprog=cat
-	env | $sortprog >bar1
-	FOO=bar exec; env | $sortprog >bar2
+	env | $sortprog | grep -v '^RANDOM=' >bar1
+	FOO=bar exec; env | $sortprog | grep -v '^RANDOM=' >bar2
 	cmp -s bar1 bar2
 ---
 name: xxx-what-do-you-call-this-1
diff --git a/funcs.c b/funcs.c
index e5f20d8..485335f 100644
--- a/funcs.c
+++ b/funcs.c
@@ -25,7 +25,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/funcs.c,v 1.134 2009/09/23 18:04:56 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/funcs.c,v 1.135 2009/09/26 03:39:58 tg Exp $");
 
 #if HAVE_KILLPG
 /*
@@ -94,7 +94,7 @@ const struct builtin mkshbuiltins[] = {
 #endif
 	{"pwd", c_pwd},
 	{"*=readonly", c_typeset},
-	{"=typeset", c_typeset},
+	{T__typeset, c_typeset},
 	{"+unalias", c_unalias},
 	{"whence", c_whence},
 #ifndef MKSH_UNEMPLOYED
@@ -2309,7 +2309,7 @@ c_set(const char **wp)
 	const char **owp;
 
 	if (wp[1] == NULL) {
-		static const char *args [] = { "set", "-", NULL };
+		static const char *args[] = { "set", "-", NULL };
 		return (c_typeset(args));
 	}
 
diff --git a/jobs.c b/jobs.c
index 76bce7e..b7c526a 100644
--- a/jobs.c
+++ b/jobs.c
@@ -22,7 +22,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/jobs.c,v 1.60 2009/09/20 16:40:55 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/jobs.c,v 1.61 2009/09/26 03:39:59 tg Exp $");
 
 #if HAVE_KILLPG
 #define mksh_killpg		killpg
@@ -416,8 +416,8 @@ exchild(struct op *t, int flags,
 	else
 		p->pid = i;
 
-#if !HAVE_ARC4RANDOM || !defined(MKSH_SMALL)
-	/* Ensure next child gets a (slightly) different $RANDOM sequence */
+#if !HAVE_ARC4RANDOM
+	/* ensure next child gets a (slightly) different $RANDOM sequence */
 	change_random(((unsigned long)p->pid << 1) | (ischild ? 1 : 0));
 #endif
 
diff --git a/main.c b/main.c
index dc8b3ff..001a215 100644
--- a/main.c
+++ b/main.c
@@ -33,7 +33,7 @@
 #include <locale.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/main.c,v 1.148 2009/09/26 01:08:27 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/main.c,v 1.149 2009/09/26 03:40:00 tg Exp $");
 
 extern char **environ;
 
@@ -47,17 +47,17 @@ static void remove_temps(struct temp *);
 
 static const char initifs[] = "IFS= \t\n";
 
-static const char initsubs[] = "${PS2=> } ${PS3=#? } ${PS4=+ }";
+static const char initsubs[] =
+    "${PS2=> } ${PS3=#? } ${PS4=+ } ${SECONDS=0} ${TMOUT=0}";
 
 static const char *initcoms[] = {
-	"typeset", "-r", initvsn, NULL,
-	"typeset", "-x", "SHELL", "PATH", "HOME", NULL,
-	"typeset", "-i10", "COLUMNS=0", "LINES=0", "OPTIND=1", NULL,
-	"typeset", "-Ui10", "PGRP", "PPID", "RANDOM", "USER_ID", NULL,
-	"eval", "typeset -i10 SECONDS=\"${SECONDS-0}\" TMOUT=\"${TMOUT-0}\"",
-	NULL,
-	"alias", "integer=typeset -i", "local=typeset", NULL,
+	T_typeset, "-r", initvsn, NULL,
+	T_typeset, "-x", "HOME", "PATH", "RANDOM", "SHELL", NULL,
+	T_typeset, "-i10", "COLUMNS", "LINES", "OPTIND", "PGRP", "PPID",
+	    "RANDOM", "SECONDS", "TMOUT", "USER_ID", NULL,
 	"alias",
+	"integer=typeset -i",
+	T_local_typeset,
 	"hash=alias -t",	/* not "alias -t --": hash -r needs to work */
 	"type=whence -v",
 #ifndef MKSH_UNEMPLOYED
@@ -101,8 +101,14 @@ main(int argc, const char *argv[])
 	char *cp;
 #endif
 
+	kshpid = procpid = getpid();
+	ksheuid = geteuid();
+	kshpgrp = getpgrp();
+	ppid = getppid();
+
 #if !HAVE_ARC4RANDOM
-	change_random((unsigned long)time(NULL) * getpid());
+	change_random((unsigned long)time(NULL));
+	change_random(((unsigned long)ksheuid << 16) | kshpid);
 #endif
 
 	/* make sure argv[] is sane */
@@ -204,13 +210,14 @@ main(int argc, const char *argv[])
 #endif
 
 #ifdef MKSH_BINSHREDUCED
-	/* Set FPOSIX if we're called as -sh or /bin/sh or so */
+	/* set FPOSIX if we're called as -sh or /bin/sh or so */
 	{
 		const char *cc;
 
 		cc = kshname;
 		i = 0; argi = 0;
 		while (cc[i] != '\0')
+			/* the following line matches '-' and '/' ;-) */
 			if ((cc[i++] | 2) == '/')
 				argi = i;
 		if (((cc[argi] | 0x20) == 's') && ((cc[argi + 1] | 0x20) == 'h'))
@@ -223,7 +230,6 @@ main(int argc, const char *argv[])
 		for (wp = (const char **)environ; *wp != NULL; wp++)
 			typeset(*wp, IMPORT | EXPORT, 0, 0, 0);
 
-	kshpid = procpid = getpid();
 	typeset(initifs, 0, 0, 0, 0);	/* for security */
 
 	/* assign default shell variable values */
@@ -252,31 +258,38 @@ main(int argc, const char *argv[])
 			/* setstr can't fail here */
 			setstr(pwd_v, current_wd, KSH_RETURN_ERROR);
 	}
-	ppid = getppid();
-#if !HAVE_ARC4RANDOM || !defined(MKSH_SMALL)
-	change_random(((unsigned long)kshname) ^
-	    ((unsigned long)time(NULL) * kshpid * ppid));
-#endif
-#if HAVE_ARC4RANDOM
-	Flag(FARC4RANDOM) = 2;	/* use arc4random(3) until $RANDOM is written */
-#endif
 
 	for (wp = initcoms; *wp != NULL; wp++) {
 		shcomexec(wp);
 		while (*wp != NULL)
 			wp++;
 	}
+	setint(global("COLUMNS"), 0);
+	setint(global("LINES"), 0);
+	setint(global("OPTIND"), 1);
+	vp = global("RANDOM");
+#if HAVE_ARC4RANDOM
+	/* avoid calling setspec */
+	Flag(FARC4RANDOM) = 1;
+	vp->flag |= ISSET | INT_U;
+#else
+	vp->flag |= INT_U;
+	setint(vp, (mksh_ari_t)((unsigned long)kshname + 33 * ppid));
+#endif
 
-	safe_prompt = (ksheuid = geteuid()) ? "$ " : "# ";
+	safe_prompt = ksheuid ? "$ " : "# ";
 	vp = global("PS1");
 	/* Set PS1 if unset or we are root and prompt doesn't contain a # */
 	if (!(vp->flag & ISSET) ||
 	    (!ksheuid && !strchr(str_val(vp), '#')))
 		/* setstr can't fail here */
 		setstr(vp, safe_prompt, KSH_RETURN_ERROR);
-	setint(global("PGRP"), (mksh_uari_t)(kshpgrp = getpgrp()));
-	setint(global("PPID"), (mksh_uari_t)ppid);
-	setint(global("USER_ID"), (mksh_uari_t)ksheuid);
+	setint((vp = global("PGRP")), (mksh_uari_t)kshpgrp);
+	vp->flag |= INT_U;
+	setint((vp = global("PPID")), (mksh_uari_t)ppid);
+	vp->flag |= INT_U;
+	setint((vp = global("USER_ID")), (mksh_uari_t)ksheuid);
+	vp->flag |= INT_U;
 
 	/* Set this before parsing arguments */
 #if HAVE_SETRESUGID
@@ -408,7 +421,7 @@ main(int argc, const char *argv[])
 
 	if (restricted) {
 		static const char *restr_com[] = {
-			"typeset", "-r", "PATH",
+			T_typeset, "-r", "PATH",
 			"ENV", "SHELL",
 			NULL
 		};
@@ -1263,27 +1276,6 @@ hash(const char *cp)
 	return (h);
 }
 
-#if !HAVE_ARC4RANDOM || !defined(MKSH_SMALL)
-uint32_t
-hashmem(const void *cp, size_t len)
-{
-	register uint32_t h = 0;
-	register const uint8_t *bp = (const uint8_t *)cp;
-
-	while (len--) {
-		h += *bp++;
-		h += h << 10;
-		h ^= h >> 6;
-	}
-
-	h += h << 3;
-	h ^= h >> 11;
-	h += h << 15;
-
-	return (h);
-}
-#endif
-
 static void
 texpand(struct table *tp, size_t nsize)
 {
diff --git a/mksh.1 b/mksh.1
index 5f0a40c..1b41e25 100644
--- a/mksh.1
+++ b/mksh.1
@@ -1,4 +1,4 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.191 2009/09/20 17:23:51 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.192 2009/09/26 03:40:00 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.129 2009/05/28 06:09:06 jmc Exp $
 .\"-
 .\" Copyright © 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
@@ -48,7 +48,7 @@
 .el .xD \\$1 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8
 ..
 .\"-
-.Dd $Mdocdate: September 20 2009 $
+.Dd $Mdocdate: September 26 2009 $
 .Dt MKSH 1
 .Os MirBSD
 .Sh NAME
@@ -1807,10 +1807,11 @@ if the shell doesn't know where it is.
 Every time
 .Ev RANDOM
 is referenced, it is assigned a 15-bit pseudo-random number, i.e. between
-0 and 32767, first.
-See the description of
-.Ic set \-o Ic arc4random
-below for details.
+0 and 32767, first, which is taken from
+.Xr arc4random 3
+if available,
+.Xr rand 3
+otherwise.
 .It Ev REPLY
 Default parameter for the
 .Ic read
@@ -3735,17 +3736,10 @@ Print commands and parameter assignments when they are executed, preceded by
 the value of
 .Ev PS4 .
 .It Ic arc4random
-Use
+If this shell option, which cannot be unset, exists,
 .Xr arc4random 3
-high-quality random numbers for the value of
-.Ev RANDOM
-if set (to either 1 or 2), or a semi-predictable sequence from
-.Xr rand 3
-if unset.
-Setting this flag will change its value to 1; the default value is 2,
-which means it automatically switches to 0 if
-.Ev RANDOM
-is written to.
+is used for the value of
+.Ev RANDOM .
 .It Ic bgnice
 Background jobs are run with lower priority.
 .It Ic braceexpand
diff --git a/sh.h b/sh.h
index 7305375..ec4a087 100644
--- a/sh.h
+++ b/sh.h
@@ -134,9 +134,9 @@
 #endif
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.348 2009/09/24 17:15:32 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.349 2009/09/26 03:40:01 tg Exp $");
 #endif
-#define MKSH_VERSION "R39 2009/09/24"
+#define MKSH_VERSION "R39 2009/09/25"
 
 #ifndef MKSH_INCLUDES_ONLY
 
@@ -567,8 +567,11 @@ EXTERN char null[] I__("");
 /* helpers for string pooling */
 #define T_synerr "syntax error"
 EXTERN const char r_fc_e_[] I__("r=fc -e -");
-#define fc_e_	(r_fc_e_ + 2)		/* "fc -e -" */
-#define fc_e_n	7			/* strlen(fc_e_) */
+#define fc_e_		(r_fc_e_ + 2)		/* "fc -e -" */
+#define fc_e_n		7			/* strlen(fc_e_) */
+EXTERN const char T_local_typeset[] I__("local=typeset");
+#define T__typeset	(T_local_typeset + 5)	/* "=typeset" */
+#define T_typeset	(T_local_typeset + 6)	/* "typeset" */
 
 enum temp_type {
 	TT_HEREDOC_EXP,	/* expanded heredoc */
@@ -963,21 +966,6 @@ struct builtin {
 
 extern const struct builtin mkshbuiltins[];
 
-/* var spec values */
-#define V_NONE		0
-#define V_COLUMNS	1
-#define V_HISTFILE	2
-#define V_HISTSIZE	3
-#define V_IFS		4
-#define V_LINENO	5
-#define V_LINES		6
-#define V_OPTIND	7
-#define V_PATH		8
-#define V_RANDOM	9
-#define V_SECONDS	10
-#define V_TMOUT		11
-#define V_TMPDIR	12
-
 /* values for set_prompt() */
 #define PS1	0	/* command */
 #define PS2	1	/* command continuation */
@@ -1601,11 +1589,9 @@ void initvar(void);
 struct tbl *global(const char *);
 struct tbl *local(const char *, bool);
 char *str_val(struct tbl *);
-mksh_ari_t intval(struct tbl *);
 int setstr(struct tbl *, const char *, int);
 struct tbl *setint_v(struct tbl *, struct tbl *, bool);
 void setint(struct tbl *, mksh_ari_t);
-int getint(struct tbl *, mksh_ari_t *, bool);
 struct tbl *typeset(const char *, Tflag, Tflag, int, int);
 void unset(struct tbl *, int);
 const char *skip_varname(const char *, int);
@@ -1613,7 +1599,7 @@ const char *skip_wdvarname(const char *, int);
 int is_wdvarname(const char *, int);
 int is_wdvarassign(const char *);
 char **makenv(void);
-#if !HAVE_ARC4RANDOM || !defined(MKSH_SMALL)
+#if !HAVE_ARC4RANDOM
 void change_random(unsigned long);
 #endif
 void change_winsz(void);
diff --git a/sh_flags.h b/sh_flags.h
index 689f2e9..82e0385 100644
--- a/sh_flags.h
+++ b/sh_flags.h
@@ -1,5 +1,5 @@
 #if defined(SHFLAGS_DEFNS)
-__RCSID("$MirOS: src/bin/mksh/sh_flags.h,v 1.2 2009/09/24 17:15:33 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh_flags.h,v 1.3 2009/09/26 03:40:02 tg Exp $");
 #define FN(sname,cname,ochar,flags)	/* nothing */
 #elif defined(SHFLAGS_ENUMS)
 #define FN(sname,cname,ochar,flags)	cname,
@@ -22,9 +22,8 @@ __RCSID("$MirOS: src/bin/mksh/sh_flags.h,v 1.2 2009/09/24 17:15:33 tg Exp $");
 F0("allexport", FEXPORT, 'a', OF_ANY)
 
 #if HAVE_ARC4RANDOM
-/* ./.	for $RANDOM (non-standard), use the following function scheme: */
-/*	  0:rand(3)  1:arc4random(3)  2:switch from 1 to 0 on write */
-FN("arc4random", FARC4RANDOM, 0, OF_ANY)
+/* ./.	backwards compat: available if arc4random(3) is used for $RANDOM */
+FN("arc4random", FARC4RANDOM, 0, OF_INTERNAL)
 #endif
 
 #if HAVE_NICE
diff --git a/syn.c b/syn.c
index bd26e02..f3d771c 100644
--- a/syn.c
+++ b/syn.c
@@ -22,7 +22,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/syn.c,v 1.43 2009/09/23 18:04:58 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/syn.c,v 1.44 2009/09/26 03:40:02 tg Exp $");
 
 struct nesting_state {
 	int start_token;	/* token than began nesting (eg, FOR) */
@@ -877,7 +877,7 @@ assign_command(char *s)
 	return ((strcmp(s, "alias") == 0) ||
 	    (strcmp(s, "export") == 0) ||
 	    (strcmp(s, "readonly") == 0) ||
-	    (strcmp(s, "typeset") == 0));
+	    (strcmp(s, T_typeset) == 0));
 }
 
 /* Check if we are in the middle of reading an alias */
diff --git a/var.c b/var.c
index 7bb09fd..cdd737d 100644
--- a/var.c
+++ b/var.c
@@ -22,7 +22,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/var.c,v 1.91 2009/09/23 18:22:38 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/var.c,v 1.92 2009/09/26 03:40:02 tg Exp $");
 
 /*
  * Variables
@@ -42,10 +42,16 @@ 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 int rnd_get(void);
+#if HAVE_ARC4RANDOM
 static void rnd_set(unsigned long);
+#else
+#define rnd_set change_random
+#endif
 
 uint8_t set_refflag = 0;
 
@@ -101,38 +107,33 @@ popblock(void)
 }
 
 /* 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)
 {
-	static const struct {
-		const char *name;
-		int v;
-	} names[] = {
-		{ "COLUMNS",		V_COLUMNS },
-#if HAVE_PERSISTENT_HISTORY
-		{ "HISTFILE",		V_HISTFILE },
-#endif
-		{ "HISTSIZE",		V_HISTSIZE },
-		{ "IFS",		V_IFS },
-		{ "LINENO",		V_LINENO },
-		{ "LINES",		V_LINES },
-		{ "OPTIND",		V_OPTIND },
-		{ "PATH",		V_PATH },
-		{ "RANDOM",		V_RANDOM },
-		{ "SECONDS",		V_SECONDS },
-		{ "TMOUT",		V_TMOUT },
-		{ "TMPDIR",		V_TMPDIR },
-		{ NULL,			0 }
-	};
-	int i;
+	int i = 0;
 	struct tbl *tp;
 
 	ktinit(&specials, APERM,
 	    /* must be 80% of 2^n (currently 12 specials) */ 16);
-	for (i = 0; names[i].name; i++) {
-		tp = ktenter(&specials, names[i].name, hash(names[i].name));
+	while (i < V_MAX - 1) {
+		tp = ktenter(&specials, initvar_names[i],
+		    hash(initvar_names[i]));
 		tp->flag = DEFINED|ISSET;
-		tp->type = names[i].v;
+		tp->type = ++i;
 	}
 }
 
@@ -384,7 +385,7 @@ str_val(struct tbl *vp)
 }
 
 /* get variable integer value, with error checking */
-mksh_ari_t
+static mksh_ari_t
 intval(struct tbl *vp)
 {
 	mksh_ari_t num;
@@ -461,7 +462,7 @@ setint(struct tbl *vq, mksh_ari_t n)
 		setspec(vq);
 }
 
-int
+static int
 getint(struct tbl *vp, mksh_ari_t *nump, bool arith)
 {
 	char *s;
@@ -964,150 +965,55 @@ makenv(void)
 	return ((char **)XPclose(denv));
 }
 
-/*
- * Get us a random number, either from rand(3) or arc4random(3), with
- * the latter being preferred. If Flag(FARC4RANDOM) is 0, we use rand(3),
- * otherwise arc4random(3). We have static caches to make change_random
- * and writes to $RANDOM a cheap operation.
- */
-#if HAVE_ARC4RANDOM && !defined(MKSH_SMALL)
-static uint32_t rnd_cache[2];
-static unsigned char rnd_lastflag = 2;
-#if HAVE_ARC4RANDOM_PUSHB
-static bool rnd_wpush = false;
-#define rnd_mix(v,w) rnd_cmix(v,w)
-#else
-#define rnd_mix(v,w) rnd_cmix(v)
-#endif
-
-static void rnd_mix(unsigned long, bool);
-
-static void
-rnd_mix(unsigned long newval, bool wantpush)
-{
-	struct {
-		union {
-			int rval;
-			uint32_t arval;
-		} v0;
-		uint32_t v1;
-		uint32_t v2;
-		unsigned long v3;
-#if HAVE_ARC4RANDOM_PUSHB
-		bool neededpush;
-		bool wantingpush;
-#endif
-	} v;
-
-#if HAVE_ARC4RANDOM_PUSHB
-	v.neededpush = rnd_wpush;
-	v.wantingpush = wantpush;
-	rnd_wpush = v.neededpush || v.wantingpush;
-#endif
-
-	v.v0.rval = rand();
-	v.v1 = rnd_cache[0];
-	v.v2 = rnd_cache[1];
-	v.v3 = newval;
-
-	rnd_cache[0] = hashmem(&v, sizeof(v));
-	v.v0.arval = arc4random();
-	rnd_cache[1] = hashmem(&v, sizeof(v));
-}
-#endif
-
+#if HAVE_ARC4RANDOM
 static int
 rnd_get(void)
 {
-#if HAVE_ARC4RANDOM && defined(MKSH_SMALL)
 	return (arc4random() & 0x7FFF);
-#else
-#if HAVE_ARC4RANDOM
-#if HAVE_ARC4RANDOM_PUSHB
-	uint32_t rv = 0;
-#endif
-	if (Flag(FARC4RANDOM) != rnd_lastflag) {
-		if (Flag(FARC4RANDOM) == 0)
-			/* transition to 0 by set: srand */
-			srand(arc4random() & 0x7FFF);
-		else if (rnd_lastflag == 0)
-			/* transition from 0: addrandom */
-			rnd_mix(rand(), true);
-		rnd_lastflag = Flag(FARC4RANDOM);
-	}
-	if (Flag(FARC4RANDOM)) {
-		if (rnd_cache[0] || rnd_cache[1]) {
-#if HAVE_ARC4RANDOM_PUSHB
-			if (rnd_wpush) {
-				rv = arc4random_pushb(rnd_cache,
-				    sizeof(rnd_cache));
-				rnd_wpush = false;
-			} else
-#endif
-			arc4random_addrandom((void *)rnd_cache,
-			    sizeof(rnd_cache));
-		}
-		rnd_cache[0] = rnd_cache[1] = 0;
-		return ((
-#if HAVE_ARC4RANDOM_PUSHB
-		    rv ? rv :
-#endif
-		    arc4random()) & 0x7FFF);
-	}
-#endif
-	return (rand() & 0x7FFF);
-#endif
 }
 
 static void
 rnd_set(unsigned long newval)
 {
-#if HAVE_ARC4RANDOM && defined(MKSH_SMALL)
 #if HAVE_ARC4RANDOM_PUSHB
 	arc4random_pushb(&newval, sizeof(newval));
 #else
 	arc4random_addrandom((void *)&newval, sizeof(newval));
 #endif
+}
 #else
-#if HAVE_ARC4RANDOM
-	rnd_mix(newval, true);
-	if (Flag(FARC4RANDOM) == 1)
-		return;
-	if (Flag(FARC4RANDOM) == 2)
-		Flag(FARC4RANDOM) = 0;
-	/* transition to 0 by write: only srand */
-	rnd_lastflag = 0;
-#endif
-	srand(newval & 0x7FFF);
-#endif
+static int
+rnd_get(void)
+{
+	return (rand() & 0x7FFF);
 }
 
-#if !HAVE_ARC4RANDOM || !defined(MKSH_SMALL)
 /*
  * Called after a fork to bump the random number generator.
  * Done to ensure children will not get the same random number sequence
  * as the parent processes.
+ * Also called as rnd_set - mksh R40+ no longer has the traditional
+ * repeatability of randomness sequences, state is always retained.
  */
 void
 change_random(unsigned long newval)
 {
-	int rval = 0;
+	register unsigned int h;
 
-#if HAVE_ARC4RANDOM
-	if (Flag(FARC4RANDOM)) {
-		rnd_mix(newval, false);
-		return;
+	h = rand();
+	while (newval) {
+		h += (newval & 0xFF);
+		h += h << 10;
+		h ^= h >> 6;
+		newval >>= 8;
 	}
-#endif
 
-	rval += newval & 0x7FFF;
-	newval >>= 15;
-	rval += newval & 0x7FFF;
-	newval >>= 15;
-	rval += newval + rand();
-	rval = (rval & 0x7FFF) ^ (rval >> 15);
+	h += h << 3;
+	h ^= h >> 11;
+	h += h << 15;
 
-	srand(rval);
+	/* pass all of it, in case RAND_MAX is large */
+	srand(h);
 }
 #endif
 
diff --git a/var_spec.h b/var_spec.h
new file mode 100644
index 0000000..4035cc9
--- /dev/null
+++ b/var_spec.h
@@ -0,0 +1,39 @@
+#if defined(VARSPEC_DEFNS)
+__RCSID("$MirOS: src/bin/mksh/var_spec.h,v 1.1 2009/09/26 03:40:03 tg Exp $");
+#define FN(name)			/* nothing */
+#elif defined(VARSPEC_ENUMS)
+#define FN(name)			V_##name,
+#define F0(name)			V_##name = 0,
+#elif defined(VARSPEC_ITEMS)
+#define F0(name)			/* nothing */
+#define FN(name)			#name,
+#endif
+
+#ifndef F0
+#define F0 FN
+#endif
+
+/* 0 is always V_NONE */
+F0(NONE)
+
+/* 1 and up are special variables */
+FN(COLUMNS)
+#if HAVE_PERSISTENT_HISTORY
+FN(HISTFILE)
+#endif
+FN(HISTSIZE)
+FN(IFS)
+FN(LINENO)
+FN(LINES)
+FN(OPTIND)
+FN(PATH)
+FN(RANDOM)
+FN(SECONDS)
+FN(TMOUT)
+FN(TMPDIR)
+
+#undef FN
+#undef F0
+#undef VARSPEC_DEFNS
+#undef VARSPEC_ENUMS
+#undef VARSPEC_ITEMS