add “set -o arc4random”, RTFM for details

Build.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# $MirOS: src/bin/mksh/Build.sh,v 1.250 2007/07/31 11:11:23 tg Exp $
+# $MirOS: src/bin/mksh/Build.sh,v 1.251 2007/08/12 13:42:19 tg Exp $
 #-
 # Environment used: CC CFLAGS CPPFLAGS LDFLAGS LIBS NOWARN NROFF TARGET_OS
 # CPPFLAGS recognised:	MKSH_SMALL MKSH_ASSUME_UTF8 MKSH_NEED_MKNOD MKSH_NOPWNAM
@@ -760,9 +760,13 @@ if test $HAVE_ARC4RANDOM = 0 && test -f "$srcdir/arc4random.c"; then
 fi
 ac_cppflags ARC4RANDOM
 
-ac_test arc4random_push arc4random 0 <<-'EOF'
+ac_test arc4random_pushb arc4random 0 <<-'EOF'
-	extern void arc4random_push(int);
+	#include <sys/types.h>
-	int main(void) { arc4random_push(1); return (0); }
+	#if HAVE_STDINT_H
+	#include <stdint.h>
+	#endif
+	extern uint32_t arc4random_pushb(void *, size_t);
+	int main(int ac, char *av[]) { return (arc4random_pushb(*av, ac)); }
 EOF
 
 ac_test flock_ex '' 'flock and mmap' <<-'EOF'
@@ -853,11 +857,11 @@ ac_test '!' arc4random_decl arc4random 1 'if arc4random() does not need to be de
 	long arc4random(void);		/* this clashes if defined before */
 	int main(void) { return (arc4random()); }
 EOF
-ac_test '!' arc4random_push_decl arc4random_push 1 'if arc4random_push() does not need to be declared' <<-'EOF'
+ac_test '!' arc4random_pushb_decl arc4random_pushb 1 'if arc4random_pushb() does not need to be declared' <<-'EOF'
 	#define MKSH_INCLUDES_ONLY
 	#include "sh.h"
-	void arc4random_push(long);	/* this clashes if defined before */
+	int arc4random_pushb(char, int); /* this clashes if defined before */
-	int main(void) { arc4random_push(1); return (0); }
+	int main(int ac, char *av[]) { return (arc4random_pushb(**av, ac)); }
 EOF
 ac_test sys_siglist_decl sys_siglist 1 'if sys_siglist[] does not need to be declared' <<-'EOF'
 	#define MKSH_INCLUDES_ONLY

Makefile

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/Makefile,v 1.45 2007/07/31 11:11:23 tg Exp $
+# $MirOS: src/bin/mksh/Makefile,v 1.46 2007/08/12 13:42:20 tg Exp $
 #-
 # use CPPFLAGS=-DDEBUG __CRAZY=Yes to check for certain more stuff
 
@@ -17,12 +17,12 @@ CPPFLAGS+=	-DMKSH_ASSUME_UTF8 \
 		-DHAVE_GRP_H=1 -DHAVE_ULIMIT_H=0 -DHAVE_VALUES_H=0 \
 		-DHAVE_RLIM_T=1 -DHAVE_SIG_T=1 -DHAVE_SYS_SIGNAME=1 \
 		-DHAVE_SYS_SIGLIST=1 -DHAVE_STRSIGNAL=0 -DHAVE_ARC4RANDOM=1 \
-		-DHAVE_ARC4RANDOM_PUSH=1 -DHAVE_FLOCK_EX=1 \
+		-DHAVE_ARC4RANDOM_PUSHB=1 -DHAVE_FLOCK_EX=1 \
 		-DHAVE_SETLOCALE_CTYPE=0 -DHAVE_LANGINFO_CODESET=0 \
 		-DHAVE_MKNOD=1 -DHAVE_REVOKE=1 -DHAVE_SETMODE=1 \
 		-DHAVE_SETRESUGID=1 -DHAVE_SETGROUPS=1 -DHAVE_STRCASESTR=1 \
 		-DHAVE_STRLCPY=1 -DHAVE_ARC4RANDOM_DECL=1 \
-		-DHAVE_ARC4RANDOM_PUSH_DECL=1 -DHAVE_SYS_SIGLIST_DECL=1 \
+		-DHAVE_ARC4RANDOM_PUSHB_DECL=1 -DHAVE_SYS_SIGLIST_DECL=1 \
 		-DHAVE_PERSISTENT_HISTORY=1
 COPTS+=		-std=gnu99 -Wall
 .endif

check.t

@@ -1,4 +1,4 @@
-# $MirOS: src/bin/mksh/check.t,v 1.132 2007/07/31 11:11:23 tg Exp $
+# $MirOS: src/bin/mksh/check.t,v 1.133 2007/08/12 13:42:20 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 $
@@ -7,7 +7,7 @@
 # http://www.research.att.com/~gsf/public/ifs.sh
 
 expected-stdout:
-	@(#)MIRBSD KSH R30 2007/07/31
+	@(#)MIRBSD KSH R30 2007/08/12
 description:
 	Check version of shell.
 category: pdksh

jobs.c

@@ -2,7 +2,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/jobs.c,v 1.25 2007/07/22 13:34:50 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/jobs.c,v 1.26 2007/08/12 13:42:21 tg Exp $");
 
 /* Order important! */
 #define PRUNNING	0
@@ -369,6 +369,9 @@ exchild(struct op *t, int flags,
 	else
 		p->pid = i;
 
+	/* Ensure next child gets a (slightly) different $RANDOM sequence */
+	change_random((p->pid << 1) | (ischild ? 1 : 0));
+
 	/* job control set up */
 	if (Flag(FMONITOR) && !(flags&XXCOM)) {
 		int	dotty = 0;
@@ -437,8 +440,6 @@ exchild(struct op *t, int flags,
 	}
 
 	/* shell (parent) stuff */
-	/* Ensure next child gets a (slightly) different $RANDOM sequence */
-	change_random();
 	if (!(flags & XPIPEO)) {	/* last process in a job */
 		j_startjob(j);
 		if (flags & XCOPROC) {

main.c

@@ -13,7 +13,7 @@
 #include <locale.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/main.c,v 1.84 2007/07/22 13:34:51 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/main.c,v 1.85 2007/08/12 13:42:21 tg Exp $");
 
 extern char **environ;
 
@@ -222,8 +222,9 @@ main(int argc, const char *argv[])
 			setstr(pwd_v, current_wd, KSH_RETURN_ERROR);
 	}
 	ppid = getppid();
-#if !HAVE_ARC4RANDOM
+	change_random(((u_long)kshname) ^ ((u_long)time(NULL) * kshpid * ppid));
-	srand(((long)kshname) ^ ((long)time(NULL) * kshpid * ppid));
+#if HAVE_ARC4RANDOM
+	Flag(FARC4RANDOM) = 2;	/* use arc4random(3) until $RANDOM is written */
 #endif
 	setint(global("PPID"), (long)ppid);
 

misc.c

@@ -6,7 +6,7 @@
 #include <grp.h>
 #endif
 
-__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.64 2007/07/26 13:23:51 tg Exp $\t"
+__RCSID("$MirOS: src/bin/mksh/misc.c,v 1.65 2007/08/12 13:42:21 tg Exp $\t"
 	MKSH_SH_H_ID);
 
 #undef USE_CHVT
@@ -104,6 +104,9 @@ const struct shoption options[] = {
 	 * entries MUST match the order of sh_flag F* enumerations in sh.h.
 	 */
 	{ "allexport",	'a',		OF_ANY },
+#if HAVE_ARC4RANDOM
+	{ "arc4random",	  0,		OF_ANY },
+#endif
 	{ "braceexpand",  0,		OF_ANY }, /* non-standard */
 	{ "bgnice",	  0,		OF_ANY },
 	{ NULL,		'c',	    OF_CMDLINE },
@@ -232,7 +235,7 @@ change_flag(enum sh_flag f,
 	char oldval;
 
 	oldval = Flag(f);
-	Flag(f) = newval;
+	Flag(f) = newval ? 1 : 0;	/* needed for tristates */
 	if (f == FMONITOR) {
 		if (what != OF_CMDLINE && newval != oldval)
 			j_change();

mksh.1

@@ -1,7 +1,7 @@
-.\" $MirOS: src/bin/mksh/mksh.1,v 1.93 2007/07/31 15:29:40 tg Exp $
+.\" $MirOS: src/bin/mksh/mksh.1,v 1.94 2007/08/12 13:42:22 tg Exp $
 .\" $OpenBSD: ksh.1,v 1.120 2007/05/31 20:47:44 otto Exp $
 .\"
-.Dd July 31, 2007
+.Dd August 12, 2007
 .Dt MKSH 1
 .Os MirBSD
 .Sh NAME
@@ -1590,16 +1590,9 @@ if the shell doesn't know where it is.
 Every time
 .Ev RANDOM
 is referenced, it is assigned a pseudo-random number first.
-By default,
+See the description of
-.Xr arc4random 3
+.Ic set -o Ic arc4random
-is used to produce unsigned 15\-bit values (0\-32767)
+below for details.
-whose quality depends on the operating environment.
-If
-.Ev RANDOM
-is assigned a value, it is used as the seed to
-.Xr srand 3
-and subsequent references yield a semi-predictable sequence from
-.Xr rand 3 .
 .It Ev REPLY
 Default parameter for the
 .Ic read
@@ -3344,6 +3337,18 @@ during file name generation.
 Print commands and parameter assignments when they are executed, preceded by
 the value of
 .Ev PS4 .
+.It Ic arc4random
+Use
+.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.
 .It Ic bgnice
 Background jobs are run with lower priority.
 .It Ic braceexpand

sh.h

@@ -8,8 +8,8 @@
 /*	$OpenBSD: c_test.h,v 1.4 2004/12/20 11:34:26 otto Exp $	*/
 /*	$OpenBSD: tty.h,v 1.5 2004/12/20 11:34:26 otto Exp $	*/
 
-#define MKSH_SH_H_ID "$MirOS: src/bin/mksh/sh.h,v 1.167 2007/08/06 12:02:39 tg Exp $"
+#define MKSH_SH_H_ID "$MirOS: src/bin/mksh/sh.h,v 1.168 2007/08/12 13:42:23 tg Exp $"
-#define MKSH_VERSION "R30 2007/07/31"
+#define MKSH_VERSION "R30 2007/08/12"
 
 #if HAVE_SYS_PARAM_H
 #include <sys/param.h>
@@ -194,8 +194,8 @@ typedef int bool;
 extern u_int32_t arc4random(void);
 #endif
 
-#if !HAVE_ARC4RANDOM_PUSH_DECL
+#if !HAVE_ARC4RANDOM_PUSHB_DECL
-extern void arc4random_push(int);
+extern uint32_t arc4random_pushb(void *, size_t);
 #endif
 
 #if !HAVE_SETMODE
@@ -393,6 +393,9 @@ extern const struct shoption options[];
  */
 enum sh_flag {
 	FEXPORT = 0,	/* -a: export all */
+#if HAVE_ARC4RANDOM
+	FARC4RANDOM,	/* use 0:rand(3) 1:arc4random(3) 2:switch on write */
+#endif
 	FBRACEEXPAND,	/* enable {} globbing */
 	FBGNICE,	/* bgnice */
 	FCOMMAND,	/* -c: (invocation) execute specified command */
@@ -431,7 +434,7 @@ enum sh_flag {
 	FNFLAGS		/* (place holder: how many flags are there) */
 };
 
-#define Flag(f)	(shell_flags[(int) (f)])
+#define Flag(f)	(shell_flags[(int)(f)])
 
 EXTERN char shell_flags[FNFLAGS];
 
@@ -1479,7 +1482,7 @@ const char *skip_wdvarname(const char *, int);
 int is_wdvarname(const char *, int);
 int is_wdvarassign(const char *);
 char **makenv(void);
-void change_random(void);
+void change_random(uint64_t);
 int array_ref_len(const char *);
 char *arrayname(const char *);
 void set_array(const char *, int, const char **);

var.c

@@ -2,7 +2,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/var.c,v 1.42 2007/07/22 14:01:50 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/var.c,v 1.43 2007/08/12 13:42:23 tg Exp $");
 
 /*
  * Variables
@@ -23,6 +23,8 @@ static void	getspec(struct tbl *);
 static void	setspec(struct tbl *);
 static void	unsetspec(struct tbl *);
 static struct tbl *arraysearch(struct tbl *, int);
+static int rnd_get(void);
+static void rnd_set(long);
 
 /*
  * create a new block for function calls and simple commands
@@ -849,25 +851,96 @@ makenv(void)
 }
 
 /*
- * Someone has set the srand() value, therefore from now on
+ * Get us a random number, either from rand(3) or arc4random(3), with
- * we return values from rand() instead of arc4random()
+ * 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
-static int use_rand = 0;
+static uint64_t rnd_cache = 0;
+static char rnd_lastflag = 2;
 #endif
 
+static int
+rnd_get(void)
+{
+#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_cache ^= rand();
+		}
+		rnd_lastflag = Flag(FARC4RANDOM);
+	}
+	if (Flag(FARC4RANDOM)) {
+		if (rnd_cache)
+#if HAVE_ARC4RANDOM_PUSHB
+			rv = arc4random_pushb(&rnd_cache, sizeof (rnd_cache));
+#else
+			arc4random_addrandom(&rnd_cache, sizeof (rnd_cache));
+#endif
+		rnd_cache = 0;
+		return ((
+#if HAVE_ARC4RANDOM_PUSHB
+		    rv ? rv :
+#endif
+		    arc4random()) & 0x7FFF);
+	}
+#endif
+	return (rand() & 0x7FFF);
+}
+
+static void
+rnd_set(long newval)
+{
+#if HAVE_ARC4RANDOM
+	rnd_cache ^= (((uint64_t)newval) << 15) | rand();
+	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);
+}
+
 /*
  * Called after a fork in parent to bump the random number generator.
  * Done to ensure children will not get the same random number sequence
  * if the parent doesn't use $RANDOM.
  */
 void
-change_random(void)
+change_random(uint64_t newval)
 {
+	int rval = 0;
+
+	newval &= 0x00001FFFFFFFFFFF;
+	newval |= (uint64_t)rand() << 45;
+
 #if HAVE_ARC4RANDOM
-	if (use_rand)
+	if (Flag(FARC4RANDOM)) {
+		rnd_cache ^= newval;
+		return;
+	}
 #endif
-		rand();
+
+	rval += newval & 0x7FFF;
+	newval >>= 15;
+	rval += newval & 0x7FFF;
+	newval >>= 15;
+	rval += newval & 0x7FFF;
+	newval >>= 15;
+	rval += newval;
+	rval = (rval & 0x7FFF) ^ (rval >> 15);
+
+	srand(rval);
 }
 
 /*
@@ -918,12 +991,7 @@ getspec(struct tbl *vp)
 		break;
 	case V_RANDOM:
 		vp->flag &= ~SPECIAL;
-#if HAVE_ARC4RANDOM
+		setint(vp, rnd_get());
-		if (!use_rand)
-			setint(vp, arc4random() & 0x7FFF);
-		else
-#endif
-			setint(vp, rand() & 0x7FFF);
 		vp->flag |= SPECIAL;
 		break;
 	case V_HISTSIZE:
@@ -963,7 +1031,7 @@ setspec(struct tbl *vp)
 		break;
 	case V_OPTIND:
 		vp->flag &= ~SPECIAL;
-		getopts_reset((int) intval(vp));
+		getopts_reset((int)intval(vp));
 		vp->flag |= SPECIAL;
 		break;
 	case V_TMPDIR:
@@ -985,7 +1053,7 @@ setspec(struct tbl *vp)
 		break;
 	case V_HISTSIZE:
 		vp->flag &= ~SPECIAL;
-		sethistsize((int) intval(vp));
+		sethistsize((int)intval(vp));
 		vp->flag |= SPECIAL;
 		break;
 #if HAVE_PERSISTENT_HISTORY
@@ -999,13 +1067,7 @@ setspec(struct tbl *vp)
 		break;
 	case V_RANDOM:
 		vp->flag &= ~SPECIAL;
-		srand((unsigned int)intval(vp));
+		rnd_set(intval(vp));
-#if HAVE_ARC4RANDOM
-		use_rand = 1;
-#if HAVE_ARC4RANDOM_PUSH
-		arc4random_push((unsigned)vp ^ (unsigned)rand());
-#endif
-#endif
 		vp->flag |= SPECIAL;
 		break;
 	case V_SECONDS:
@@ -1026,7 +1088,7 @@ setspec(struct tbl *vp)
 	case V_LINENO:
 		vp->flag &= ~SPECIAL;
 		/* The -1 is because line numbering starts at 1. */
-		user_lineno = (unsigned int) intval(vp) - current_lineno - 1;
+		user_lineno = (unsigned int)intval(vp) - current_lineno - 1;
 		vp->flag |= SPECIAL;
 		break;
 	}