svn commit: r346420 - in head: lib/libc/gen share/man/man9 sys/conf sys/libkern sys/sys

Conrad Meyer cem at FreeBSD.org
Fri Apr 19 22:08:20 UTC 2019 

Author: cem
Date: Fri Apr 19 22:08:17 2019
New Revision: 346420
URL: https://svnweb.freebsd.org/changeset/base/346420

Log:
  Revert r346410 and r346411
  
  libkern in .PATH has too many filename conflicts with libc and my -DNO_CLEAN
  tinderbox didn't catch that ahead of time.  Mea culpa.

Added:
  head/lib/libc/gen/arc4random_uniform.c
     - copied unchanged from r346409, head/lib/libc/gen/arc4random_uniform.c
Deleted:
  head/sys/libkern/arc4random_uniform.c
Modified:
  head/lib/libc/gen/Makefile.inc
  head/share/man/man9/Makefile
  head/share/man/man9/random.9
  head/sys/conf/files
  head/sys/sys/libkern.h
  head/sys/sys/param.h

Modified: head/lib/libc/gen/Makefile.inc
==============================================================================
--- head/lib/libc/gen/Makefile.inc	Fri Apr 19 21:58:51 2019	(r346419)
+++ head/lib/libc/gen/Makefile.inc	Fri Apr 19 22:08:17 2019	(r346420)
@@ -3,7 +3,6 @@
 
 # machine-independent gen sources
 .PATH: ${LIBC_SRCTOP}/${LIBC_ARCH}/gen ${LIBC_SRCTOP}/gen
-.PATH: ${SRCTOP}/sys/libkern
 
 CONFS=	shells
 

Copied: head/lib/libc/gen/arc4random_uniform.c (from r346409, head/lib/libc/gen/arc4random_uniform.c)
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ head/lib/libc/gen/arc4random_uniform.c	Fri Apr 19 22:08:17 2019	(r346420, copy of r346409, head/lib/libc/gen/arc4random_uniform.c)
@@ -0,0 +1,58 @@
+/*	$OpenBSD: arc4random_uniform.c,v 1.2 2015/09/13 08:31:47 guenther Exp $	*/
+
+/*
+ * Copyright (c) 2008, Damien Miller <djm at openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * $FreeBSD$
+ */
+
+#include <sys/types.h>
+#include <stdlib.h>
+
+/*
+ * Calculate a uniformly distributed random number less than upper_bound
+ * avoiding "modulo bias".
+ *
+ * Uniformity is achieved by generating new random numbers until the one
+ * returned is outside the range [0, 2**32 % upper_bound).  This
+ * guarantees the selected random number will be inside
+ * [2**32 % upper_bound, 2**32) which maps back to [0, upper_bound)
+ * after reduction modulo upper_bound.
+ */
+uint32_t
+arc4random_uniform(uint32_t upper_bound)
+{
+	uint32_t r, min;
+
+	if (upper_bound < 2)
+		return 0;
+
+	/* 2**32 % x == (2**32 - x) % x */
+	min = -upper_bound % upper_bound;
+
+	/*
+	 * This could theoretically loop forever but each retry has
+	 * p > 0.5 (worst case, usually far better) of selecting a
+	 * number inside the range we need, so it should rarely need
+	 * to re-roll.
+	 */
+	for (;;) {
+		r = arc4random();
+		if (r >= min)
+			break;
+	}
+
+	return r % upper_bound;
+}

Modified: head/share/man/man9/Makefile
==============================================================================
--- head/share/man/man9/Makefile	Fri Apr 19 21:58:51 2019	(r346419)
+++ head/share/man/man9/Makefile	Fri Apr 19 22:08:17 2019	(r346420)
@@ -1668,8 +1668,6 @@ MLINKS+=psignal.9 gsignal.9 \
 	psignal.9 tdsignal.9
 MLINKS+=random.9 arc4rand.9 \
 	random.9 arc4random.9 \
-	random.9 arc4random_buf.9 \
-	random.9 arc4random_uniform.9 \
 	random.9 is_random_seeded.9 \
 	random.9 read_random.9 \
 	random.9 read_random_uio.9 \

Modified: head/share/man/man9/random.9
==============================================================================
--- head/share/man/man9/random.9	Fri Apr 19 21:58:51 2019	(r346419)
+++ head/share/man/man9/random.9	Fri Apr 19 22:08:17 2019	(r346420)
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\" "
-.Dd April 19, 2019
+.Dd April 16, 2019
 .Dt RANDOM 9
 .Os
 .Sh NAME
@@ -45,8 +45,6 @@
 .Fn arc4random "void"
 .Ft void
 .Fn arc4random_buf "void *ptr" "size_t len"
-.Ft uint32_t
-.Fn arc4random_uniform "uint32_t upper_bound"
 .Ft void
 .Fn arc4rand "void *ptr" "u_int length" "int reseed"
 .Pp
@@ -81,15 +79,6 @@ fills
 with
 .Fa len
 bytes of random data.
-.Pp
-.Fn arc4random_uniform
-will return a single 32-bit value, uniformly distributed but less than
-.Fa upper_bound .
-This is recommended over constructions like
-.Dq Li arc4random() % upper_bound
-as it avoids "modulo bias" when the upper bound is not a power of two.
-In the worst case, this function may consume multiple iterations
-to ensure uniformity.
 .Pp
 The
 .Fn arc4rand

Modified: head/sys/conf/files
==============================================================================
--- head/sys/conf/files	Fri Apr 19 21:58:51 2019	(r346419)
+++ head/sys/conf/files	Fri Apr 19 22:08:17 2019	(r346420)
@@ -3985,7 +3985,6 @@ kgssapi/gsstest.c		optional kgssapi_debug
 # the file should be moved to conf/files.<arch> from here.
 #
 libkern/arc4random.c		standard
-libkern/arc4random_uniform.c	standard
 crypto/chacha20/chacha.c	standard
 libkern/asprintf.c		standard
 libkern/bcd.c			standard

Modified: head/sys/sys/libkern.h
==============================================================================
--- head/sys/sys/libkern.h	Fri Apr 19 21:58:51 2019	(r346419)
+++ head/sys/sys/libkern.h	Fri Apr 19 22:08:17 2019	(r346420)
@@ -128,7 +128,6 @@ struct malloc_type;
 uint32_t arc4random(void);
 void	 arc4random_buf(void *, size_t);
 void	 arc4rand(void *, u_int, int);
-uint32_t arc4random_uniform(uint32_t);
 int	 timingsafe_bcmp(const void *, const void *, size_t);
 void	*bsearch(const void *, const void *, size_t,
 	    size_t, int (*)(const void *, const void *));

Modified: head/sys/sys/param.h
==============================================================================
--- head/sys/sys/param.h	Fri Apr 19 21:58:51 2019	(r346419)
+++ head/sys/sys/param.h	Fri Apr 19 22:08:17 2019	(r346420)
@@ -60,7 +60,7 @@
  *		in the range 5 to 9.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1300021	/* Master, propagated to newvers */
+#define __FreeBSD_version 1300020	/* Master, propagated to newvers */
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,

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