Split arc4random_uniform into it's own file, to assist other projects

now using this as upstream code.  The particular problem is systems
that contain older arc4random derivations lacking arc4random_uniform().
ok tedu miod

3 files changed, 60 insertions, 39 deletions

diff --git a/src/lib/libc/crypt/Makefile.inc b/src/lib/libc/crypt/Makefile.inc
index 2ade095162..b4f25648e3 100644
--- a/src/lib/libc/crypt/Makefile.inc
+++ b/src/lib/libc/crypt/Makefile.inc
@@ -1,8 +1,9 @@
-#       $OpenBSD: Makefile.inc,v 1.21 2014/05/16 22:11:00 jmc Exp $
+#       $OpenBSD: Makefile.inc,v 1.22 2014/07/12 13:24:54 deraadt Exp $
 
 .PATH: ${LIBCSRCDIR}/arch/${MACHINE_CPU}/crypt ${LIBCSRCDIR}/crypt
 
-SRCS+=  crypt.c crypt2.c cryptutil.c arc4random.c blowfish.c bcrypt.c
+SRCS+=  crypt.c crypt2.c cryptutil.c arc4random.c arc4random_uniform.c \
+        blowfish.c bcrypt.c
 
 MAN+=   crypt.3 blowfish.3 arc4random.3
 MLINKS+=crypt.3 setkey.3 crypt.3 crypt_checkpass.3 crypt.3 encrypt.3
diff --git a/src/lib/libc/crypt/arc4random.c b/src/lib/libc/crypt/arc4random.c
index 13b94ed111..9460af1e54 100644
--- a/src/lib/libc/crypt/arc4random.c
+++ b/src/lib/libc/crypt/arc4random.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: arc4random.c,v 1.40 2014/07/09 16:52:09 bcook Exp $   */
+/*      $OpenBSD: arc4random.c,v 1.41 2014/07/12 13:24:54 deraadt Exp $ */
 
 /*
  * Copyright (c) 1996, David Mazieres <dm@uun.org>
@@ -211,39 +211,3 @@ arc4random_buf(void *buf, size_t n)
         _rs_random_buf(buf, n);
         _ARC4_UNLOCK();
 }
-
-/*
- * 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;
-}
diff --git a/src/lib/libc/crypt/arc4random_uniform.c b/src/lib/libc/crypt/arc4random_uniform.c
new file mode 100644
index 0000000000..1aa9a622f1
--- /dev/null
+++ b/src/lib/libc/crypt/arc4random_uniform.c
@@ -0,0 +1,56 @@
+/*      $OpenBSD: arc4random_uniform.c,v 1.1 2014/07/12 13:24:54 deraadt Exp $  */
+
+/*
+ * Copyright (c) 2008, Damien Miller <djm@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.
+ */
+
+#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;
+}