From 54c91185c9273b9699693910fa95383c86f2af22 Mon Sep 17 00:00:00 2001
From: David CARLIER <devnexen@gmail.com>
Date: Sat, 16 Jan 2021 12:47:33 +0000
Subject: [PATCH] random generator update for Mac proposal

using getentropy for seeding, reading 256 bytes at a time to avoid
 the EIO errno since this is the maximum.
---
 configure.ac |  1 +
 random.c     | 20 ++++++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 3d1c5b6225..f672f6d7f7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1876,6 +1876,7 @@ AC_CHECK_FUNCS(ftruncate)
 AC_CHECK_FUNCS(ftruncate64)		# used for Win32 platform
 AC_CHECK_FUNCS(getattrlist)
 AC_CHECK_FUNCS(getcwd)
+AC_CHECK_FUNCS(getentropy)
 AC_CHECK_FUNCS(getgidx)
 AC_CHECK_FUNCS(getgrnam)
 AC_CHECK_FUNCS(getgrnam_r)
diff --git a/random.c b/random.c
index 28b7a9fba4..7b78efe7ca 100644
--- a/random.c
+++ b/random.c
@@ -49,7 +49,7 @@
 # include <sys/param.h>
 #endif
 
-#if defined HAVE_GETRANDOM
+#if defined HAVE_GETRANDOM || defined HAVE_GETENTROPY
 # include <sys/random.h>
 #elif defined __linux__ && defined __NR_getrandom
 # include <linux/random.h>
@@ -425,7 +425,23 @@ random_init(int argc, VALUE *argv, VALUE obj)
 # define USE_DEV_URANDOM 0
 #endif
 
-#if USE_DEV_URANDOM
+#if HAVE_GETENTROPY
+# define MAX_SEED_LEN_PER_READ 256
+static int
+fill_random_bytes_urandom(void *seed, size_t size)
+{
+     unsigned char *p = (unsigned char *)seed;
+     while (size) {
+	size_t len = size < MAX_SEED_LEN_PER_READ ? size : MAX_SEED_LEN_PER_READ;
+	if (getentropy(p, len) != 0) {
+            return -1;
+	}
+	p += len;
+	size -= len;
+     }
+     return 0;
+}
+#elif USE_DEV_URANDOM
 static int
 fill_random_bytes_urandom(void *seed, size_t size)
 {