From ee2d10ad0c0e04d0b9da4535a6fff265ac2501e5 Mon Sep 17 00:00:00 2001
From: James Hilliard <james.hilliard1@gmail.com>
Date: Thu, 27 Jul 2017 15:34:09 +0300
Subject: [PATCH] Check if sys/random.h is required for getentropy on OSX.

---
 configure.ac   |  8 ++++++++
 src/random.cpp | 14 +++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index aea5d7160..1fc4e3219 100644
--- a/configure.ac
+++ b/configure.ac
@@ -675,6 +675,14 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>]],
  [ AC_MSG_RESULT(no)]
 )
 
+AC_MSG_CHECKING(for getentropy via random.h)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <unistd.h>
+ #include <sys/random.h>]],
+ [[ getentropy(nullptr, 32) ]])],
+ [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_GETENTROPY_RAND, 1,[Define this symbol if the BSD getentropy system call is available with sys/random.h]) ],
+ [ AC_MSG_RESULT(no)]
+)
+
 AC_MSG_CHECKING(for sysctl KERN_ARND)
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>
   #include <sys/sysctl.h>]],
diff --git a/src/random.cpp b/src/random.cpp
index b308e8f4a..e07ef4447 100644
--- a/src/random.cpp
+++ b/src/random.cpp
@@ -27,9 +27,12 @@
 #include <sys/syscall.h>
 #include <linux/random.h>
 #endif
-#ifdef HAVE_GETENTROPY
+#if defined(HAVE_GETENTROPY) || (defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX))
 #include <unistd.h>
 #endif
+#if defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX)
+#include <sys/random.h>
+#endif
 #ifdef HAVE_SYSCTL_ARND
 #include <sys/sysctl.h>
 #endif
@@ -237,6 +240,15 @@ void GetOSRand(unsigned char *ent32)
     if (getentropy(ent32, NUM_OS_RANDOM_BYTES) != 0) {
         RandFailure();
     }
+#elif defined(HAVE_GETENTROPY_RAND) && defined(MAC_OSX)
+    // We need a fallback for OSX < 10.12
+    if (&getentropy != NULL) {
+        if (getentropy(ent32, NUM_OS_RANDOM_BYTES) != 0) {
+            RandFailure();
+        }
+    } else {
+        GetDevURandom(ent32);
+    }
 #elif defined(HAVE_SYSCTL_ARND)
     /* FreeBSD and similar. It is possible for the call to return less
      * bytes than requested, so need to read in a loop.