From bcd96d92f3239aff3152afe8ff4e72f3aa2ea287 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 7 Jul 2015 06:26:06 +0000
Subject: random.c: try getrandom

* random.c (fill_random_bytes_syscall): try getrandom system call
  on Linux if supported by the kernel.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51182 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 random.c | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

(limited to 'random.c')

diff --git a/random.c b/random.c
index a5a63629e4..853c287040 100644
--- a/random.c
+++ b/random.c
@@ -77,6 +77,12 @@ The original copyright notice follows.
 #include <sys/time.h>
 #endif
 
+#ifdef HAVE_SYSCALL_H
+#include <syscall.h>
+#elif defined HAVE_SYS_SYSCALL_H
+#include <sys/syscall.h>
+#endif
+
 #ifdef _WIN32
 # if !defined(_WIN32_WINNT) || _WIN32_WINNT < 0x0400
 #  undef _WIN32_WINNT
@@ -84,8 +90,8 @@ The original copyright notice follows.
 #  undef __WINCRYPT_H__
 # endif
 #include <wincrypt.h>
-#include "ruby_atomic.h"
 #endif
+#include "ruby_atomic.h"
 
 typedef int int_must_be_32bit_at_least[sizeof(int) * CHAR_BIT < 32 ? -1 : 1];
 
@@ -509,6 +515,22 @@ fill_random_bytes_syscall(void *seed, size_t size)
     CryptGenRandom(prov, size, seed);
     return 0;
 }
+#elif defined __linux__ && defined SYS_getrandom
+static int
+fill_random_bytes_syscall(void *seed, size_t size)
+{
+    static rb_atomic_t try_syscall = 1;
+    if (try_syscall) {
+	errno = 0;
+	ret = syscall(SYS_getrandom, seed, size, 0)
+	    if (errno == ENOSYS) {
+		try_syscall = 0;
+		return -1;
+	    }
+	if ((size_t)ret == size) return 0;
+    }
+    return 0;
+}
 #else
 # define fill_random_bytes_syscall(seed, size) -1
 #endif
-- 
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