From dbda86271e551c642a980929866fcd07082ee483 Mon Sep 17 00:00:00 2001
From: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 2 Oct 2015 20:51:34 +0000
Subject: [PATCH] Backport PR libstdc++/65142 fix from mainline

	PR libstdc++/65142
	* src/c++11/random.cc (random_device::_M_getval()): Check read result
	and retry after short reads.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch@228424 138bc75d-0d04-0410-961f-82ee72b054a4
---
 libstdc++-v3/ChangeLog           |  6 ++++++
 libstdc++-v3/src/c++11/random.cc | 23 +++++++++++++++++++----
 2 files changed, 25 insertions(+), 4 deletions(-)

#diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
#index 6d2d628..70774cc 100644
#--- a/libstdc++-v3/ChangeLog
#+++ b/libstdc++-v3/ChangeLog
#@@ -1,3 +1,9 @@
#+2015-10-02  Jonathan Wakely  <jwakely@redhat.com>
#+
#+	PR libstdc++/65142
#+	* src/c++11/random.cc (random_device::_M_getval()): Check read result
#+	and retry after short reads.
#+
# 2015-09-03  Jonathan Wakely  <jwakely@redhat.com>
# 
# 	Backport from mainline
diff --git a/libstdc++-v3/src/c++11/random.cc b/libstdc++-v3/src/c++11/random.cc
index f61daea..d175e79 100644
--- a/libstdc++-v3/src/c++11/random.cc
+++ b/libstdc++-v3/src/c++11/random.cc
@@ -30,6 +30,7 @@
 # include <cpuid.h>
 #endif
 
+#include <cerrno>
 #include <cstdio>
 
 #ifdef _GLIBCXX_HAVE_UNISTD_H
@@ -129,13 +130,27 @@ namespace std _GLIBCXX_VISIBILITY(default)
 #endif
 
     result_type __ret;
+    void* p = &__ret;
+    size_t n = sizeof(result_type);
 #ifdef _GLIBCXX_HAVE_UNISTD_H
-    read(fileno(static_cast<FILE*>(_M_file)),
-	 static_cast<void*>(&__ret), sizeof(result_type));
+    do
+      {
+	const int e = read(fileno(static_cast<FILE*>(_M_file)), p, n);
+	if (e > 0)
+	  {
+	    n -= e;
+	    p = static_cast<char*>(p) + e;
+	  }
+	else if (e != -1 || errno != EINTR)
+	  __throw_runtime_error(__N("random_device could not be read"));
+      }
+    while (n > 0);
 #else
-    std::fread(static_cast<void*>(&__ret), sizeof(result_type),
-	       1, static_cast<FILE*>(_M_file));
+    const size_t e = std::fread(p, n, 1, static_cast<FILE*>(_M_file));
+    if (e != 1)
+      __throw_runtime_error(__N("random_device could not be read"));
 #endif
+
     return __ret;
   }
 
-- 
1.9.4