From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 17 Sep 2015 15:06:42 +0000 (+0100)
Subject: Make std::random_device retry after short reads
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=a2b4d73daf5854c40b71e0b655a9507bf6977279;p=gcc.git

Make std::random_device retry after short reads

	PR libstdc++/65142
	* src/c++11/random.cc (random_device::_M_getval()): Retry after short
	reads.

From-SVN: r227872
---

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index c70ad43a2eb..25aa16b2973 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,9 @@
 2015-09-17  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/65142
+	* src/c++11/random.cc (random_device::_M_getval()): Retry after short
+	reads.
+
 	* include/std/system_error (error_code::operator bool(),
 	error_condition::operator bool()): Remove redundant conditional
 	expression.
diff --git a/libstdc++-v3/src/c++11/random.cc b/libstdc++-v3/src/c++11/random.cc
index 1d102c755b2..f1d6125128a 100644
--- a/libstdc++-v3/src/c++11/random.cc
+++ b/libstdc++-v3/src/c++11/random.cc
@@ -130,16 +130,26 @@ namespace std _GLIBCXX_VISIBILITY(default)
 #endif
 
     result_type __ret;
-
+    void* p = &__ret;
+    size_t n = sizeof(result_type);
 #ifdef _GLIBCXX_HAVE_UNISTD_H
-    auto e = 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
-    auto e = 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
-    if (e != sizeof(result_type))
-      __throw_runtime_error(__N("random_device could not read enough bytes"));
 
     return __ret;
   }