libc++: add NaCl and PNaCl support for std::random_device

Summary:
The NaCl sandbox doesn't allow opening files under /dev, but it offers an API which provides the same capabilities. This is the same random device emulation that nacl_io performs for POSIX support, but nacl_io is an optional library so libc++ can't assume that device emulation will be performed. Note that NaCl only supports /dev/urandom, not /dev/random.

This patch also cleans up some of the preprocessor #endif, and fixes the test for Win32 (it accepts any token, and would therefore never throw regardless of the token provided).

Test Plan: ninja check-libcxx

Reviewers: dschuff, mclow.lists, danalbert

Subscribers: jfb, cfe-commits

Differential Revision: http://reviews.llvm.org/D6442

llvm-svn: 223068

1 files changed, 43 insertions, 6 deletions

diff --git a/libcxx/src/random.cpp b/libcxx/src/random.cpp
index 86017ef0d46..15ed65b58cf 100644
--- a/libcxx/src/random.cpp
+++ b/libcxx/src/random.cpp
@@ -11,23 +11,27 @@
 // Must be defined before including stdlib.h to enable rand_s().
 #define _CRT_RAND_S
 #include <stdio.h>
-#endif
+#endif // defined(_WIN32)
 
 #include "random"
 #include "system_error"
 
-#ifdef __sun__
+#if defined(__sun__)
 #define rename solaris_headers_are_broken
-#endif
+#endif // defined(__sun__)
 #if !defined(_WIN32)
 #include <fcntl.h>
 #include <unistd.h>
-#endif // defined(_WIN32)
+#endif // !defined(_WIN32)
 #include <errno.h>
+#if defined(_LIBCPP_USING_NACL_RANDOM)
+#include <nacl/nacl_random.h>
+#endif // defined(_LIBCPP_USING_NACL_RANDOM)
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #if defined(_WIN32)
+
 random_device::random_device(const string&)
 {
 }
@@ -45,7 +49,39 @@ random_device::operator()()
         __throw_system_error(err, "random_device rand_s failed.");
     return r;
 }
-#else
+
+#elif defined(_LIBCPP_USING_NACL_RANDOM)
+
+random_device::random_device(const string& __token)
+{
+    if (__token != "/dev/urandom")
+        __throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
+    int error = nacl_secure_random_init();
+    if (error)
+        __throw_system_error(error, ("random device failed to open " + __token).c_str());
+}
+
+random_device::~random_device()
+{
+}
+
+unsigned
+random_device::operator()()
+{
+    unsigned r;
+    size_t n = sizeof(r);
+    char* p = reinterpret_cast<char*>(&r);
+    size_t bytes_written;
+    int error = nacl_secure_random(&r, n, &bytes_written);
+    if (error != 0)
+        __throw_system_error(error, "random_device failed getting bytes");
+    else if (bytes_written != n)
+        __throw_runtime_error("random_device failed to obtain enough bytes");
+    return r;
+}
+
+#else // !defined(_WIN32) && !defined(_LIBCPP_USING_NACL_RANDOM)
+
 random_device::random_device(const string& __token)
     : __f_(open(__token.c_str(), O_RDONLY))
 {
@@ -80,7 +116,8 @@ random_device::operator()()
     }
     return r;
 }
-#endif // defined(_WIN32)
+
+#endif // defined(_WIN32) || defined(_LIBCPP_USING_NACL_RANDOM)
 
 double
 random_device::entropy() const _NOEXCEPT