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[libcxx] Support getentropy as a source of randomness for std::random_device

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Use this source use on Fuchsia where this is the oficially way
to obtain randomness. This could be also used on other platforms
that already support getentropy such as *BSD or Linux.

Differential Revision: https://reviews.llvm.org/D40319

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@319523 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Petr Hosek
2017-12-01 06:34:33 +00:00
parent aec189a8d1
commit 4861f6dfdd
2 changed files with 29 additions and 2 deletions
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2
include/__config
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@@ -273,6 +273,8 @@
// random data even when using sandboxing mechanisms such as chroots, // random data even when using sandboxing mechanisms such as chroots,
// Capsicum, etc. // Capsicum, etc.
# define _LIBCPP_USING_ARC4_RANDOM # define _LIBCPP_USING_ARC4_RANDOM
#elif defined(__Fuchsia__)
# define _LIBCPP_USING_GETENTROPY
#elif defined(__native_client__) #elif defined(__native_client__)
// NaCl's sandbox (which PNaCl also runs in) doesn't allow filesystem access, // NaCl's sandbox (which PNaCl also runs in) doesn't allow filesystem access,
// including accesses to the special files under /dev. C++11's // including accesses to the special files under /dev. C++11's

29
src/random.cpp
View File

@@ -25,7 +25,9 @@
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#if defined(_LIBCPP_USING_DEV_RANDOM) #if defined(_LIBCPP_USING_GETENTROPY)
#include <sys/random.h>
#elif defined(_LIBCPP_USING_DEV_RANDOM)
#include <fcntl.h> #include <fcntl.h>
#include <unistd.h> #include <unistd.h>
#elif defined(_LIBCPP_USING_NACL_RANDOM) #elif defined(_LIBCPP_USING_NACL_RANDOM)
@@ -35,7 +37,30 @@
_LIBCPP_BEGIN_NAMESPACE_STD _LIBCPP_BEGIN_NAMESPACE_STD
#if defined(_LIBCPP_USING_ARC4_RANDOM) #if defined(_LIBCPP_USING_GETENTROPY)
random_device::random_device(const string& __token)
{
if (__token != "/dev/urandom")
__throw_system_error(ENOENT, ("random device not supported " + __token).c_str());
}
random_device::~random_device()
{
}
unsigned
random_device::operator()()
{
unsigned r;
size_t n = sizeof(r);
int err = getentropy(&r, n);
if (err)
__throw_system_error(errno, "random_device getentropy failed");
return r;
}
#elif defined(_LIBCPP_USING_ARC4_RANDOM)
random_device::random_device(const string& __token) random_device::random_device(const string& __token)
{ {