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premiere-libtorrent
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fixed race condition in random number generator

This commit is contained in:
Arvid Norberg 2018-06-03 19:33:00 +02:00 committed by Arvid Norberg
parent 2408200475
commit 049d867c12
2 changed files with 13 additions and 12 deletions
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1
ChangeLog
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@ -1,4 +1,5 @@
* fixed race condition in random number generator
* fix race condition in stat_cache (disk storage) * fix race condition in stat_cache (disk storage)
* improve error handling of failing to change file priority * improve error handling of failing to change file priority
The API for custom storage implementations was altered The API for custom storage implementations was altered

24
src/random.cpp
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@ -33,6 +33,7 @@ POSSIBILITY OF SUCH DAMAGE.
#include "libtorrent/config.hpp" #include "libtorrent/config.hpp"
#include "libtorrent/random.hpp" #include "libtorrent/random.hpp"
#include "libtorrent/assert.hpp" #include "libtorrent/assert.hpp"
#include "libtorrent/thread.hpp"
#ifdef BOOST_NO_CXX11_HDR_RANDOM #ifdef BOOST_NO_CXX11_HDR_RANDOM
#include "libtorrent/aux_/disable_warnings_push.hpp" #include "libtorrent/aux_/disable_warnings_push.hpp"
@ -46,10 +47,6 @@ POSSIBILITY OF SUCH DAMAGE.
#include <random> #include <random>
#endif #endif
#if !TORRENT_THREADSAFE_STATIC
#include "libtorrent/thread.hpp"
#endif
namespace libtorrent namespace libtorrent
{ {
#ifdef BOOST_NO_CXX11_HDR_RANDOM #ifdef BOOST_NO_CXX11_HDR_RANDOM
@ -73,25 +70,28 @@ namespace libtorrent
#else #else
#if !TORRENT_THREADSAFE_STATIC
// because local statics are not atomic pre c++11
// do it manually, probably at a higher cost
namespace namespace
{ {
static mutex random_device_mutex; #if !TORRENT_THREADSAFE_STATIC
static random_device* dev = NULL; // because local statics are not atomic pre c++11
static mt19937* rnd = NULL; // do it manually, probably at a higher cost
} random_device* dev = NULL;
mt19937* rnd = NULL;
#endif #endif
mutex random_device_mutex;
}
boost::uint32_t random() boost::uint32_t random()
{ {
// TODO: use a thread local mt19937 instance instead!
mutex::scoped_lock l(random_device_mutex);
#if TORRENT_THREADSAFE_STATIC #if TORRENT_THREADSAFE_STATIC
static random_device dev; static random_device dev;
static mt19937 random_engine(dev()); static mt19937 random_engine(dev());
return uniform_int_distribution<boost::uint32_t>(0, UINT_MAX)(random_engine); return uniform_int_distribution<boost::uint32_t>(0, UINT_MAX)(random_engine);
#else #else
mutex::scoped_lock l(random_device_mutex);
if (dev == NULL) if (dev == NULL)
{ {