// Copyright (c) 2012 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "base/threading/thread_local_storage.h" #include #include "base/check.h" namespace base { namespace internal { bool PlatformThreadLocalStorage::AllocTLS(TLSKey* key) { TLSKey value = TlsAlloc(); if (value != TLS_OUT_OF_INDEXES) { *key = value; return true; } return false; } void PlatformThreadLocalStorage::FreeTLS(TLSKey key) { BOOL ret = TlsFree(key); DCHECK(ret); } void PlatformThreadLocalStorage::SetTLSValue(TLSKey key, void* value) { BOOL ret = TlsSetValue(key, value); DCHECK(ret); } } // namespace internal } // namespace base // Thread Termination Callbacks. // Windows doesn't support a per-thread destructor with its // TLS primitives. So, we build it manually by inserting a // function to be called on each thread's exit. // This magic is from http://www.codeproject.com/threads/tls.asp // and it works for VC++ 7.0 and later. // Force a reference to _tls_used to make the linker create the TLS directory // if it's not already there. (e.g. if __declspec(thread) is not used). // Force a reference to p_thread_callback_base to prevent whole program // optimization from discarding the variable. #ifdef _WIN64 #pragma comment(linker, "/INCLUDE:_tls_used") #pragma comment(linker, "/INCLUDE:p_thread_callback_base") #else // _WIN64 #pragma comment(linker, "/INCLUDE:__tls_used") #pragma comment(linker, "/INCLUDE:_p_thread_callback_base") #endif // _WIN64 // Static callback function to call with each thread termination. void NTAPI OnThreadExit(PVOID module, DWORD reason, PVOID reserved) { // On XP SP0 & SP1, the DLL_PROCESS_ATTACH is never seen. It is sent on SP2+ // and on W2K and W2K3. So don't assume it is sent. if (DLL_THREAD_DETACH == reason || DLL_PROCESS_DETACH == reason) base::internal::PlatformThreadLocalStorage::OnThreadExit(); } // .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are // called automatically by the OS loader code (not the CRT) when the module is // loaded and on thread creation. They are NOT called if the module has been // loaded by a LoadLibrary() call. It must have implicitly been loaded at // process startup. // By implicitly loaded, I mean that it is directly referenced by the main EXE // or by one of its dependent DLLs. Delay-loaded DLL doesn't count as being // implicitly loaded. // // See VC\crt\src\tlssup.c for reference. // extern "C" suppresses C++ name mangling so we know the symbol name for the // linker /INCLUDE:symbol pragma above. extern "C" { // The linker must not discard p_thread_callback_base. (We force a reference // to this variable with a linker /INCLUDE:symbol pragma to ensure that.) If // this variable is discarded, the OnThreadExit function will never be called. #ifdef _WIN64 // .CRT section is merged with .rdata on x64 so it must be constant data. #pragma const_seg(".CRT$XLB") // When defining a const variable, it must have external linkage to be sure the // linker doesn't discard it. extern const PIMAGE_TLS_CALLBACK p_thread_callback_base; const PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit; // Reset the default section. #pragma const_seg() #else // _WIN64 #pragma data_seg(".CRT$XLB") PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit; // Reset the default section. #pragma data_seg() #endif // _WIN64 } // extern "C"