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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "base/threading/thread_local_storage.h" | |
6 | |
7 #include <windows.h> | |
8 | |
9 #include "base/logging.h" | |
10 | |
11 namespace base { | |
12 | |
13 namespace internal { | |
14 | |
15 bool PlatformThreadLocalStorage::AllocTLS(TLSKey* key) { | |
16 TLSKey value = TlsAlloc(); | |
17 if (value != TLS_OUT_OF_INDEXES) { | |
18 *key = value; | |
19 return true; | |
20 } | |
21 return false; | |
22 } | |
23 | |
24 void PlatformThreadLocalStorage::FreeTLS(TLSKey key) { | |
25 BOOL ret = TlsFree(key); | |
26 DCHECK(ret); | |
27 } | |
28 | |
29 void* PlatformThreadLocalStorage::GetTLSValue(TLSKey key) { | |
30 return TlsGetValue(key); | |
31 } | |
32 | |
33 void PlatformThreadLocalStorage::SetTLSValue(TLSKey key, void* value) { | |
34 BOOL ret = TlsSetValue(key, value); | |
35 DCHECK(ret); | |
36 } | |
37 | |
38 } // namespace internal | |
39 | |
40 } // namespace base | |
41 | |
42 // Thread Termination Callbacks. | |
43 // Windows doesn't support a per-thread destructor with its | |
44 // TLS primitives. So, we build it manually by inserting a | |
45 // function to be called on each thread's exit. | |
46 // This magic is from http://www.codeproject.com/threads/tls.asp | |
47 // and it works for VC++ 7.0 and later. | |
48 | |
49 // Force a reference to _tls_used to make the linker create the TLS directory | |
50 // if it's not already there. (e.g. if __declspec(thread) is not used). | |
51 // Force a reference to p_thread_callback_base to prevent whole program | |
52 // optimization from discarding the variable. | |
53 #ifdef _WIN64 | |
54 | |
55 #pragma comment(linker, "/INCLUDE:_tls_used") | |
56 #pragma comment(linker, "/INCLUDE:p_thread_callback_base") | |
57 | |
58 #else // _WIN64 | |
59 | |
60 #pragma comment(linker, "/INCLUDE:__tls_used") | |
61 #pragma comment(linker, "/INCLUDE:_p_thread_callback_base") | |
62 | |
63 #endif // _WIN64 | |
64 | |
65 // Static callback function to call with each thread termination. | |
66 void NTAPI OnThreadExit(PVOID module, DWORD reason, PVOID reserved) { | |
67 // On XP SP0 & SP1, the DLL_PROCESS_ATTACH is never seen. It is sent on SP2+ | |
68 // and on W2K and W2K3. So don't assume it is sent. | |
69 if (DLL_THREAD_DETACH == reason || DLL_PROCESS_DETACH == reason) | |
70 base::internal::PlatformThreadLocalStorage::OnThreadExit(); | |
71 } | |
72 | |
73 // .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are | |
74 // called automatically by the OS loader code (not the CRT) when the module is | |
75 // loaded and on thread creation. They are NOT called if the module has been | |
76 // loaded by a LoadLibrary() call. It must have implicitly been loaded at | |
77 // process startup. | |
78 // By implicitly loaded, I mean that it is directly referenced by the main EXE | |
79 // or by one of its dependent DLLs. Delay-loaded DLL doesn't count as being | |
80 // implicitly loaded. | |
81 // | |
82 // See VC\crt\src\tlssup.c for reference. | |
83 | |
84 // extern "C" suppresses C++ name mangling so we know the symbol name for the | |
85 // linker /INCLUDE:symbol pragma above. | |
86 extern "C" { | |
87 // The linker must not discard p_thread_callback_base. (We force a reference | |
88 // to this variable with a linker /INCLUDE:symbol pragma to ensure that.) If | |
89 // this variable is discarded, the OnThreadExit function will never be called. | |
90 #ifdef _WIN64 | |
91 | |
92 // .CRT section is merged with .rdata on x64 so it must be constant data. | |
93 #pragma const_seg(".CRT$XLB") | |
94 // When defining a const variable, it must have external linkage to be sure the | |
95 // linker doesn't discard it. | |
96 extern const PIMAGE_TLS_CALLBACK p_thread_callback_base; | |
97 const PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit; | |
98 | |
99 // Reset the default section. | |
100 #pragma const_seg() | |
101 | |
102 #else // _WIN64 | |
103 | |
104 #pragma data_seg(".CRT$XLB") | |
105 PIMAGE_TLS_CALLBACK p_thread_callback_base = OnThreadExit; | |
106 | |
107 // Reset the default section. | |
108 #pragma data_seg() | |
109 | |
110 #endif // _WIN64 | |
111 } // extern "C" | |
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