contrib/compiler-rt/lib/asan/asan_win_dll_thunk.cc

   1 //===-- asan_win_dll_thunk.cc ---------------------------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file is a part of AddressSanitizer, an address sanity checker.
  11 //
  12 // This file defines a family of thunks that should be statically linked into
  13 // the DLLs that have ASan instrumentation in order to delegate the calls to the
  14 // shared runtime that lives in the main binary.
  15 // See https://github.com/google/sanitizers/issues/209 for the details.
  16 //===----------------------------------------------------------------------===//
  17
  18 // Only compile this code when building asan_dll_thunk.lib
  19 // Using #ifdef rather than relying on Makefiles etc.
  20 // simplifies the build procedure.
  21 #ifdef ASAN_DLL_THUNK
  22 #include "asan_init_version.h"
  23 #include "asan_globals_win.h"
  24 #include "interception/interception.h"
  25 #include "sanitizer_common/sanitizer_platform_interceptors.h"
  26
  27 #ifdef _M_IX86
  28 #define WINAPI __stdcall
  29 #else
  30 #define WINAPI
  31 #endif
  32
  33 // ---------- Function interception helper functions and macros ----------- {{{1
  34 extern "C" {
  35 void *WINAPI GetModuleHandleA(const char *module_name);
  36 void *WINAPI GetProcAddress(void *module, const char *proc_name);
  37 void abort();
  38 }
  39
  40 using namespace __sanitizer;
  41
  42 static uptr getRealProcAddressOrDie(const char *name) {
  43   uptr ret =
  44       __interception::InternalGetProcAddress((void *)GetModuleHandleA(0), name);
  45   if (!ret)
  46     abort();
  47   return ret;
  48 }
  49
  50 // We need to intercept some functions (e.g. ASan interface, memory allocator --
  51 // let's call them "hooks") exported by the DLL thunk and forward the hooks to
  52 // the runtime in the main module.
  53 // However, we don't want to keep two lists of these hooks.
  54 // To avoid that, the list of hooks should be defined using the
  55 // INTERCEPT_WHEN_POSSIBLE macro. Then, all these hooks can be intercepted
  56 // at once by calling INTERCEPT_HOOKS().
  57
  58 // Use macro+template magic to automatically generate the list of hooks.
  59 // Each hook at line LINE defines a template class with a static
  60 // FunctionInterceptor<LINE>::Execute() method intercepting the hook.
  61 // The default implementation of FunctionInterceptor<LINE> is to call
  62 // the Execute() method corresponding to the previous line.
  63 template<int LINE>
  64 struct FunctionInterceptor {
  65   static void Execute() { FunctionInterceptor<LINE-1>::Execute(); }
  66 };
  67
  68 // There shouldn't be any hooks with negative definition line number.
  69 template<>
  70 struct FunctionInterceptor<0> {
  71   static void Execute() {}
  72 };
  73
  74 #define INTERCEPT_WHEN_POSSIBLE(main_function, dll_function)                   \
  75   template <> struct FunctionInterceptor<__LINE__> {                           \
  76     static void Execute() {                                                    \
  77       uptr wrapper = getRealProcAddressOrDie(main_function);                   \
  78       if (!__interception::OverrideFunction((uptr)dll_function, wrapper, 0))   \
  79         abort();                                                               \
  80       FunctionInterceptor<__LINE__ - 1>::Execute();                            \
  81     }                                                                          \
  82   };
  83
  84 // Special case of hooks -- ASan own interface functions.  Those are only called
  85 // after __asan_init, thus an empty implementation is sufficient.
  86 #define INTERFACE_FUNCTION(name)                                               \
  87   extern "C" __declspec(noinline) void name() {                                \
  88     volatile int prevent_icf = (__LINE__ << 8); (void)prevent_icf;             \
  89     __debugbreak();                                                            \
  90   }                                                                            \
  91   INTERCEPT_WHEN_POSSIBLE(#name, name)
  92
  93 // INTERCEPT_HOOKS must be used after the last INTERCEPT_WHEN_POSSIBLE.
  94 #define INTERCEPT_HOOKS FunctionInterceptor<__LINE__>::Execute
  95
  96 // We can't define our own version of strlen etc. because that would lead to
  97 // link-time or even type mismatch errors.  Instead, we can declare a function
  98 // just to be able to get its address.  Me may miss the first few calls to the
  99 // functions since it can be called before __asan_init, but that would lead to
 100 // false negatives in the startup code before user's global initializers, which
 101 // isn't a big deal.
 102 #define INTERCEPT_LIBRARY_FUNCTION(name)                                       \
 103   extern "C" void name();                                                      \
 104   INTERCEPT_WHEN_POSSIBLE(WRAPPER_NAME(name), name)
 105
 106 // Disable compiler warnings that show up if we declare our own version
 107 // of a compiler intrinsic (e.g. strlen).
 108 #pragma warning(disable: 4391)
 109 #pragma warning(disable: 4392)
 110
 111 static void InterceptHooks();
 112 // }}}
 113
 114 // ---------- Function wrapping helpers ----------------------------------- {{{1
 115 #define WRAP_V_V(name)                                                         \
 116   extern "C" void name() {                                                     \
 117     typedef decltype(name) *fntype;                                            \
 118     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 119     fn();                                                                      \
 120   }                                                                            \
 121   INTERCEPT_WHEN_POSSIBLE(#name, name);
 122
 123 #define WRAP_V_W(name)                                                         \
 124   extern "C" void name(void *arg) {                                            \
 125     typedef decltype(name) *fntype;                                            \
 126     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 127     fn(arg);                                                                   \
 128   }                                                                            \
 129   INTERCEPT_WHEN_POSSIBLE(#name, name);
 130
 131 #define WRAP_V_WW(name)                                                        \
 132   extern "C" void name(void *arg1, void *arg2) {                               \
 133     typedef decltype(name) *fntype;                                            \
 134     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 135     fn(arg1, arg2);                                                            \
 136   }                                                                            \
 137   INTERCEPT_WHEN_POSSIBLE(#name, name);
 138
 139 #define WRAP_V_WWW(name)                                                       \
 140   extern "C" void name(void *arg1, void *arg2, void *arg3) {                   \
 141     typedef decltype(name) *fntype;                                            \
 142     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 143     fn(arg1, arg2, arg3);                                                      \
 144   }                                                                            \
 145   INTERCEPT_WHEN_POSSIBLE(#name, name);
 146
 147 #define WRAP_W_V(name)                                                         \
 148   extern "C" void *name() {                                                    \
 149     typedef decltype(name) *fntype;                                            \
 150     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 151     return fn();                                                               \
 152   }                                                                            \
 153   INTERCEPT_WHEN_POSSIBLE(#name, name);
 154
 155 #define WRAP_W_W(name)                                                         \
 156   extern "C" void *name(void *arg) {                                           \
 157     typedef decltype(name) *fntype;                                            \
 158     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 159     return fn(arg);                                                            \
 160   }                                                                            \
 161   INTERCEPT_WHEN_POSSIBLE(#name, name);
 162
 163 #define WRAP_W_WW(name)                                                        \
 164   extern "C" void *name(void *arg1, void *arg2) {                              \
 165     typedef decltype(name) *fntype;                                            \
 166     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 167     return fn(arg1, arg2);                                                     \
 168   }                                                                            \
 169   INTERCEPT_WHEN_POSSIBLE(#name, name);
 170
 171 #define WRAP_W_WWW(name)                                                       \
 172   extern "C" void *name(void *arg1, void *arg2, void *arg3) {                  \
 173     typedef decltype(name) *fntype;                                            \
 174     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 175     return fn(arg1, arg2, arg3);                                               \
 176   }                                                                            \
 177   INTERCEPT_WHEN_POSSIBLE(#name, name);
 178
 179 #define WRAP_W_WWWW(name)                                                      \
 180   extern "C" void *name(void *arg1, void *arg2, void *arg3, void *arg4) {      \
 181     typedef decltype(name) *fntype;                                            \
 182     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 183     return fn(arg1, arg2, arg3, arg4);                                         \
 184   }                                                                            \
 185   INTERCEPT_WHEN_POSSIBLE(#name, name);
 186
 187 #define WRAP_W_WWWWW(name)                                                     \
 188   extern "C" void *name(void *arg1, void *arg2, void *arg3, void *arg4,        \
 189                         void *arg5) {                                          \
 190     typedef decltype(name) *fntype;                                            \
 191     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 192     return fn(arg1, arg2, arg3, arg4, arg5);                                   \
 193   }                                                                            \
 194   INTERCEPT_WHEN_POSSIBLE(#name, name);
 195
 196 #define WRAP_W_WWWWWW(name)                                                    \
 197   extern "C" void *name(void *arg1, void *arg2, void *arg3, void *arg4,        \
 198                         void *arg5, void *arg6) {                              \
 199     typedef decltype(name) *fntype;                                            \
 200     static fntype fn = (fntype)getRealProcAddressOrDie(#name);                 \
 201     return fn(arg1, arg2, arg3, arg4, arg5, arg6);                             \
 202   }                                                                            \
 203   INTERCEPT_WHEN_POSSIBLE(#name, name);
 204 // }}}
 205
 206 // ----------------- ASan own interface functions --------------------
 207 // Don't use the INTERFACE_FUNCTION machinery for this function as we actually
 208 // want to call it in the __asan_init interceptor.
 209 WRAP_W_V(__asan_should_detect_stack_use_after_return)
 210 WRAP_W_V(__asan_get_shadow_memory_dynamic_address)
 211
 212 extern "C" {
 213   int __asan_option_detect_stack_use_after_return;
 214   uptr __asan_shadow_memory_dynamic_address;
 215
 216   // Manually wrap __asan_init as we need to initialize
 217   // __asan_option_detect_stack_use_after_return afterwards.
 218   void __asan_init() {
 219     typedef void (*fntype)();
 220     static fntype fn = 0;
 221     // __asan_init is expected to be called by only one thread.
 222     if (fn) return;
 223
 224     fn = (fntype)getRealProcAddressOrDie("__asan_init");
 225     fn();
 226     __asan_option_detect_stack_use_after_return =
 227         (__asan_should_detect_stack_use_after_return() != 0);
 228     __asan_shadow_memory_dynamic_address =
 229         (uptr)__asan_get_shadow_memory_dynamic_address();
 230     InterceptHooks();
 231   }
 232 }
 233
 234 extern "C" void __asan_version_mismatch_check() {
 235   // Do nothing.
 236 }
 237
 238 INTERFACE_FUNCTION(__asan_handle_no_return)
 239 INTERFACE_FUNCTION(__asan_unhandled_exception_filter)
 240
 241 INTERFACE_FUNCTION(__asan_report_store1)
 242 INTERFACE_FUNCTION(__asan_report_store2)
 243 INTERFACE_FUNCTION(__asan_report_store4)
 244 INTERFACE_FUNCTION(__asan_report_store8)
 245 INTERFACE_FUNCTION(__asan_report_store16)
 246 INTERFACE_FUNCTION(__asan_report_store_n)
 247
 248 INTERFACE_FUNCTION(__asan_report_load1)
 249 INTERFACE_FUNCTION(__asan_report_load2)
 250 INTERFACE_FUNCTION(__asan_report_load4)
 251 INTERFACE_FUNCTION(__asan_report_load8)
 252 INTERFACE_FUNCTION(__asan_report_load16)
 253 INTERFACE_FUNCTION(__asan_report_load_n)
 254
 255 INTERFACE_FUNCTION(__asan_store1)
 256 INTERFACE_FUNCTION(__asan_store2)
 257 INTERFACE_FUNCTION(__asan_store4)
 258 INTERFACE_FUNCTION(__asan_store8)
 259 INTERFACE_FUNCTION(__asan_store16)
 260 INTERFACE_FUNCTION(__asan_storeN)
 261
 262 INTERFACE_FUNCTION(__asan_load1)
 263 INTERFACE_FUNCTION(__asan_load2)
 264 INTERFACE_FUNCTION(__asan_load4)
 265 INTERFACE_FUNCTION(__asan_load8)
 266 INTERFACE_FUNCTION(__asan_load16)
 267 INTERFACE_FUNCTION(__asan_loadN)
 268
 269 INTERFACE_FUNCTION(__asan_memcpy);
 270 INTERFACE_FUNCTION(__asan_memset);
 271 INTERFACE_FUNCTION(__asan_memmove);
 272
 273 INTERFACE_FUNCTION(__asan_set_shadow_00);
 274 INTERFACE_FUNCTION(__asan_set_shadow_f1);
 275 INTERFACE_FUNCTION(__asan_set_shadow_f2);
 276 INTERFACE_FUNCTION(__asan_set_shadow_f3);
 277 INTERFACE_FUNCTION(__asan_set_shadow_f5);
 278 INTERFACE_FUNCTION(__asan_set_shadow_f8);
 279
 280 INTERFACE_FUNCTION(__asan_alloca_poison);
 281 INTERFACE_FUNCTION(__asan_allocas_unpoison);
 282
 283 INTERFACE_FUNCTION(__asan_register_globals)
 284 INTERFACE_FUNCTION(__asan_unregister_globals)
 285
 286 INTERFACE_FUNCTION(__asan_before_dynamic_init)
 287 INTERFACE_FUNCTION(__asan_after_dynamic_init)
 288
 289 INTERFACE_FUNCTION(__asan_poison_stack_memory)
 290 INTERFACE_FUNCTION(__asan_unpoison_stack_memory)
 291
 292 INTERFACE_FUNCTION(__asan_poison_memory_region)
 293 INTERFACE_FUNCTION(__asan_unpoison_memory_region)
 294
 295 INTERFACE_FUNCTION(__asan_address_is_poisoned)
 296 INTERFACE_FUNCTION(__asan_region_is_poisoned)
 297
 298 INTERFACE_FUNCTION(__asan_get_current_fake_stack)
 299 INTERFACE_FUNCTION(__asan_addr_is_in_fake_stack)
 300
 301 INTERFACE_FUNCTION(__asan_stack_malloc_0)
 302 INTERFACE_FUNCTION(__asan_stack_malloc_1)
 303 INTERFACE_FUNCTION(__asan_stack_malloc_2)
 304 INTERFACE_FUNCTION(__asan_stack_malloc_3)
 305 INTERFACE_FUNCTION(__asan_stack_malloc_4)
 306 INTERFACE_FUNCTION(__asan_stack_malloc_5)
 307 INTERFACE_FUNCTION(__asan_stack_malloc_6)
 308 INTERFACE_FUNCTION(__asan_stack_malloc_7)
 309 INTERFACE_FUNCTION(__asan_stack_malloc_8)
 310 INTERFACE_FUNCTION(__asan_stack_malloc_9)
 311 INTERFACE_FUNCTION(__asan_stack_malloc_10)
 312
 313 INTERFACE_FUNCTION(__asan_stack_free_0)
 314 INTERFACE_FUNCTION(__asan_stack_free_1)
 315 INTERFACE_FUNCTION(__asan_stack_free_2)
 316 INTERFACE_FUNCTION(__asan_stack_free_4)
 317 INTERFACE_FUNCTION(__asan_stack_free_5)
 318 INTERFACE_FUNCTION(__asan_stack_free_6)
 319 INTERFACE_FUNCTION(__asan_stack_free_7)
 320 INTERFACE_FUNCTION(__asan_stack_free_8)
 321 INTERFACE_FUNCTION(__asan_stack_free_9)
 322 INTERFACE_FUNCTION(__asan_stack_free_10)
 323
 324 // FIXME: we might want to have a sanitizer_win_dll_thunk?
 325 INTERFACE_FUNCTION(__sanitizer_annotate_contiguous_container)
 326 INTERFACE_FUNCTION(__sanitizer_contiguous_container_find_bad_address)
 327 INTERFACE_FUNCTION(__sanitizer_cov)
 328 INTERFACE_FUNCTION(__sanitizer_cov_dump)
 329 INTERFACE_FUNCTION(__sanitizer_dump_coverage)
 330 INTERFACE_FUNCTION(__sanitizer_dump_trace_pc_guard_coverage)
 331 INTERFACE_FUNCTION(__sanitizer_cov_indir_call16)
 332 INTERFACE_FUNCTION(__sanitizer_cov_init)
 333 INTERFACE_FUNCTION(__sanitizer_cov_module_init)
 334 INTERFACE_FUNCTION(__sanitizer_cov_trace_basic_block)
 335 INTERFACE_FUNCTION(__sanitizer_cov_trace_func_enter)
 336 INTERFACE_FUNCTION(__sanitizer_cov_trace_pc_guard)
 337 INTERFACE_FUNCTION(__sanitizer_cov_trace_pc_guard_init)
 338 INTERFACE_FUNCTION(__sanitizer_cov_with_check)
 339 INTERFACE_FUNCTION(__sanitizer_get_allocated_size)
 340 INTERFACE_FUNCTION(__sanitizer_get_coverage_guards)
 341 INTERFACE_FUNCTION(__sanitizer_get_current_allocated_bytes)
 342 INTERFACE_FUNCTION(__sanitizer_get_estimated_allocated_size)
 343 INTERFACE_FUNCTION(__sanitizer_get_free_bytes)
 344 INTERFACE_FUNCTION(__sanitizer_get_heap_size)
 345 INTERFACE_FUNCTION(__sanitizer_get_ownership)
 346 INTERFACE_FUNCTION(__sanitizer_get_total_unique_caller_callee_pairs)
 347 INTERFACE_FUNCTION(__sanitizer_get_total_unique_coverage)
 348 INTERFACE_FUNCTION(__sanitizer_get_unmapped_bytes)
 349 INTERFACE_FUNCTION(__sanitizer_maybe_open_cov_file)
 350 INTERFACE_FUNCTION(__sanitizer_print_stack_trace)
 351 INTERFACE_FUNCTION(__sanitizer_symbolize_pc)
 352 INTERFACE_FUNCTION(__sanitizer_symbolize_global)
 353 INTERFACE_FUNCTION(__sanitizer_ptr_cmp)
 354 INTERFACE_FUNCTION(__sanitizer_ptr_sub)
 355 INTERFACE_FUNCTION(__sanitizer_report_error_summary)
 356 INTERFACE_FUNCTION(__sanitizer_reset_coverage)
 357 INTERFACE_FUNCTION(__sanitizer_get_number_of_counters)
 358 INTERFACE_FUNCTION(__sanitizer_update_counter_bitset_and_clear_counters)
 359 INTERFACE_FUNCTION(__sanitizer_sandbox_on_notify)
 360 INTERFACE_FUNCTION(__sanitizer_set_death_callback)
 361 INTERFACE_FUNCTION(__sanitizer_set_report_path)
 362 INTERFACE_FUNCTION(__sanitizer_set_report_fd)
 363 INTERFACE_FUNCTION(__sanitizer_unaligned_load16)
 364 INTERFACE_FUNCTION(__sanitizer_unaligned_load32)
 365 INTERFACE_FUNCTION(__sanitizer_unaligned_load64)
 366 INTERFACE_FUNCTION(__sanitizer_unaligned_store16)
 367 INTERFACE_FUNCTION(__sanitizer_unaligned_store32)
 368 INTERFACE_FUNCTION(__sanitizer_unaligned_store64)
 369 INTERFACE_FUNCTION(__sanitizer_verify_contiguous_container)
 370 INTERFACE_FUNCTION(__sanitizer_install_malloc_and_free_hooks)
 371 INTERFACE_FUNCTION(__sanitizer_start_switch_fiber)
 372 INTERFACE_FUNCTION(__sanitizer_finish_switch_fiber)
 373 INTERFACE_FUNCTION(__sanitizer_get_module_and_offset_for_pc)
 374
 375 // TODO(timurrrr): Add more interface functions on the as-needed basis.
 376
 377 // ----------------- Memory allocation functions ---------------------
 378 WRAP_V_W(free)
 379 WRAP_V_W(_free_base)
 380 WRAP_V_WW(_free_dbg)
 381
 382 WRAP_W_W(malloc)
 383 WRAP_W_W(_malloc_base)
 384 WRAP_W_WWWW(_malloc_dbg)
 385
 386 WRAP_W_WW(calloc)
 387 WRAP_W_WW(_calloc_base)
 388 WRAP_W_WWWWW(_calloc_dbg)
 389 WRAP_W_WWW(_calloc_impl)
 390
 391 WRAP_W_WW(realloc)
 392 WRAP_W_WW(_realloc_base)
 393 WRAP_W_WWW(_realloc_dbg)
 394 WRAP_W_WWW(_recalloc)
 395 WRAP_W_WWW(_recalloc_base)
 396
 397 WRAP_W_W(_msize)
 398 WRAP_W_W(_expand)
 399 WRAP_W_W(_expand_dbg)
 400
 401 // TODO(timurrrr): Might want to add support for _aligned_* allocation
 402 // functions to detect a bit more bugs.  Those functions seem to wrap malloc().
 403
 404 // TODO(timurrrr): Do we need to add _Crt* stuff here? (see asan_malloc_win.cc).
 405
 406 INTERCEPT_LIBRARY_FUNCTION(atoi);
 407 INTERCEPT_LIBRARY_FUNCTION(atol);
 408
 409 #ifdef _WIN64
 410 INTERCEPT_LIBRARY_FUNCTION(__C_specific_handler);
 411 #else
 412 INTERCEPT_LIBRARY_FUNCTION(_except_handler3);
 413
 414 // _except_handler4 checks -GS cookie which is different for each module, so we
 415 // can't use INTERCEPT_LIBRARY_FUNCTION(_except_handler4).
 416 INTERCEPTOR(int, _except_handler4, void *a, void *b, void *c, void *d) {
 417   __asan_handle_no_return();
 418   return REAL(_except_handler4)(a, b, c, d);
 419 }
 420 #endif
 421
 422 INTERCEPT_LIBRARY_FUNCTION(frexp);
 423 INTERCEPT_LIBRARY_FUNCTION(longjmp);
 424 #if SANITIZER_INTERCEPT_MEMCHR
 425 INTERCEPT_LIBRARY_FUNCTION(memchr);
 426 #endif
 427 INTERCEPT_LIBRARY_FUNCTION(memcmp);
 428 INTERCEPT_LIBRARY_FUNCTION(memcpy);
 429 INTERCEPT_LIBRARY_FUNCTION(memmove);
 430 INTERCEPT_LIBRARY_FUNCTION(memset);
 431 INTERCEPT_LIBRARY_FUNCTION(strcat);  // NOLINT
 432 INTERCEPT_LIBRARY_FUNCTION(strchr);
 433 INTERCEPT_LIBRARY_FUNCTION(strcmp);
 434 INTERCEPT_LIBRARY_FUNCTION(strcpy);  // NOLINT
 435 INTERCEPT_LIBRARY_FUNCTION(strcspn);
 436 INTERCEPT_LIBRARY_FUNCTION(strdup);
 437 INTERCEPT_LIBRARY_FUNCTION(strlen);
 438 INTERCEPT_LIBRARY_FUNCTION(strncat);
 439 INTERCEPT_LIBRARY_FUNCTION(strncmp);
 440 INTERCEPT_LIBRARY_FUNCTION(strncpy);
 441 INTERCEPT_LIBRARY_FUNCTION(strnlen);
 442 INTERCEPT_LIBRARY_FUNCTION(strpbrk);
 443 INTERCEPT_LIBRARY_FUNCTION(strrchr);
 444 INTERCEPT_LIBRARY_FUNCTION(strspn);
 445 INTERCEPT_LIBRARY_FUNCTION(strstr);
 446 INTERCEPT_LIBRARY_FUNCTION(strtol);
 447 INTERCEPT_LIBRARY_FUNCTION(wcslen);
 448
 449 // Must be after all the interceptor declarations due to the way INTERCEPT_HOOKS
 450 // is defined.
 451 void InterceptHooks() {
 452   INTERCEPT_HOOKS();
 453 #ifndef _WIN64
 454   INTERCEPT_FUNCTION(_except_handler4);
 455 #endif
 456 }
 457
 458 // We want to call __asan_init before C/C++ initializers/constructors are
 459 // executed, otherwise functions like memset might be invoked.
 460 // For some strange reason, merely linking in asan_preinit.cc doesn't work
 461 // as the callback is never called...  Is link.exe doing something too smart?
 462
 463 // In DLLs, the callbacks are expected to return 0,
 464 // otherwise CRT initialization fails.
 465 static int call_asan_init() {
 466   __asan_init();
 467   return 0;
 468 }
 469 #pragma section(".CRT$XIB", long, read)  // NOLINT
 470 __declspec(allocate(".CRT$XIB")) int (*__asan_preinit)() = call_asan_init;
 471
 472 static void WINAPI asan_thread_init(void *mod, unsigned long reason,
 473                                    void *reserved) {
 474   if (reason == /*DLL_PROCESS_ATTACH=*/1) __asan_init();
 475 }
 476
 477 #pragma section(".CRT$XLAB", long, read)  // NOLINT
 478 __declspec(allocate(".CRT$XLAB")) void (WINAPI *__asan_tls_init)(void *,
 479     unsigned long, void *) = asan_thread_init;
 480
 481 ASAN_LINK_GLOBALS_WIN()
 482
 483 #endif // ASAN_DLL_THUNK