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      1 //=-- ubsan_signals_standalone.cc
      2 //------------------------------------------------===//
      3 //
      4 //                     The LLVM Compiler Infrastructure
      5 //
      6 // This file is distributed under the University of Illinois Open Source
      7 // License. See LICENSE.TXT for details.
      8 //
      9 //===----------------------------------------------------------------------===//
     10 //
     11 // Installs signal handlers and related interceptors for UBSan standalone.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "ubsan_platform.h"
     16 #include "sanitizer_common/sanitizer_platform.h"
     17 #if CAN_SANITIZE_UB
     18 #include "interception/interception.h"
     19 #include "sanitizer_common/sanitizer_stacktrace.h"
     20 #include "ubsan_diag.h"
     21 #include "ubsan_init.h"
     22 
     23 // Interception of signals breaks too many things on Android.
     24 // * It requires that ubsan is the first dependency of the main executable for
     25 // the interceptors to work correctly. This complicates deployment, as it
     26 // prevents us from enabling ubsan on random platform modules independently.
     27 // * For this to work with ART VM, ubsan signal handler has to be set after the
     28 // debuggerd handler, but before the ART handler.
     29 // * Interceptors don't work at all when ubsan runtime is loaded late, ex. when
     30 // it is part of an APK that does not use wrap.sh method.
     31 #if SANITIZER_FUCHSIA || SANITIZER_ANDROID
     32 
     33 namespace __ubsan {
     34 void InitializeDeadlySignals() {}
     35 }
     36 
     37 #else
     38 
     39 #define COMMON_INTERCEPT_FUNCTION(name) INTERCEPT_FUNCTION(name)
     40 #include "sanitizer_common/sanitizer_signal_interceptors.inc"
     41 
     42 namespace __ubsan {
     43 
     44 static void OnStackUnwind(const SignalContext &sig, const void *,
     45                           BufferedStackTrace *stack) {
     46   GetStackTrace(stack, kStackTraceMax, sig.pc, sig.bp, sig.context,
     47                 common_flags()->fast_unwind_on_fatal);
     48 }
     49 
     50 static void UBsanOnDeadlySignal(int signo, void *siginfo, void *context) {
     51   HandleDeadlySignal(siginfo, context, GetTid(), &OnStackUnwind, nullptr);
     52 }
     53 
     54 static bool is_initialized = false;
     55 
     56 void InitializeDeadlySignals() {
     57   if (is_initialized)
     58     return;
     59   is_initialized = true;
     60   InitializeSignalInterceptors();
     61   InstallDeadlySignalHandlers(&UBsanOnDeadlySignal);
     62 }
     63 
     64 } // namespace __ubsan
     65 
     66 #endif
     67 
     68 #endif // CAN_SANITIZE_UB
     69