1 //===- PrettyStackTrace.cpp - Pretty Crash Handling -----------------------===// 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 defines some helpful functions for dealing with the possibility of 11 // Unix signals occurring while your program is running. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/Support/PrettyStackTrace.h" 16 #include "llvm-c/ErrorHandling.h" 17 #include "llvm/ADT/SmallString.h" 18 #include "llvm/Config/config.h" // Get autoconf configuration settings 19 #include "llvm/Support/Compiler.h" 20 #include "llvm/Support/Signals.h" 21 #include "llvm/Support/Watchdog.h" 22 #include "llvm/Support/raw_ostream.h" 23 24 #include <tuple> 25 26 #ifdef HAVE_CRASHREPORTERCLIENT_H 27 #include <CrashReporterClient.h> 28 #endif 29 30 using namespace llvm; 31 32 // If backtrace support is not enabled, compile out support for pretty stack 33 // traces. This has the secondary effect of not requiring thread local storage 34 // when backtrace support is disabled. 35 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 36 37 // We need a thread local pointer to manage the stack of our stack trace 38 // objects, but we *really* cannot tolerate destructors running and do not want 39 // to pay any overhead of synchronizing. As a consequence, we use a raw 40 // thread-local variable. 41 static LLVM_THREAD_LOCAL PrettyStackTraceEntry *PrettyStackTraceHead = nullptr; 42 43 namespace llvm { 44 PrettyStackTraceEntry *ReverseStackTrace(PrettyStackTraceEntry *Head) { 45 PrettyStackTraceEntry *Prev = nullptr; 46 while (Head) 47 std::tie(Prev, Head, Head->NextEntry) = 48 std::make_tuple(Head, Head->NextEntry, Prev); 49 return Prev; 50 } 51 } 52 53 static void PrintStack(raw_ostream &OS) { 54 // Print out the stack in reverse order. To avoid recursion (which is likely 55 // to fail if we crashed due to stack overflow), we do an up-front pass to 56 // reverse the stack, then print it, then reverse it again. 57 unsigned ID = 0; 58 PrettyStackTraceEntry *ReversedStack = 59 llvm::ReverseStackTrace(PrettyStackTraceHead); 60 for (const PrettyStackTraceEntry *Entry = ReversedStack; Entry; 61 Entry = Entry->getNextEntry()) { 62 OS << ID++ << ".\t"; 63 sys::Watchdog W(5); 64 Entry->print(OS); 65 } 66 llvm::ReverseStackTrace(ReversedStack); 67 } 68 69 /// PrintCurStackTrace - Print the current stack trace to the specified stream. 70 static void PrintCurStackTrace(raw_ostream &OS) { 71 // Don't print an empty trace. 72 if (!PrettyStackTraceHead) return; 73 74 // If there are pretty stack frames registered, walk and emit them. 75 OS << "Stack dump:\n"; 76 77 PrintStack(OS); 78 OS.flush(); 79 } 80 81 // Integrate with crash reporter libraries. 82 #if defined (__APPLE__) && defined(HAVE_CRASHREPORTERCLIENT_H) 83 // If any clients of llvm try to link to libCrashReporterClient.a themselves, 84 // only one crash info struct will be used. 85 extern "C" { 86 CRASH_REPORTER_CLIENT_HIDDEN 87 struct crashreporter_annotations_t gCRAnnotations 88 __attribute__((section("__DATA," CRASHREPORTER_ANNOTATIONS_SECTION))) 89 = { CRASHREPORTER_ANNOTATIONS_VERSION, 0, 0, 0, 0, 0, 0 }; 90 } 91 #elif defined(__APPLE__) && HAVE_CRASHREPORTER_INFO 92 extern "C" const char *__crashreporter_info__ 93 __attribute__((visibility("hidden"))) = 0; 94 asm(".desc ___crashreporter_info__, 0x10"); 95 #endif 96 97 /// CrashHandler - This callback is run if a fatal signal is delivered to the 98 /// process, it prints the pretty stack trace. 99 static void CrashHandler(void *) { 100 #ifndef __APPLE__ 101 // On non-apple systems, just emit the crash stack trace to stderr. 102 PrintCurStackTrace(errs()); 103 #else 104 // Otherwise, emit to a smallvector of chars, send *that* to stderr, but also 105 // put it into __crashreporter_info__. 106 SmallString<2048> TmpStr; 107 { 108 raw_svector_ostream Stream(TmpStr); 109 PrintCurStackTrace(Stream); 110 } 111 112 if (!TmpStr.empty()) { 113 #ifdef HAVE_CRASHREPORTERCLIENT_H 114 // Cast to void to avoid warning. 115 (void)CRSetCrashLogMessage(std::string(TmpStr.str()).c_str()); 116 #elif HAVE_CRASHREPORTER_INFO 117 __crashreporter_info__ = strdup(std::string(TmpStr.str()).c_str()); 118 #endif 119 errs() << TmpStr.str(); 120 } 121 122 #endif 123 } 124 125 // defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 126 #endif 127 128 PrettyStackTraceEntry::PrettyStackTraceEntry() { 129 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 130 // Link ourselves. 131 NextEntry = PrettyStackTraceHead; 132 PrettyStackTraceHead = this; 133 #endif 134 } 135 136 PrettyStackTraceEntry::~PrettyStackTraceEntry() { 137 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 138 assert(PrettyStackTraceHead == this && 139 "Pretty stack trace entry destruction is out of order"); 140 PrettyStackTraceHead = NextEntry; 141 #endif 142 } 143 144 void PrettyStackTraceString::print(raw_ostream &OS) const { OS << Str << "\n"; } 145 146 PrettyStackTraceFormat::PrettyStackTraceFormat(const char *Format, ...) { 147 va_list AP; 148 va_start(AP, Format); 149 const int SizeOrError = vsnprintf(nullptr, 0, Format, AP); 150 va_end(AP); 151 if (SizeOrError < 0) { 152 return; 153 } 154 155 const int Size = SizeOrError + 1; // '\0' 156 Str.resize(Size); 157 va_start(AP, Format); 158 vsnprintf(Str.data(), Size, Format, AP); 159 va_end(AP); 160 } 161 162 void PrettyStackTraceFormat::print(raw_ostream &OS) const { OS << Str << "\n"; } 163 164 void PrettyStackTraceProgram::print(raw_ostream &OS) const { 165 OS << "Program arguments: "; 166 // Print the argument list. 167 for (unsigned i = 0, e = ArgC; i != e; ++i) 168 OS << ArgV[i] << ' '; 169 OS << '\n'; 170 } 171 172 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 173 static bool RegisterCrashPrinter() { 174 sys::AddSignalHandler(CrashHandler, nullptr); 175 return false; 176 } 177 #endif 178 179 void llvm::EnablePrettyStackTrace() { 180 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 181 // The first time this is called, we register the crash printer. 182 static bool HandlerRegistered = RegisterCrashPrinter(); 183 (void)HandlerRegistered; 184 #endif 185 } 186 187 const void *llvm::SavePrettyStackState() { 188 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 189 return PrettyStackTraceHead; 190 #else 191 return nullptr; 192 #endif 193 } 194 195 void llvm::RestorePrettyStackState(const void *Top) { 196 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES 197 PrettyStackTraceHead = 198 static_cast<PrettyStackTraceEntry *>(const_cast<void *>(Top)); 199 #endif 200 } 201 202 void LLVMEnablePrettyStackTrace() { 203 EnablePrettyStackTrace(); 204 } 205