lib/Support/PrettyStackTrace.cpp

   1 //===- PrettyStackTrace.cpp - Pretty Crash Handling -----------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines some helpful functions for dealing with the possibility of
  10 // Unix signals occurring while your program is running.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Support/PrettyStackTrace.h"
  15 #include "llvm-c/ErrorHandling.h"
  16 #include "llvm/ADT/SmallString.h"
  17 #include "llvm/Config/config.h" // Get autoconf configuration settings
  18 #include "llvm/Support/Compiler.h"
  19 #include "llvm/Support/Signals.h"
  20 #include "llvm/Support/Watchdog.h"
  21 #include "llvm/Support/raw_ostream.h"
  22
  23 #include <cstdarg>
  24 #include <cstdio>
  25 #include <tuple>
  26
  27 #ifdef HAVE_CRASHREPORTERCLIENT_H
  28 #include <CrashReporterClient.h>
  29 #endif
  30
  31 using namespace llvm;
  32
  33 // If backtrace support is not enabled, compile out support for pretty stack
  34 // traces.  This has the secondary effect of not requiring thread local storage
  35 // when backtrace support is disabled.
  36 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
  37
  38 // We need a thread local pointer to manage the stack of our stack trace
  39 // objects, but we *really* cannot tolerate destructors running and do not want
  40 // to pay any overhead of synchronizing. As a consequence, we use a raw
  41 // thread-local variable.
  42 static LLVM_THREAD_LOCAL PrettyStackTraceEntry *PrettyStackTraceHead = nullptr;
  43
  44 namespace llvm {
  45 PrettyStackTraceEntry *ReverseStackTrace(PrettyStackTraceEntry *Head) {
  46   PrettyStackTraceEntry *Prev = nullptr;
  47   while (Head)
  48     std::tie(Prev, Head, Head->NextEntry) =
  49         std::make_tuple(Head, Head->NextEntry, Prev);
  50   return Prev;
  51 }
  52 }
  53
  54 static void PrintStack(raw_ostream &OS) {
  55   // Print out the stack in reverse order. To avoid recursion (which is likely
  56   // to fail if we crashed due to stack overflow), we do an up-front pass to
  57   // reverse the stack, then print it, then reverse it again.
  58   unsigned ID = 0;
  59   PrettyStackTraceEntry *ReversedStack =
  60       llvm::ReverseStackTrace(PrettyStackTraceHead);
  61   for (const PrettyStackTraceEntry *Entry = ReversedStack; Entry;
  62        Entry = Entry->getNextEntry()) {
  63     OS << ID++ << ".\t";
  64     sys::Watchdog W(5);
  65     Entry->print(OS);
  66   }
  67   llvm::ReverseStackTrace(ReversedStack);
  68 }
  69
  70 /// PrintCurStackTrace - Print the current stack trace to the specified stream.
  71 static void PrintCurStackTrace(raw_ostream &OS) {
  72   // Don't print an empty trace.
  73   if (!PrettyStackTraceHead) return;
  74
  75   // If there are pretty stack frames registered, walk and emit them.
  76   OS << "Stack dump:\n";
  77
  78   PrintStack(OS);
  79   OS.flush();
  80 }
  81
  82 // Integrate with crash reporter libraries.
  83 #if defined (__APPLE__) && defined(HAVE_CRASHREPORTERCLIENT_H)
  84 //  If any clients of llvm try to link to libCrashReporterClient.a themselves,
  85 //  only one crash info struct will be used.
  86 extern "C" {
  87 CRASH_REPORTER_CLIENT_HIDDEN
  88 struct crashreporter_annotations_t gCRAnnotations
  89         __attribute__((section("__DATA," CRASHREPORTER_ANNOTATIONS_SECTION)))
  90 #if CRASHREPORTER_ANNOTATIONS_VERSION < 5
  91         = { CRASHREPORTER_ANNOTATIONS_VERSION, 0, 0, 0, 0, 0, 0 };
  92 #else
  93         = { CRASHREPORTER_ANNOTATIONS_VERSION, 0, 0, 0, 0, 0, 0, 0 };
  94 #endif
  95 }
  96 #elif defined(__APPLE__) && HAVE_CRASHREPORTER_INFO
  97 extern "C" const char *__crashreporter_info__
  98     __attribute__((visibility("hidden"))) = 0;
  99 asm(".desc ___crashreporter_info__, 0x10");
 100 #endif
 101
 102 /// CrashHandler - This callback is run if a fatal signal is delivered to the
 103 /// process, it prints the pretty stack trace.
 104 static void CrashHandler(void *) {
 105 #ifndef __APPLE__
 106   // On non-apple systems, just emit the crash stack trace to stderr.
 107   PrintCurStackTrace(errs());
 108 #else
 109   // Otherwise, emit to a smallvector of chars, send *that* to stderr, but also
 110   // put it into __crashreporter_info__.
 111   SmallString<2048> TmpStr;
 112   {
 113     raw_svector_ostream Stream(TmpStr);
 114     PrintCurStackTrace(Stream);
 115   }
 116
 117   if (!TmpStr.empty()) {
 118 #ifdef HAVE_CRASHREPORTERCLIENT_H
 119     // Cast to void to avoid warning.
 120     (void)CRSetCrashLogMessage(TmpStr.c_str());
 121 #elif HAVE_CRASHREPORTER_INFO
 122     __crashreporter_info__ = strdup(TmpStr.c_str());
 123 #endif
 124     errs() << TmpStr.str();
 125   }
 126
 127 #endif
 128 }
 129
 130 // defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
 131 #endif
 132
 133 PrettyStackTraceEntry::PrettyStackTraceEntry() {
 134 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
 135   // Link ourselves.
 136   NextEntry = PrettyStackTraceHead;
 137   PrettyStackTraceHead = this;
 138 #endif
 139 }
 140
 141 PrettyStackTraceEntry::~PrettyStackTraceEntry() {
 142 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
 143   assert(PrettyStackTraceHead == this &&
 144          "Pretty stack trace entry destruction is out of order");
 145   PrettyStackTraceHead = NextEntry;
 146 #endif
 147 }
 148
 149 void PrettyStackTraceString::print(raw_ostream &OS) const { OS << Str << "\n"; }
 150
 151 PrettyStackTraceFormat::PrettyStackTraceFormat(const char *Format, ...) {
 152   va_list AP;
 153   va_start(AP, Format);
 154   const int SizeOrError = vsnprintf(nullptr, 0, Format, AP);
 155   va_end(AP);
 156   if (SizeOrError < 0) {
 157     return;
 158   }
 159
 160   const int Size = SizeOrError + 1; // '\0'
 161   Str.resize(Size);
 162   va_start(AP, Format);
 163   vsnprintf(Str.data(), Size, Format, AP);
 164   va_end(AP);
 165 }
 166
 167 void PrettyStackTraceFormat::print(raw_ostream &OS) const { OS << Str << "\n"; }
 168
 169 void PrettyStackTraceProgram::print(raw_ostream &OS) const {
 170   OS << "Program arguments: ";
 171   // Print the argument list.
 172   for (unsigned i = 0, e = ArgC; i != e; ++i)
 173     OS << ArgV[i] << ' ';
 174   OS << '\n';
 175 }
 176
 177 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
 178 static bool RegisterCrashPrinter() {
 179   sys::AddSignalHandler(CrashHandler, nullptr);
 180   return false;
 181 }
 182 #endif
 183
 184 void llvm::EnablePrettyStackTrace() {
 185 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
 186   // The first time this is called, we register the crash printer.
 187   static bool HandlerRegistered = RegisterCrashPrinter();
 188   (void)HandlerRegistered;
 189 #endif
 190 }
 191
 192 const void *llvm::SavePrettyStackState() {
 193 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
 194   return PrettyStackTraceHead;
 195 #else
 196   return nullptr;
 197 #endif
 198 }
 199
 200 void llvm::RestorePrettyStackState(const void *Top) {
 201 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
 202   PrettyStackTraceHead =
 203       static_cast<PrettyStackTraceEntry *>(const_cast<void *>(Top));
 204 #endif
 205 }
 206
 207 void LLVMEnablePrettyStackTrace() {
 208   EnablePrettyStackTrace();
 209 }