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/Core.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#ifdef HAVE_CRASHREPORTERCLIENT_H
25#include <CrashReporterClient.h>
26#endif
27
28using namespace llvm;
29
30// If backtrace support is not enabled, compile out support for pretty stack
31// traces.  This has the secondary effect of not requiring thread local storage
32// when backtrace support is disabled.
33#if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
34
35// We need a thread local pointer to manage the stack of our stack trace
36// objects, but we *really* cannot tolerate destructors running and do not want
37// to pay any overhead of synchronizing. As a consequence, we use a raw
38// thread-local variable.
39static LLVM_THREAD_LOCAL const PrettyStackTraceEntry *PrettyStackTraceHead =
40    nullptr;
41
42static unsigned PrintStack(const PrettyStackTraceEntry *Entry, raw_ostream &OS){
43  unsigned NextID = 0;
44  if (Entry->getNextEntry())
45    NextID = PrintStack(Entry->getNextEntry(), OS);
46  OS << NextID << ".\t";
47  {
48    sys::Watchdog W(5);
49    Entry->print(OS);
50  }
51
52  return NextID+1;
53}
54
55/// PrintCurStackTrace - Print the current stack trace to the specified stream.
56static void PrintCurStackTrace(raw_ostream &OS) {
57  // Don't print an empty trace.
58  if (!PrettyStackTraceHead) return;
59
60  // If there are pretty stack frames registered, walk and emit them.
61  OS << "Stack dump:\n";
62
63  PrintStack(PrettyStackTraceHead, OS);
64  OS.flush();
65}
66
67// Integrate with crash reporter libraries.
68#if defined (__APPLE__) && HAVE_CRASHREPORTERCLIENT_H
69//  If any clients of llvm try to link to libCrashReporterClient.a themselves,
70//  only one crash info struct will be used.
71extern "C" {
72CRASH_REPORTER_CLIENT_HIDDEN
73struct crashreporter_annotations_t gCRAnnotations
74        __attribute__((section("__DATA," CRASHREPORTER_ANNOTATIONS_SECTION)))
75        = { CRASHREPORTER_ANNOTATIONS_VERSION, 0, 0, 0, 0, 0, 0 };
76}
77#elif defined (__APPLE__) && HAVE_CRASHREPORTER_INFO
78static const char *__crashreporter_info__ = 0;
79asm(".desc ___crashreporter_info__, 0x10");
80#endif
81
82
83/// CrashHandler - This callback is run if a fatal signal is delivered to the
84/// process, it prints the pretty stack trace.
85static void CrashHandler(void *) {
86#ifndef __APPLE__
87  // On non-apple systems, just emit the crash stack trace to stderr.
88  PrintCurStackTrace(errs());
89#else
90  // Otherwise, emit to a smallvector of chars, send *that* to stderr, but also
91  // put it into __crashreporter_info__.
92  SmallString<2048> TmpStr;
93  {
94    raw_svector_ostream Stream(TmpStr);
95    PrintCurStackTrace(Stream);
96  }
97
98  if (!TmpStr.empty()) {
99#ifdef HAVE_CRASHREPORTERCLIENT_H
100    // Cast to void to avoid warning.
101    (void)CRSetCrashLogMessage(std::string(TmpStr.str()).c_str());
102#elif HAVE_CRASHREPORTER_INFO
103    __crashreporter_info__ = strdup(std::string(TmpStr.str()).c_str());
104#endif
105    errs() << TmpStr.str();
106  }
107
108#endif
109}
110
111// defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
112#endif
113
114PrettyStackTraceEntry::PrettyStackTraceEntry() {
115#if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
116  // Link ourselves.
117  NextEntry = PrettyStackTraceHead;
118  PrettyStackTraceHead = this;
119#endif
120}
121
122PrettyStackTraceEntry::~PrettyStackTraceEntry() {
123#if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
124  assert(PrettyStackTraceHead == this &&
125         "Pretty stack trace entry destruction is out of order");
126  PrettyStackTraceHead = getNextEntry();
127#endif
128}
129
130void PrettyStackTraceString::print(raw_ostream &OS) const {
131  OS << Str << "\n";
132}
133
134void PrettyStackTraceProgram::print(raw_ostream &OS) const {
135  OS << "Program arguments: ";
136  // Print the argument list.
137  for (unsigned i = 0, e = ArgC; i != e; ++i)
138    OS << ArgV[i] << ' ';
139  OS << '\n';
140}
141
142#if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
143static bool RegisterCrashPrinter() {
144  sys::AddSignalHandler(CrashHandler, nullptr);
145  return false;
146}
147#endif
148
149void llvm::EnablePrettyStackTrace() {
150#if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
151  // The first time this is called, we register the crash printer.
152  static bool HandlerRegistered = RegisterCrashPrinter();
153  (void)HandlerRegistered;
154#endif
155}
156
157void LLVMEnablePrettyStackTrace() {
158  EnablePrettyStackTrace();
159}
160