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/Signals.h"
20 #include "llvm/Support/Watchdog.h"
21 #include "llvm/Support/raw_ostream.h"
22 
23 #ifdef HAVE_CRASHREPORTERCLIENT_H
24 #include <CrashReporterClient.h>
25 #endif
26 
27 using namespace llvm;
28 
29 // We need a thread local pointer to manage the stack of our stack trace
30 // objects, but we *really* cannot tolerate destructors running and do not want
31 // to pay any overhead of synchronizing. As a consequence, we use a raw
32 // thread-local variable. Some day, we should be able to use a limited subset
33 // of C++11's thread_local, but compilers aren't up for it today.
34 // FIXME: This should be moved to a Compiler.h abstraction.
35 #ifdef _MSC_VER
36 // MSVC supports this with a __declspec.
37 #define LLVM_THREAD_LOCAL __declspec(thread)
38 #else
39 // Clang, GCC, and all compatible compilers tend to use __thread. But we need
40 // to work aronud a bug in the combination of Clang's compilation of
41 // local-dynamic TLS and the ppc64 linker relocations which we do by forcing to
42 // general-dynamic.
43 // FIXME: Make this conditional on the Clang version once this is fixed in
44 // top-of-tree.
45 #if defined(__clang__) && defined(__powerpc64__)
46 #define LLVM_THREAD_LOCAL __thread __attribute__((tls_model("general-dynamic")))
47 #else
48 #define LLVM_THREAD_LOCAL __thread
49 #endif
50 #endif
51 
52 static LLVM_THREAD_LOCAL const PrettyStackTraceEntry *PrettyStackTraceHead =
53     nullptr;
54 
55 static unsigned PrintStack(const PrettyStackTraceEntry *Entry, raw_ostream &OS){
56   unsigned NextID = 0;
57   if (Entry->getNextEntry())
58     NextID = PrintStack(Entry->getNextEntry(), OS);
59   OS << NextID << ".\t";
60   {
61     sys::Watchdog W(5);
62     Entry->print(OS);
63   }
64 
65   return NextID+1;
66 }
67 
68 /// PrintCurStackTrace - Print the current stack trace to the specified stream.
69 static void PrintCurStackTrace(raw_ostream &OS) {
70   // Don't print an empty trace.
71   if (!PrettyStackTraceHead) return;
72 
73   // If there are pretty stack frames registered, walk and emit them.
74   OS << "Stack dump:\n";
75 
76   PrintStack(PrettyStackTraceHead, OS);
77   OS.flush();
78 }
79 
80 // Integrate with crash reporter libraries.
81 #if defined (__APPLE__) && HAVE_CRASHREPORTERCLIENT_H
82 //  If any clients of llvm try to link to libCrashReporterClient.a themselves,
83 //  only one crash info struct will be used.
84 extern "C" {
85 CRASH_REPORTER_CLIENT_HIDDEN
86 struct crashreporter_annotations_t gCRAnnotations
87         __attribute__((section("__DATA," CRASHREPORTER_ANNOTATIONS_SECTION)))
88         = { CRASHREPORTER_ANNOTATIONS_VERSION, 0, 0, 0, 0, 0, 0 };
89 }
90 #elif defined (__APPLE__) && HAVE_CRASHREPORTER_INFO
91 static const char *__crashreporter_info__ = 0;
92 asm(".desc ___crashreporter_info__, 0x10");
93 #endif
94 
95 
96 /// CrashHandler - This callback is run if a fatal signal is delivered to the
97 /// process, it prints the pretty stack trace.
98 static void CrashHandler(void *) {
99 #ifndef __APPLE__
100   // On non-apple systems, just emit the crash stack trace to stderr.
101   PrintCurStackTrace(errs());
102 #else
103   // Otherwise, emit to a smallvector of chars, send *that* to stderr, but also
104   // put it into __crashreporter_info__.
105   SmallString<2048> TmpStr;
106   {
107     raw_svector_ostream Stream(TmpStr);
108     PrintCurStackTrace(Stream);
109   }
110 
111   if (!TmpStr.empty()) {
112 #ifdef HAVE_CRASHREPORTERCLIENT_H
113     // Cast to void to avoid warning.
114     (void)CRSetCrashLogMessage(std::string(TmpStr.str()).c_str());
115 #elif HAVE_CRASHREPORTER_INFO
116     __crashreporter_info__ = strdup(std::string(TmpStr.str()).c_str());
117 #endif
118     errs() << TmpStr.str();
119   }
120 
121 #endif
122 }
123 
124 PrettyStackTraceEntry::PrettyStackTraceEntry() {
125   // Link ourselves.
126   NextEntry = PrettyStackTraceHead;
127   PrettyStackTraceHead = this;
128 }
129 
130 PrettyStackTraceEntry::~PrettyStackTraceEntry() {
131   assert(PrettyStackTraceHead == this &&
132          "Pretty stack trace entry destruction is out of order");
133   PrettyStackTraceHead = getNextEntry();
134 }
135 
136 void PrettyStackTraceString::print(raw_ostream &OS) const {
137   OS << Str << "\n";
138 }
139 
140 void PrettyStackTraceProgram::print(raw_ostream &OS) const {
141   OS << "Program arguments: ";
142   // Print the argument list.
143   for (unsigned i = 0, e = ArgC; i != e; ++i)
144     OS << ArgV[i] << ' ';
145   OS << '\n';
146 }
147 
148 static bool RegisterCrashPrinter() {
149   sys::AddSignalHandler(CrashHandler, nullptr);
150   return false;
151 }
152 
153 void llvm::EnablePrettyStackTrace() {
154   // The first time this is called, we register the crash printer.
155   static bool HandlerRegistered = RegisterCrashPrinter();
156   (void)HandlerRegistered;
157 }
158 
159 void LLVMEnablePrettyStackTrace() {
160   EnablePrettyStackTrace();
161 }
162