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 <cstdarg>
25 #include <cstdio>
26 #include <tuple>
27
28 #ifdef HAVE_CRASHREPORTERCLIENT_H
29 #include <CrashReporterClient.h>
30 #endif
31
32 using namespace llvm;
33
34 // If backtrace support is not enabled, compile out support for pretty stack
35 // traces. This has the secondary effect of not requiring thread local storage
36 // when backtrace support is disabled.
37 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
38
39 // We need a thread local pointer to manage the stack of our stack trace
40 // objects, but we *really* cannot tolerate destructors running and do not want
41 // to pay any overhead of synchronizing. As a consequence, we use a raw
42 // thread-local variable.
43 static LLVM_THREAD_LOCAL PrettyStackTraceEntry *PrettyStackTraceHead = nullptr;
44
45 namespace llvm {
ReverseStackTrace(PrettyStackTraceEntry * Head)46 PrettyStackTraceEntry *ReverseStackTrace(PrettyStackTraceEntry *Head) {
47 PrettyStackTraceEntry *Prev = nullptr;
48 while (Head)
49 std::tie(Prev, Head, Head->NextEntry) =
50 std::make_tuple(Head, Head->NextEntry, Prev);
51 return Prev;
52 }
53 }
54
PrintStack(raw_ostream & OS)55 static void PrintStack(raw_ostream &OS) {
56 // Print out the stack in reverse order. To avoid recursion (which is likely
57 // to fail if we crashed due to stack overflow), we do an up-front pass to
58 // reverse the stack, then print it, then reverse it again.
59 unsigned ID = 0;
60 PrettyStackTraceEntry *ReversedStack =
61 llvm::ReverseStackTrace(PrettyStackTraceHead);
62 for (const PrettyStackTraceEntry *Entry = ReversedStack; Entry;
63 Entry = Entry->getNextEntry()) {
64 OS << ID++ << ".\t";
65 sys::Watchdog W(5);
66 Entry->print(OS);
67 }
68 llvm::ReverseStackTrace(ReversedStack);
69 }
70
71 /// PrintCurStackTrace - Print the current stack trace to the specified stream.
PrintCurStackTrace(raw_ostream & OS)72 static void PrintCurStackTrace(raw_ostream &OS) {
73 // Don't print an empty trace.
74 if (!PrettyStackTraceHead) return;
75
76 // If there are pretty stack frames registered, walk and emit them.
77 OS << "Stack dump:\n";
78
79 PrintStack(OS);
80 OS.flush();
81 }
82
83 // Integrate with crash reporter libraries.
84 #if defined (__APPLE__) && defined(HAVE_CRASHREPORTERCLIENT_H)
85 // If any clients of llvm try to link to libCrashReporterClient.a themselves,
86 // only one crash info struct will be used.
87 extern "C" {
88 CRASH_REPORTER_CLIENT_HIDDEN
89 struct crashreporter_annotations_t gCRAnnotations
90 __attribute__((section("__DATA," CRASHREPORTER_ANNOTATIONS_SECTION)))
91 #if CRASHREPORTER_ANNOTATIONS_VERSION < 5
92 = { CRASHREPORTER_ANNOTATIONS_VERSION, 0, 0, 0, 0, 0, 0 };
93 #else
94 = { CRASHREPORTER_ANNOTATIONS_VERSION, 0, 0, 0, 0, 0, 0, 0 };
95 #endif
96 }
97 #elif defined(__APPLE__) && HAVE_CRASHREPORTER_INFO
98 extern "C" const char *__crashreporter_info__
99 __attribute__((visibility("hidden"))) = 0;
100 asm(".desc ___crashreporter_info__, 0x10");
101 #endif
102
103 /// CrashHandler - This callback is run if a fatal signal is delivered to the
104 /// process, it prints the pretty stack trace.
CrashHandler(void *)105 static void CrashHandler(void *) {
106 #ifndef __APPLE__
107 // On non-apple systems, just emit the crash stack trace to stderr.
108 PrintCurStackTrace(errs());
109 #else
110 // Otherwise, emit to a smallvector of chars, send *that* to stderr, but also
111 // put it into __crashreporter_info__.
112 SmallString<2048> TmpStr;
113 {
114 raw_svector_ostream Stream(TmpStr);
115 PrintCurStackTrace(Stream);
116 }
117
118 if (!TmpStr.empty()) {
119 #ifdef HAVE_CRASHREPORTERCLIENT_H
120 // Cast to void to avoid warning.
121 (void)CRSetCrashLogMessage(TmpStr.c_str());
122 #elif HAVE_CRASHREPORTER_INFO
123 __crashreporter_info__ = strdup(TmpStr.c_str());
124 #endif
125 errs() << TmpStr.str();
126 }
127
128 #endif
129 }
130
131 // defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
132 #endif
133
PrettyStackTraceEntry()134 PrettyStackTraceEntry::PrettyStackTraceEntry() {
135 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
136 // Link ourselves.
137 NextEntry = PrettyStackTraceHead;
138 PrettyStackTraceHead = this;
139 #endif
140 }
141
~PrettyStackTraceEntry()142 PrettyStackTraceEntry::~PrettyStackTraceEntry() {
143 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
144 assert(PrettyStackTraceHead == this &&
145 "Pretty stack trace entry destruction is out of order");
146 PrettyStackTraceHead = NextEntry;
147 #endif
148 }
149
print(raw_ostream & OS) const150 void PrettyStackTraceString::print(raw_ostream &OS) const { OS << Str << "\n"; }
151
PrettyStackTraceFormat(const char * Format,...)152 PrettyStackTraceFormat::PrettyStackTraceFormat(const char *Format, ...) {
153 va_list AP;
154 va_start(AP, Format);
155 const int SizeOrError = vsnprintf(nullptr, 0, Format, AP);
156 va_end(AP);
157 if (SizeOrError < 0) {
158 return;
159 }
160
161 const int Size = SizeOrError + 1; // '\0'
162 Str.resize(Size);
163 va_start(AP, Format);
164 vsnprintf(Str.data(), Size, Format, AP);
165 va_end(AP);
166 }
167
print(raw_ostream & OS) const168 void PrettyStackTraceFormat::print(raw_ostream &OS) const { OS << Str << "\n"; }
169
print(raw_ostream & OS) const170 void PrettyStackTraceProgram::print(raw_ostream &OS) const {
171 OS << "Program arguments: ";
172 // Print the argument list.
173 for (unsigned i = 0, e = ArgC; i != e; ++i)
174 OS << ArgV[i] << ' ';
175 OS << '\n';
176 }
177
178 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
RegisterCrashPrinter()179 static bool RegisterCrashPrinter() {
180 sys::AddSignalHandler(CrashHandler, nullptr);
181 return false;
182 }
183 #endif
184
EnablePrettyStackTrace()185 void llvm::EnablePrettyStackTrace() {
186 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
187 // The first time this is called, we register the crash printer.
188 static bool HandlerRegistered = RegisterCrashPrinter();
189 (void)HandlerRegistered;
190 #endif
191 }
192
SavePrettyStackState()193 const void *llvm::SavePrettyStackState() {
194 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
195 return PrettyStackTraceHead;
196 #else
197 return nullptr;
198 #endif
199 }
200
RestorePrettyStackState(const void * Top)201 void llvm::RestorePrettyStackState(const void *Top) {
202 #if defined(HAVE_BACKTRACE) && ENABLE_BACKTRACES
203 PrettyStackTraceHead =
204 static_cast<PrettyStackTraceEntry *>(const_cast<void *>(Top));
205 #endif
206 }
207
LLVMEnablePrettyStackTrace()208 void LLVMEnablePrettyStackTrace() {
209 EnablePrettyStackTrace();
210 }
211