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 occuring while your program is running.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Support/PrettyStackTrace.h"
16 #include "llvm/Support/raw_ostream.h"
17 #include "llvm/System/Signals.h"
18 #include "llvm/System/ThreadLocal.h"
19 #include "llvm/ADT/SmallString.h"
20 using namespace llvm;
21 
22 namespace llvm {
23   bool DisablePrettyStackTrace = false;
24 }
25 
26 // FIXME: This should be thread local when llvm supports threads.
27 static sys::ThreadLocal<const PrettyStackTraceEntry> PrettyStackTraceHead;
28 
29 static unsigned PrintStack(const PrettyStackTraceEntry *Entry, raw_ostream &OS){
30   unsigned NextID = 0;
31   if (Entry->getNextEntry())
32     NextID = PrintStack(Entry->getNextEntry(), OS);
33   OS << NextID << ".\t";
34   Entry->print(OS);
35 
36   return NextID+1;
37 }
38 
39 /// PrintCurStackTrace - Print the current stack trace to the specified stream.
40 static void PrintCurStackTrace(raw_ostream &OS) {
41   // Don't print an empty trace.
42   if (PrettyStackTraceHead.get() == 0) return;
43 
44   // If there are pretty stack frames registered, walk and emit them.
45   OS << "Stack dump:\n";
46 
47   PrintStack(PrettyStackTraceHead.get(), OS);
48   OS.flush();
49 }
50 
51 // Integrate with crash reporter.
52 #ifdef __APPLE__
53 static const char *__crashreporter_info__ = 0;
54 asm(".desc ___crashreporter_info__, 0x10");
55 #endif
56 
57 
58 /// CrashHandler - This callback is run if a fatal signal is delivered to the
59 /// process, it prints the pretty stack trace.
60 static void CrashHandler(void *Cookie) {
61 #ifndef __APPLE__
62   // On non-apple systems, just emit the crash stack trace to stderr.
63   PrintCurStackTrace(errs());
64 #else
65   // Otherwise, emit to a smallvector of chars, send *that* to stderr, but also
66   // put it into __crashreporter_info__.
67   SmallString<2048> TmpStr;
68   {
69     raw_svector_ostream Stream(TmpStr);
70     PrintCurStackTrace(Stream);
71   }
72 
73   if (!TmpStr.empty()) {
74     __crashreporter_info__ = strdup(std::string(TmpStr.str()).c_str());
75     errs() << TmpStr.str();
76   }
77 
78 #endif
79 }
80 
81 static bool RegisterCrashPrinter() {
82   if (!DisablePrettyStackTrace)
83     sys::AddSignalHandler(CrashHandler, 0);
84   return false;
85 }
86 
87 PrettyStackTraceEntry::PrettyStackTraceEntry() {
88   // The first time this is called, we register the crash printer.
89   static bool HandlerRegistered = RegisterCrashPrinter();
90   HandlerRegistered = HandlerRegistered;
91 
92   // Link ourselves.
93   NextEntry = PrettyStackTraceHead.get();
94   PrettyStackTraceHead.set(this);
95 }
96 
97 PrettyStackTraceEntry::~PrettyStackTraceEntry() {
98   assert(PrettyStackTraceHead.get() == this &&
99          "Pretty stack trace entry destruction is out of order");
100   PrettyStackTraceHead.set(getNextEntry());
101 }
102 
103 void PrettyStackTraceString::print(raw_ostream &OS) const {
104   OS << Str << "\n";
105 }
106 
107 void PrettyStackTraceProgram::print(raw_ostream &OS) const {
108   OS << "Program arguments: ";
109   // Print the argument list.
110   for (unsigned i = 0, e = ArgC; i != e; ++i)
111     OS << ArgV[i] << ' ';
112   OS << '\n';
113 }
114 
115