1 //===- Signals.cpp - Signal Handling support --------------------*- C++ -*-===//
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/Signals.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/Config/config.h"
19 #include "llvm/Support/ErrorOr.h"
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/FileUtilities.h"
22 #include "llvm/Support/Format.h"
23 #include "llvm/Support/ManagedStatic.h"
24 #include "llvm/Support/MemoryBuffer.h"
25 #include "llvm/Support/Mutex.h"
26 #include "llvm/Support/Program.h"
27 #include "llvm/Support/StringSaver.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/Support/Options.h"
30 #include <vector>
31 
32 //===----------------------------------------------------------------------===//
33 //=== WARNING: Implementation here must contain only TRULY operating system
34 //===          independent code.
35 //===----------------------------------------------------------------------===//
36 
37 using namespace llvm;
38 
39 static cl::opt<bool>
40     DisableSymbolication("disable-symbolication",
41                          cl::desc("Disable symbolizing crash backtraces."),
42                          cl::init(false), cl::Hidden);
43 
44 static ManagedStatic<std::vector<std::pair<void (*)(void *), void *>>>
45     CallBacksToRun;
46 void sys::RunSignalHandlers() {
47   if (!CallBacksToRun.isConstructed())
48     return;
49   for (auto &I : *CallBacksToRun)
50     I.first(I.second);
51   CallBacksToRun->clear();
52 }
53 
54 static bool findModulesAndOffsets(void **StackTrace, int Depth,
55                                   const char **Modules, intptr_t *Offsets,
56                                   const char *MainExecutableName,
57                                   StringSaver &StrPool);
58 
59 /// Format a pointer value as hexadecimal. Zero pad it out so its always the
60 /// same width.
61 static FormattedNumber format_ptr(void *PC) {
62   // Each byte is two hex digits plus 2 for the 0x prefix.
63   unsigned PtrWidth = 2 + 2 * sizeof(void *);
64   return format_hex((uint64_t)PC, PtrWidth);
65 }
66 
67 static bool printSymbolizedStackTrace(StringRef Argv0,
68                                       void **StackTrace, int Depth,
69                                       llvm::raw_ostream &OS)
70   LLVM_ATTRIBUTE_USED;
71 
72 /// Helper that launches llvm-symbolizer and symbolizes a backtrace.
73 static bool printSymbolizedStackTrace(StringRef Argv0,
74                                       void **StackTrace, int Depth,
75                                       llvm::raw_ostream &OS) {
76   if (DisableSymbolication)
77     return false;
78 
79   // Don't recursively invoke the llvm-symbolizer binary.
80   if (Argv0.find("llvm-symbolizer") != std::string::npos)
81     return false;
82 
83   // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
84   // into actual instruction addresses.
85   // Use llvm-symbolizer tool to symbolize the stack traces. First look for it
86   // alongside our binary, then in $PATH.
87   ErrorOr<std::string> LLVMSymbolizerPathOrErr = std::error_code();
88   if (!Argv0.empty()) {
89     StringRef Parent = llvm::sys::path::parent_path(Argv0);
90     if (!Parent.empty())
91       LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer", Parent);
92   }
93   if (!LLVMSymbolizerPathOrErr)
94     LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer");
95   if (!LLVMSymbolizerPathOrErr)
96     return false;
97   const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
98 
99   // If we don't know argv0 or the address of main() at this point, try
100   // to guess it anyway (it's possible on some platforms).
101   std::string MainExecutableName =
102       Argv0.empty() ? sys::fs::getMainExecutable(nullptr, nullptr)
103                     : (std::string)Argv0;
104   BumpPtrAllocator Allocator;
105   StringSaver StrPool(Allocator);
106   std::vector<const char *> Modules(Depth, nullptr);
107   std::vector<intptr_t> Offsets(Depth, 0);
108   if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
109                              MainExecutableName.c_str(), StrPool))
110     return false;
111   int InputFD;
112   SmallString<32> InputFile, OutputFile;
113   sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
114   sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
115   FileRemover InputRemover(InputFile.c_str());
116   FileRemover OutputRemover(OutputFile.c_str());
117 
118   {
119     raw_fd_ostream Input(InputFD, true);
120     for (int i = 0; i < Depth; i++) {
121       if (Modules[i])
122         Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
123     }
124   }
125 
126   Optional<StringRef> Redirects[] = {InputFile.str(), OutputFile.str(), llvm::None};
127   const char *Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
128 #ifdef LLVM_ON_WIN32
129                         // Pass --relative-address on Windows so that we don't
130                         // have to add ImageBase from PE file.
131                         // FIXME: Make this the default for llvm-symbolizer.
132                         "--relative-address",
133 #endif
134                         "--demangle", nullptr};
135   int RunResult =
136       sys::ExecuteAndWait(LLVMSymbolizerPath, Args, nullptr, Redirects);
137   if (RunResult != 0)
138     return false;
139 
140   // This report format is based on the sanitizer stack trace printer.  See
141   // sanitizer_stacktrace_printer.cc in compiler-rt.
142   auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
143   if (!OutputBuf)
144     return false;
145   StringRef Output = OutputBuf.get()->getBuffer();
146   SmallVector<StringRef, 32> Lines;
147   Output.split(Lines, "\n");
148   auto CurLine = Lines.begin();
149   int frame_no = 0;
150   for (int i = 0; i < Depth; i++) {
151     if (!Modules[i]) {
152       OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << '\n';
153       continue;
154     }
155     // Read pairs of lines (function name and file/line info) until we
156     // encounter empty line.
157     for (;;) {
158       if (CurLine == Lines.end())
159         return false;
160       StringRef FunctionName = *CurLine++;
161       if (FunctionName.empty())
162         break;
163       OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << ' ';
164       if (!FunctionName.startswith("??"))
165         OS << FunctionName << ' ';
166       if (CurLine == Lines.end())
167         return false;
168       StringRef FileLineInfo = *CurLine++;
169       if (!FileLineInfo.startswith("??"))
170         OS << FileLineInfo;
171       else
172         OS << "(" << Modules[i] << '+' << format_hex(Offsets[i], 0) << ")";
173       OS << "\n";
174     }
175   }
176   return true;
177 }
178 
179 // Include the platform-specific parts of this class.
180 #ifdef LLVM_ON_UNIX
181 #include "Unix/Signals.inc"
182 #endif
183 #ifdef LLVM_ON_WIN32
184 #include "Windows/Signals.inc"
185 #endif
186