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/ADT/STLExtras.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/Config/config.h"
18 #include "llvm/Support/ErrorOr.h"
19 #include "llvm/Support/FileSystem.h"
20 #include "llvm/Support/FileUtilities.h"
21 #include "llvm/Support/Format.h"
22 #include "llvm/Support/ManagedStatic.h"
23 #include "llvm/Support/MemoryBuffer.h"
24 #include "llvm/Support/Mutex.h"
25 #include "llvm/Support/Program.h"
26 #include "llvm/Support/Signals.h"
27 #include "llvm/Support/StringSaver.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include <vector>
30 
31 namespace llvm {
32 using namespace sys;
33 
34 //===----------------------------------------------------------------------===//
35 //=== WARNING: Implementation here must contain only TRULY operating system
36 //===          independent code.
37 //===----------------------------------------------------------------------===//
38 
39 static ManagedStatic<std::vector<std::pair<void (*)(void *), void *>>>
40     CallBacksToRun;
RunSignalHandlers()41 void sys::RunSignalHandlers() {
42   if (!CallBacksToRun.isConstructed())
43     return;
44   for (auto &I : *CallBacksToRun)
45     I.first(I.second);
46   CallBacksToRun->clear();
47 }
48 }
49 
50 using namespace llvm;
51 
52 static bool findModulesAndOffsets(void **StackTrace, int Depth,
53                                   const char **Modules, intptr_t *Offsets,
54                                   const char *MainExecutableName,
55                                   StringSaver &StrPool);
56 
57 /// Format a pointer value as hexadecimal. Zero pad it out so its always the
58 /// same width.
format_ptr(void * PC)59 static FormattedNumber format_ptr(void *PC) {
60   // Each byte is two hex digits plus 2 for the 0x prefix.
61   unsigned PtrWidth = 2 + 2 * sizeof(void *);
62   return format_hex((uint64_t)PC, PtrWidth);
63 }
64 
65 static bool printSymbolizedStackTrace(StringRef Argv0,
66                                       void **StackTrace, int Depth,
67                                       llvm::raw_ostream &OS)
68   LLVM_ATTRIBUTE_USED;
69 
70 /// Helper that launches llvm-symbolizer and symbolizes a backtrace.
printSymbolizedStackTrace(StringRef Argv0,void ** StackTrace,int Depth,llvm::raw_ostream & OS)71 static bool printSymbolizedStackTrace(StringRef Argv0,
72                                       void **StackTrace, int Depth,
73                                       llvm::raw_ostream &OS) {
74   // Don't recursively invoke the llvm-symbolizer binary.
75   if (Argv0.find("llvm-symbolizer") != std::string::npos)
76     return false;
77 
78   // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
79   // into actual instruction addresses.
80   // Use llvm-symbolizer tool to symbolize the stack traces. First look for it
81   // alongside our binary, then in $PATH.
82   ErrorOr<std::string> LLVMSymbolizerPathOrErr = std::error_code();
83   if (!Argv0.empty()) {
84     StringRef Parent = llvm::sys::path::parent_path(Argv0);
85     if (!Parent.empty())
86       LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer", Parent);
87   }
88   if (!LLVMSymbolizerPathOrErr)
89     LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer");
90   if (!LLVMSymbolizerPathOrErr)
91     return false;
92   const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
93 
94   // If we don't know argv0 or the address of main() at this point, try
95   // to guess it anyway (it's possible on some platforms).
96   std::string MainExecutableName =
97       Argv0.empty() ? sys::fs::getMainExecutable(nullptr, nullptr)
98                     : (std::string)Argv0;
99   BumpPtrAllocator Allocator;
100   StringSaver StrPool(Allocator);
101   std::vector<const char *> Modules(Depth, nullptr);
102   std::vector<intptr_t> Offsets(Depth, 0);
103   if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
104                              MainExecutableName.c_str(), StrPool))
105     return false;
106   int InputFD;
107   SmallString<32> InputFile, OutputFile;
108   sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
109   sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
110   FileRemover InputRemover(InputFile.c_str());
111   FileRemover OutputRemover(OutputFile.c_str());
112 
113   {
114     raw_fd_ostream Input(InputFD, true);
115     for (int i = 0; i < Depth; i++) {
116       if (Modules[i])
117         Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
118     }
119   }
120 
121   StringRef InputFileStr(InputFile);
122   StringRef OutputFileStr(OutputFile);
123   StringRef StderrFileStr;
124   const StringRef *Redirects[] = {&InputFileStr, &OutputFileStr,
125                                   &StderrFileStr};
126   const char *Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
127 #ifdef LLVM_ON_WIN32
128                         // Pass --relative-address on Windows so that we don't
129                         // have to add ImageBase from PE file.
130                         // FIXME: Make this the default for llvm-symbolizer.
131                         "--relative-address",
132 #endif
133                         "--demangle", nullptr};
134   int RunResult =
135       sys::ExecuteAndWait(LLVMSymbolizerPath, Args, nullptr, Redirects);
136   if (RunResult != 0)
137     return false;
138 
139   // This report format is based on the sanitizer stack trace printer.  See
140   // sanitizer_stacktrace_printer.cc in compiler-rt.
141   auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
142   if (!OutputBuf)
143     return false;
144   StringRef Output = OutputBuf.get()->getBuffer();
145   SmallVector<StringRef, 32> Lines;
146   Output.split(Lines, "\n");
147   auto CurLine = Lines.begin();
148   int frame_no = 0;
149   for (int i = 0; i < Depth; i++) {
150     if (!Modules[i]) {
151       OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << '\n';
152       continue;
153     }
154     // Read pairs of lines (function name and file/line info) until we
155     // encounter empty line.
156     for (;;) {
157       if (CurLine == Lines.end())
158         return false;
159       StringRef FunctionName = *CurLine++;
160       if (FunctionName.empty())
161         break;
162       OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << ' ';
163       if (!FunctionName.startswith("??"))
164         OS << FunctionName << ' ';
165       if (CurLine == Lines.end())
166         return false;
167       StringRef FileLineInfo = *CurLine++;
168       if (!FileLineInfo.startswith("??"))
169         OS << FileLineInfo;
170       else
171         OS << "(" << Modules[i] << '+' << format_hex(Offsets[i], 0) << ")";
172       OS << "\n";
173     }
174   }
175   return true;
176 }
177 
178 // Include the platform-specific parts of this class.
179 #ifdef LLVM_ON_UNIX
180 #include "Unix/Signals.inc"
181 #endif
182 #ifdef LLVM_ON_WIN32
183 #include "Windows/Signals.inc"
184 #endif
185