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      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;
     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.
     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(void **StackTrace, int Depth,
     66                                       llvm::raw_ostream &OS)
     67   LLVM_ATTRIBUTE_USED;
     68 
     69 /// Helper that launches llvm-symbolizer and symbolizes a backtrace.
     70 static bool printSymbolizedStackTrace(void **StackTrace, int Depth,
     71                                       llvm::raw_ostream &OS) {
     72   // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
     73   // into actual instruction addresses.
     74   // Use llvm-symbolizer tool to symbolize the stack traces.
     75   ErrorOr<std::string> LLVMSymbolizerPathOrErr =
     76       sys::findProgramByName("llvm-symbolizer");
     77   if (!LLVMSymbolizerPathOrErr)
     78     return false;
     79   const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
     80   // We don't know argv0 or the address of main() at this point, but try
     81   // to guess it anyway (it's possible on some platforms).
     82   std::string MainExecutableName = sys::fs::getMainExecutable(nullptr, nullptr);
     83   if (MainExecutableName.empty() ||
     84       MainExecutableName.find("llvm-symbolizer") != std::string::npos)
     85     return false;
     86 
     87   BumpPtrAllocator Allocator;
     88   StringSaver StrPool(Allocator);
     89   std::vector<const char *> Modules(Depth, nullptr);
     90   std::vector<intptr_t> Offsets(Depth, 0);
     91   if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
     92                              MainExecutableName.c_str(), StrPool))
     93     return false;
     94   int InputFD;
     95   SmallString<32> InputFile, OutputFile;
     96   sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
     97   sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
     98   FileRemover InputRemover(InputFile.c_str());
     99   FileRemover OutputRemover(OutputFile.c_str());
    100 
    101   {
    102     raw_fd_ostream Input(InputFD, true);
    103     for (int i = 0; i < Depth; i++) {
    104       if (Modules[i])
    105         Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
    106     }
    107   }
    108 
    109   StringRef InputFileStr(InputFile);
    110   StringRef OutputFileStr(OutputFile);
    111   StringRef StderrFileStr;
    112   const StringRef *Redirects[] = {&InputFileStr, &OutputFileStr,
    113                                   &StderrFileStr};
    114   const char *Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
    115 #ifdef LLVM_ON_WIN32
    116                         // Pass --relative-address on Windows so that we don't
    117                         // have to add ImageBase from PE file.
    118                         // FIXME: Make this the default for llvm-symbolizer.
    119                         "--relative-address",
    120 #endif
    121                         "--demangle", nullptr};
    122   int RunResult =
    123       sys::ExecuteAndWait(LLVMSymbolizerPath, Args, nullptr, Redirects);
    124   if (RunResult != 0)
    125     return false;
    126 
    127   // This report format is based on the sanitizer stack trace printer.  See
    128   // sanitizer_stacktrace_printer.cc in compiler-rt.
    129   auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
    130   if (!OutputBuf)
    131     return false;
    132   StringRef Output = OutputBuf.get()->getBuffer();
    133   SmallVector<StringRef, 32> Lines;
    134   Output.split(Lines, "\n");
    135   auto CurLine = Lines.begin();
    136   int frame_no = 0;
    137   for (int i = 0; i < Depth; i++) {
    138     if (!Modules[i]) {
    139       OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << '\n';
    140       continue;
    141     }
    142     // Read pairs of lines (function name and file/line info) until we
    143     // encounter empty line.
    144     for (;;) {
    145       if (CurLine == Lines.end())
    146         return false;
    147       StringRef FunctionName = *CurLine++;
    148       if (FunctionName.empty())
    149         break;
    150       OS << '#' << frame_no++ << ' ' << format_ptr(StackTrace[i]) << ' ';
    151       if (!FunctionName.startswith("??"))
    152         OS << FunctionName << ' ';
    153       if (CurLine == Lines.end())
    154         return false;
    155       StringRef FileLineInfo = *CurLine++;
    156       if (!FileLineInfo.startswith("??"))
    157         OS << FileLineInfo;
    158       else
    159         OS << "(" << Modules[i] << '+' << format_hex(Offsets[i], 0) << ")";
    160       OS << "\n";
    161     }
    162   }
    163   return true;
    164 }
    165 
    166 // Include the platform-specific parts of this class.
    167 #ifdef LLVM_ON_UNIX
    168 #include "Unix/Signals.inc"
    169 #endif
    170 #ifdef LLVM_ON_WIN32
    171 #include "Windows/Signals.inc"
    172 #endif
    173