Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/lib/Support/Signals.cpp
Line
Count
Source (jump to first uncovered line)
1
//===- Signals.cpp - Signal Handling support --------------------*- C++ -*-===//
2
//
3
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4
// See https://llvm.org/LICENSE.txt for license information.
5
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6
//
7
//===----------------------------------------------------------------------===//
8
//
9
// This file defines some helpful functions for dealing with the possibility of
10
// Unix signals occurring while your program is running.
11
//
12
//===----------------------------------------------------------------------===//
13
14
#include "llvm/Support/Signals.h"
15
#include "llvm/ADT/STLExtras.h"
16
#include "llvm/ADT/StringRef.h"
17
#include "llvm/Config/llvm-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/FormatVariadic.h"
23
#include "llvm/Support/FormatAdapters.h"
24
#include "llvm/Support/ManagedStatic.h"
25
#include "llvm/Support/MemoryBuffer.h"
26
#include "llvm/Support/Mutex.h"
27
#include "llvm/Support/Program.h"
28
#include "llvm/Support/StringSaver.h"
29
#include "llvm/Support/raw_ostream.h"
30
#include "llvm/Support/Options.h"
31
#include <vector>
32
33
//===----------------------------------------------------------------------===//
34
//=== WARNING: Implementation here must contain only TRULY operating system
35
//===          independent code.
36
//===----------------------------------------------------------------------===//
37
38
using namespace llvm;
39
40
// Use explicit storage to avoid accessing cl::opt in a signal handler.
41
static bool DisableSymbolicationFlag = false;
42
static cl::opt<bool, true>
43
    DisableSymbolication("disable-symbolication",
44
                         cl::desc("Disable symbolizing crash backtraces."),
45
                         cl::location(DisableSymbolicationFlag), cl::Hidden);
46
47
// Callbacks to run in signal handler must be lock-free because a signal handler
48
// could be running as we add new callbacks. We don't add unbounded numbers of
49
// callbacks, an array is therefore sufficient.
50
struct CallbackAndCookie {
51
  sys::SignalHandlerCallback Callback;
52
  void *Cookie;
53
  enum class Status { Empty, Initializing, Initialized, Executing };
54
  std::atomic<Status> Flag;
55
};
56
static constexpr size_t MaxSignalHandlerCallbacks = 8;
57
static CallbackAndCookie CallBacksToRun[MaxSignalHandlerCallbacks];
58
59
// Signal-safe.
60
0
void sys::RunSignalHandlers() {
61
0
  for (size_t I = 0; I < MaxSignalHandlerCallbacks; ++I) {
62
0
    auto &RunMe = CallBacksToRun[I];
63
0
    auto Expected = CallbackAndCookie::Status::Initialized;
64
0
    auto Desired = CallbackAndCookie::Status::Executing;
65
0
    if (!RunMe.Flag.compare_exchange_strong(Expected, Desired))
66
0
      continue;
67
0
    (*RunMe.Callback)(RunMe.Cookie);
68
0
    RunMe.Callback = nullptr;
69
0
    RunMe.Cookie = nullptr;
70
0
    RunMe.Flag.store(CallbackAndCookie::Status::Empty);
71
0
  }
72
0
}
73
74
// Signal-safe.
75
static void insertSignalHandler(sys::SignalHandlerCallback FnPtr,
76
266k
                                void *Cookie) {
77
394k
  for (size_t I = 0; I < MaxSignalHandlerCallbacks; 
++I128k
) {
78
394k
    auto &SetMe = CallBacksToRun[I];
79
394k
    auto Expected = CallbackAndCookie::Status::Empty;
80
394k
    auto Desired = CallbackAndCookie::Status::Initializing;
81
394k
    if (!SetMe.Flag.compare_exchange_strong(Expected, Desired))
82
128k
      continue;
83
266k
    SetMe.Callback = FnPtr;
84
266k
    SetMe.Cookie = Cookie;
85
266k
    SetMe.Flag.store(CallbackAndCookie::Status::Initialized);
86
266k
    return;
87
266k
  }
88
266k
  
report_fatal_error("too many signal callbacks already registered")0
;
89
266k
}
90
91
static bool findModulesAndOffsets(void **StackTrace, int Depth,
92
                                  const char **Modules, intptr_t *Offsets,
93
                                  const char *MainExecutableName,
94
                                  StringSaver &StrPool);
95
96
/// Format a pointer value as hexadecimal. Zero pad it out so its always the
97
/// same width.
98
0
static FormattedNumber format_ptr(void *PC) {
99
0
  // Each byte is two hex digits plus 2 for the 0x prefix.
100
0
  unsigned PtrWidth = 2 + 2 * sizeof(void *);
101
0
  return format_hex((uint64_t)PC, PtrWidth);
102
0
}
103
104
/// Helper that launches llvm-symbolizer and symbolizes a backtrace.
105
LLVM_ATTRIBUTE_USED
106
static bool printSymbolizedStackTrace(StringRef Argv0, void **StackTrace,
107
0
                                      int Depth, llvm::raw_ostream &OS) {
108
0
  if (DisableSymbolicationFlag)
109
0
    return false;
110
0
111
0
  // Don't recursively invoke the llvm-symbolizer binary.
112
0
  if (Argv0.find("llvm-symbolizer") != std::string::npos)
113
0
    return false;
114
0
115
0
  // FIXME: Subtract necessary number from StackTrace entries to turn return addresses
116
0
  // into actual instruction addresses.
117
0
  // Use llvm-symbolizer tool to symbolize the stack traces. First look for it
118
0
  // alongside our binary, then in $PATH.
119
0
  ErrorOr<std::string> LLVMSymbolizerPathOrErr = std::error_code();
120
0
  if (!Argv0.empty()) {
121
0
    StringRef Parent = llvm::sys::path::parent_path(Argv0);
122
0
    if (!Parent.empty())
123
0
      LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer", Parent);
124
0
  }
125
0
  if (!LLVMSymbolizerPathOrErr)
126
0
    LLVMSymbolizerPathOrErr = sys::findProgramByName("llvm-symbolizer");
127
0
  if (!LLVMSymbolizerPathOrErr)
128
0
    return false;
129
0
  const std::string &LLVMSymbolizerPath = *LLVMSymbolizerPathOrErr;
130
0
131
0
  // If we don't know argv0 or the address of main() at this point, try
132
0
  // to guess it anyway (it's possible on some platforms).
133
0
  std::string MainExecutableName =
134
0
      sys::fs::exists(Argv0) ? (std::string)Argv0
135
0
                             : sys::fs::getMainExecutable(nullptr, nullptr);
136
0
  BumpPtrAllocator Allocator;
137
0
  StringSaver StrPool(Allocator);
138
0
  std::vector<const char *> Modules(Depth, nullptr);
139
0
  std::vector<intptr_t> Offsets(Depth, 0);
140
0
  if (!findModulesAndOffsets(StackTrace, Depth, Modules.data(), Offsets.data(),
141
0
                             MainExecutableName.c_str(), StrPool))
142
0
    return false;
143
0
  int InputFD;
144
0
  SmallString<32> InputFile, OutputFile;
145
0
  sys::fs::createTemporaryFile("symbolizer-input", "", InputFD, InputFile);
146
0
  sys::fs::createTemporaryFile("symbolizer-output", "", OutputFile);
147
0
  FileRemover InputRemover(InputFile.c_str());
148
0
  FileRemover OutputRemover(OutputFile.c_str());
149
0
150
0
  {
151
0
    raw_fd_ostream Input(InputFD, true);
152
0
    for (int i = 0; i < Depth; i++) {
153
0
      if (Modules[i])
154
0
        Input << Modules[i] << " " << (void*)Offsets[i] << "\n";
155
0
    }
156
0
  }
157
0
158
0
  Optional<StringRef> Redirects[] = {StringRef(InputFile),
159
0
                                     StringRef(OutputFile), StringRef("")};
160
0
  StringRef Args[] = {"llvm-symbolizer", "--functions=linkage", "--inlining",
161
#ifdef _WIN32
162
                      // Pass --relative-address on Windows so that we don't
163
                      // have to add ImageBase from PE file.
164
                      // FIXME: Make this the default for llvm-symbolizer.
165
                      "--relative-address",
166
#endif
167
                      "--demangle"};
168
0
  int RunResult =
169
0
      sys::ExecuteAndWait(LLVMSymbolizerPath, Args, None, Redirects);
170
0
  if (RunResult != 0)
171
0
    return false;
172
0
173
0
  // This report format is based on the sanitizer stack trace printer.  See
174
0
  // sanitizer_stacktrace_printer.cc in compiler-rt.
175
0
  auto OutputBuf = MemoryBuffer::getFile(OutputFile.c_str());
176
0
  if (!OutputBuf)
177
0
    return false;
178
0
  StringRef Output = OutputBuf.get()->getBuffer();
179
0
  SmallVector<StringRef, 32> Lines;
180
0
  Output.split(Lines, "\n");
181
0
  auto CurLine = Lines.begin();
182
0
  int frame_no = 0;
183
0
  for (int i = 0; i < Depth; i++) {
184
0
    auto PrintLineHeader = [&]() {
185
0
      OS << right_justify(formatv("#{0}", frame_no++).str(),
186
0
                          std::log10(Depth) + 2)
187
0
         << ' ' << format_ptr(StackTrace[i]) << ' ';
188
0
    };
189
0
    if (!Modules[i]) {
190
0
      PrintLineHeader();
191
0
      OS << '\n';
192
0
      continue;
193
0
    }
194
0
    // Read pairs of lines (function name and file/line info) until we
195
0
    // encounter empty line.
196
0
    for (;;) {
197
0
      if (CurLine == Lines.end())
198
0
        return false;
199
0
      StringRef FunctionName = *CurLine++;
200
0
      if (FunctionName.empty())
201
0
        break;
202
0
      PrintLineHeader();
203
0
      if (!FunctionName.startswith("??"))
204
0
        OS << FunctionName << ' ';
205
0
      if (CurLine == Lines.end())
206
0
        return false;
207
0
      StringRef FileLineInfo = *CurLine++;
208
0
      if (!FileLineInfo.startswith("??"))
209
0
        OS << FileLineInfo;
210
0
      else
211
0
        OS << "(" << Modules[i] << '+' << format_hex(Offsets[i], 0) << ")";
212
0
      OS << "\n";
213
0
    }
214
0
  }
215
0
  return true;
216
0
}
217
218
// Include the platform-specific parts of this class.
219
#ifdef LLVM_ON_UNIX
220
#include "Unix/Signals.inc"
221
#endif
222
#ifdef _WIN32
223
#include "Windows/Signals.inc"
224
#endif