1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_DEBUG_STACK_TRACE_H_ 6 #define BASE_DEBUG_STACK_TRACE_H_ 7 8 #include <stddef.h> 9 10 #include <iosfwd> 11 #include <string> 12 13 #include "base/base_export.h" 14 #include "base/debug/debugging_buildflags.h" 15 #include "base/macros.h" 16 #include "build/build_config.h" 17 18 #if defined(OS_POSIX) 19 #include <unistd.h> 20 #endif 21 22 #if defined(OS_WIN) 23 struct _EXCEPTION_POINTERS; 24 struct _CONTEXT; 25 #endif 26 27 namespace base { 28 namespace debug { 29 30 // Enables stack dump to console output on exception and signals. 31 // When enabled, the process will quit immediately. This is meant to be used in 32 // unit_tests only! This is not thread-safe: only call from main thread. 33 // In sandboxed processes, this has to be called before the sandbox is turned 34 // on. 35 // Calling this function on Linux opens /proc/self/maps and caches its 36 // contents. In non-official builds, this function also opens the object files 37 // that are loaded in memory and caches their file descriptors (this cannot be 38 // done in official builds because it has security implications). 39 BASE_EXPORT bool EnableInProcessStackDumping(); 40 41 #if defined(OS_POSIX) 42 BASE_EXPORT void SetStackDumpFirstChanceCallback(bool (*handler)(int, 43 void*, 44 void*)); 45 #endif 46 47 // Returns end of the stack, or 0 if we couldn't get it. 48 #if BUILDFLAG(CAN_UNWIND_WITH_FRAME_POINTERS) 49 BASE_EXPORT uintptr_t GetStackEnd(); 50 #endif 51 52 // A stacktrace can be helpful in debugging. For example, you can include a 53 // stacktrace member in a object (probably around #ifndef NDEBUG) so that you 54 // can later see where the given object was created from. 55 class BASE_EXPORT StackTrace { 56 public: 57 // Creates a stacktrace from the current location. 58 StackTrace(); 59 60 // Creates a stacktrace from the current location, of up to |count| entries. 61 // |count| will be limited to at most |kMaxTraces|. 62 explicit StackTrace(size_t count); 63 64 // Creates a stacktrace from an existing array of instruction 65 // pointers (such as returned by Addresses()). |count| will be 66 // limited to at most |kMaxTraces|. 67 StackTrace(const void* const* trace, size_t count); 68 69 #if defined(OS_WIN) 70 // Creates a stacktrace for an exception. 71 // Note: this function will throw an import not found (StackWalk64) exception 72 // on system without dbghelp 5.1. 73 StackTrace(_EXCEPTION_POINTERS* exception_pointers); 74 StackTrace(const _CONTEXT* context); 75 #endif 76 77 // Copying and assignment are allowed with the default functions. 78 79 // Gets an array of instruction pointer values. |*count| will be set to the 80 // number of elements in the returned array. 81 const void* const* Addresses(size_t* count) const; 82 83 // Prints the stack trace to stderr. 84 void Print() const; 85 86 #if !defined(__UCLIBC__) & !defined(_AIX) 87 // Resolves backtrace to symbols and write to stream. 88 void OutputToStream(std::ostream* os) const; 89 #endif 90 91 // Resolves backtrace to symbols and returns as string. 92 std::string ToString() const; 93 94 private: 95 #if defined(OS_WIN) 96 void InitTrace(const _CONTEXT* context_record); 97 #endif 98 99 // From http://msdn.microsoft.com/en-us/library/bb204633.aspx, 100 // the sum of FramesToSkip and FramesToCapture must be less than 63, 101 // so set it to 62. Even if on POSIX it could be a larger value, it usually 102 // doesn't give much more information. 103 static const int kMaxTraces = 62; 104 105 void* trace_[kMaxTraces]; 106 107 // The number of valid frames in |trace_|. 108 size_t count_; 109 }; 110 111 #if BUILDFLAG(CAN_UNWIND_WITH_FRAME_POINTERS) 112 // Traces the stack by using frame pointers. This function is faster but less 113 // reliable than StackTrace. It should work for debug and profiling builds, 114 // but not for release builds (although there are some exceptions). 115 // 116 // Writes at most |max_depth| frames (instruction pointers) into |out_trace| 117 // after skipping |skip_initial| frames. Note that the function itself is not 118 // added to the trace so |skip_initial| should be 0 in most cases. 119 // Returns number of frames written. 120 BASE_EXPORT size_t TraceStackFramePointers(const void** out_trace, 121 size_t max_depth, 122 size_t skip_initial); 123 124 // Links stack frame |fp| to |parent_fp|, so that during stack unwinding 125 // TraceStackFramePointers() visits |parent_fp| after visiting |fp|. 126 // Both frame pointers must come from __builtin_frame_address(). 127 // Destructor restores original linkage of |fp| to avoid corrupting caller's 128 // frame register on return. 129 // 130 // This class can be used to repair broken stack frame chain in cases 131 // when execution flow goes into code built without frame pointers: 132 // 133 // void DoWork() { 134 // Call_SomeLibrary(); 135 // } 136 // static __thread void* g_saved_fp; 137 // void Call_SomeLibrary() { 138 // g_saved_fp = __builtin_frame_address(0); 139 // some_library_call(...); // indirectly calls SomeLibrary_Callback() 140 // } 141 // void SomeLibrary_Callback() { 142 // ScopedStackFrameLinker linker(__builtin_frame_address(0), g_saved_fp); 143 // ... 144 // TraceStackFramePointers(...); 145 // } 146 // 147 // This produces the following trace: 148 // 149 // #0 SomeLibrary_Callback() 150 // #1 <address of the code inside SomeLibrary that called #0> 151 // #2 DoWork() 152 // ...rest of the trace... 153 // 154 // SomeLibrary doesn't use frame pointers, so when SomeLibrary_Callback() 155 // is called, stack frame register contains bogus value that becomes callback' 156 // parent frame address. Without ScopedStackFrameLinker unwinding would've 157 // stopped at that bogus frame address yielding just two first frames (#0, #1). 158 // ScopedStackFrameLinker overwrites callback's parent frame address with 159 // Call_SomeLibrary's frame, so unwinder produces full trace without even 160 // noticing that stack frame chain was broken. 161 class BASE_EXPORT ScopedStackFrameLinker { 162 public: 163 ScopedStackFrameLinker(void* fp, void* parent_fp); 164 ~ScopedStackFrameLinker(); 165 166 private: 167 void* fp_; 168 void* parent_fp_; 169 void* original_parent_fp_; 170 171 DISALLOW_COPY_AND_ASSIGN(ScopedStackFrameLinker); 172 }; 173 174 #endif // BUILDFLAG(CAN_UNWIND_WITH_FRAME_POINTERS) 175 176 namespace internal { 177 178 #if defined(OS_POSIX) && !defined(OS_ANDROID) 179 // POSIX doesn't define any async-signal safe function for converting 180 // an integer to ASCII. We'll have to define our own version. 181 // itoa_r() converts a (signed) integer to ASCII. It returns "buf", if the 182 // conversion was successful or NULL otherwise. It never writes more than "sz" 183 // bytes. Output will be truncated as needed, and a NUL character is always 184 // appended. 185 BASE_EXPORT char *itoa_r(intptr_t i, 186 char *buf, 187 size_t sz, 188 int base, 189 size_t padding); 190 #endif // defined(OS_POSIX) && !defined(OS_ANDROID) 191 192 } // namespace internal 193 194 } // namespace debug 195 } // namespace base 196 197 #endif // BASE_DEBUG_STACK_TRACE_H_ 198
