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      1 /*
      2  * Copyright (C) 2013 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef _BACKTRACE_BACKTRACE_H
     18 #define _BACKTRACE_BACKTRACE_H
     19 
     20 #include <inttypes.h>
     21 #include <stdint.h>
     22 
     23 #include <string>
     24 #include <vector>
     25 
     26 #include <backtrace/backtrace_constants.h>
     27 #include <backtrace/BacktraceMap.h>
     28 
     29 #if __LP64__
     30 #define PRIPTR "016" PRIxPTR
     31 typedef uint64_t word_t;
     32 #else
     33 #define PRIPTR "08" PRIxPTR
     34 typedef uint32_t word_t;
     35 #endif
     36 
     37 enum BacktraceUnwindError : uint32_t {
     38   BACKTRACE_UNWIND_NO_ERROR,
     39   // Something failed while trying to perform the setup to begin the unwind.
     40   BACKTRACE_UNWIND_ERROR_SETUP_FAILED,
     41   // There is no map information to use with the unwind.
     42   BACKTRACE_UNWIND_ERROR_MAP_MISSING,
     43   // An error occurred that indicates a programming error.
     44   BACKTRACE_UNWIND_ERROR_INTERNAL,
     45   // The thread to unwind has disappeared before the unwind can begin.
     46   BACKTRACE_UNWIND_ERROR_THREAD_DOESNT_EXIST,
     47   // The thread to unwind has not responded to a signal in a timely manner.
     48   BACKTRACE_UNWIND_ERROR_THREAD_TIMEOUT,
     49   // Attempt to do an unsupported operation.
     50   BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION,
     51   // Attempt to do an offline unwind without a context.
     52   BACKTRACE_UNWIND_ERROR_NO_CONTEXT,
     53 };
     54 
     55 struct backtrace_frame_data_t {
     56   size_t num;             // The current fame number.
     57   uintptr_t pc;           // The absolute pc.
     58   uintptr_t rel_pc;       // The relative pc.
     59   uintptr_t sp;           // The top of the stack.
     60   size_t stack_size;      // The size of the stack, zero indicate an unknown stack size.
     61   backtrace_map_t map;    // The map associated with the given pc.
     62   std::string func_name;  // The function name associated with this pc, NULL if not found.
     63   uintptr_t func_offset;  // pc relative to the start of the function, only valid if func_name is not NULL.
     64 };
     65 
     66 #if defined(__APPLE__)
     67 struct __darwin_ucontext;
     68 typedef __darwin_ucontext ucontext_t;
     69 #else
     70 struct ucontext;
     71 typedef ucontext ucontext_t;
     72 #endif
     73 
     74 struct backtrace_stackinfo_t {
     75   uint64_t start;
     76   uint64_t end;
     77   const uint8_t* data;
     78 };
     79 
     80 class Backtrace {
     81 public:
     82   // Create the correct Backtrace object based on what is to be unwound.
     83   // If pid < 0 or equals the current pid, then the Backtrace object
     84   // corresponds to the current process.
     85   // If pid < 0 or equals the current pid and tid >= 0, then the Backtrace
     86   // object corresponds to a thread in the current process.
     87   // If pid >= 0 and tid < 0, then the Backtrace object corresponds to a
     88   // different process.
     89   // Tracing a thread in a different process is not supported.
     90   // If map is NULL, then create the map and manage it internally.
     91   // If map is not NULL, the map is still owned by the caller.
     92   static Backtrace* Create(pid_t pid, pid_t tid, BacktraceMap* map = NULL);
     93 
     94   // Create an offline Backtrace object that can be used to do an unwind without a process
     95   // that is still running. If cache_file is set to true, then elf information will be cached
     96   // for this call. The cached information survives until the calling process ends. This means
     97   // that subsequent calls to create offline Backtrace objects will continue to use the same
     98   // cache. It also assumes that the elf files used for each offline unwind are the same.
     99   static Backtrace* CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
    100                                   const backtrace_stackinfo_t& stack, bool cache_file = false);
    101 
    102   virtual ~Backtrace();
    103 
    104   // Get the current stack trace and store in the backtrace_ structure.
    105   virtual bool Unwind(size_t num_ignore_frames, ucontext_t* context = NULL) = 0;
    106 
    107   // Get the function name and offset into the function given the pc.
    108   // If the string is empty, then no valid function name was found,
    109   // or the pc is not in any valid map.
    110   virtual std::string GetFunctionName(uintptr_t pc, uintptr_t* offset,
    111                                       const backtrace_map_t* map = NULL);
    112 
    113   // Fill in the map data associated with the given pc.
    114   virtual void FillInMap(uintptr_t pc, backtrace_map_t* map);
    115 
    116   // Read the data at a specific address.
    117   virtual bool ReadWord(uintptr_t ptr, word_t* out_value) = 0;
    118 
    119   // Read arbitrary data from a specific address. If a read request would
    120   // span from one map to another, this call only reads up until the end
    121   // of the current map.
    122   // Returns the total number of bytes actually read.
    123   virtual size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) = 0;
    124 
    125   // Create a string representing the formatted line of backtrace information
    126   // for a single frame.
    127   virtual std::string FormatFrameData(size_t frame_num);
    128   virtual std::string FormatFrameData(const backtrace_frame_data_t* frame);
    129 
    130   pid_t Pid() const { return pid_; }
    131   pid_t Tid() const { return tid_; }
    132   size_t NumFrames() const { return frames_.size(); }
    133 
    134   const backtrace_frame_data_t* GetFrame(size_t frame_num) {
    135     if (frame_num >= frames_.size()) {
    136       return NULL;
    137     }
    138     return &frames_[frame_num];
    139   }
    140 
    141   typedef std::vector<backtrace_frame_data_t>::iterator iterator;
    142   iterator begin() { return frames_.begin(); }
    143   iterator end() { return frames_.end(); }
    144 
    145   typedef std::vector<backtrace_frame_data_t>::const_iterator const_iterator;
    146   const_iterator begin() const { return frames_.begin(); }
    147   const_iterator end() const { return frames_.end(); }
    148 
    149   BacktraceMap* GetMap() { return map_; }
    150 
    151   BacktraceUnwindError GetError() { return error_; }
    152 
    153   std::string GetErrorString(BacktraceUnwindError error);
    154 
    155 protected:
    156   Backtrace(pid_t pid, pid_t tid, BacktraceMap* map);
    157 
    158   // The name returned is not demangled, GetFunctionName() takes care of
    159   // demangling the name.
    160   virtual std::string GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) = 0;
    161 
    162   virtual bool VerifyReadWordArgs(uintptr_t ptr, word_t* out_value);
    163 
    164   bool BuildMap();
    165 
    166   pid_t pid_;
    167   pid_t tid_;
    168 
    169   BacktraceMap* map_;
    170   bool map_shared_;
    171 
    172   std::vector<backtrace_frame_data_t> frames_;
    173 
    174   BacktraceUnwindError error_;
    175 };
    176 
    177 #endif // _BACKTRACE_BACKTRACE_H
    178