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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 #include <inttypes.h>
     18 #include <stdint.h>
     19 #include <stdlib.h>
     20 #include <sys/types.h>
     21 #include <ucontext.h>
     22 
     23 #include <string>
     24 
     25 #include <android-base/stringprintf.h>
     26 
     27 #include <backtrace/Backtrace.h>
     28 #include <backtrace/BacktraceMap.h>
     29 
     30 #include "BacktraceLog.h"
     31 #include "thread_utils.h"
     32 #include "UnwindCurrent.h"
     33 #include "UnwindPtrace.h"
     34 
     35 using android::base::StringPrintf;
     36 
     37 //-------------------------------------------------------------------------
     38 // Backtrace functions.
     39 //-------------------------------------------------------------------------
     40 Backtrace::Backtrace(pid_t pid, pid_t tid, BacktraceMap* map)
     41     : pid_(pid), tid_(tid), map_(map), map_shared_(true) {
     42   if (map_ == nullptr) {
     43     map_ = BacktraceMap::Create(pid);
     44     map_shared_ = false;
     45   }
     46 }
     47 
     48 Backtrace::~Backtrace() {
     49   if (map_ && !map_shared_) {
     50     delete map_;
     51     map_ = nullptr;
     52   }
     53 }
     54 
     55 std::string Backtrace::GetFunctionName(uintptr_t pc, uintptr_t* offset, const backtrace_map_t* map) {
     56   backtrace_map_t map_value;
     57   if (map == nullptr) {
     58     FillInMap(pc, &map_value);
     59     map = &map_value;
     60   }
     61   // If no map is found, or this map is backed by a device, then return nothing.
     62   if (map->start == 0 || (map->flags & PROT_DEVICE_MAP)) {
     63     return "";
     64   }
     65   std::string func_name = GetFunctionNameRaw(pc, offset);
     66   return func_name;
     67 }
     68 
     69 bool Backtrace::VerifyReadWordArgs(uintptr_t ptr, word_t* out_value) {
     70   if (ptr & (sizeof(word_t)-1)) {
     71     BACK_LOGW("invalid pointer %p", reinterpret_cast<void*>(ptr));
     72     *out_value = static_cast<word_t>(-1);
     73     return false;
     74   }
     75   return true;
     76 }
     77 
     78 std::string Backtrace::FormatFrameData(size_t frame_num) {
     79   if (frame_num >= frames_.size()) {
     80     return "";
     81   }
     82   return FormatFrameData(&frames_[frame_num]);
     83 }
     84 
     85 std::string Backtrace::FormatFrameData(const backtrace_frame_data_t* frame) {
     86   uintptr_t relative_pc;
     87   std::string map_name;
     88   if (BacktraceMap::IsValid(frame->map)) {
     89     relative_pc = BacktraceMap::GetRelativePc(frame->map, frame->pc);
     90     if (!frame->map.name.empty()) {
     91       map_name = frame->map.name.c_str();
     92       if (map_name[0] == '[' && map_name[map_name.size() - 1] == ']') {
     93         map_name.resize(map_name.size() - 1);
     94         map_name += StringPrintf(":%" PRIPTR "]", frame->map.start);
     95       }
     96     } else {
     97       map_name = StringPrintf("<anonymous:%" PRIPTR ">", frame->map.start);
     98     }
     99   } else {
    100     map_name = "<unknown>";
    101     relative_pc = frame->pc;
    102   }
    103 
    104   std::string line(StringPrintf("#%02zu pc %" PRIPTR "  ", frame->num, relative_pc));
    105   line += map_name;
    106   // Special handling for non-zero offset maps, we need to print that
    107   // information.
    108   if (frame->map.offset != 0) {
    109     line += " (offset " + StringPrintf("0x%" PRIxPTR, frame->map.offset) + ")";
    110   }
    111   if (!frame->func_name.empty()) {
    112     line += " (" + frame->func_name;
    113     if (frame->func_offset) {
    114       line += StringPrintf("+%" PRIuPTR, frame->func_offset);
    115     }
    116     line += ')';
    117   }
    118 
    119   return line;
    120 }
    121 
    122 void Backtrace::FillInMap(uintptr_t pc, backtrace_map_t* map) {
    123   if (map_ != nullptr) {
    124     map_->FillIn(pc, map);
    125   }
    126 }
    127 
    128 Backtrace* Backtrace::Create(pid_t pid, pid_t tid, BacktraceMap* map) {
    129   if (pid == BACKTRACE_CURRENT_PROCESS) {
    130     pid = getpid();
    131     if (tid == BACKTRACE_CURRENT_THREAD) {
    132       tid = gettid();
    133     }
    134   } else if (tid == BACKTRACE_CURRENT_THREAD) {
    135     tid = pid;
    136   }
    137 
    138   if (pid == getpid()) {
    139     return new UnwindCurrent(pid, tid, map);
    140   } else {
    141     return new UnwindPtrace(pid, tid, map);
    142   }
    143 }
    144 
    145 std::string Backtrace::GetErrorString(BacktraceUnwindError error) {
    146   switch (error) {
    147   case BACKTRACE_UNWIND_NO_ERROR:
    148     return "No error";
    149   case BACKTRACE_UNWIND_ERROR_SETUP_FAILED:
    150     return "Setup failed";
    151   case BACKTRACE_UNWIND_ERROR_MAP_MISSING:
    152     return "No map found";
    153   case BACKTRACE_UNWIND_ERROR_INTERNAL:
    154     return "Internal libbacktrace error, please submit a bugreport";
    155   case BACKTRACE_UNWIND_ERROR_THREAD_DOESNT_EXIST:
    156     return "Thread doesn't exist";
    157   case BACKTRACE_UNWIND_ERROR_THREAD_TIMEOUT:
    158     return "Thread has not responded to signal in time";
    159   case BACKTRACE_UNWIND_ERROR_UNSUPPORTED_OPERATION:
    160     return "Attempt to use an unsupported feature";
    161   case BACKTRACE_UNWIND_ERROR_NO_CONTEXT:
    162     return "Attempt to do an offline unwind without a context";
    163   }
    164 }
    165