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* Copyright (C) 2013 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <inttypes.h>
#include <stdint.h>
#include <string>
#include <vector>
#include <backtrace/backtrace_constants.h>
#include <backtrace/BacktraceMap.h>
#if __LP64__
#define PRIPTR "016" PRIxPTR
typedef uint64_t word_t;
#define PRIPTR "08" PRIxPTR
typedef uint32_t word_t;
enum BacktraceUnwindError : uint32_t {
// Something failed while trying to perform the setup to begin the unwind.
// There is no map information to use with the unwind.
// An error occurred that indicates a programming error.
// The thread to unwind has disappeared before the unwind can begin.
// The thread to unwind has not responded to a signal in a timely manner.
// Attempt to do an unsupported operation.
// Attempt to do an offline unwind without a context.
struct backtrace_frame_data_t {
size_t num; // The current fame number.
uintptr_t pc; // The absolute pc.
uintptr_t sp; // The top of the stack.
size_t stack_size; // The size of the stack, zero indicate an unknown stack size.
backtrace_map_t map; // The map associated with the given pc.
std::string func_name; // The function name associated with this pc, NULL if not found.
uintptr_t func_offset; // pc relative to the start of the function, only valid if func_name is not NULL.
#if defined(__APPLE__)
struct __darwin_ucontext;
typedef __darwin_ucontext ucontext_t;
struct ucontext;
typedef ucontext ucontext_t;
struct backtrace_stackinfo_t {
uint64_t start;
uint64_t end;
const uint8_t* data;
class Backtrace {
// Create the correct Backtrace object based on what is to be unwound.
// If pid < 0 or equals the current pid, then the Backtrace object
// corresponds to the current process.
// If pid < 0 or equals the current pid and tid >= 0, then the Backtrace
// object corresponds to a thread in the current process.
// If pid >= 0 and tid < 0, then the Backtrace object corresponds to a
// different process.
// Tracing a thread in a different process is not supported.
// If map is NULL, then create the map and manage it internally.
// If map is not NULL, the map is still owned by the caller.
static Backtrace* Create(pid_t pid, pid_t tid, BacktraceMap* map = NULL);
// Create an offline Backtrace object that can be used to do an unwind without a process
// that is still running. If cache_file is set to true, then elf information will be cached
// for this call. The cached information survives until the calling process ends. This means
// that subsequent calls to create offline Backtrace objects will continue to use the same
// cache. It also assumes that the elf files used for each offline unwind are the same.
static Backtrace* CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
const backtrace_stackinfo_t& stack, bool cache_file = false);
virtual ~Backtrace();
// Get the current stack trace and store in the backtrace_ structure.
virtual bool Unwind(size_t num_ignore_frames, ucontext_t* context = NULL) = 0;
// Get the function name and offset into the function given the pc.
// If the string is empty, then no valid function name was found,
// or the pc is not in any valid map.
virtual std::string GetFunctionName(uintptr_t pc, uintptr_t* offset,
const backtrace_map_t* map = NULL);
// Fill in the map data associated with the given pc.
virtual void FillInMap(uintptr_t pc, backtrace_map_t* map);
// Read the data at a specific address.
virtual bool ReadWord(uintptr_t ptr, word_t* out_value) = 0;
// Read arbitrary data from a specific address. If a read request would
// span from one map to another, this call only reads up until the end
// of the current map.
// Returns the total number of bytes actually read.
virtual size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) = 0;
// Create a string representing the formatted line of backtrace information
// for a single frame.
virtual std::string FormatFrameData(size_t frame_num);
virtual std::string FormatFrameData(const backtrace_frame_data_t* frame);
pid_t Pid() const { return pid_; }
pid_t Tid() const { return tid_; }
size_t NumFrames() const { return frames_.size(); }
const backtrace_frame_data_t* GetFrame(size_t frame_num) {
if (frame_num >= frames_.size()) {
return NULL;
return &frames_[frame_num];
typedef std::vector<backtrace_frame_data_t>::iterator iterator;
iterator begin() { return frames_.begin(); }
iterator end() { return frames_.end(); }
typedef std::vector<backtrace_frame_data_t>::const_iterator const_iterator;
const_iterator begin() const { return frames_.begin(); }
const_iterator end() const { return frames_.end(); }
BacktraceMap* GetMap() { return map_; }
BacktraceUnwindError GetError() { return error_; }
std::string GetErrorString(BacktraceUnwindError error);
Backtrace(pid_t pid, pid_t tid, BacktraceMap* map);
// The name returned is not demangled, GetFunctionName() takes care of
// demangling the name.
virtual std::string GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) = 0;
virtual bool VerifyReadWordArgs(uintptr_t ptr, word_t* out_value);
bool BuildMap();
pid_t pid_;
pid_t tid_;
BacktraceMap* map_;
bool map_shared_;
std::vector<backtrace_frame_data_t> frames_;
BacktraceUnwindError error_;