File indexing completed on 2025-03-09 05:09:08

 /*
  * backward.hpp
  * Copyright 2013 Google Inc. All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
 
 #ifndef H_6B9572DA_A64B_49E6_B234_051480991C89
 #define H_6B9572DA_A64B_49E6_B234_051480991C89
 
 #ifndef __cplusplus
 #error "It's not going to compile without a C++ compiler..."
 #endif
 
 #if defined(BACKWARD_CXX11)
 #elif defined(BACKWARD_CXX98)
 #else
 #if __cplusplus >= 201103L || (defined(_MSC_VER) && _MSC_VER >= 1800)
 #define BACKWARD_CXX11
 #define BACKWARD_ATLEAST_CXX11
 #define BACKWARD_ATLEAST_CXX98
 #if __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
 #define BACKWARD_ATLEAST_CXX17
 #endif
 #else
 #define BACKWARD_CXX98
 #define BACKWARD_ATLEAST_CXX98
 #endif
 #endif
 
 // You can define one of the following (or leave it to the auto-detection):
 //
 // #define BACKWARD_SYSTEM_LINUX
 //  - specialization for linux
 //
 // #define BACKWARD_SYSTEM_DARWIN
 //  - specialization for Mac OS X 10.5 and later.
 //
 // #define BACKWARD_SYSTEM_WINDOWS
 //  - specialization for Windows (Clang 9 and MSVC2017)
 //
 // #define BACKWARD_SYSTEM_UNKNOWN
 //  - placebo implementation, does nothing.
 //
 #if defined(BACKWARD_SYSTEM_LINUX)
 #elif defined(BACKWARD_SYSTEM_DARWIN)
 #elif defined(BACKWARD_SYSTEM_UNKNOWN)
 #elif defined(BACKWARD_SYSTEM_WINDOWS)
 #else
 #if defined(__linux) || defined(__linux__)
 #define BACKWARD_SYSTEM_LINUX
 #elif defined(__APPLE__)
 #define BACKWARD_SYSTEM_DARWIN
 #elif defined(_WIN32)
 #define BACKWARD_SYSTEM_WINDOWS
 #else
 #define BACKWARD_SYSTEM_UNKNOWN
 #endif
 #endif
 
 #define NOINLINE __attribute__((noinline))
 
 #include <algorithm>
 #include <cctype>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <fstream>
 #include <iomanip>
 #include <iostream>
 #include <limits>
 #include <new>
 #include <sstream>
 #include <streambuf>
 #include <string>
 #include <vector>
 #include <exception>
 #include <iterator>
 #include <filesystem>
 
 #if defined(BACKWARD_SYSTEM_LINUX)
 
 // On linux, backtrace can back-trace or "walk" the stack using the following
 // libraries:
 //
 // #define BACKWARD_HAS_UNWIND 1
 //  - unwind comes from libgcc, but I saw an equivalent inside clang itself.
 //  - with unwind, the stacktrace is as accurate as it can possibly be, since
 //  this is used by the C++ runtime in gcc/clang for stack unwinding on
 //  exception.
 //  - normally libgcc is already linked to your program by default.
 //
 // #define BACKWARD_HAS_LIBUNWIND 1
 //  - libunwind provides, in some cases, a more accurate stacktrace as it knows
 //  to decode signal handler frames and lets us edit the context registers when
 //  unwinding, allowing stack traces over bad function references.
 //
 // #define BACKWARD_HAS_BACKTRACE == 1
 //  - backtrace seems to be a little bit more portable than libunwind, but on
 //  linux, it uses unwind anyway, but abstract away a tiny information that is
 //  sadly really important in order to get perfectly accurate stack traces.
 //  - backtrace is part of the (e)glib library.
 //
 // The default is:
 // #define BACKWARD_HAS_UNWIND == 1
 //
 // Note that only one of the define should be set to 1 at a time.
 //
 #if BACKWARD_HAS_UNWIND == 1
 #elif BACKWARD_HAS_LIBUNWIND == 1
 #elif BACKWARD_HAS_BACKTRACE == 1
 #else
 #undef BACKWARD_HAS_UNWIND
 #define BACKWARD_HAS_UNWIND 1
 #undef BACKWARD_HAS_LIBUNWIND
 #define BACKWARD_HAS_LIBUNWIND 0
 #undef BACKWARD_HAS_BACKTRACE
 #define BACKWARD_HAS_BACKTRACE 0
 #endif
 
 // On linux, backward can extract detailed information about a stack trace
 // using one of the following libraries:
 //
 // #define BACKWARD_HAS_DW 1
 //  - libdw gives you the most juicy details out of your stack traces:
 //    - object filename
 //    - function name
 //    - source filename
 //    - line and column numbers
 //    - source code snippet (assuming the file is accessible)
 //    - variable names (if not optimized out)
 //    - variable values (not supported by backward-cpp)
 //  - You need to link with the lib "dw":
 //    - apt-get install libdw-dev
 //    - g++/clang++ -ldw ...
 //
 // #define BACKWARD_HAS_BFD 1
 //  - With libbfd, you get a fair amount of details:
 //    - object filename
 //    - function name
 //    - source filename
 //    - line numbers
 //    - source code snippet (assuming the file is accessible)
 //  - You need to link with the lib "bfd":
 //    - apt-get install binutils-dev
 //    - g++/clang++ -lbfd ...
 //
 // #define BACKWARD_HAS_DWARF 1
 //  - libdwarf gives you the most juicy details out of your stack traces:
 //    - object filename
 //    - function name
 //    - source filename
 //    - line and column numbers
 //    - source code snippet (assuming the file is accessible)
 //    - variable names (if not optimized out)
 //    - variable values (not supported by backward-cpp)
 //  - You need to link with the lib "dwarf":
 //    - apt-get install libdwarf-dev
 //    - g++/clang++ -ldwarf ...
 //
 // #define BACKWARD_HAS_BACKTRACE_SYMBOL 1
 //  - backtrace provides minimal details for a stack trace:
 //    - object filename
 //    - function name
 //  - backtrace is part of the (e)glib library.
 //
 // The default is:
 // #define BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 //
 // Note that only one of the define should be set to 1 at a time.
 //
 #if BACKWARD_HAS_DW == 1
 #elif BACKWARD_HAS_BFD == 1
 #elif BACKWARD_HAS_DWARF == 1
 #elif BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 #else
 #undef BACKWARD_HAS_DW
 #define BACKWARD_HAS_DW 0
 #undef BACKWARD_HAS_BFD
 #define BACKWARD_HAS_BFD 0
 #undef BACKWARD_HAS_DWARF
 #define BACKWARD_HAS_DWARF 0
 #undef BACKWARD_HAS_BACKTRACE_SYMBOL
 #define BACKWARD_HAS_BACKTRACE_SYMBOL 1
 #endif
 
 #include <cxxabi.h>
 #include <fcntl.h>
 #ifdef __ANDROID__
 //      Old Android API levels define _Unwind_Ptr in both link.h and
 // unwind.h         Rename the one in link.h as we are not going to be using
 // it
 #define _Unwind_Ptr _Unwind_Ptr_Custom
 #include <link.h>
 #undef _Unwind_Ptr
 #else
 #include <link.h>
 #endif
 #if defined(__ppc__) || defined(__powerpc) || defined(__powerpc__) ||        \
     defined(__POWERPC__)
 // Linux kernel header required for the struct pt_regs definition
 // to access the NIP (Next Instruction Pointer) register value
 #include <asm/ptrace.h>
 #endif
 #include <signal.h>
 #include <sys/stat.h>
 #include <syscall.h>
 #include <unistd.h>
 #ifndef _GNU_SOURCE
 #define _GNU_SOURCE
 #include <dlfcn.h>
 #undef _GNU_SOURCE
 #else
 #include <dlfcn.h>
 #endif
 
 #if BACKWARD_HAS_BFD == 1
 //              NOTE: defining PACKAGE{,_VERSION} is required before including
 //                    bfd.h on some platforms, see also:
 //                    https://sourceware.org/bugzilla/show_bug.cgi?id=14243
 #ifndef PACKAGE
 #define PACKAGE
 #endif
 #ifndef PACKAGE_VERSION
 #define PACKAGE_VERSION
 #endif
 #include <bfd.h>
 #endif
 
 #if BACKWARD_HAS_DW == 1
 #include <dwarf.h>
 #include <elfutils/libdw.h>
 #include <elfutils/libdwfl.h>
 #endif
 
 #if BACKWARD_HAS_DWARF == 1
 #include <algorithm>
 #include <dwarf.h>
 #include <libdwarf.h>
 #include <libelf.h>
 #include <map>
 #endif
 
 #if (BACKWARD_HAS_BACKTRACE == 1) || (BACKWARD_HAS_BACKTRACE_SYMBOL == 1)
 // then we shall rely on backtrace
 #include <execinfo.h>
 #endif
 
 #endif // defined(BACKWARD_SYSTEM_LINUX)
 
 #if defined(BACKWARD_SYSTEM_DARWIN)
 // On Darwin, backtrace can back-trace or "walk" the stack using the following
 // libraries:
 //
 // #define BACKWARD_HAS_UNWIND 1
 //  - unwind comes from libgcc, but I saw an equivalent inside clang itself.
 //  - with unwind, the stacktrace is as accurate as it can possibly be, since
 //  this is used by the C++ runtime in gcc/clang for stack unwinding on
 //  exception.
 //  - normally libgcc is already linked to your program by default.
 //
 // #define BACKWARD_HAS_LIBUNWIND 1
 //  - libunwind comes from clang, which implements an API compatible version.
 //  - libunwind provides, in some cases, a more accurate stacktrace as it knows
 //  to decode signal handler frames and lets us edit the context registers when
 //  unwinding, allowing stack traces over bad function references.
 //
 // #define BACKWARD_HAS_BACKTRACE == 1
 //  - backtrace is available by default, though it does not produce as much
 //  information as another library might.
 //
 // The default is:
 // #define BACKWARD_HAS_UNWIND == 1
 //
 // Note that only one of the define should be set to 1 at a time.
 //
 #if BACKWARD_HAS_UNWIND == 1
 #elif BACKWARD_HAS_BACKTRACE == 1
 #elif BACKWARD_HAS_LIBUNWIND == 1
 #else
 #undef BACKWARD_HAS_UNWIND
 #define BACKWARD_HAS_UNWIND 1
 #undef BACKWARD_HAS_BACKTRACE
 #define BACKWARD_HAS_BACKTRACE 0
 #undef BACKWARD_HAS_LIBUNWIND
 #define BACKWARD_HAS_LIBUNWIND 0
 #endif
 
 // On Darwin, backward can extract detailed information about a stack trace
 // using one of the following libraries:
 //
 // #define BACKWARD_HAS_BACKTRACE_SYMBOL 1
 //  - backtrace provides minimal details for a stack trace:
 //    - object filename
 //    - function name
 //
 // The default is:
 // #define BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 //
 #if BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 #else
 #undef BACKWARD_HAS_BACKTRACE_SYMBOL
 #define BACKWARD_HAS_BACKTRACE_SYMBOL 1
 #endif
 
 #include <cxxabi.h>
 #include <fcntl.h>
 #include <pthread.h>
 #include <signal.h>
 #include <sys/stat.h>
 #include <unistd.h>
 
 #if (BACKWARD_HAS_BACKTRACE == 1) || (BACKWARD_HAS_BACKTRACE_SYMBOL == 1)
 #include <execinfo.h>
 #endif
 #endif // defined(BACKWARD_SYSTEM_DARWIN)
 
 #if defined(BACKWARD_SYSTEM_WINDOWS)
 
 #include <condition_variable>
 #include <mutex>
 #include <thread>
 
 #include <basetsd.h>
 
 #ifdef _WIN64
 typedef SSIZE_T ssize_t;
 #else
 typedef int ssize_t;
 #endif
 
 #ifndef NOMINMAX
 #define NOMINMAX
 #endif
 #include <windows.h>
 #include <winnt.h>
 
 #include <psapi.h>
 #include <signal.h>
 
 #ifndef __clang__
 #undef NOINLINE
 #define NOINLINE __declspec(noinline)
 #endif
 
 #ifdef _MSC_VER
 #pragma comment(lib, "psapi.lib")
 #pragma comment(lib, "dbghelp.lib")
 #endif
 
 // Comment / packing is from stackoverflow:
 // https://stackoverflow.com/questions/6205981/windows-c-stack-trace-from-a-running-app/28276227#28276227
 // Some versions of imagehlp.dll lack the proper packing directives themselves
 // so we need to do it.
 #pragma pack(push, before_imagehlp, 8)
 #include <imagehlp.h>
 #pragma pack(pop, before_imagehlp)
 
 // TODO maybe these should be undefined somewhere else?
 #undef BACKWARD_HAS_UNWIND
 #undef BACKWARD_HAS_BACKTRACE
 #if BACKWARD_HAS_PDB_SYMBOL == 1
 #else
 #undef BACKWARD_HAS_PDB_SYMBOL
 #define BACKWARD_HAS_PDB_SYMBOL 1
 #endif
 
 #endif
 
 #if BACKWARD_HAS_UNWIND == 1
 
 #include <unwind.h>
 // while gcc's unwind.h defines something like that:
 //  extern _Unwind_Ptr _Unwind_GetIP (struct _Unwind_Context *);
 //  extern _Unwind_Ptr _Unwind_GetIPInfo (struct _Unwind_Context *, int *);
 //
 // clang's unwind.h defines something like this:
 //  uintptr_t _Unwind_GetIP(struct _Unwind_Context* __context);
 //
 // Even if the _Unwind_GetIPInfo can be linked to, it is not declared, worse we
 // cannot just redeclare it because clang's unwind.h doesn't define _Unwind_Ptr
 // anyway.
 //
 // Luckily we can play on the fact that the guard macros have a different name:
 #ifdef __CLANG_UNWIND_H
 // In fact, this function still comes from libgcc (on my different linux boxes,
 // clang links against libgcc).
 #include <inttypes.h>
 extern "C" uintptr_t _Unwind_GetIPInfo(_Unwind_Context *, int *);
 #endif
 
 #endif // BACKWARD_HAS_UNWIND == 1
 
 #if BACKWARD_HAS_LIBUNWIND == 1
 #define UNW_LOCAL_ONLY
 #include <libunwind.h>
 #endif // BACKWARD_HAS_LIBUNWIND == 1
 
 #ifdef BACKWARD_ATLEAST_CXX11
 #include <unordered_map>
 #include <utility> // for std::swap
 namespace backward {
 namespace details {
 template <typename K, typename V> struct hashtable {
   typedef std::unordered_map<K, V> type;
 };
 using std::move;
 } // namespace details
 } // namespace backward
 #else // NOT BACKWARD_ATLEAST_CXX11
 #define nullptr NULL
 #define override
 #include <map>
 namespace backward {
 namespace details {
 template <typename K, typename V> struct hashtable {
   typedef std::map<K, V> type;
 };
 template <typename T> const T &move(const T &v) { return v; }
 template <typename T> T &move(T &v) { return v; }
 } // namespace details
 } // namespace backward
 #endif // BACKWARD_ATLEAST_CXX11
 
 namespace backward {
 namespace details {
 #if defined(BACKWARD_SYSTEM_WINDOWS)
 const char kBackwardPathDelimiter[] = ";";
 #else
 const char kBackwardPathDelimiter[] = ":";
 #endif
 } // namespace details
 } // namespace backward
 
 namespace backward {
 
 namespace system_tag {
 struct linux_tag; // seems that I cannot call that "linux" because the name
 // is already defined... so I am adding _tag everywhere.
 struct darwin_tag;
 struct windows_tag;
 struct unknown_tag;
 
 #if defined(BACKWARD_SYSTEM_LINUX)
 typedef linux_tag current_tag;
 #elif defined(BACKWARD_SYSTEM_DARWIN)
 typedef darwin_tag current_tag;
 #elif defined(BACKWARD_SYSTEM_WINDOWS)
 typedef windows_tag current_tag;
 #elif defined(BACKWARD_SYSTEM_UNKNOWN)
 typedef unknown_tag current_tag;
 #else
 #error "May I please get my system defines?"
 #endif
 } // namespace system_tag
 
 namespace trace_resolver_tag {
 #if defined(BACKWARD_SYSTEM_LINUX)
 struct libdw;
 struct libbfd;
 struct libdwarf;
 struct backtrace_symbol;
 
 #if BACKWARD_HAS_DW == 1
 typedef libdw current;
 #elif BACKWARD_HAS_BFD == 1
 typedef libbfd current;
 #elif BACKWARD_HAS_DWARF == 1
 typedef libdwarf current;
 #elif BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 typedef backtrace_symbol current;
 #else
 #error "You shall not pass, until you know what you want."
 #endif
 #elif defined(BACKWARD_SYSTEM_DARWIN)
 struct backtrace_symbol;
 
 #if BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 typedef backtrace_symbol current;
 #else
 #error "You shall not pass, until you know what you want."
 #endif
 #elif defined(BACKWARD_SYSTEM_WINDOWS)
 struct pdb_symbol;
 #if BACKWARD_HAS_PDB_SYMBOL == 1
 typedef pdb_symbol current;
 #else
 #error "You shall not pass, until you know what you want."
 #endif
 #endif
 } // namespace trace_resolver_tag
 
 namespace details {
 
 template <typename T> struct rm_ptr { typedef T type; };
 
 template <typename T> struct rm_ptr<T *> { typedef T type; };
 
 template <typename T> struct rm_ptr<const T *> { typedef const T type; };
 
 template <typename R, typename T, R (*F)(T)> struct deleter {
   template <typename U> void operator()(U &ptr) const { (*F)(ptr); }
 };
 
 template <typename T> struct default_delete {
   void operator()(T &ptr) const { delete ptr; }
 };
 
 template <typename T, typename Deleter = deleter<void, void *, &::free> >
 class handle {
   struct dummy;
   T _val;
   bool _empty;
 
 #ifdef BACKWARD_ATLEAST_CXX11
   handle(const handle &) = delete;
   handle &operator=(const handle &) = delete;
 #endif
 
 public:
   ~handle() {
     if (!_empty) {
       Deleter()(_val);
     }
   }
 
   explicit handle() : _val(), _empty(true) {}
   explicit handle(T val) : _val(val), _empty(false) {
     if (!_val)
       _empty = true;
   }
 
 #ifdef BACKWARD_ATLEAST_CXX11
   handle(handle &&from) : _empty(true) { swap(from); }
   handle &operator=(handle &&from) {
     swap(from);
     return *this;
   }
 #else
   explicit handle(const handle &from) : _empty(true) {
     // some sort of poor man's move semantic.
     swap(const_cast<handle &>(from));
   }
   handle &operator=(const handle &from) {
     // some sort of poor man's move semantic.
     swap(const_cast<handle &>(from));
     return *this;
   }
 #endif
 
   void reset(T new_val) {
     handle tmp(new_val);
     swap(tmp);
   }
 
   void update(T new_val) {
     _val = new_val;
     _empty = !static_cast<bool>(new_val);
   }
 
   operator const dummy *() const {
     if (_empty) {
       return nullptr;
     }
     return reinterpret_cast<const dummy *>(_val);
   }
   T get() { return _val; }
   T release() {
     _empty = true;
     return _val;
   }
   void swap(handle &b) {
     using std::swap;
     swap(b._val, _val);     // can throw, we are safe here.
     swap(b._empty, _empty); // should not throw: if you cannot swap two
     // bools without throwing... It's a lost cause anyway!
   }
 
   T &operator->() { return _val; }
   const T &operator->() const { return _val; }
 
   typedef typename rm_ptr<T>::type &ref_t;
   typedef const typename rm_ptr<T>::type &const_ref_t;
   ref_t operator*() { return *_val; }
   const_ref_t operator*() const { return *_val; }
   ref_t operator[](size_t idx) { return _val[idx]; }
 
   // Watch out, we've got a badass over here
   T *operator&() {
     _empty = false;
     return &_val;
   }
 };
 
 // Default demangler implementation (do nothing).
 template <typename TAG> struct demangler_impl {
   static std::string demangle(const char *funcname) { return funcname; }
 };
 
 #if defined(BACKWARD_SYSTEM_LINUX) || defined(BACKWARD_SYSTEM_DARWIN)
 
 template <> struct demangler_impl<system_tag::current_tag> {
   demangler_impl() : _demangle_buffer_length(0) {}
 
   std::string demangle(const char *funcname) {
     using namespace details;
     char *result = abi::__cxa_demangle(funcname, _demangle_buffer.get(),
                                        &_demangle_buffer_length, nullptr);
     if (result) {
       _demangle_buffer.update(result);
       return result;
     }
     return funcname;
   }
 
 private:
   details::handle<char *> _demangle_buffer;
   size_t _demangle_buffer_length;
 };
 
 #endif // BACKWARD_SYSTEM_LINUX || BACKWARD_SYSTEM_DARWIN
 
 struct demangler : public demangler_impl<system_tag::current_tag> {};
 
 // Split a string on the platform's PATH delimiter.  Example: if delimiter
 // is ":" then:
 //   ""              --> []
 //   ":"             --> ["",""]
 //   "::"            --> ["","",""]
 //   "/a/b/c"        --> ["/a/b/c"]
 //   "/a/b/c:/d/e/f" --> ["/a/b/c","/d/e/f"]
 //   etc.
 inline std::vector<std::string> split_source_prefixes(const std::string &s) {
   std::vector<std::string> out;
   size_t last = 0;
   size_t next = 0;
   size_t delimiter_size = sizeof(kBackwardPathDelimiter) - 1;
   while ((next = s.find(kBackwardPathDelimiter, last)) != std::string::npos) {
     out.push_back(s.substr(last, next - last));
     last = next + delimiter_size;
   }
   if (last <= s.length()) {
     out.push_back(s.substr(last));
   }
   return out;
 }
 
 } // namespace details
 
 /*************** A TRACE ***************/
 
 struct Trace {
   void *addr;
   size_t idx;
 
   Trace() : addr(nullptr), idx(0) {}
 
   explicit Trace(void *_addr, size_t _idx) : addr(_addr), idx(_idx) {}
 };
 
 struct ResolvedTrace : public Trace {
 
   struct SourceLoc {
     std::string function;
     std::string filename;
     unsigned line;
     unsigned col;
 
     SourceLoc() : line(0), col(0) {}
 
     bool operator==(const SourceLoc &b) const {
       return function == b.function && filename == b.filename &&
              line == b.line && col == b.col;
     }
 
     bool operator!=(const SourceLoc &b) const { return !(*this == b); }
   };
 
   // In which binary object this trace is located.
   std::string object_filename;
 
   // The function in the object that contain the trace. This is not the same
   // as source.function which can be an function inlined in object_function.
   std::string object_function;
 
   // The source location of this trace. It is possible for filename to be
   // empty and for line/col to be invalid (value 0) if this information
   // couldn't be deduced, for example if there is no debug information in the
   // binary object.
   SourceLoc source;
 
   // An optionals list of "inliners". All the successive sources location
   // from where the source location of the trace (the attribute right above)
   // is inlined. It is especially useful when you compiled with optimization.
   typedef std::vector<SourceLoc> source_locs_t;
   source_locs_t inliners;
 
   ResolvedTrace() : Trace() {}
   ResolvedTrace(const Trace &mini_trace) : Trace(mini_trace) {}
 };
 
 /*************** STACK TRACE ***************/
 
 // default implemention.
 template <typename TAG> class StackTraceImpl {
 public:
   size_t size() const { return 0; }
   Trace operator[](size_t) const { return Trace(); }
   size_t load_here(size_t = 0) { return 0; }
   size_t load_from(void *, size_t = 0, void * = nullptr, void * = nullptr) {
     return 0;
   }
   size_t thread_id() const { return 0; }
   void skip_n_firsts(size_t) {}
 };
 
 class StackTraceImplBase {
 public:
   StackTraceImplBase()
       : _thread_id(0), _skip(0), _context(nullptr), _error_addr(nullptr) {}
 
   size_t thread_id() const { return _thread_id; }
 
   void skip_n_firsts(size_t n) { _skip = n; }
 
 protected:
   void load_thread_info() {
 #ifdef BACKWARD_SYSTEM_LINUX
 #ifndef __ANDROID__
     _thread_id = static_cast<size_t>(syscall(SYS_gettid));
 #else
     _thread_id = static_cast<size_t>(gettid());
 #endif
     if (_thread_id == static_cast<size_t>(getpid())) {
       // If the thread is the main one, let's hide that.
       // I like to keep little secret sometimes.
       _thread_id = 0;
     }
 #elif defined(BACKWARD_SYSTEM_DARWIN)
     _thread_id = reinterpret_cast<size_t>(pthread_self());
     if (pthread_main_np() == 1) {
       // If the thread is the main one, let's hide that.
       _thread_id = 0;
     }
 #endif
   }
 
   void set_context(void *context) { _context = context; }
   void *context() const { return _context; }
 
   void set_error_addr(void *error_addr) { _error_addr = error_addr; }
   void *error_addr() const { return _error_addr; }
 
   size_t skip_n_firsts() const { return _skip; }
 
 private:
   size_t _thread_id;
   size_t _skip;
   void *_context;
   void *_error_addr;
 };
 
 class StackTraceImplHolder : public StackTraceImplBase {
 public:
   size_t size() const {
     return (_stacktrace.size() >= skip_n_firsts())
                ? _stacktrace.size() - skip_n_firsts()
                : 0;
   }
   Trace operator[](size_t idx) const {
     if (idx >= size()) {
       return Trace();
     }
     return Trace(_stacktrace[idx + skip_n_firsts()], idx);
   }
   void *const *begin() const {
     if (size()) {
       return &_stacktrace[skip_n_firsts()];
     }
     return nullptr;
   }
 
 protected:
   std::vector<void *> _stacktrace;
 };
 
 #if BACKWARD_HAS_UNWIND == 1
 
 namespace details {
 
 template <typename F> class Unwinder {
 public:
   size_t operator()(F &f, size_t depth) {
     _f = &f;
     _index = -1;
     _depth = depth;
     _Unwind_Backtrace(&this->backtrace_trampoline, this);
     if (_index == -1) {
       // _Unwind_Backtrace has failed to obtain any backtraces
       return 0;
     } else {
       return static_cast<size_t>(_index);
     }
   }
 
 private:
   F *_f;
   ssize_t _index;
   size_t _depth;
 
   static _Unwind_Reason_Code backtrace_trampoline(_Unwind_Context *ctx,
                                                   void *self) {
     return (static_cast<Unwinder *>(self))->backtrace(ctx);
   }
 
   _Unwind_Reason_Code backtrace(_Unwind_Context *ctx) {
     if (_index >= 0 && static_cast<size_t>(_index) >= _depth)
       return _URC_END_OF_STACK;
 
     int ip_before_instruction = 0;
     uintptr_t ip = _Unwind_GetIPInfo(ctx, &ip_before_instruction);
 
     if (!ip_before_instruction) {
       // calculating 0-1 for unsigned, looks like a possible bug to sanitizers,
       // so let's do it explicitly:
       if (ip == 0) {
         ip = std::numeric_limits<uintptr_t>::max(); // set it to 0xffff... (as
                                                     // from casting 0-1)
       } else {
         ip -= 1; // else just normally decrement it (no overflow/underflow will
                  // happen)
       }
     }
 
     if (_index >= 0) { // ignore first frame.
       (*_f)(static_cast<size_t>(_index), reinterpret_cast<void *>(ip));
     }
     _index += 1;
     return _URC_NO_REASON;
   }
 };
 
 template <typename F> size_t unwind(F f, size_t depth) {
   Unwinder<F> unwinder;
   return unwinder(f, depth);
 }
 
 } // namespace details
 
 template <>
 class StackTraceImpl<system_tag::current_tag> : public StackTraceImplHolder {
 public:
   NOINLINE
   size_t load_here(size_t depth = 32, void *context = nullptr,
                    void *error_addr = nullptr) {
     load_thread_info();
     set_context(context);
     set_error_addr(error_addr);
     if (depth == 0) {
       return 0;
     }
     _stacktrace.resize(depth);
     size_t trace_cnt = details::unwind(callback(*this), depth);
     _stacktrace.resize(trace_cnt);
     skip_n_firsts(0);
     return size();
   }
   size_t load_from(void *addr, size_t depth = 32, void *context = nullptr,
                    void *error_addr = nullptr) {
     load_here(depth + 8, context, error_addr);
 
     for (size_t i = 0; i < _stacktrace.size(); ++i) {
       if (_stacktrace[i] == addr) {
         skip_n_firsts(i);
         break;
       }
     }
 
     _stacktrace.resize(std::min(_stacktrace.size(), skip_n_firsts() + depth));
     return size();
   }
 
 private:
   struct callback {
     StackTraceImpl &self;
     callback(StackTraceImpl &_self) : self(_self) {}
 
     void operator()(size_t idx, void *addr) { self._stacktrace[idx] = addr; }
   };
 };
 
 #elif BACKWARD_HAS_LIBUNWIND == 1
 
 template <>
 class StackTraceImpl<system_tag::current_tag> : public StackTraceImplHolder {
 public:
   __attribute__((noinline)) size_t load_here(size_t depth = 32,
                                              void *_context = nullptr,
                                              void *_error_addr = nullptr) {
     set_context(_context);
     set_error_addr(_error_addr);
     load_thread_info();
     if (depth == 0) {
       return 0;
     }
     _stacktrace.resize(depth + 1);
 
     int result = 0;
 
     unw_context_t ctx;
     size_t index = 0;
 
     // Add the tail call. If the Instruction Pointer is the crash address it
     // means we got a bad function pointer dereference, so we "unwind" the
     // bad pointer manually by using the return address pointed to by the
     // Stack Pointer as the Instruction Pointer and letting libunwind do
     // the rest
 
     if (context()) {
       ucontext_t *uctx = reinterpret_cast<ucontext_t *>(context());
 #ifdef REG_RIP         // x86_64
       if (uctx->uc_mcontext.gregs[REG_RIP] ==
           reinterpret_cast<greg_t>(error_addr())) {
         uctx->uc_mcontext.gregs[REG_RIP] =
             *reinterpret_cast<size_t *>(uctx->uc_mcontext.gregs[REG_RSP]);
       }
       _stacktrace[index] =
           reinterpret_cast<void *>(uctx->uc_mcontext.gregs[REG_RIP]);
       ++index;
       ctx = *reinterpret_cast<unw_context_t *>(uctx);
 #elif defined(REG_EIP) // x86_32
       if (uctx->uc_mcontext.gregs[REG_EIP] ==
           reinterpret_cast<greg_t>(error_addr())) {
         uctx->uc_mcontext.gregs[REG_EIP] =
             *reinterpret_cast<size_t *>(uctx->uc_mcontext.gregs[REG_ESP]);
       }
       _stacktrace[index] =
           reinterpret_cast<void *>(uctx->uc_mcontext.gregs[REG_EIP]);
       ++index;
       ctx = *reinterpret_cast<unw_context_t *>(uctx);
 #elif defined(__arm__)
       // libunwind uses its own context type for ARM unwinding.
       // Copy the registers from the signal handler's context so we can
       // unwind
       unw_getcontext(&ctx);
       ctx.regs[UNW_ARM_R0] = uctx->uc_mcontext.arm_r0;
       ctx.regs[UNW_ARM_R1] = uctx->uc_mcontext.arm_r1;
       ctx.regs[UNW_ARM_R2] = uctx->uc_mcontext.arm_r2;
       ctx.regs[UNW_ARM_R3] = uctx->uc_mcontext.arm_r3;
       ctx.regs[UNW_ARM_R4] = uctx->uc_mcontext.arm_r4;
       ctx.regs[UNW_ARM_R5] = uctx->uc_mcontext.arm_r5;
       ctx.regs[UNW_ARM_R6] = uctx->uc_mcontext.arm_r6;
       ctx.regs[UNW_ARM_R7] = uctx->uc_mcontext.arm_r7;
       ctx.regs[UNW_ARM_R8] = uctx->uc_mcontext.arm_r8;
       ctx.regs[UNW_ARM_R9] = uctx->uc_mcontext.arm_r9;
       ctx.regs[UNW_ARM_R10] = uctx->uc_mcontext.arm_r10;
       ctx.regs[UNW_ARM_R11] = uctx->uc_mcontext.arm_fp;
       ctx.regs[UNW_ARM_R12] = uctx->uc_mcontext.arm_ip;
       ctx.regs[UNW_ARM_R13] = uctx->uc_mcontext.arm_sp;
       ctx.regs[UNW_ARM_R14] = uctx->uc_mcontext.arm_lr;
       ctx.regs[UNW_ARM_R15] = uctx->uc_mcontext.arm_pc;
 
       // If we have crashed in the PC use the LR instead, as this was
       // a bad function dereference
       if (reinterpret_cast<unsigned long>(error_addr()) ==
           uctx->uc_mcontext.arm_pc) {
         ctx.regs[UNW_ARM_R15] =
             uctx->uc_mcontext.arm_lr - sizeof(unsigned long);
       }
       _stacktrace[index] = reinterpret_cast<void *>(ctx.regs[UNW_ARM_R15]);
       ++index;
 #elif defined(__APPLE__) && defined(__x86_64__)
       unw_getcontext(&ctx);
       // OS X's implementation of libunwind uses its own context object
       // so we need to convert the passed context to libunwind's format
       // (information about the data layout taken from unw_getcontext.s
       // in Apple's libunwind source
       ctx.data[0] = uctx->uc_mcontext->__ss.__rax;
       ctx.data[1] = uctx->uc_mcontext->__ss.__rbx;
       ctx.data[2] = uctx->uc_mcontext->__ss.__rcx;
       ctx.data[3] = uctx->uc_mcontext->__ss.__rdx;
       ctx.data[4] = uctx->uc_mcontext->__ss.__rdi;
       ctx.data[5] = uctx->uc_mcontext->__ss.__rsi;
       ctx.data[6] = uctx->uc_mcontext->__ss.__rbp;
       ctx.data[7] = uctx->uc_mcontext->__ss.__rsp;
       ctx.data[8] = uctx->uc_mcontext->__ss.__r8;
       ctx.data[9] = uctx->uc_mcontext->__ss.__r9;
       ctx.data[10] = uctx->uc_mcontext->__ss.__r10;
       ctx.data[11] = uctx->uc_mcontext->__ss.__r11;
       ctx.data[12] = uctx->uc_mcontext->__ss.__r12;
       ctx.data[13] = uctx->uc_mcontext->__ss.__r13;
       ctx.data[14] = uctx->uc_mcontext->__ss.__r14;
       ctx.data[15] = uctx->uc_mcontext->__ss.__r15;
       ctx.data[16] = uctx->uc_mcontext->__ss.__rip;
 
       // If the IP is the same as the crash address we have a bad function
       // dereference The caller's address is pointed to by %rsp, so we
       // dereference that value and set it to be the next frame's IP.
       if (uctx->uc_mcontext->__ss.__rip ==
           reinterpret_cast<__uint64_t>(error_addr())) {
         ctx.data[16] =
             *reinterpret_cast<__uint64_t *>(uctx->uc_mcontext->__ss.__rsp);
       }
       _stacktrace[index] = reinterpret_cast<void *>(ctx.data[16]);
       ++index;
 #elif defined(__APPLE__)
       unw_getcontext(&ctx)
           // TODO: Convert the ucontext_t to libunwind's unw_context_t like
           // we do in 64 bits
           if (ctx.uc_mcontext->__ss.__eip ==
               reinterpret_cast<greg_t>(error_addr())) {
         ctx.uc_mcontext->__ss.__eip = ctx.uc_mcontext->__ss.__esp;
       }
       _stacktrace[index] =
           reinterpret_cast<void *>(ctx.uc_mcontext->__ss.__eip);
       ++index;
 #endif
     }
 
     unw_cursor_t cursor;
     if (context()) {
 #if defined(UNW_INIT_SIGNAL_FRAME)
       result = unw_init_local2(&cursor, &ctx, UNW_INIT_SIGNAL_FRAME);
 #else
       result = unw_init_local(&cursor, &ctx);
 #endif
     } else {
       unw_getcontext(&ctx);
       ;
       result = unw_init_local(&cursor, &ctx);
     }
 
     if (result != 0)
       return 1;
 
     unw_word_t ip = 0;
 
     while (index <= depth && unw_step(&cursor) > 0) {
       result = unw_get_reg(&cursor, UNW_REG_IP, &ip);
       if (result == 0) {
         _stacktrace[index] = reinterpret_cast<void *>(--ip);
         ++index;
       }
     }
     --index;
 
     _stacktrace.resize(index + 1);
     skip_n_firsts(0);
     return size();
   }
 
   size_t load_from(void *addr, size_t depth = 32, void *context = nullptr,
                    void *error_addr = nullptr) {
     load_here(depth + 8, context, error_addr);
 
     for (size_t i = 0; i < _stacktrace.size(); ++i) {
       if (_stacktrace[i] == addr) {
         skip_n_firsts(i);
         _stacktrace[i] = (void *)((uintptr_t)_stacktrace[i]);
         break;
       }
     }
 
     _stacktrace.resize(std::min(_stacktrace.size(), skip_n_firsts() + depth));
     return size();
   }
 };
 
 #elif defined(BACKWARD_HAS_BACKTRACE)
 
 template <>
 class StackTraceImpl<system_tag::current_tag> : public StackTraceImplHolder {
 public:
   NOINLINE
   size_t load_here(size_t depth = 32, void *context = nullptr,
                    void *error_addr = nullptr) {
     set_context(context);
     set_error_addr(error_addr);
     load_thread_info();
     if (depth == 0) {
       return 0;
     }
     _stacktrace.resize(depth + 1);
     size_t trace_cnt = backtrace(&_stacktrace[0], _stacktrace.size());
     _stacktrace.resize(trace_cnt);
     skip_n_firsts(1);
     return size();
   }
 
   size_t load_from(void *addr, size_t depth = 32, void *context = nullptr,
                    void *error_addr = nullptr) {
     load_here(depth + 8, context, error_addr);
 
     for (size_t i = 0; i < _stacktrace.size(); ++i) {
       if (_stacktrace[i] == addr) {
         skip_n_firsts(i);
         _stacktrace[i] = (void *)((uintptr_t)_stacktrace[i] + 1);
         break;
       }
     }
 
     _stacktrace.resize(std::min(_stacktrace.size(), skip_n_firsts() + depth));
     return size();
   }
 };
 
 #elif defined(BACKWARD_SYSTEM_WINDOWS)
 
 template <>
 class StackTraceImpl<system_tag::current_tag> : public StackTraceImplHolder {
 public:
   // We have to load the machine type from the image info
   // So we first initialize the resolver, and it tells us this info
   void set_machine_type(DWORD machine_type) { machine_type_ = machine_type; }
   void set_context(CONTEXT *ctx) { ctx_ = ctx; }
   void set_thread_handle(HANDLE handle) { thd_ = handle; }
 
   NOINLINE
   size_t load_here(size_t depth = 32, void *context = nullptr,
                    void *error_addr = nullptr) {
     set_context(static_cast<CONTEXT*>(context));
     set_error_addr(error_addr);
     CONTEXT localCtx; // used when no context is provided
 
     if (depth == 0) {
       return 0;
     }
 
     if (!ctx_) {
       ctx_ = &localCtx;
       RtlCaptureContext(ctx_);
     }
 
     if (!thd_) {
       thd_ = GetCurrentThread();
     }
 
     HANDLE process = GetCurrentProcess();
 
     STACKFRAME64 s;
     memset(&s, 0, sizeof(STACKFRAME64));
 
     // TODO: 32 bit context capture
     s.AddrStack.Mode = AddrModeFlat;
     s.AddrFrame.Mode = AddrModeFlat;
     s.AddrPC.Mode = AddrModeFlat;
 #ifdef _M_X64
     s.AddrPC.Offset = ctx_->Rip;
     s.AddrStack.Offset = ctx_->Rsp;
     s.AddrFrame.Offset = ctx_->Rbp;
 #else
     s.AddrPC.Offset = ctx_->Eip;
     s.AddrStack.Offset = ctx_->Esp;
     s.AddrFrame.Offset = ctx_->Ebp;
 #endif
 
     if (!machine_type_) {
 #ifdef _M_X64
       machine_type_ = IMAGE_FILE_MACHINE_AMD64;
 #else
       machine_type_ = IMAGE_FILE_MACHINE_I386;
 #endif
     }
 
     for (;;) {
       // NOTE: this only works if PDBs are already loaded!
       SetLastError(0);
       if (!StackWalk64(machine_type_, process, thd_, &s, ctx_, NULL,
                        SymFunctionTableAccess64, SymGetModuleBase64, NULL))
         break;
 
       if (s.AddrReturn.Offset == 0)
         break;
 
       _stacktrace.push_back(reinterpret_cast<void *>(s.AddrPC.Offset));
 
       if (size() >= depth)
         break;
     }
 
     return size();
   }
 
   size_t load_from(void *addr, size_t depth = 32, void *context = nullptr,
                    void *error_addr = nullptr) {
     load_here(depth + 8, context, error_addr);
 
     for (size_t i = 0; i < _stacktrace.size(); ++i) {
       if (_stacktrace[i] == addr) {
         skip_n_firsts(i);
         break;
       }
     }
 
     _stacktrace.resize(std::min(_stacktrace.size(), skip_n_firsts() + depth));
     return size();
   }
 
 private:
   DWORD machine_type_ = 0;
   HANDLE thd_ = 0;
   CONTEXT *ctx_ = nullptr;
 };
 
 #endif
 
 class StackTrace : public StackTraceImpl<system_tag::current_tag> {};
 
 /*************** TRACE RESOLVER ***************/
 
 class TraceResolverImplBase {
 public:
   virtual ~TraceResolverImplBase() {}
 
   virtual void load_addresses(void *const*addresses, int address_count) {
     (void)addresses;
     (void)address_count;
   }
 
   template <class ST> void load_stacktrace(ST &st) {
     load_addresses(st.begin(), static_cast<int>(st.size()));
   }
 
   virtual ResolvedTrace resolve(ResolvedTrace t) { return t; }
 
 protected:
   std::string demangle(const char *funcname) {
     return _demangler.demangle(funcname);
   }
 
 private:
   details::demangler _demangler;
 };
 
 template <typename TAG> class TraceResolverImpl;
 
 #ifdef BACKWARD_SYSTEM_UNKNOWN
 
 template <> class TraceResolverImpl<system_tag::unknown_tag>
     : public TraceResolverImplBase {};
 
 #endif
 
 #ifdef BACKWARD_SYSTEM_LINUX
 
 class TraceResolverLinuxBase : public TraceResolverImplBase {
 public:
   TraceResolverLinuxBase()
       : argv0_(get_argv0()), exec_path_(read_symlink("/proc/self/exe")) {}
   std::string resolve_exec_path(Dl_info &symbol_info) const {
     // mutates symbol_info.dli_fname to be filename to open and returns filename
     // to display
     if (symbol_info.dli_fname == argv0_) {
       // dladdr returns argv[0] in dli_fname for symbols contained in
       // the main executable, which is not a valid path if the
       // executable was found by a search of the PATH environment
       // variable; In that case, we actually open /proc/self/exe, which
       // is always the actual executable (even if it was deleted/replaced!)
       // but display the path that /proc/self/exe links to.
       // However, this right away reduces probability of successful symbol
       // resolution, because libbfd may try to find *.debug files in the
       // same dir, in case symbols are stripped. As a result, it may try
       // to find a file /proc/self/<exe_name>.debug, which obviously does
       // not exist. /proc/self/exe is a last resort. First load attempt
       // should go for the original executable file path.
       symbol_info.dli_fname = "/proc/self/exe";
       return exec_path_;
     } else {
       return symbol_info.dli_fname;
     }
   }
 
 private:
   std::string argv0_;
   std::string exec_path_;
 
   static std::string get_argv0() {
     std::string argv0;
     std::ifstream ifs("/proc/self/cmdline");
     std::getline(ifs, argv0, '\0');
     return argv0;
   }
 
   static std::string read_symlink(std::string const &symlink_path) {
     std::string path;
     path.resize(100);
 
     while (true) {
       ssize_t len =
           ::readlink(symlink_path.c_str(), &*path.begin(), path.size());
       if (len < 0) {
         return "";
       }
       if (static_cast<size_t>(len) == path.size()) {
         path.resize(path.size() * 2);
       } else {
         path.resize(static_cast<std::string::size_type>(len));
         break;
       }
     }
 
     return path;
   }
 };
 
 template <typename STACKTRACE_TAG> class TraceResolverLinuxImpl;
 
 #if BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 
 template <>
 class TraceResolverLinuxImpl<trace_resolver_tag::backtrace_symbol>
     : public TraceResolverLinuxBase {
 public:
   void load_addresses(void *const*addresses, int address_count) override {
     if (address_count == 0) {
       return;
     }
     _symbols.reset(backtrace_symbols(addresses, address_count));
   }
 
   ResolvedTrace resolve(ResolvedTrace trace) override {
     char *filename = _symbols[trace.idx];
     char *funcname = filename;
     while (*funcname && *funcname != '(') {
       funcname += 1;
     }
     trace.object_filename.assign(filename,
                                  funcname); // ok even if funcname is the ending
                                             // \0 (then we assign entire string)
 
     if (*funcname) { // if it's not end of string (e.g. from last frame ip==0)
       funcname += 1;
       char *funcname_end = funcname;
       while (*funcname_end && *funcname_end != ')' && *funcname_end != '+') {
         funcname_end += 1;
       }
       *funcname_end = '\0';
       trace.object_function = this->demangle(funcname);
       trace.source.function = trace.object_function; // we cannot do better.
     }
     return trace;
   }
 
 private:
   details::handle<char **> _symbols;
 };
 
 #endif // BACKWARD_HAS_BACKTRACE_SYMBOL == 1
 
 #if BACKWARD_HAS_BFD == 1
 
 template <>
 class TraceResolverLinuxImpl<trace_resolver_tag::libbfd>
     : public TraceResolverLinuxBase {
 public:
   TraceResolverLinuxImpl() : _bfd_loaded(false) {}
 
   ResolvedTrace resolve(ResolvedTrace trace) override {
     Dl_info symbol_info;
 
     // trace.addr is a virtual address in memory pointing to some code.
     // Let's try to find from which loaded object it comes from.
     // The loaded object can be yourself btw.
     if (!dladdr(trace.addr, &symbol_info)) {
       return trace; // dat broken trace...
     }
 
     // Now we get in symbol_info:
     // .dli_fname:
     //      pathname of the shared object that contains the address.
     // .dli_fbase:
     //      where the object is loaded in memory.
     // .dli_sname:
     //      the name of the nearest symbol to trace.addr, we expect a
     //      function name.
     // .dli_saddr:
     //      the exact address corresponding to .dli_sname.
 
     if (symbol_info.dli_sname) {
       trace.object_function = demangle(symbol_info.dli_sname);
     }
 
     if (!symbol_info.dli_fname) {
       return trace;
     }
 
     trace.object_filename = resolve_exec_path(symbol_info);
     bfd_fileobject *fobj;
     // Before rushing to resolution need to ensure the executable
     // file still can be used. For that compare inode numbers of
     // what is stored by the executable's file path, and in the
     // dli_fname, which not necessarily equals to the executable.
     // It can be a shared library, or /proc/self/exe, and in the
     // latter case has drawbacks. See the exec path resolution for
     // details. In short - the dli object should be used only as
     // the last resort.
     // If inode numbers are equal, it is known dli_fname and the
     // executable file are the same. This is guaranteed by Linux,
     // because if the executable file is changed/deleted, it will
     // be done in a new inode. The old file will be preserved in
     // /proc/self/exe, and may even have inode 0. The latter can
     // happen if the inode was actually reused, and the file was
     // kept only in the main memory.
     //
     struct stat obj_stat;
     struct stat dli_stat;
     if (stat(trace.object_filename.c_str(), &obj_stat) == 0 &&
         stat(symbol_info.dli_fname, &dli_stat) == 0 &&
         obj_stat.st_ino == dli_stat.st_ino) {
       // The executable file, and the shared object containing the
       // address are the same file. Safe to use the original path.
       // this is preferable. Libbfd will search for stripped debug
       // symbols in the same directory.
       fobj = load_object_with_bfd(trace.object_filename);
     } else{
       // The original object file was *deleted*! The only hope is
       // that the debug symbols are either inside the shared
       // object file, or are in the same directory, and this is
       // not /proc/self/exe.
       fobj = nullptr;
     }
     if (fobj == nullptr || !fobj->handle) {
       fobj = load_object_with_bfd(symbol_info.dli_fname);
       if (!fobj->handle) {
         return trace;
       }
     }
 
     find_sym_result *details_selected; // to be filled.
 
     // trace.addr is the next instruction to be executed after returning
     // from the nested stack frame. In C++ this usually relate to the next
     // statement right after the function call that leaded to a new stack
     // frame. This is not usually what you want to see when printing out a
     // stacktrace...
     find_sym_result details_call_site =
         find_symbol_details(fobj, trace.addr, symbol_info.dli_fbase);
     details_selected = &details_call_site;
 
 #if BACKWARD_HAS_UNWIND == 0
     // ...this is why we also try to resolve the symbol that is right
     // before the return address. If we are lucky enough, we will get the
     // line of the function that was called. But if the code is optimized,
     // we might get something absolutely not related since the compiler
     // can reschedule the return address with inline functions and
     // tail-call optimization (among other things that I don't even know
     // or cannot even dream about with my tiny limited brain).
     find_sym_result details_adjusted_call_site = find_symbol_details(
         fobj, (void *)(uintptr_t(trace.addr) - 1), symbol_info.dli_fbase);
 
     // In debug mode, we should always get the right thing(TM).
     if (details_call_site.found && details_adjusted_call_site.found) {
       // Ok, we assume that details_adjusted_call_site is a better estimation.
       details_selected = &details_adjusted_call_site;
       trace.addr = (void *)(uintptr_t(trace.addr) - 1);
     }
 
     if (details_selected == &details_call_site && details_call_site.found) {
       // we have to re-resolve the symbol in order to reset some
       // internal state in BFD... so we can call backtrace_inliners
       // thereafter...
       details_call_site =
           find_symbol_details(fobj, trace.addr, symbol_info.dli_fbase);
     }
 #endif // BACKWARD_HAS_UNWIND
 
     if (details_selected->found) {
       if (details_selected->filename) {
         trace.source.filename = details_selected->filename;
       }
       trace.source.line = details_selected->line;
 
       if (details_selected->funcname) {
         // this time we get the name of the function where the code is
         // located, instead of the function were the address is
         // located. In short, if the code was inlined, we get the
         // function corresponding to the code. Else we already got in
         // trace.function.
         trace.source.function = demangle(details_selected->funcname);
 
         if (!symbol_info.dli_sname) {
           // for the case dladdr failed to find the symbol name of
           // the function, we might as well try to put something
           // here.
           trace.object_function = trace.source.function;
         }
       }
 
       // Maybe the source of the trace got inlined inside the function
       // (trace.source.function). Let's see if we can get all the inlined
       // calls along the way up to the initial call site.
       trace.inliners = backtrace_inliners(fobj, *details_selected);
 
 #if 0
             if (trace.inliners.size() == 0) {
                 // Maybe the trace was not inlined... or maybe it was and we
                 // are lacking the debug information. Let's try to make the
                 // world better and see if we can get the line number of the
                 // function (trace.source.function) now.
                 //
                 // We will get the location of where the function start (to be
                 // exact: the first instruction that really start the
                 // function), not where the name of the function is defined.
                 // This can be quite far away from the name of the function
                 // btw.
                 //
                 // If the source of the function is the same as the source of
                 // the trace, we cannot say if the trace was really inlined or
                 // not.  However, if the filename of the source is different
                 // between the function and the trace... we can declare it as
                 // an inliner.  This is not 100% accurate, but better than
                 // nothing.
 
                 if (symbol_info.dli_saddr) {
                     find_sym_result details = find_symbol_details(fobj,
                             symbol_info.dli_saddr,
                             symbol_info.dli_fbase);
 
                     if (details.found) {
                         ResolvedTrace::SourceLoc diy_inliner;
                         diy_inliner.line = details.line;
                         if (details.filename) {
                             diy_inliner.filename = details.filename;
                         }
                         if (details.funcname) {
                             diy_inliner.function = demangle(details.funcname);
                         } else {
                             diy_inliner.function = trace.source.function;
                         }
                         if (diy_inliner != trace.source) {
                             trace.inliners.push_back(diy_inliner);
                         }
                     }
                 }
             }
 #endif
     }
 
     return trace;
   }
 
 private:
   bool _bfd_loaded;
 
   typedef details::handle<bfd *,
                           details::deleter<bfd_boolean, bfd *, &bfd_close> >
       bfd_handle_t;
 
   typedef details::handle<asymbol **> bfd_symtab_t;
 
   struct bfd_fileobject {
     bfd_handle_t handle;
     bfd_vma base_addr;
     bfd_symtab_t symtab;
     bfd_symtab_t dynamic_symtab;
   };
 
   typedef details::hashtable<std::string, bfd_fileobject>::type fobj_bfd_map_t;
   fobj_bfd_map_t _fobj_bfd_map;
 
   bfd_fileobject *load_object_with_bfd(const std::string &filename_object) {
     using namespace details;
 
     if (!_bfd_loaded) {
       using namespace details;
       bfd_init();
       _bfd_loaded = true;
     }
 
     fobj_bfd_map_t::iterator it = _fobj_bfd_map.find(filename_object);
     if (it != _fobj_bfd_map.end()) {
       return &it->second;
     }
 
     // this new object is empty for now.
     bfd_fileobject *r = &_fobj_bfd_map[filename_object];
 
     // we do the work temporary in this one;
     bfd_handle_t bfd_handle;
 
     int fd = open(filename_object.c_str(), O_RDONLY);
     bfd_handle.reset(bfd_fdopenr(filename_object.c_str(), "default", fd));
     if (!bfd_handle) {
       close(fd);
       return r;
     }
 
     if (!bfd_check_format(bfd_handle.get(), bfd_object)) {
       return r; // not an object? You lose.
     }
 
     if ((bfd_get_file_flags(bfd_handle.get()) & HAS_SYMS) == 0) {
       return r; // that's what happen when you forget to compile in debug.
     }
 
     ssize_t symtab_storage_size = bfd_get_symtab_upper_bound(bfd_handle.get());
 
     ssize_t dyn_symtab_storage_size =
         bfd_get_dynamic_symtab_upper_bound(bfd_handle.get());
 
     if (symtab_storage_size <= 0 && dyn_symtab_storage_size <= 0) {
       return r; // weird, is the file is corrupted?
     }
 
     bfd_symtab_t symtab, dynamic_symtab;
     ssize_t symcount = 0, dyn_symcount = 0;
 
     if (symtab_storage_size > 0) {
       symtab.reset(static_cast<bfd_symbol **>(
           malloc(static_cast<size_t>(symtab_storage_size))));
       symcount = bfd_canonicalize_symtab(bfd_handle.get(), symtab.get());
     }
 
     if (dyn_symtab_storage_size > 0) {
       dynamic_symtab.reset(static_cast<bfd_symbol **>(
           malloc(static_cast<size_t>(dyn_symtab_storage_size))));
       dyn_symcount = bfd_canonicalize_dynamic_symtab(bfd_handle.get(),
                                                      dynamic_symtab.get());
     }
 
     if (symcount <= 0 && dyn_symcount <= 0) {
       return r; // damned, that's a stripped file that you got there!
     }
 
     r->handle = move(bfd_handle);
     r->symtab = move(symtab);
     r->dynamic_symtab = move(dynamic_symtab);
     return r;
   }
 
   struct find_sym_result {
     bool found;
     const char *filename;
     const char *funcname;
     unsigned int line;
   };
 
   struct find_sym_context {
     TraceResolverLinuxImpl *self;
     bfd_fileobject *fobj;
     void *addr;
     void *base_addr;
     find_sym_result result;
   };
 
   find_sym_result find_symbol_details(bfd_fileobject *fobj, void *addr,
                                       void *base_addr) {
     find_sym_context context;
     context.self = this;
     context.fobj = fobj;
     context.addr = addr;
     context.base_addr = base_addr;
     context.result.found = false;
     bfd_map_over_sections(fobj->handle.get(), &find_in_section_trampoline,
                           static_cast<void *>(&context));
     return context.result;
   }
 
   static void find_in_section_trampoline(bfd *, asection *section, void *data) {
     find_sym_context *context = static_cast<find_sym_context *>(data);
     context->self->find_in_section(
         reinterpret_cast<bfd_vma>(context->addr),
         reinterpret_cast<bfd_vma>(context->base_addr), context->fobj, section,
         context->result);
   }
 
   void find_in_section(bfd_vma addr, bfd_vma base_addr, bfd_fileobject *fobj,
                        asection *section, find_sym_result &result) {
     if (result.found)
       return;
 
 #ifdef bfd_get_section_flags
     if ((bfd_get_section_flags(fobj->handle.get(), section) & SEC_ALLOC) == 0)
 #else
     if ((bfd_section_flags(section) & SEC_ALLOC) == 0)
 #endif
       return; // a debug section is never loaded automatically.
 
 #ifdef bfd_get_section_vma
     bfd_vma sec_addr = bfd_get_section_vma(fobj->handle.get(), section);
 #else
     bfd_vma sec_addr = bfd_section_vma(section);
 #endif
 #ifdef bfd_get_section_size
     bfd_size_type size = bfd_get_section_size(section);
 #else
     bfd_size_type size = bfd_section_size(section);
 #endif
 
     // are we in the boundaries of the section?
     if (addr < sec_addr || addr >= sec_addr + size) {
       addr -= base_addr; // oops, a relocated object, lets try again...
       if (addr < sec_addr || addr >= sec_addr + size) {
         return;
       }
     }
 
 #if defined(__clang__)
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wzero-as-null-pointer-constant"
 #endif
     if (!result.found && fobj->symtab) {
       result.found = bfd_find_nearest_line(
           fobj->handle.get(), section, fobj->symtab.get(), addr - sec_addr,
           &result.filename, &result.funcname, &result.line);
     }
 
     if (!result.found && fobj->dynamic_symtab) {
       result.found = bfd_find_nearest_line(
           fobj->handle.get(), section, fobj->dynamic_symtab.get(),
           addr - sec_addr, &result.filename, &result.funcname, &result.line);
     }
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif
   }
 
   ResolvedTrace::source_locs_t
   backtrace_inliners(bfd_fileobject *fobj, find_sym_result previous_result) {
     // This function can be called ONLY after a SUCCESSFUL call to
     // find_symbol_details. The state is global to the bfd_handle.
     ResolvedTrace::source_locs_t results;
     while (previous_result.found) {
       find_sym_result result;
       result.found = bfd_find_inliner_info(fobj->handle.get(), &result.filename,
                                            &result.funcname, &result.line);
 
       if (result
               .found) /* and not (
                             cstrings_eq(previous_result.filename,
                          result.filename) and
                          cstrings_eq(previous_result.funcname, result.funcname)
                             and result.line == previous_result.line
                             )) */
       {
         ResolvedTrace::SourceLoc src_loc;
         src_loc.line = result.line;
         if (result.filename) {
           src_loc.filename = result.filename;
         }
         if (result.funcname) {
           src_loc.function = demangle(result.funcname);
         }
         results.push_back(src_loc);
       }
       previous_result = result;
     }
     return results;
   }
 
   bool cstrings_eq(const char *a, const char *b) {
     if (!a || !b) {
       return false;
     }
     return strcmp(a, b) == 0;
   }
 };
 #endif // BACKWARD_HAS_BFD == 1
 
 #if BACKWARD_HAS_DW == 1
 
 template <>
 class TraceResolverLinuxImpl<trace_resolver_tag::libdw>
     : public TraceResolverLinuxBase {
 public:
   TraceResolverLinuxImpl() : _dwfl_handle_initialized(false) {}
 
   ResolvedTrace resolve(ResolvedTrace trace) override {
     using namespace details;
 
     Dwarf_Addr trace_addr = reinterpret_cast<Dwarf_Addr>(trace.addr);
 
     if (!_dwfl_handle_initialized) {
       // initialize dwfl...
       _dwfl_cb.reset(new Dwfl_Callbacks);
       _dwfl_cb->find_elf = &dwfl_linux_proc_find_elf;
       _dwfl_cb->find_debuginfo = &dwfl_standard_find_debuginfo;
       _dwfl_cb->debuginfo_path = 0;
 
       _dwfl_handle.reset(dwfl_begin(_dwfl_cb.get()));
       _dwfl_handle_initialized = true;
 
       if (!_dwfl_handle) {
         return trace;
       }
 
       // ...from the current process.
       dwfl_report_begin(_dwfl_handle.get());
       int r = dwfl_linux_proc_report(_dwfl_handle.get(), getpid());
       dwfl_report_end(_dwfl_handle.get(), NULL, NULL);
       if (r < 0) {
         return trace;
       }
     }
 
     if (!_dwfl_handle) {
       return trace;
     }
 
     // find the module (binary object) that contains the trace's address.
     // This is not using any debug information, but the addresses ranges of
     // all the currently loaded binary object.
     Dwfl_Module *mod = dwfl_addrmodule(_dwfl_handle.get(), trace_addr);
     if (mod) {
       // now that we found it, lets get the name of it, this will be the
       // full path to the running binary or one of the loaded library.
       const char *module_name = dwfl_module_info(mod, 0, 0, 0, 0, 0, 0, 0);
       if (module_name) {
         trace.object_filename = module_name;
       }
       // We also look after the name of the symbol, equal or before this
       // address. This is found by walking the symtab. We should get the
       // symbol corresponding to the function (mangled) containing the
       // address. If the code corresponding to the address was inlined,
       // this is the name of the out-most inliner function.
       const char *sym_name = dwfl_module_addrname(mod, trace_addr);
       if (sym_name) {
         trace.object_function = demangle(sym_name);
       }
     }
 
     // now let's get serious, and find out the source location (file and
     // line number) of the address.
 
     // This function will look in .debug_aranges for the address and map it
     // to the location of the compilation unit DIE in .debug_info and
     // return it.
     Dwarf_Addr mod_bias = 0;
     Dwarf_Die *cudie = dwfl_module_addrdie(mod, trace_addr, &mod_bias);
 
 #if 1
     if (!cudie) {
       // Sadly clang does not generate the section .debug_aranges, thus
       // dwfl_module_addrdie will fail early. Clang doesn't either set
       // the lowpc/highpc/range info for every compilation unit.
       //
       // So in order to save the world:
       // for every compilation unit, we will iterate over every single
       // DIEs. Normally functions should have a lowpc/highpc/range, which
       // we will use to infer the compilation unit.
 
       // note that this is probably badly inefficient.
       while ((cudie = dwfl_module_nextcu(mod, cudie, &mod_bias))) {
         Dwarf_Die die_mem;
         Dwarf_Die *fundie =
             find_fundie_by_pc(cudie, trace_addr - mod_bias, &die_mem);
         if (fundie) {
           break;
         }
       }
     }
 #endif
 
 //#define BACKWARD_I_DO_NOT_RECOMMEND_TO_ENABLE_THIS_HORRIBLE_PIECE_OF_CODE
 #ifdef BACKWARD_I_DO_NOT_RECOMMEND_TO_ENABLE_THIS_HORRIBLE_PIECE_OF_CODE
     if (!cudie) {
       // If it's still not enough, lets dive deeper in the shit, and try
       // to save the world again: for every compilation unit, we will
       // load the corresponding .debug_line section, and see if we can
       // find our address in it.
 
       Dwarf_Addr cfi_bias;
       Dwarf_CFI *cfi_cache = dwfl_module_eh_cfi(mod, &cfi_bias);
 
       Dwarf_Addr bias;
       while ((cudie = dwfl_module_nextcu(mod, cudie, &bias))) {
         if (dwarf_getsrc_die(cudie, trace_addr - bias)) {
 
           // ...but if we get a match, it might be a false positive
           // because our (address - bias) might as well be valid in a
           // different compilation unit. So we throw our last card on
           // the table and lookup for the address into the .eh_frame
           // section.
 
           handle<Dwarf_Frame *> frame;
           dwarf_cfi_addrframe(cfi_cache, trace_addr - cfi_bias, &frame);
           if (frame) {
             break;
           }
         }
       }
     }
 #endif
 
     if (!cudie) {
       return trace; // this time we lost the game :/
     }
 
     // Now that we have a compilation unit DIE, this function will be able
     // to load the corresponding section in .debug_line (if not already
     // loaded) and hopefully find the source location mapped to our
     // address.
     Dwarf_Line *srcloc = dwarf_getsrc_die(cudie, trace_addr - mod_bias);
 
     if (srcloc) {
       const char *srcfile = dwarf_linesrc(srcloc, 0, 0);
       if (srcfile) {
         trace.source.filename = srcfile;
       }
       int line = 0, col = 0;
       dwarf_lineno(srcloc, &line);
       dwarf_linecol(srcloc, &col);
       trace.source.line = static_cast<unsigned>(line);
       trace.source.col = static_cast<unsigned>(col);
     }
 
     deep_first_search_by_pc(cudie, trace_addr - mod_bias,
                             inliners_search_cb(trace));
     if (trace.source.function.size() == 0) {
       // fallback.
       trace.source.function = trace.object_function;
     }
 
     return trace;
   }
 
 private:
   typedef details::handle<Dwfl *, details::deleter<void, Dwfl *, &dwfl_end> >
       dwfl_handle_t;
   details::handle<Dwfl_Callbacks *, details::default_delete<Dwfl_Callbacks *> >
       _dwfl_cb;
   dwfl_handle_t _dwfl_handle;
   bool _dwfl_handle_initialized;
 
   // defined here because in C++98, template function cannot take locally
   // defined types... grrr.
   struct inliners_search_cb {
     void operator()(Dwarf_Die *die) {
       switch (dwarf_tag(die)) {
         const char *name;
       case DW_TAG_subprogram:
         if ((name = dwarf_diename(die))) {
           trace.source.function = name;
         }
         break;
 
       case DW_TAG_inlined_subroutine:
         ResolvedTrace::SourceLoc sloc;
         Dwarf_Attribute attr_mem;
 
         if ((name = dwarf_diename(die))) {
           sloc.function = name;
         }
         if ((name = die_call_file(die))) {
           sloc.filename = name;
         }
 
         Dwarf_Word line = 0, col = 0;
         dwarf_formudata(dwarf_attr(die, DW_AT_call_line, &attr_mem), &line);
         dwarf_formudata(dwarf_attr(die, DW_AT_call_column, &attr_mem), &col);
         sloc.line = static_cast<unsigned>(line);
         sloc.col = static_cast<unsigned>(col);
 
         trace.inliners.push_back(sloc);
         break;
       };
     }
     ResolvedTrace &trace;
     inliners_search_cb(ResolvedTrace &t) : trace(t) {}
   };
 
   static bool die_has_pc(Dwarf_Die *die, Dwarf_Addr pc) {
     Dwarf_Addr low, high;
 
     // continuous range
     if (dwarf_hasattr(die, DW_AT_low_pc) && dwarf_hasattr(die, DW_AT_high_pc)) {
       if (dwarf_lowpc(die, &low) != 0) {
         return false;
       }
       if (dwarf_highpc(die, &high) != 0) {
         Dwarf_Attribute attr_mem;
         Dwarf_Attribute *attr = dwarf_attr(die, DW_AT_high_pc, &attr_mem);
         Dwarf_Word value;
         if (dwarf_formudata(attr, &value) != 0) {
           return false;
         }
         high = low + value;
       }
       return pc >= low && pc < high;
     }
 
     // non-continuous range.
     Dwarf_Addr base;
     ptrdiff_t offset = 0;
     while ((offset = dwarf_ranges(die, offset, &base, &low, &high)) > 0) {
       if (pc >= low && pc < high) {
         return true;
       }
     }
     return false;
   }
 
   static Dwarf_Die *find_fundie_by_pc(Dwarf_Die *parent_die, Dwarf_Addr pc,
                                       Dwarf_Die *result) {
     if (dwarf_child(parent_die, result) != 0) {
       return 0;
     }
 
     Dwarf_Die *die = result;
     do {
       switch (dwarf_tag(die)) {
       case DW_TAG_subprogram:
       case DW_TAG_inlined_subroutine:
         if (die_has_pc(die, pc)) {
           return result;
         }
       };
       bool declaration = false;
       Dwarf_Attribute attr_mem;
       dwarf_formflag(dwarf_attr(die, DW_AT_declaration, &attr_mem),
                      &declaration);
       if (!declaration) {
         // let's be curious and look deeper in the tree,
         // function are not necessarily at the first level, but
         // might be nested inside a namespace, structure etc.
         Dwarf_Die die_mem;
         Dwarf_Die *indie = find_fundie_by_pc(die, pc, &die_mem);
         if (indie) {
           *result = die_mem;
           return result;
         }
       }
     } while (dwarf_siblingof(die, result) == 0);
     return 0;
   }
 
   template <typename CB>
   static bool deep_first_search_by_pc(Dwarf_Die *parent_die, Dwarf_Addr pc,
                                       CB cb) {
     Dwarf_Die die_mem;
     if (dwarf_child(parent_die, &die_mem) != 0) {
       return false;
     }
 
     bool branch_has_pc = false;
     Dwarf_Die *die = &die_mem;
     do {
       bool declaration = false;
       Dwarf_Attribute attr_mem;
       dwarf_formflag(dwarf_attr(die, DW_AT_declaration, &attr_mem),
                      &declaration);
       if (!declaration) {
         // let's be curious and look deeper in the tree, function are
         // not necessarily at the first level, but might be nested
         // inside a namespace, structure, a function, an inlined
         // function etc.
         branch_has_pc = deep_first_search_by_pc(die, pc, cb);
       }
       if (!branch_has_pc) {
         branch_has_pc = die_has_pc(die, pc);
       }
       if (branch_has_pc) {
         cb(die);
       }
     } while (dwarf_siblingof(die, &die_mem) == 0);
     return branch_has_pc;
   }
 
   static const char *die_call_file(Dwarf_Die *die) {
     Dwarf_Attribute attr_mem;
     Dwarf_Word file_idx = 0;
 
     dwarf_formudata(dwarf_attr(die, DW_AT_call_file, &attr_mem), &file_idx);
 
     if (file_idx == 0) {
       return 0;
     }
 
     Dwarf_Die die_mem;
     Dwarf_Die *cudie = dwarf_diecu(die, &die_mem, 0, 0);
     if (!cudie) {
       return 0;
     }
 
     Dwarf_Files *files = 0;
     size_t nfiles;
     dwarf_getsrcfiles(cudie, &files, &nfiles);
     if (!files) {
       return 0;
     }
 
     return dwarf_filesrc(files, file_idx, 0, 0);
   }
 };
 #endif // BACKWARD_HAS_DW == 1
 
 #if BACKWARD_HAS_DWARF == 1
 
 template <>
 class TraceResolverLinuxImpl<trace_resolver_tag::libdwarf>
     : public TraceResolverLinuxBase {
 public:
   TraceResolverLinuxImpl() : _dwarf_loaded(false) {}
 
   ResolvedTrace resolve(ResolvedTrace trace) override {
     // trace.addr is a virtual address in memory pointing to some code.
     // Let's try to find from which loaded object it comes from.
     // The loaded object can be yourself btw.
 
     Dl_info symbol_info;
     int dladdr_result = 0;
 #if defined(__GLIBC__)
     link_map *link_map;
     // We request the link map so we can get information about offsets
     dladdr_result =
         dladdr1(trace.addr, &symbol_info, reinterpret_cast<void **>(&link_map),
                 RTLD_DL_LINKMAP);
 #else
     // Android doesn't have dladdr1. Don't use the linker map.
     dladdr_result = dladdr(trace.addr, &symbol_info);
 #endif
     if (!dladdr_result) {
       return trace; // dat broken trace...
     }
 
     // Now we get in symbol_info:
     // .dli_fname:
     //      pathname of the shared object that contains the address.
     // .dli_fbase:
     //      where the object is loaded in memory.
     // .dli_sname:
     //      the name of the nearest symbol to trace.addr, we expect a
     //      function name.
     // .dli_saddr:
     //      the exact address corresponding to .dli_sname.
     //
     // And in link_map:
     // .l_addr:
     //      difference between the address in the ELF file and the address
     //      in memory
     // l_name:
     //      absolute pathname where the object was found
 
     if (symbol_info.dli_sname) {
       trace.object_function = demangle(symbol_info.dli_sname);
     }
 
     if (!symbol_info.dli_fname) {
       return trace;
     }
 
     trace.object_filename = resolve_exec_path(symbol_info);
     dwarf_fileobject &fobj = load_object_with_dwarf(symbol_info.dli_fname);
     if (!fobj.dwarf_handle) {
       return trace; // sad, we couldn't load the object :(
     }
 
 #if defined(__GLIBC__)
     // Convert the address to a module relative one by looking at
     // the module's loading address in the link map
     Dwarf_Addr address = reinterpret_cast<uintptr_t>(trace.addr) -
                          reinterpret_cast<uintptr_t>(link_map->l_addr);
 #else
     Dwarf_Addr address = reinterpret_cast<uintptr_t>(trace.addr);
 #endif
 
     if (trace.object_function.empty()) {
       symbol_cache_t::iterator it = fobj.symbol_cache.lower_bound(address);
 
       if (it != fobj.symbol_cache.end()) {
         if (it->first != address) {
           if (it != fobj.symbol_cache.begin()) {
             --it;
           }
         }
         trace.object_function = demangle(it->second.c_str());
       }
     }
 
     // Get the Compilation Unit DIE for the address
     Dwarf_Die die = find_die(fobj, address);
 
     if (!die) {
       return trace; // this time we lost the game :/
     }
 
     // libdwarf doesn't give us direct access to its objects, it always
     // allocates a copy for the caller. We keep that copy alive in a cache
     // and we deallocate it later when it's no longer required.
     die_cache_entry &die_object = get_die_cache(fobj, die);
     if (die_object.isEmpty())
       return trace; // We have no line section for this DIE
 
     die_linemap_t::iterator it = die_object.line_section.lower_bound(address);
 
     if (it != die_object.line_section.end()) {
       if (it->first != address) {
         if (it == die_object.line_section.begin()) {
           // If we are on the first item of the line section
           // but the address does not match it means that
           // the address is below the range of the DIE. Give up.
           return trace;
         } else {
           --it;
         }
       }
     } else {
       return trace; // We didn't find the address.
     }
 
     // Get the Dwarf_Line that the address points to and call libdwarf
     // to get source file, line and column info.
     Dwarf_Line line = die_object.line_buffer[it->second];
     Dwarf_Error error = DW_DLE_NE;
 
     char *filename;
     if (dwarf_linesrc(line, &filename, &error) == DW_DLV_OK) {
       trace.source.filename = std::string(filename);
       dwarf_dealloc(fobj.dwarf_handle.get(), filename, DW_DLA_STRING);
     }
 
     Dwarf_Unsigned number = 0;
     if (dwarf_lineno(line, &number, &error) == DW_DLV_OK) {
       trace.source.line = number;
     } else {
       trace.source.line = 0;
     }
 
     if (dwarf_lineoff_b(line, &number, &error) == DW_DLV_OK) {
       trace.source.col = number;
     } else {
       trace.source.col = 0;
     }
 
     std::vector<std::string> namespace_stack;
     deep_first_search_by_pc(fobj, die, address, namespace_stack,
                             inliners_search_cb(trace, fobj, die));
 
     dwarf_dealloc(fobj.dwarf_handle.get(), die, DW_DLA_DIE);
 
     return trace;
   }
 
 public:
   static int close_dwarf(Dwarf_Debug dwarf) {
     return dwarf_finish(dwarf, NULL);
   }
 
 private:
   bool _dwarf_loaded;
 
   typedef details::handle<int, details::deleter<int, int, &::close> >
       dwarf_file_t;
 
   typedef details::handle<Elf *, details::deleter<int, Elf *, &elf_end> >
       dwarf_elf_t;
 
   typedef details::handle<Dwarf_Debug,
                           details::deleter<int, Dwarf_Debug, &close_dwarf> >
       dwarf_handle_t;
 
   typedef std::map<Dwarf_Addr, int> die_linemap_t;
 
   typedef std::map<Dwarf_Off, Dwarf_Off> die_specmap_t;
 
   struct die_cache_entry {
     die_specmap_t spec_section;
     die_linemap_t line_section;
     Dwarf_Line *line_buffer;
     Dwarf_Signed line_count;
     Dwarf_Line_Context line_context;
 
     inline bool isEmpty() {
       return line_buffer == NULL || line_count == 0 || line_context == NULL ||
              line_section.empty();
     }
 
     die_cache_entry() : line_buffer(0), line_count(0), line_context(0) {}
 
     ~die_cache_entry() {
       if (line_context) {
         dwarf_srclines_dealloc_b(line_context);
       }
     }
   };
 
   typedef std::map<Dwarf_Off, die_cache_entry> die_cache_t;
 
   typedef std::map<uintptr_t, std::string> symbol_cache_t;
 
   struct dwarf_fileobject {
     dwarf_file_t file_handle;
     dwarf_elf_t elf_handle;
     dwarf_handle_t dwarf_handle;
     symbol_cache_t symbol_cache;
 
     // Die cache
     die_cache_t die_cache;
     die_cache_entry *current_cu;
   };
 
   typedef details::hashtable<std::string, dwarf_fileobject>::type
       fobj_dwarf_map_t;
   fobj_dwarf_map_t _fobj_dwarf_map;
 
   static bool cstrings_eq(const char *a, const char *b) {
     if (!a || !b) {
       return false;
     }
     return strcmp(a, b) == 0;
   }
 
   dwarf_fileobject &load_object_with_dwarf(const std::string &filename_object) {
 
     if (!_dwarf_loaded) {
       // Set the ELF library operating version
       // If that fails there's nothing we can do
       _dwarf_loaded = elf_version(EV_CURRENT) != EV_NONE;
     }
 
     fobj_dwarf_map_t::iterator it = _fobj_dwarf_map.find(filename_object);
     if (it != _fobj_dwarf_map.end()) {
       return it->second;
     }
 
     // this new object is empty for now
     dwarf_fileobject &r = _fobj_dwarf_map[filename_object];
 
     dwarf_file_t file_handle;
     file_handle.reset(open(filename_object.c_str(), O_RDONLY));
     if (file_handle.get() < 0) {
       return r;
     }
 
     // Try to get an ELF handle. We need to read the ELF sections
     // because we want to see if there is a .gnu_debuglink section
     // that points to a split debug file
     dwarf_elf_t elf_handle;
     elf_handle.reset(elf_begin(file_handle.get(), ELF_C_READ, NULL));
     if (!elf_handle) {
       return r;
     }
 
     const char *e_ident = elf_getident(elf_handle.get(), 0);
     if (!e_ident) {
       return r;
     }
 
     // Get the number of sections
     // We use the new APIs as elf_getshnum is deprecated
     size_t shdrnum = 0;
     if (elf_getshdrnum(elf_handle.get(), &shdrnum) == -1) {
       return r;
     }
 
     // Get the index to the string section
     size_t shdrstrndx = 0;
     if (elf_getshdrstrndx(elf_handle.get(), &shdrstrndx) == -1) {
       return r;
     }
 
     std::string debuglink;
     // Iterate through the ELF sections to try to get a gnu_debuglink
     // note and also to cache the symbol table.
     // We go the preprocessor way to avoid having to create templated
     // classes or using gelf (which might throw a compiler error if 64 bit
     // is not supported
 #define ELF_GET_DATA(ARCH)                                                     \
   Elf_Scn *elf_section = 0;                                                    \
   Elf_Data *elf_data = 0;                                                      \
   Elf##ARCH##_Shdr *section_header = 0;                                        \
   Elf_Scn *symbol_section = 0;                                                 \
   size_t symbol_count = 0;                                                     \
   size_t symbol_strings = 0;                                                   \
   Elf##ARCH##_Sym *symbol = 0;                                                 \
   const char *section_name = 0;                                                \
                                                                                \
   while ((elf_section = elf_nextscn(elf_handle.get(), elf_section)) != NULL) { \
     section_header = elf##ARCH##_getshdr(elf_section);                         \
     if (section_header == NULL) {                                              \
       return r;                                                                \
     }                                                                          \
                                                                                \
     if ((section_name = elf_strptr(elf_handle.get(), shdrstrndx,               \
                                    section_header->sh_name)) == NULL) {        \
       return r;                                                                \
     }                                                                          \
                                                                                \
     if (cstrings_eq(section_name, ".gnu_debuglink")) {                         \
       elf_data = elf_getdata(elf_section, NULL);                               \
       if (elf_data && elf_data->d_size > 0) {                                  \
         debuglink =                                                            \
             std::string(reinterpret_cast<const char *>(elf_data->d_buf));      \
       }                                                                        \
     }                                                                          \
                                                                                \
     switch (section_header->sh_type) {                                         \
     case SHT_SYMTAB:                                                           \
       symbol_section = elf_section;                                            \
       symbol_count = section_header->sh_size / section_header->sh_entsize;     \
       symbol_strings = section_header->sh_link;                                \
       break;                                                                   \
                                                                                \
     /* We use .dynsyms as a last resort, we prefer .symtab */                  \
     case SHT_DYNSYM:                                                           \
       if (!symbol_section) {                                                   \
         symbol_section = elf_section;                                          \
         symbol_count = section_header->sh_size / section_header->sh_entsize;   \
         symbol_strings = section_header->sh_link;                              \
       }                                                                        \
       break;                                                                   \
     }                                                                          \
   }                                                                            \
                                                                                \
   if (symbol_section && symbol_count && symbol_strings) {                      \
     elf_data = elf_getdata(symbol_section, NULL);                              \
     symbol = reinterpret_cast<Elf##ARCH##_Sym *>(elf_data->d_buf);             \
     for (size_t i = 0; i < symbol_count; ++i) {                                \
       int type = ELF##ARCH##_ST_TYPE(symbol->st_info);                         \
       if (type == STT_FUNC && symbol->st_value > 0) {                          \
         r.symbol_cache[symbol->st_value] = std::string(                        \
             elf_strptr(elf_handle.get(), symbol_strings, symbol->st_name));    \
       }                                                                        \
       ++symbol;                                                                \
     }                                                                          \
   }
 
     if (e_ident[EI_CLASS] == ELFCLASS32) {
       ELF_GET_DATA(32)
     } else if (e_ident[EI_CLASS] == ELFCLASS64) {
       // libelf might have been built without 64 bit support
 #if __LIBELF64
       ELF_GET_DATA(64)
 #endif
     }
 
     if (!debuglink.empty()) {
       // We have a debuglink section! Open an elf instance on that
       // file instead. If we can't open the file, then return
       // the elf handle we had already opened.
       dwarf_file_t debuglink_file;
       debuglink_file.reset(open(debuglink.c_str(), O_RDONLY));
       if (debuglink_file.get() > 0) {
         dwarf_elf_t debuglink_elf;
         debuglink_elf.reset(elf_begin(debuglink_file.get(), ELF_C_READ, NULL));
 
         // If we have a valid elf handle, return the new elf handle
         // and file handle and discard the original ones
         if (debuglink_elf) {
           elf_handle = move(debuglink_elf);
           file_handle = move(debuglink_file);
         }
       }
     }
 
     // Ok, we have a valid ELF handle, let's try to get debug symbols
     Dwarf_Debug dwarf_debug;
     Dwarf_Error error = DW_DLE_NE;
     dwarf_handle_t dwarf_handle;
 
     int dwarf_result = dwarf_elf_init(elf_handle.get(), DW_DLC_READ, NULL, NULL,
                                       &dwarf_debug, &error);
 
     // We don't do any special handling for DW_DLV_NO_ENTRY specially.
     // If we get an error, or the file doesn't have debug information
     // we just return.
     if (dwarf_result != DW_DLV_OK) {
       return r;
     }
 
     dwarf_handle.reset(dwarf_debug);
 
     r.file_handle = move(file_handle);
     r.elf_handle = move(elf_handle);
     r.dwarf_handle = move(dwarf_handle);
 
     return r;
   }
 
   die_cache_entry &get_die_cache(dwarf_fileobject &fobj, Dwarf_Die die) {
     Dwarf_Error error = DW_DLE_NE;
 
     // Get the die offset, we use it as the cache key
     Dwarf_Off die_offset;
     if (dwarf_dieoffset(die, &die_offset, &error) != DW_DLV_OK) {
       die_offset = 0;
     }
 
     die_cache_t::iterator it = fobj.die_cache.find(die_offset);
 
     if (it != fobj.die_cache.end()) {
       fobj.current_cu = &it->second;
       return it->second;
     }
 
     die_cache_entry &de = fobj.die_cache[die_offset];
     fobj.current_cu = &de;
 
     Dwarf_Addr line_addr;
     Dwarf_Small table_count;
 
     // The addresses in the line section are not fully sorted (they might
     // be sorted by block of code belonging to the same file), which makes
     // it necessary to do so before searching is possible.
     //
     // As libdwarf allocates a copy of everything, let's get the contents
     // of the line section and keep it around. We also create a map of
     // program counter to line table indices so we can search by address
     // and get the line buffer index.
     //
     // To make things more difficult, the same address can span more than
     // one line, so we need to keep the index pointing to the first line
     // by using insert instead of the map's [ operator.
 
     // Get the line context for the DIE
     if (dwarf_srclines_b(die, 0, &table_count, &de.line_context, &error) ==
         DW_DLV_OK) {
       // Get the source lines for this line context, to be deallocated
       // later
       if (dwarf_srclines_from_linecontext(de.line_context, &de.line_buffer,
                                           &de.line_count,
                                           &error) == DW_DLV_OK) {
 
         // Add all the addresses to our map
         for (int i = 0; i < de.line_count; i++) {
           if (dwarf_lineaddr(de.line_buffer[i], &line_addr, &error) !=
               DW_DLV_OK) {
             line_addr = 0;
           }
           de.line_section.insert(std::pair<Dwarf_Addr, int>(line_addr, i));
         }
       }
     }
 
     // For each CU, cache the function DIEs that contain the
     // DW_AT_specification attribute. When building with -g3 the function
     // DIEs are separated in declaration and specification, with the
     // declaration containing only the name and parameters and the
     // specification the low/high pc and other compiler attributes.
     //
     // We cache those specifications so we don't skip over the declarations,
     // because they have no pc, and we can do namespace resolution for
     // DWARF function names.
     Dwarf_Debug dwarf = fobj.dwarf_handle.get();
     Dwarf_Die current_die = 0;
     if (dwarf_child(die, &current_die, &error) == DW_DLV_OK) {
       for (;;) {
         Dwarf_Die sibling_die = 0;
 
         Dwarf_Half tag_value;
         dwarf_tag(current_die, &tag_value, &error);
 
         if (tag_value == DW_TAG_subprogram ||
             tag_value == DW_TAG_inlined_subroutine) {
 
           Dwarf_Bool has_attr = 0;
           if (dwarf_hasattr(current_die, DW_AT_specification, &has_attr,
                             &error) == DW_DLV_OK) {
             if (has_attr) {
               Dwarf_Attribute attr_mem;
               if (dwarf_attr(current_die, DW_AT_specification, &attr_mem,
                              &error) == DW_DLV_OK) {
                 Dwarf_Off spec_offset = 0;
                 if (dwarf_formref(attr_mem, &spec_offset, &error) ==
                     DW_DLV_OK) {
                   Dwarf_Off spec_die_offset;
                   if (dwarf_dieoffset(current_die, &spec_die_offset, &error) ==
                       DW_DLV_OK) {
                     de.spec_section[spec_offset] = spec_die_offset;
                   }
                 }
               }
               dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
             }
           }
         }
 
         int result = dwarf_siblingof(dwarf, current_die, &sibling_die, &error);
         if (result == DW_DLV_ERROR) {
           break;
         } else if (result == DW_DLV_NO_ENTRY) {
           break;
         }
 
         if (current_die != die) {
           dwarf_dealloc(dwarf, current_die, DW_DLA_DIE);
           current_die = 0;
         }
 
         current_die = sibling_die;
       }
     }
     return de;
   }
 
   static Dwarf_Die get_referenced_die(Dwarf_Debug dwarf, Dwarf_Die die,
                                       Dwarf_Half attr, bool global) {
     Dwarf_Error error = DW_DLE_NE;
     Dwarf_Attribute attr_mem;
 
     Dwarf_Die found_die = NULL;
     if (dwarf_attr(die, attr, &attr_mem, &error) == DW_DLV_OK) {
       Dwarf_Off offset;
       int result = 0;
       if (global) {
         result = dwarf_global_formref(attr_mem, &offset, &error);
       } else {
         result = dwarf_formref(attr_mem, &offset, &error);
       }
 
       if (result == DW_DLV_OK) {
         if (dwarf_offdie(dwarf, offset, &found_die, &error) != DW_DLV_OK) {
           found_die = NULL;
         }
       }
       dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
     }
     return found_die;
   }
 
   static std::string get_referenced_die_name(Dwarf_Debug dwarf, Dwarf_Die die,
                                              Dwarf_Half attr, bool global) {
     Dwarf_Error error = DW_DLE_NE;
     std::string value;
 
     Dwarf_Die found_die = get_referenced_die(dwarf, die, attr, global);
 
     if (found_die) {
       char *name;
       if (dwarf_diename(found_die, &name, &error) == DW_DLV_OK) {
         if (name) {
           value = std::string(name);
         }
         dwarf_dealloc(dwarf, name, DW_DLA_STRING);
       }
       dwarf_dealloc(dwarf, found_die, DW_DLA_DIE);
     }
 
     return value;
   }
 
   // Returns a spec DIE linked to the passed one. The caller should
   // deallocate the DIE
   static Dwarf_Die get_spec_die(dwarf_fileobject &fobj, Dwarf_Die die) {
     Dwarf_Debug dwarf = fobj.dwarf_handle.get();
     Dwarf_Error error = DW_DLE_NE;
     Dwarf_Off die_offset;
     if (fobj.current_cu &&
         dwarf_die_CU_offset(die, &die_offset, &error) == DW_DLV_OK) {
       die_specmap_t::iterator it =
           fobj.current_cu->spec_section.find(die_offset);
 
       // If we have a DIE that completes the current one, check if
       // that one has the pc we are looking for
       if (it != fobj.current_cu->spec_section.end()) {
         Dwarf_Die spec_die = 0;
         if (dwarf_offdie(dwarf, it->second, &spec_die, &error) == DW_DLV_OK) {
           return spec_die;
         }
       }
     }
 
     // Maybe we have an abstract origin DIE with the function information?
     return get_referenced_die(fobj.dwarf_handle.get(), die,
                               DW_AT_abstract_origin, true);
   }
 
   static bool die_has_pc(dwarf_fileobject &fobj, Dwarf_Die die, Dwarf_Addr pc) {
     Dwarf_Addr low_pc = 0, high_pc = 0;
     Dwarf_Half high_pc_form = 0;
     Dwarf_Form_Class return_class;
     Dwarf_Error error = DW_DLE_NE;
     Dwarf_Debug dwarf = fobj.dwarf_handle.get();
     bool has_lowpc = false;
     bool has_highpc = false;
     bool has_ranges = false;
 
     if (dwarf_lowpc(die, &low_pc, &error) == DW_DLV_OK) {
       // If we have a low_pc check if there is a high pc.
       // If we don't have a high pc this might mean we have a base
       // address for the ranges list or just an address.
       has_lowpc = true;
 
       if (dwarf_highpc_b(die, &high_pc, &high_pc_form, &return_class, &error) ==
           DW_DLV_OK) {
         // We do have a high pc. In DWARF 4+ this is an offset from the
         // low pc, but in earlier versions it's an absolute address.
 
         has_highpc = true;
         // In DWARF 2/3 this would be a DW_FORM_CLASS_ADDRESS
         if (return_class == DW_FORM_CLASS_CONSTANT) {
           high_pc = low_pc + high_pc;
         }
 
         // We have low and high pc, check if our address
         // is in that range
         return pc >= low_pc && pc < high_pc;
       }
     } else {
       // Reset the low_pc, in case dwarf_lowpc failing set it to some
       // undefined value.
       low_pc = 0;
     }
 
     // Check if DW_AT_ranges is present and search for the PC in the
     // returned ranges list. We always add the low_pc, as it not set it will
     // be 0, in case we had a DW_AT_low_pc and DW_AT_ranges pair
     bool result = false;
 
     Dwarf_Attribute attr;
     if (dwarf_attr(die, DW_AT_ranges, &attr, &error) == DW_DLV_OK) {
 
       Dwarf_Off offset;
       if (dwarf_global_formref(attr, &offset, &error) == DW_DLV_OK) {
         Dwarf_Ranges *ranges;
         Dwarf_Signed ranges_count = 0;
         Dwarf_Unsigned byte_count = 0;
 
         if (dwarf_get_ranges_a(dwarf, offset, die, &ranges, &ranges_count,
                                &byte_count, &error) == DW_DLV_OK) {
           has_ranges = ranges_count != 0;
           for (int i = 0; i < ranges_count; i++) {
             if (ranges[i].dwr_addr1 != 0 &&
                 pc >= ranges[i].dwr_addr1 + low_pc &&
                 pc < ranges[i].dwr_addr2 + low_pc) {
               result = true;
               break;
             }
           }
           dwarf_ranges_dealloc(dwarf, ranges, ranges_count);
         }
       }
     }
 
     // Last attempt. We might have a single address set as low_pc.
     if (!result && low_pc != 0 && pc == low_pc) {
       result = true;
     }
 
     // If we don't have lowpc, highpc and ranges maybe this DIE is a
     // declaration that relies on a DW_AT_specification DIE that happens
     // later. Use the specification cache we filled when we loaded this CU.
     if (!result && (!has_lowpc && !has_highpc && !has_ranges)) {
       Dwarf_Die spec_die = get_spec_die(fobj, die);
       if (spec_die) {
         result = die_has_pc(fobj, spec_die, pc);
         dwarf_dealloc(dwarf, spec_die, DW_DLA_DIE);
       }
     }
 
     return result;
   }
 
   static void get_type(Dwarf_Debug dwarf, Dwarf_Die die, std::string &type) {
     Dwarf_Error error = DW_DLE_NE;
 
     Dwarf_Die child = 0;
     if (dwarf_child(die, &child, &error) == DW_DLV_OK) {
       get_type(dwarf, child, type);
     }
 
     if (child) {
       type.insert(0, "::");
       dwarf_dealloc(dwarf, child, DW_DLA_DIE);
     }
 
     char *name;
     if (dwarf_diename(die, &name, &error) == DW_DLV_OK) {
       type.insert(0, std::string(name));
       dwarf_dealloc(dwarf, name, DW_DLA_STRING);
     } else {
       type.insert(0, "<unknown>");
     }
   }
 
   static std::string get_type_by_signature(Dwarf_Debug dwarf, Dwarf_Die die) {
     Dwarf_Error error = DW_DLE_NE;
 
     Dwarf_Sig8 signature;
     Dwarf_Bool has_attr = 0;
     if (dwarf_hasattr(die, DW_AT_signature, &has_attr, &error) == DW_DLV_OK) {
       if (has_attr) {
         Dwarf_Attribute attr_mem;
         if (dwarf_attr(die, DW_AT_signature, &attr_mem, &error) == DW_DLV_OK) {
           if (dwarf_formsig8(attr_mem, &signature, &error) != DW_DLV_OK) {
             return std::string("<no type signature>");
           }
         }
         dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
       }
     }
 
     Dwarf_Unsigned next_cu_header;
     Dwarf_Sig8 tu_signature;
     std::string result;
     bool found = false;
 
     while (dwarf_next_cu_header_d(dwarf, 0, 0, 0, 0, 0, 0, 0, &tu_signature, 0,
                                   &next_cu_header, 0, &error) == DW_DLV_OK) {
 
       if (strncmp(signature.signature, tu_signature.signature, 8) == 0) {
         Dwarf_Die type_cu_die = 0;
         if (dwarf_siblingof_b(dwarf, 0, 0, &type_cu_die, &error) == DW_DLV_OK) {
           Dwarf_Die child_die = 0;
           if (dwarf_child(type_cu_die, &child_die, &error) == DW_DLV_OK) {
             get_type(dwarf, child_die, result);
             found = !result.empty();
             dwarf_dealloc(dwarf, child_die, DW_DLA_DIE);
           }
           dwarf_dealloc(dwarf, type_cu_die, DW_DLA_DIE);
         }
       }
     }
 
     if (found) {
       while (dwarf_next_cu_header_d(dwarf, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                                     &next_cu_header, 0, &error) == DW_DLV_OK) {
         // Reset the cu header state. Unfortunately, libdwarf's
         // next_cu_header API keeps its own iterator per Dwarf_Debug
         // that can't be reset. We need to keep fetching elements until
         // the end.
       }
     } else {
       // If we couldn't resolve the type just print out the signature
       std::ostringstream string_stream;
       string_stream << "<0x" << std::hex << std::setfill('0');
       for (int i = 0; i < 8; ++i) {
         string_stream << std::setw(2) << std::hex
                       << (int)(unsigned char)(signature.signature[i]);
       }
       string_stream << ">";
       result = string_stream.str();
     }
     return result;
   }
 
   struct type_context_t {
     bool is_const;
     bool is_typedef;
     bool has_type;
     bool has_name;
     std::string text;
 
     type_context_t()
         : is_const(false), is_typedef(false), has_type(false), has_name(false) {
     }
   };
 
   // Types are resolved from right to left: we get the variable name first
   // and then all specifiers (like const or pointer) in a chain of DW_AT_type
   // DIEs. Call this function recursively until we get a complete type
   // string.
   static void set_parameter_string(dwarf_fileobject &fobj, Dwarf_Die die,
                                    type_context_t &context) {
     char *name;
     Dwarf_Error error = DW_DLE_NE;
 
     // typedefs contain also the base type, so we skip it and only
     // print the typedef name
     if (!context.is_typedef) {
       if (dwarf_diename(die, &name, &error) == DW_DLV_OK) {
         if (!context.text.empty()) {
           context.text.insert(0, " ");
         }
         context.text.insert(0, std::string(name));
         dwarf_dealloc(fobj.dwarf_handle.get(), name, DW_DLA_STRING);
       }
     } else {
       context.is_typedef = false;
       context.has_type = true;
       if (context.is_const) {
         context.text.insert(0, "const ");
         context.is_const = false;
       }
     }
 
     bool next_type_is_const = false;
     bool is_keyword = true;
 
     Dwarf_Half tag = 0;
     Dwarf_Bool has_attr = 0;
     if (dwarf_tag(die, &tag, &error) == DW_DLV_OK) {
       switch (tag) {
       case DW_TAG_structure_type:
       case DW_TAG_union_type:
       case DW_TAG_class_type:
       case DW_TAG_enumeration_type:
         context.has_type = true;
         if (dwarf_hasattr(die, DW_AT_signature, &has_attr, &error) ==
             DW_DLV_OK) {
           // If we have a signature it means the type is defined
           // in .debug_types, so we need to load the DIE pointed
           // at by the signature and resolve it
           if (has_attr) {
             std::string type =
                 get_type_by_signature(fobj.dwarf_handle.get(), die);
             if (context.is_const)
               type.insert(0, "const ");
 
             if (!context.text.empty())
               context.text.insert(0, " ");
             context.text.insert(0, type);
           }
 
           // Treat enums like typedefs, and skip printing its
           // base type
           context.is_typedef = (tag == DW_TAG_enumeration_type);
         }
         break;
       case DW_TAG_const_type:
         next_type_is_const = true;
         break;
       case DW_TAG_pointer_type:
         context.text.insert(0, "*");
         break;
       case DW_TAG_reference_type:
         context.text.insert(0, "&");
         break;
       case DW_TAG_restrict_type:
         context.text.insert(0, "restrict ");
         break;
       case DW_TAG_rvalue_reference_type:
         context.text.insert(0, "&&");
         break;
       case DW_TAG_volatile_type:
         context.text.insert(0, "volatile ");
         break;
       case DW_TAG_typedef:
         // Propagate the const-ness to the next type
         // as typedefs are linked to its base type
         next_type_is_const = context.is_const;
         context.is_typedef = true;
         context.has_type = true;
         break;
       case DW_TAG_base_type:
         context.has_type = true;
         break;
       case DW_TAG_formal_parameter:
         context.has_name = true;
         break;
       default:
         is_keyword = false;
         break;
       }
     }
 
     if (!is_keyword && context.is_const) {
       context.text.insert(0, "const ");
     }
 
     context.is_const = next_type_is_const;
 
     Dwarf_Die ref =
         get_referenced_die(fobj.dwarf_handle.get(), die, DW_AT_type, true);
     if (ref) {
       set_parameter_string(fobj, ref, context);
       dwarf_dealloc(fobj.dwarf_handle.get(), ref, DW_DLA_DIE);
     }
 
     if (!context.has_type && context.has_name) {
       context.text.insert(0, "void ");
       context.has_type = true;
     }
   }
 
   // Resolve the function return type and parameters
   static void set_function_parameters(std::string &function_name,
                                       std::vector<std::string> &ns,
                                       dwarf_fileobject &fobj, Dwarf_Die die) {
     Dwarf_Debug dwarf = fobj.dwarf_handle.get();
     Dwarf_Error error = DW_DLE_NE;
     Dwarf_Die current_die = 0;
     std::string parameters;
     bool has_spec = true;
     // Check if we have a spec DIE. If we do we use it as it contains
     // more information, like parameter names.
     Dwarf_Die spec_die = get_spec_die(fobj, die);
     if (!spec_die) {
       has_spec = false;
       spec_die = die;
     }
 
     std::vector<std::string>::const_iterator it = ns.begin();
     std::string ns_name;
     for (it = ns.begin(); it < ns.end(); ++it) {
       ns_name.append(*it).append("::");
     }
 
     if (!ns_name.empty()) {
       function_name.insert(0, ns_name);
     }
 
     // See if we have a function return type. It can be either on the
     // current die or in its spec one (usually true for inlined functions)
     std::string return_type =
         get_referenced_die_name(dwarf, die, DW_AT_type, true);
     if (return_type.empty()) {
       return_type = get_referenced_die_name(dwarf, spec_die, DW_AT_type, true);
     }
     if (!return_type.empty()) {
       return_type.append(" ");
       function_name.insert(0, return_type);
     }
 
     if (dwarf_child(spec_die, &current_die, &error) == DW_DLV_OK) {
       for (;;) {
         Dwarf_Die sibling_die = 0;
 
         Dwarf_Half tag_value;
         dwarf_tag(current_die, &tag_value, &error);
 
         if (tag_value == DW_TAG_formal_parameter) {
           // Ignore artificial (ie, compiler generated) parameters
           bool is_artificial = false;
           Dwarf_Attribute attr_mem;
           if (dwarf_attr(current_die, DW_AT_artificial, &attr_mem, &error) ==
               DW_DLV_OK) {
             Dwarf_Bool flag = 0;
             if (dwarf_formflag(attr_mem, &flag, &error) == DW_DLV_OK) {
               is_artificial = flag != 0;
             }
             dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
           }
 
           if (!is_artificial) {
             type_context_t context;
             set_parameter_string(fobj, current_die, context);
 
             if (parameters.empty()) {
               parameters.append("(");
             } else {
               parameters.append(", ");
             }
             parameters.append(context.text);
           }
         }
 
         int result = dwarf_siblingof(dwarf, current_die, &sibling_die, &error);
         if (result == DW_DLV_ERROR) {
           break;
         } else if (result == DW_DLV_NO_ENTRY) {
           break;
         }
 
         if (current_die != die) {
           dwarf_dealloc(dwarf, current_die, DW_DLA_DIE);
           current_die = 0;
         }
 
         current_die = sibling_die;
       }
     }
     if (parameters.empty())
       parameters = "(";
     parameters.append(")");
 
     // If we got a spec DIE we need to deallocate it
     if (has_spec)
       dwarf_dealloc(dwarf, spec_die, DW_DLA_DIE);
 
     function_name.append(parameters);
   }
 
   // defined here because in C++98, template function cannot take locally
   // defined types... grrr.
   struct inliners_search_cb {
     void operator()(Dwarf_Die die, std::vector<std::string> &ns) {
       Dwarf_Error error = DW_DLE_NE;
       Dwarf_Half tag_value;
       Dwarf_Attribute attr_mem;
       Dwarf_Debug dwarf = fobj.dwarf_handle.get();
 
       dwarf_tag(die, &tag_value, &error);
 
       switch (tag_value) {
         char *name;
       case DW_TAG_subprogram:
         if (!trace.source.function.empty())
           break;
         if (dwarf_diename(die, &name, &error) == DW_DLV_OK) {
           trace.source.function = std::string(name);
           dwarf_dealloc(dwarf, name, DW_DLA_STRING);
         } else {
           // We don't have a function name in this DIE.
           // Check if there is a referenced non-defining
           // declaration.
           trace.source.function =
               get_referenced_die_name(dwarf, die, DW_AT_abstract_origin, true);
           if (trace.source.function.empty()) {
             trace.source.function =
                 get_referenced_die_name(dwarf, die, DW_AT_specification, true);
           }
         }
 
         // Append the function parameters, if available
         set_function_parameters(trace.source.function, ns, fobj, die);
 
         // If the object function name is empty, it's possible that
         // there is no dynamic symbol table (maybe the executable
         // was stripped or not built with -rdynamic). See if we have
         // a DWARF linkage name to use instead. We try both
         // linkage_name and MIPS_linkage_name because the MIPS tag
         // was the unofficial one until it was adopted in DWARF4.
         // Old gcc versions generate MIPS_linkage_name
         if (trace.object_function.empty()) {
           details::demangler demangler;
 
           if (dwarf_attr(die, DW_AT_linkage_name, &attr_mem, &error) !=
               DW_DLV_OK) {
             if (dwarf_attr(die, DW_AT_MIPS_linkage_name, &attr_mem, &error) !=
                 DW_DLV_OK) {
               break;
             }
           }
 
           char *linkage;
           if (dwarf_formstring(attr_mem, &linkage, &error) == DW_DLV_OK) {
             trace.object_function = demangler.demangle(linkage);
             dwarf_dealloc(dwarf, linkage, DW_DLA_STRING);
           }
           dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
         }
         break;
 
       case DW_TAG_inlined_subroutine:
         ResolvedTrace::SourceLoc sloc;
 
         if (dwarf_diename(die, &name, &error) == DW_DLV_OK) {
           sloc.function = std::string(name);
           dwarf_dealloc(dwarf, name, DW_DLA_STRING);
         } else {
           // We don't have a name for this inlined DIE, it could
           // be that there is an abstract origin instead.
           // Get the DW_AT_abstract_origin value, which is a
           // reference to the source DIE and try to get its name
           sloc.function =
               get_referenced_die_name(dwarf, die, DW_AT_abstract_origin, true);
         }
 
         set_function_parameters(sloc.function, ns, fobj, die);
 
         std::string file = die_call_file(dwarf, die, cu_die);
         if (!file.empty())
           sloc.filename = file;
 
         Dwarf_Unsigned number = 0;
         if (dwarf_attr(die, DW_AT_call_line, &attr_mem, &error) == DW_DLV_OK) {
           if (dwarf_formudata(attr_mem, &number, &error) == DW_DLV_OK) {
             sloc.line = number;
           }
           dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
         }
 
         if (dwarf_attr(die, DW_AT_call_column, &attr_mem, &error) ==
             DW_DLV_OK) {
           if (dwarf_formudata(attr_mem, &number, &error) == DW_DLV_OK) {
             sloc.col = number;
           }
           dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
         }
 
         trace.inliners.push_back(sloc);
         break;
       };
     }
     ResolvedTrace &trace;
     dwarf_fileobject &fobj;
     Dwarf_Die cu_die;
     inliners_search_cb(ResolvedTrace &t, dwarf_fileobject &f, Dwarf_Die c)
         : trace(t), fobj(f), cu_die(c) {}
   };
 
   static Dwarf_Die find_fundie_by_pc(dwarf_fileobject &fobj,
                                      Dwarf_Die parent_die, Dwarf_Addr pc,
                                      Dwarf_Die result) {
     Dwarf_Die current_die = 0;
     Dwarf_Error error = DW_DLE_NE;
     Dwarf_Debug dwarf = fobj.dwarf_handle.get();
 
     if (dwarf_child(parent_die, &current_die, &error) != DW_DLV_OK) {
       return NULL;
     }
 
     for (;;) {
       Dwarf_Die sibling_die = 0;
       Dwarf_Half tag_value;
       dwarf_tag(current_die, &tag_value, &error);
 
       switch (tag_value) {
       case DW_TAG_subprogram:
       case DW_TAG_inlined_subroutine:
         if (die_has_pc(fobj, current_die, pc)) {
           return current_die;
         }
       };
       bool declaration = false;
       Dwarf_Attribute attr_mem;
       if (dwarf_attr(current_die, DW_AT_declaration, &attr_mem, &error) ==
           DW_DLV_OK) {
         Dwarf_Bool flag = 0;
         if (dwarf_formflag(attr_mem, &flag, &error) == DW_DLV_OK) {
           declaration = flag != 0;
         }
         dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
       }
 
       if (!declaration) {
         // let's be curious and look deeper in the tree, functions are
         // not necessarily at the first level, but might be nested
         // inside a namespace, structure, a function, an inlined
         // function etc.
         Dwarf_Die die_mem = 0;
         Dwarf_Die indie = find_fundie_by_pc(fobj, current_die, pc, die_mem);
         if (indie) {
           result = die_mem;
           return result;
         }
       }
 
       int res = dwarf_siblingof(dwarf, current_die, &sibling_die, &error);
       if (res == DW_DLV_ERROR) {
         return NULL;
       } else if (res == DW_DLV_NO_ENTRY) {
         break;
       }
 
       if (current_die != parent_die) {
         dwarf_dealloc(dwarf, current_die, DW_DLA_DIE);
         current_die = 0;
       }
 
       current_die = sibling_die;
     }
     return NULL;
   }
 
   template <typename CB>
   static bool deep_first_search_by_pc(dwarf_fileobject &fobj,
                                       Dwarf_Die parent_die, Dwarf_Addr pc,
                                       std::vector<std::string> &ns, CB cb) {
     Dwarf_Die current_die = 0;
     Dwarf_Debug dwarf = fobj.dwarf_handle.get();
     Dwarf_Error error = DW_DLE_NE;
 
     if (dwarf_child(parent_die, &current_die, &error) != DW_DLV_OK) {
       return false;
     }
 
     bool branch_has_pc = false;
     bool has_namespace = false;
     for (;;) {
       Dwarf_Die sibling_die = 0;
 
       Dwarf_Half tag;
       if (dwarf_tag(current_die, &tag, &error) == DW_DLV_OK) {
         if (tag == DW_TAG_namespace || tag == DW_TAG_class_type) {
           char *ns_name = NULL;
           if (dwarf_diename(current_die, &ns_name, &error) == DW_DLV_OK) {
             if (ns_name) {
               ns.push_back(std::string(ns_name));
             } else {
               ns.push_back("<unknown>");
             }
             dwarf_dealloc(dwarf, ns_name, DW_DLA_STRING);
           } else {
             ns.push_back("<unknown>");
           }
           has_namespace = true;
         }
       }
 
       bool declaration = false;
       Dwarf_Attribute attr_mem;
       if (tag != DW_TAG_class_type &&
           dwarf_attr(current_die, DW_AT_declaration, &attr_mem, &error) ==
               DW_DLV_OK) {
         Dwarf_Bool flag = 0;
         if (dwarf_formflag(attr_mem, &flag, &error) == DW_DLV_OK) {
           declaration = flag != 0;
         }
         dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
       }
 
       if (!declaration) {
         // let's be curious and look deeper in the tree, function are
         // not necessarily at the first level, but might be nested
         // inside a namespace, structure, a function, an inlined
         // function etc.
         branch_has_pc = deep_first_search_by_pc(fobj, current_die, pc, ns, cb);
       }
 
       if (!branch_has_pc) {
         branch_has_pc = die_has_pc(fobj, current_die, pc);
       }
 
       if (branch_has_pc) {
         cb(current_die, ns);
       }
 
       int result = dwarf_siblingof(dwarf, current_die, &sibling_die, &error);
       if (result == DW_DLV_ERROR) {
         return false;
       } else if (result == DW_DLV_NO_ENTRY) {
         break;
       }
 
       if (current_die != parent_die) {
         dwarf_dealloc(dwarf, current_die, DW_DLA_DIE);
         current_die = 0;
       }
 
       if (has_namespace) {
         has_namespace = false;
         ns.pop_back();
       }
       current_die = sibling_die;
     }
 
     if (has_namespace) {
       ns.pop_back();
     }
     return branch_has_pc;
   }
 
   static std::string die_call_file(Dwarf_Debug dwarf, Dwarf_Die die,
                                    Dwarf_Die cu_die) {
     Dwarf_Attribute attr_mem;
     Dwarf_Error error = DW_DLE_NE;
     Dwarf_Unsigned file_index;
 
     std::string file;
 
     if (dwarf_attr(die, DW_AT_call_file, &attr_mem, &error) == DW_DLV_OK) {
       if (dwarf_formudata(attr_mem, &file_index, &error) != DW_DLV_OK) {
         file_index = 0;
       }
       dwarf_dealloc(dwarf, attr_mem, DW_DLA_ATTR);
 
       if (file_index == 0) {
         return file;
       }
 
       char **srcfiles = 0;
       Dwarf_Signed file_count = 0;
       if (dwarf_srcfiles(cu_die, &srcfiles, &file_count, &error) == DW_DLV_OK) {
         if (file_count > 0 && file_index <= static_cast<Dwarf_Unsigned>(file_count)) {
           file = std::string(srcfiles[file_index - 1]);
     }
 
         // Deallocate all strings!
         for (int i = 0; i < file_count; ++i) {
           dwarf_dealloc(dwarf, srcfiles[i], DW_DLA_STRING);
         }
         dwarf_dealloc(dwarf, srcfiles, DW_DLA_LIST);
       }
     }
     return file;
   }
 
   Dwarf_Die find_die(dwarf_fileobject &fobj, Dwarf_Addr addr) {
     // Let's get to work! First see if we have a debug_aranges section so
     // we can speed up the search
 
     Dwarf_Debug dwarf = fobj.dwarf_handle.get();
     Dwarf_Error error = DW_DLE_NE;
     Dwarf_Arange *aranges;
     Dwarf_Signed arange_count;
 
     Dwarf_Die returnDie;
     bool found = false;
     if (dwarf_get_aranges(dwarf, &aranges, &arange_count, &error) !=
         DW_DLV_OK) {
       aranges = NULL;
     }
 
     if (aranges) {
       // We have aranges. Get the one where our address is.
       Dwarf_Arange arange;
       if (dwarf_get_arange(aranges, arange_count, addr, &arange, &error) ==
           DW_DLV_OK) {
 
         // We found our address. Get the compilation-unit DIE offset
         // represented by the given address range.
         Dwarf_Off cu_die_offset;
         if (dwarf_get_cu_die_offset(arange, &cu_die_offset, &error) ==
             DW_DLV_OK) {
           // Get the DIE at the offset returned by the aranges search.
           // We set is_info to 1 to specify that the offset is from
           // the .debug_info section (and not .debug_types)
           int dwarf_result =
               dwarf_offdie_b(dwarf, cu_die_offset, 1, &returnDie, &error);
 
           found = dwarf_result == DW_DLV_OK;
         }
         dwarf_dealloc(dwarf, arange, DW_DLA_ARANGE);
       }
     }
 
     if (found)
       return returnDie; // The caller is responsible for freeing the die
 
     // The search for aranges failed. Try to find our address by scanning
     // all compilation units.
     Dwarf_Unsigned next_cu_header;
     Dwarf_Half tag = 0;
     returnDie = 0;
 
     while (!found &&
            dwarf_next_cu_header_d(dwarf, 1, 0, 0, 0, 0, 0, 0, 0, 0,
                                   &next_cu_header, 0, &error) == DW_DLV_OK) {
 
       if (returnDie)
         dwarf_dealloc(dwarf, returnDie, DW_DLA_DIE);
 
       if (dwarf_siblingof(dwarf, 0, &returnDie, &error) == DW_DLV_OK) {
         if ((dwarf_tag(returnDie, &tag, &error) == DW_DLV_OK) &&
             tag == DW_TAG_compile_unit) {
           if (die_has_pc(fobj, returnDie, addr)) {
             found = true;
           }
         }
       }
     }
 
     if (found) {
       while (dwarf_next_cu_header_d(dwarf, 1, 0, 0, 0, 0, 0, 0, 0, 0,
                                     &next_cu_header, 0, &error) == DW_DLV_OK) {
         // Reset the cu header state. Libdwarf's next_cu_header API
         // keeps its own iterator per Dwarf_Debug that can't be reset.
         // We need to keep fetching elements until the end.
       }
     }
 
     if (found)
       return returnDie;
 
     // We couldn't find any compilation units with ranges or a high/low pc.
     // Try again by looking at all DIEs in all compilation units.
     Dwarf_Die cudie;
     while (dwarf_next_cu_header_d(dwarf, 1, 0, 0, 0, 0, 0, 0, 0, 0,
                                   &next_cu_header, 0, &error) == DW_DLV_OK) {
       if (dwarf_siblingof(dwarf, 0, &cudie, &error) == DW_DLV_OK) {
         Dwarf_Die die_mem = 0;
         Dwarf_Die resultDie = find_fundie_by_pc(fobj, cudie, addr, die_mem);
 
         if (resultDie) {
           found = true;
           break;
         }
       }
     }
 
     if (found) {
       while (dwarf_next_cu_header_d(dwarf, 1, 0, 0, 0, 0, 0, 0, 0, 0,
                                     &next_cu_header, 0, &error) == DW_DLV_OK) {
         // Reset the cu header state. Libdwarf's next_cu_header API
         // keeps its own iterator per Dwarf_Debug that can't be reset.
         // We need to keep fetching elements until the end.
       }
     }
 
     if (found)
       return cudie;
 
     // We failed.
     return NULL;
   }
 };
 #endif // BACKWARD_HAS_DWARF == 1
 
 template <>
 class TraceResolverImpl<system_tag::linux_tag>
     : public TraceResolverLinuxImpl<trace_resolver_tag::current> {};
 
 #endif // BACKWARD_SYSTEM_LINUX
 
 #ifdef BACKWARD_SYSTEM_DARWIN
 
 template <typename STACKTRACE_TAG> class TraceResolverDarwinImpl;
 
 template <>
 class TraceResolverDarwinImpl<trace_resolver_tag::backtrace_symbol>
     : public TraceResolverImplBase {
 public:
   void load_addresses(void *const*addresses, int address_count) override {
     if (address_count == 0) {
       return;
     }
     _symbols.reset(backtrace_symbols(addresses, address_count));
   }
 
   ResolvedTrace resolve(ResolvedTrace trace) override {
     // parse:
     // <n>  <file>  <addr>  <mangled-name> + <offset>
     char *filename = _symbols[trace.idx];
 
     // skip "<n>  "
     while (*filename && *filename != ' ')
       filename++;
     while (*filename == ' ')
       filename++;
 
     // find start of <mangled-name> from end (<file> may contain a space)
     char *p = filename + strlen(filename) - 1;
     // skip to start of " + <offset>"
     while (p > filename && *p != ' ')
       p--;
     while (p > filename && *p == ' ')
       p--;
     while (p > filename && *p != ' ')
       p--;
     while (p > filename && *p == ' ')
       p--;
     char *funcname_end = p + 1;
 
     // skip to start of "<manged-name>"
     while (p > filename && *p != ' ')
       p--;
     char *funcname = p + 1;
 
     // skip to start of "  <addr>  "
     while (p > filename && *p == ' ')
       p--;
     while (p > filename && *p != ' ')
       p--;
     while (p > filename && *p == ' ')
       p--;
 
     // skip "<file>", handling the case where it contains a
     char *filename_end = p + 1;
     if (p == filename) {
       // something went wrong, give up
       filename_end = filename + strlen(filename);
       funcname = filename_end;
     }
     trace.object_filename.assign(
         filename, filename_end); // ok even if filename_end is the ending \0
                                  // (then we assign entire string)
 
     if (*funcname) { // if it's not end of string
       *funcname_end = '\0';
 
       trace.object_function = this->demangle(funcname);
       trace.object_function += " ";
       trace.object_function += (funcname_end + 1);
       trace.source.function = trace.object_function; // we cannot do better.
     }
     return trace;
   }
 
 private:
   details::handle<char **> _symbols;
 };
 
 template <>
 class TraceResolverImpl<system_tag::darwin_tag>
     : public TraceResolverDarwinImpl<trace_resolver_tag::current> {};
 
 #endif // BACKWARD_SYSTEM_DARWIN
 
 #ifdef BACKWARD_SYSTEM_WINDOWS
 
 // Load all symbol info
 // Based on:
 // https://stackoverflow.com/questions/6205981/windows-c-stack-trace-from-a-running-app/28276227#28276227
 
 struct module_data {
   std::string image_name;
   std::string module_name;
   void *base_address;
   DWORD load_size;
 };
 
 class get_mod_info {
   HANDLE process;
   static const int buffer_length = 4096;
 
 public:
   get_mod_info(HANDLE h) : process(h) {}
 
   module_data operator()(HMODULE module) {
     module_data ret;
     char temp[buffer_length];
     MODULEINFO mi;
 
     GetModuleInformation(process, module, &mi, sizeof(mi));
     ret.base_address = mi.lpBaseOfDll;
     ret.load_size = mi.SizeOfImage;
 
     GetModuleFileNameExA(process, module, temp, sizeof(temp));
     ret.image_name = temp;
     GetModuleBaseNameA(process, module, temp, sizeof(temp));
     ret.module_name = temp;
     std::vector<char> img(ret.image_name.begin(), ret.image_name.end());
     std::vector<char> mod(ret.module_name.begin(), ret.module_name.end());
     SymLoadModule64(process, 0, &img[0], &mod[0], (DWORD64)ret.base_address,
                     ret.load_size);
     return ret;
   }
 };
 
 template <> class TraceResolverImpl<system_tag::windows_tag>
     : public TraceResolverImplBase {
 public:
   TraceResolverImpl() {
 
     HANDLE process = GetCurrentProcess();
 
     std::vector<module_data> modules;
     DWORD cbNeeded;
     std::vector<HMODULE> module_handles(1);
     SymInitialize(process, NULL, false);
     DWORD symOptions = SymGetOptions();
     symOptions |= SYMOPT_LOAD_LINES | SYMOPT_UNDNAME;
     SymSetOptions(symOptions);
     EnumProcessModules(process, &module_handles[0],
                        static_cast<DWORD>(module_handles.size() * sizeof(HMODULE)),
                &cbNeeded);
     module_handles.resize(cbNeeded / sizeof(HMODULE));
     EnumProcessModules(process, &module_handles[0],
                        static_cast<DWORD>(module_handles.size() * sizeof(HMODULE)),
                &cbNeeded);
     std::transform(module_handles.begin(), module_handles.end(),
                    std::back_inserter(modules), get_mod_info(process));
     void *base = modules[0].base_address;
     IMAGE_NT_HEADERS *h = ImageNtHeader(base);
     image_type = h->FileHeader.Machine;
   }
 
   static const int max_sym_len = 255;
   struct symbol_t {
     SYMBOL_INFO sym;
     char buffer[max_sym_len];
   } sym;
 
   DWORD64 displacement;
 
   ResolvedTrace resolve(ResolvedTrace t) override {
     HANDLE process = GetCurrentProcess();
 
     char name[256];
 
     memset(&sym, 0, sizeof(sym));
     sym.sym.SizeOfStruct = sizeof(SYMBOL_INFO);
     sym.sym.MaxNameLen = max_sym_len;
 
     if (!SymFromAddr(process, (ULONG64)t.addr, &displacement, &sym.sym)) {
       // TODO:  error handling everywhere
       char* lpMsgBuf;
       DWORD dw = GetLastError();
 
       if (FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                              FORMAT_MESSAGE_FROM_SYSTEM |
                              FORMAT_MESSAGE_IGNORE_INSERTS,
                          NULL, dw, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                          (char*)&lpMsgBuf, 0, NULL)) {
         std::fprintf(stderr, "%s\n", lpMsgBuf);
         LocalFree(lpMsgBuf);
       }
 
       // abort();
     }
     UnDecorateSymbolName(sym.sym.Name, (PSTR)name, 256, UNDNAME_COMPLETE);
 
     DWORD offset = 0;
     IMAGEHLP_LINE line;
     if (SymGetLineFromAddr(process, (ULONG64)t.addr, &offset, &line)) {
       t.object_filename = line.FileName;
       t.source.filename = line.FileName;
       t.source.line = line.LineNumber;
       t.source.col = offset;
     }
 
     t.source.function = name;
     t.object_filename = "";
     t.object_function = name;
 
     return t;
   }
 
   DWORD machine_type() const { return image_type; }
 
 private:
   DWORD image_type;
 };
 
 #endif
 
 class TraceResolver : public TraceResolverImpl<system_tag::current_tag> {};
 
 /*************** CODE SNIPPET ***************/
 
 class SourceFile {
 public:
   typedef std::vector<std::pair<unsigned, std::string> > lines_t;
 
   SourceFile() {}
   SourceFile(const std::string &path) {
     // 1. If BACKWARD_CXX_SOURCE_PREFIXES is set then assume it contains
     //    a colon-separated list of path prefixes.  Try prepending each
     //    to the given path until a valid file is found.
     const std::vector<std::string> &prefixes = get_paths_from_env_variable();
     for (size_t i = 0; i < prefixes.size(); ++i) {
       // Double slashes (//) should not be a problem.
       std::string new_path = prefixes[i] + '/' + path;
       _file.reset(new std::ifstream(new_path.c_str()));
       if (is_open())
         break;
     }
     // 2. If no valid file found then fallback to opening the path as-is.
     if (!_file || !is_open()) {
       _file.reset(new std::ifstream(path.c_str()));
     }
   }
   bool is_open() const { return _file->is_open(); }
 
   lines_t &get_lines(unsigned line_start, unsigned line_count, lines_t &lines) {
     using namespace std;
     // This function make uses of the dumbest algo ever:
     //  1) seek(0)
     //  2) read lines one by one and discard until line_start
     //  3) read line one by one until line_start + line_count
     //
     // If you are getting snippets many time from the same file, it is
     // somewhat a waste of CPU, feel free to benchmark and propose a
     // better solution ;)
 
     _file->clear();
     _file->seekg(0);
     string line;
     unsigned line_idx;
 
     for (line_idx = 1; line_idx < line_start; ++line_idx) {
       std::getline(*_file, line);
       if (!*_file) {
         return lines;
       }
     }
 
     // think of it like a lambda in C++98 ;)
     // but look, I will reuse it two times!
     // What a good boy am I.
     struct isspace {
       bool operator()(char c) { return std::isspace(c); }
     };
 
     bool started = false;
     for (; line_idx < line_start + line_count; ++line_idx) {
       getline(*_file, line);
       if (!*_file) {
         return lines;
       }
       if (!started) {
         if (std::find_if(line.begin(), line.end(), not_isspace()) == line.end())
           continue;
         started = true;
       }
       lines.push_back(make_pair(line_idx, line));
     }
 
     lines.erase(
         std::find_if(lines.rbegin(), lines.rend(), not_isempty()).base(),
         lines.end());
     return lines;
   }
 
   lines_t get_lines(unsigned line_start, unsigned line_count) {
     lines_t lines;
     return get_lines(line_start, line_count, lines);
   }
 
   // there is no find_if_not in C++98, lets do something crappy to
   // workaround.
   struct not_isspace {
     bool operator()(char c) { return !std::isspace(c); }
   };
   // and define this one here because C++98 is not happy with local defined
   // struct passed to template functions, fuuuu.
   struct not_isempty {
     bool operator()(const lines_t::value_type &p) {
       return !(std::find_if(p.second.begin(), p.second.end(), not_isspace()) ==
                p.second.end());
     }
   };
 
   void swap(SourceFile &b) { _file.swap(b._file); }
 
 #ifdef BACKWARD_ATLEAST_CXX11
   SourceFile(SourceFile &&from) : _file(nullptr) { swap(from); }
   SourceFile &operator=(SourceFile &&from) {
     swap(from);
     return *this;
   }
 #else
   explicit SourceFile(const SourceFile &from) {
     // some sort of poor man's move semantic.
     swap(const_cast<SourceFile &>(from));
   }
   SourceFile &operator=(const SourceFile &from) {
     // some sort of poor man's move semantic.
     swap(const_cast<SourceFile &>(from));
     return *this;
   }
 #endif
 
 private:
   details::handle<std::ifstream *, details::default_delete<std::ifstream *> >
       _file;
 
   std::vector<std::string> get_paths_from_env_variable_impl() {
     std::vector<std::string> paths;
     const char *prefixes_str = std::getenv("BACKWARD_CXX_SOURCE_PREFIXES");
     if (prefixes_str && prefixes_str[0]) {
       paths = details::split_source_prefixes(prefixes_str);
     }
     return paths;
   }
 
   const std::vector<std::string> &get_paths_from_env_variable() {
     static std::vector<std::string> paths = get_paths_from_env_variable_impl();
     return paths;
   }
 
 #ifdef BACKWARD_ATLEAST_CXX11
   SourceFile(const SourceFile &) = delete;
   SourceFile &operator=(const SourceFile &) = delete;
 #endif
 };
 
 class SnippetFactory {
 public:
   typedef SourceFile::lines_t lines_t;
 
   lines_t get_snippet(const std::string &filename, unsigned line_start,
                       unsigned context_size) {
 
     SourceFile &src_file = get_src_file(filename);
     unsigned start = line_start - context_size / 2;
     return src_file.get_lines(start, context_size);
   }
 
   lines_t get_combined_snippet(const std::string &filename_a, unsigned line_a,
                                const std::string &filename_b, unsigned line_b,
                                unsigned context_size) {
     SourceFile &src_file_a = get_src_file(filename_a);
     SourceFile &src_file_b = get_src_file(filename_b);
 
     lines_t lines =
         src_file_a.get_lines(line_a - context_size / 4, context_size / 2);
     src_file_b.get_lines(line_b - context_size / 4, context_size / 2, lines);
     return lines;
   }
 
   lines_t get_coalesced_snippet(const std::string &filename, unsigned line_a,
                                 unsigned line_b, unsigned context_size) {
     SourceFile &src_file = get_src_file(filename);
 
     using std::max;
     using std::min;
     unsigned a = min(line_a, line_b);
     unsigned b = max(line_a, line_b);
 
     if ((b - a) < (context_size / 3)) {
       return src_file.get_lines((a + b - context_size + 1) / 2, context_size);
     }
 
     lines_t lines = src_file.get_lines(a - context_size / 4, context_size / 2);
     src_file.get_lines(b - context_size / 4, context_size / 2, lines);
     return lines;
   }
 
 private:
   typedef details::hashtable<std::string, SourceFile>::type src_files_t;
   src_files_t _src_files;
 
   SourceFile &get_src_file(const std::string &filename) {
     src_files_t::iterator it = _src_files.find(filename);
     if (it != _src_files.end()) {
       return it->second;
     }
     SourceFile &new_src_file = _src_files[filename];
     new_src_file = SourceFile(filename);
     return new_src_file;
   }
 };
 
 /*************** PRINTER ***************/
 
 namespace ColorMode {
 enum type { automatic, never, always };
 }
 
 class cfile_streambuf : public std::streambuf {
 public:
   cfile_streambuf(FILE *_sink) : sink(_sink) {}
   int_type underflow() override { return traits_type::eof(); }
   int_type overflow(int_type ch) override {
     if (traits_type::not_eof(ch) && fputc(ch, sink) != EOF) {
       return ch;
     }
     return traits_type::eof();
   }
 
   std::streamsize xsputn(const char_type *s, std::streamsize count) override {
     return static_cast<std::streamsize>(
         fwrite(s, sizeof *s, static_cast<size_t>(count), sink));
   }
 
 #ifdef BACKWARD_ATLEAST_CXX11
 public:
   cfile_streambuf(const cfile_streambuf &) = delete;
   cfile_streambuf &operator=(const cfile_streambuf &) = delete;
 #else
 private:
   cfile_streambuf(const cfile_streambuf &);
   cfile_streambuf &operator=(const cfile_streambuf &);
 #endif
 
 private:
   FILE *sink;
   std::vector<char> buffer;
 };
 
 #ifdef BACKWARD_SYSTEM_LINUX
 
 namespace Color {
 enum type { yellow = 33, purple = 35, reset = 39 };
 } // namespace Color
 
 class Colorize {
 public:
   Colorize(std::ostream &os) : _os(os), _reset(false), _enabled(false) {}
 
   void activate(ColorMode::type mode) { _enabled = mode == ColorMode::always; }
 
   void activate(ColorMode::type mode, FILE *fp) { activate(mode, fileno(fp)); }
 
   void set_color(Color::type ccode) {
     if (!_enabled)
       return;
 
     // I assume that the terminal can handle basic colors. Seriously I
     // don't want to deal with all the termcap shit.
     _os << "\033[" << static_cast<int>(ccode) << "m";
     _reset = (ccode != Color::reset);
   }
 
   ~Colorize() {
     if (_reset) {
       set_color(Color::reset);
     }
   }
 
 private:
   void activate(ColorMode::type mode, int fd) {
     activate(mode == ColorMode::automatic && isatty(fd) ? ColorMode::always
                                                         : mode);
   }
 
   std::ostream &_os;
   bool _reset;
   bool _enabled;
 };
 
 #else // ndef BACKWARD_SYSTEM_LINUX
 
 namespace Color {
 enum type { yellow = 0, purple = 0, reset = 0 };
 } // namespace Color
 
 class Colorize {
 public:
   Colorize(std::ostream &) {}
   void activate(ColorMode::type) {}
   void activate(ColorMode::type, FILE *) {}
   void set_color(Color::type) {}
 };
 
 #endif // BACKWARD_SYSTEM_LINUX
 
 class Printer {
 public:
   bool snippet;
   ColorMode::type color_mode;
   bool address;
   bool object;
   int inliner_context_size;
   int trace_context_size;
   bool reverse;
 
   Printer()
       : snippet(true), color_mode(ColorMode::automatic), address(false),
         object(false), inliner_context_size(5), trace_context_size(7),
         reverse(true) {}
 
   template <typename ST> FILE *print(ST &st, FILE *fp = stderr) {
     cfile_streambuf obuf(fp);
     std::ostream os(&obuf);
     Colorize colorize(os);
     colorize.activate(color_mode, fp);
     print_stacktrace(st, os, colorize);
     return fp;
   }
 
   template <typename ST> std::ostream &print(ST &st, std::ostream &os) {
     Colorize colorize(os);
     colorize.activate(color_mode);
     print_stacktrace(st, os, colorize);
     return os;
   }
 
   template <typename IT>
   FILE *print(IT begin, IT end, FILE *fp = stderr, size_t thread_id = 0) {
     cfile_streambuf obuf(fp);
     std::ostream os(&obuf);
     Colorize colorize(os);
     colorize.activate(color_mode, fp);
     print_stacktrace(begin, end, os, thread_id, colorize);
     return fp;
   }
 
   template <typename IT>
   std::ostream &print(IT begin, IT end, std::ostream &os,
                       size_t thread_id = 0) {
     Colorize colorize(os);
     colorize.activate(color_mode);
     print_stacktrace(begin, end, os, thread_id, colorize);
     return os;
   }
 
   TraceResolver const &resolver() const { return _resolver; }
 
 private:
   TraceResolver _resolver;
   SnippetFactory _snippets;
 
   template <typename ST>
   void print_stacktrace(ST &st, std::ostream &os, Colorize &colorize) {
     print_header(os, st.thread_id());
     _resolver.load_stacktrace(st);
     if ( reverse ) {
       for (size_t trace_idx = st.size(); trace_idx > 0; --trace_idx) {
         print_trace(os, _resolver.resolve(st[trace_idx - 1]), colorize);
       }
     } else {
       for (size_t trace_idx = 0; trace_idx < st.size(); ++trace_idx) {
         print_trace(os, _resolver.resolve(st[trace_idx]), colorize);
       }
     }
   }
 
   template <typename IT>
   void print_stacktrace(IT begin, IT end, std::ostream &os, size_t thread_id,
                         Colorize &colorize) {
     print_header(os, thread_id);
     for (; begin != end; ++begin) {
       print_trace(os, *begin, colorize);
     }
   }
 
   void print_header(std::ostream &os, size_t thread_id) {
     os << "Stack trace (most recent call last)";
     if (thread_id) {
       os << " in thread " << thread_id;
     }
     os << ":\n";
   }
 
   void print_trace(std::ostream &os, const ResolvedTrace &trace,
                    Colorize &colorize) {
     os << "#" << std::left << std::setw(2) << trace.idx << std::right;
     bool already_indented = true;
 
     if (!trace.source.filename.size() || object) {
       os << "   Object \"" << trace.object_filename << "\", at " << trace.addr
          << ", in " << trace.object_function << "\n";
       already_indented = false;
     }
 
     for (size_t inliner_idx = trace.inliners.size(); inliner_idx > 0;
          --inliner_idx) {
       if (!already_indented) {
         os << "   ";
       }
       const ResolvedTrace::SourceLoc &inliner_loc =
           trace.inliners[inliner_idx - 1];
       print_source_loc(os, " | ", inliner_loc);
       if (snippet) {
         print_snippet(os, "    | ", inliner_loc, colorize, Color::purple,
                       inliner_context_size);
       }
       already_indented = false;
     }
 
     if (trace.source.filename.size()) {
       if (!already_indented) {
         os << "   ";
       }
       print_source_loc(os, "   ", trace.source, trace.addr);
       if (snippet) {
         print_snippet(os, "      ", trace.source, colorize, Color::yellow,
                       trace_context_size);
       }
     }
   }
 
   void print_snippet(std::ostream &os, const char *indent,
                      const ResolvedTrace::SourceLoc &source_loc,
                      Colorize &colorize, Color::type color_code,
                      int context_size) {
     using namespace std;
     typedef SnippetFactory::lines_t lines_t;
 
     lines_t lines = _snippets.get_snippet(source_loc.filename, source_loc.line,
                                           static_cast<unsigned>(context_size));
 
     for (lines_t::const_iterator it = lines.begin(); it != lines.end(); ++it) {
       if (it->first == source_loc.line) {
         colorize.set_color(color_code);
         os << indent << ">";
       } else {
         os << indent << " ";
       }
       os << std::setw(4) << it->first << ": " << it->second << "\n";
       if (it->first == source_loc.line) {
         colorize.set_color(Color::reset);
       }
     }
   }
 
   void print_source_loc(std::ostream &os, const char *indent,
                         const ResolvedTrace::SourceLoc &source_loc,
                         void *addr = nullptr) {
     os << indent << "Source \"" << source_loc.filename << "\", line "
        << source_loc.line << ", in " << source_loc.function;
 
     if (address && addr != nullptr) {
       os << " [" << addr << "]";
     }
     os << "\n";
   }
 };
 
 /*************** SIGNALS HANDLING ***************/
 namespace {
   std::filesystem::path _dump_path;
 }
 
 #if defined(BACKWARD_SYSTEM_LINUX) || defined(BACKWARD_SYSTEM_DARWIN)
 
 class SignalHandling {
 public:
   static std::vector<int> make_default_signals() {
     const int posix_signals[] = {
       // Signals for which the default action is "Core".
       SIGABRT, // Abort signal from abort(3)
       SIGBUS,  // Bus error (bad memory access)
       SIGFPE,  // Floating point exception
       SIGILL,  // Illegal Instruction
       SIGIOT,  // IOT trap. A synonym for SIGABRT
       SIGQUIT, // Quit from keyboard
       SIGSEGV, // Invalid memory reference
       SIGSYS,  // Bad argument to routine (SVr4)
       SIGTRAP, // Trace/breakpoint trap
       SIGXCPU, // CPU time limit exceeded (4.2BSD)
       SIGXFSZ, // File size limit exceeded (4.2BSD)
 #if defined(BACKWARD_SYSTEM_DARWIN)
       SIGEMT, // emulation instruction executed
 #endif
     };
     return std::vector<int>(posix_signals,
                             posix_signals +
                                 sizeof posix_signals / sizeof posix_signals[0]);
   }
 
   SignalHandling(const std::vector<int> &posix_signals = make_default_signals(),
                  std::filesystem::path dump_path = {})
       : _loaded(false) {
     _dump_path = dump_path;
     bool success = true;
 
     const size_t stack_size = 1024 * 1024 * 8;
     _stack_content.reset(static_cast<char *>(malloc(stack_size)));
     if (_stack_content) {
       stack_t ss;
       ss.ss_sp = _stack_content.get();
       ss.ss_size = stack_size;
       ss.ss_flags = 0;
       if (sigaltstack(&ss, nullptr) < 0) {
         success = false;
       }
     } else {
       success = false;
     }
 
     for (size_t i = 0; i < posix_signals.size(); ++i) {
       struct sigaction action;
       memset(&action, 0, sizeof action);
       action.sa_flags =
           static_cast<int>(SA_SIGINFO | SA_ONSTACK | SA_NODEFER | SA_RESETHAND);
       sigfillset(&action.sa_mask);
       sigdelset(&action.sa_mask, posix_signals[i]);
 #if defined(__clang__)
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdisabled-macro-expansion"
 #endif
       action.sa_sigaction = &sig_handler;
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif
 
       int r = sigaction(posix_signals[i], &action, nullptr);
       if (r < 0)
         success = false;
     }
 
     _loaded = success;
   }
 
   bool loaded() const { return _loaded; }
 
   static void handleSignal(int, siginfo_t *info, void *_ctx) {
     ucontext_t *uctx = static_cast<ucontext_t *>(_ctx);
 
     StackTrace st;
     void *error_addr = nullptr;
 #ifdef REG_RIP // x86_64
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext.gregs[REG_RIP]);
 #elif defined(REG_EIP) // x86_32
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext.gregs[REG_EIP]);
 #elif defined(__arm__)
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext.arm_pc);
 #elif defined(__aarch64__)
     #if defined(__APPLE__)
       error_addr = reinterpret_cast<void *>(uctx->uc_mcontext->__ss.__pc);
     #else
       error_addr = reinterpret_cast<void *>(uctx->uc_mcontext.pc);
     #endif
 #elif defined(__mips__)
     error_addr = reinterpret_cast<void *>(
         reinterpret_cast<struct sigcontext *>(&uctx->uc_mcontext)->sc_pc);
 #elif defined(__ppc__) || defined(__powerpc) || defined(__powerpc__) ||        \
     defined(__POWERPC__)
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext.regs->nip);
 #elif defined(__riscv)
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext.__gregs[REG_PC]);
 #elif defined(__s390x__)
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext.psw.addr);
 #elif defined(__APPLE__) && defined(__x86_64__)
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext->__ss.__rip);
 #elif defined(__APPLE__)
     error_addr = reinterpret_cast<void *>(uctx->uc_mcontext->__ss.__eip);
 #else
 #warning ":/ sorry, ain't know no nothing none not of your architecture!"
 #endif
     if (error_addr) {
       st.load_from(error_addr, 32, reinterpret_cast<void *>(uctx),
                    info->si_addr);
     } else {
       st.load_here(32, reinterpret_cast<void *>(uctx), info->si_addr);
     }
 
     Printer printer;
     printer.address = true;
 
     if (!_dump_path.empty()) {
       std::ofstream error_stream;
       error_stream.open(_dump_path);
       printer.print(st, error_stream);
       error_stream.close();
     } else {
       printer.print(st, stderr);
     }
 
 #if (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 700) || \
     (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200809L)
     psiginfo(info, nullptr);
 #else
     (void)info;
 #endif
   }
 
 private:
   details::handle<char *> _stack_content;
   bool _loaded;
 
 #ifdef __GNUC__
   __attribute__((noreturn))
 #endif
   static void
   sig_handler(int signo, siginfo_t *info, void *_ctx) {
     handleSignal(signo, info, _ctx);
 
     // try to forward the signal.
     raise(info->si_signo);
 
     // terminate the process immediately.
     puts("watf? exit");
     _exit(EXIT_FAILURE);
   }
 };
 
 #endif // BACKWARD_SYSTEM_LINUX || BACKWARD_SYSTEM_DARWIN
 
 #ifdef BACKWARD_SYSTEM_WINDOWS
 
 class SignalHandling {
 public:
   static std::vector<int> make_default_signals() { return {}; }
 
   SignalHandling(const std::vector<int> & = std::vector<int>(),
                 std::filesystem::path dump_path = {})
       : reporter_thread_([]() {
           /* We handle crashes in a utility thread:
             backward structures and some Windows functions called here
             need stack space, which we do not have when we encounter a
             stack overflow.
             To support reporting stack traces during a stack overflow,
             we create a utility thread at startup, which waits until a
             crash happens or the program exits normally. */
 
           {
             std::unique_lock<std::mutex> lk(mtx());
             cv().wait(lk, [] { return crashed() != crash_status::running; });
           }
           if (crashed() == crash_status::crashed) {
             handle_stacktrace(skip_recs());
           }
           {
             std::unique_lock<std::mutex> lk(mtx());
             crashed() = crash_status::ending;
           }
           cv().notify_one();
         }) {
         _dump_path = dump_path;
     SetUnhandledExceptionFilter(crash_handler);
 
     signal(SIGABRT, signal_handler);
     _set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT);
 
     std::set_terminate(&terminator);
 #ifndef BACKWARD_ATLEAST_CXX17
     std::set_unexpected(&terminator);
 #endif
     _set_purecall_handler(&terminator);
     _set_invalid_parameter_handler(&invalid_parameter_handler);
   }
   bool loaded() const { return true; }
 
   ~SignalHandling() {
     {
       std::unique_lock<std::mutex> lk(mtx());
       crashed() = crash_status::normal_exit;
     }
 
     cv().notify_one();
 
     reporter_thread_.join();
   }
 
 private:
   static CONTEXT *ctx() {
     static CONTEXT data;
     return &data;
   }
 
   enum class crash_status { running, crashed, normal_exit, ending };
 
   static crash_status &crashed() {
     static crash_status data;
     return data;
   }
 
   static std::mutex &mtx() {
     static std::mutex data;
     return data;
   }
 
   static std::condition_variable &cv() {
     static std::condition_variable data;
     return data;
   }
 
   static HANDLE &thread_handle() {
     static HANDLE handle;
     return handle;
   }
 
   std::thread reporter_thread_;
 
   // TODO: how not to hardcode these?
   static const constexpr int signal_skip_recs =
 #ifdef __clang__
       // With clang, RtlCaptureContext also captures the stack frame of the
       // current function Below that, there are 3 internal Windows functions
       4
 #else
       // With MSVC cl, RtlCaptureContext misses the stack frame of the current
       // function The first entries during StackWalk are the 3 internal Windows
       // functions
       3
 #endif
       ;
 
   static int &skip_recs() {
     static int data;
     return data;
   }
 
   static inline void terminator() {
     crash_handler(signal_skip_recs);
     abort();
   }
 
   static inline void signal_handler(int) {
     crash_handler(signal_skip_recs);
     abort();
   }
 
   static inline void __cdecl invalid_parameter_handler(const wchar_t *,
                                                        const wchar_t *,
                                                        const wchar_t *,
                                                        unsigned int,
                                                        uintptr_t) {
     crash_handler(signal_skip_recs);
     abort();
   }
 
   NOINLINE static LONG WINAPI crash_handler(EXCEPTION_POINTERS *info) {
     // The exception info supplies a trace from exactly where the issue was,
     // no need to skip records
     crash_handler(0, info->ContextRecord);
     return EXCEPTION_CONTINUE_SEARCH;
   }
 
   NOINLINE static void crash_handler(int skip, CONTEXT *ct = nullptr) {
 
     if (ct == nullptr) {
       RtlCaptureContext(ctx());
     } else {
       memcpy(ctx(), ct, sizeof(CONTEXT));
     }
     DuplicateHandle(GetCurrentProcess(), GetCurrentThread(),
                     GetCurrentProcess(), &thread_handle(), 0, FALSE,
                     DUPLICATE_SAME_ACCESS);
 
     skip_recs() = skip;
 
     {
       std::unique_lock<std::mutex> lk(mtx());
       crashed() = crash_status::crashed;
     }
 
     cv().notify_one();
 
     {
       std::unique_lock<std::mutex> lk(mtx());
       cv().wait(lk, [] { return crashed() != crash_status::crashed; });
     }
   }
 
   static void handle_stacktrace(int skip_frames = 0) {
     // printer creates the TraceResolver, which can supply us a machine type
     // for stack walking. Without this, StackTrace can only guess using some
     // macros.
     // StackTrace also requires that the PDBs are already loaded, which is done
     // in the constructor of TraceResolver
     Printer printer;
 
     StackTrace st;
     st.set_machine_type(printer.resolver().machine_type());
     st.set_thread_handle(thread_handle());
     st.load_here(32 + skip_frames, ctx());
     st.skip_n_firsts(skip_frames);
 
     printer.address = true;
 
     if (!_dump_path.empty()) {
       std::ofstream error_stream;
       error_stream.open(_dump_path);
       printer.print(st, error_stream);
       error_stream.close();
     } else {
       printer.print(st, stderr);
     }
 
   }
 };
 
 #endif // BACKWARD_SYSTEM_WINDOWS
 
 #ifdef BACKWARD_SYSTEM_UNKNOWN
 
 class SignalHandling {
 public:
   SignalHandling(const std::vector<int> & = std::vector<int>(), const
 std::filesystem::path & = {}) {}
   bool init() { return false; }
   bool loaded() { return false; }
 };
 
 #endif // BACKWARD_SYSTEM_UNKNOWN
 
 } // namespace backward
 
 #endif /* H_GUARD */