backtrace.cpp

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//
// backtrace.cpp
//
// Copyright (C) 1996 Limit Point Systems, Inc.
//
// Author: Curtis Janssen <cljanss@limitpt.com>
// Maintainer: LPS
//
// This file is part of the SC Toolkit.
//
// The SC Toolkit is free software; you can redistribute it and/or modify
// it under the terms of the GNU Library General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
//
// The SC Toolkit is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public License
// along with the SC Toolkit; see the file COPYING.LIB.  If not, write to
// the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
//
// The U.S. Government is granted a limited license as per AL 91-7.
//
 
#include "backtrace.h"
 
#include <cstring>
#include <iterator>
#include <sstream>
 
#if defined(TTG_HAS_LIBUNWIND)
#define UNW_LOCAL_ONLY
#include <libunwind.h>
#else
#if __has_include(<execinfo.h>)
#define TTG_HAS_BACKTRACE
#include <execinfo.h>
#endif
#endif
 
#if __has_include(<cxxabi.h>)
#include <cxxabi.h>
#define TTG_HAS_CXA_DEMANGLE
#endif
 
namespace ttg {
  namespace detail {
    Backtrace::Backtrace(const std::string &prefix) : prefix_(prefix) {
#ifdef TTG_HAS_LIBUNWIND
      {
        unw_cursor_t cursor;
        unw_context_t uc;
        unw_word_t ip, sp, offp;
        int frame = 0;
 
        unw_getcontext(&uc);
        unw_init_local(&cursor, &uc);
        while (unw_step(&cursor) > 0) {
          unw_get_reg(&cursor, UNW_REG_IP, &ip);
          unw_get_reg(&cursor, UNW_REG_SP, &sp);
          char name[32768];
          unw_get_proc_name(&cursor, name, 32768, &offp);
          std::ostringstream oss;
          oss << prefix_ << "frame " << frame << ": "
              << "ip = 0x" << (long)ip << " sp = 0x" << (long)sp << " symbol = " << __demangle(name);
          frames_.push_back(oss.str());
          ++frame;
        }
      }
#elif defined(TTG_HAS_BACKTRACE)  // !TTG_HAS_LIBUNWIND
      void *stack_addrs[1024];
      const int naddrs = backtrace(stack_addrs, 1024);
      char **frame_symbols = backtrace_symbols(stack_addrs, naddrs);
      // starting @ 1 to skip this function
      for (int i = 1; i < naddrs; ++i) {
        // extract (mangled) function name
        // parsing frame_symbols[i] is OS-specific
        // for unknown OS ... just return the whole string
        std::string mangled_function_name = frame_symbols[i];
#if defined(__APPLE__)
        {
          // "frame_id /path/to/exec address symbol"
          std::istringstream iss(std::string(frame_symbols[i]), std::istringstream::in);
          std::string frame, file, address;
          iss >> frame >> file >> address >> mangled_function_name;
        }
#elif defined(__linux__)
        {
          // "/path/to/exec(symbol+0x...) [address]"
          // parse from the back to avoid dealing with parentheses in the path
          const auto last_right_bracket = mangled_function_name.rfind(']');
          const auto last_left_bracket = mangled_function_name.rfind('[', last_right_bracket);
          const auto last_right_parens = mangled_function_name.rfind(')', last_left_bracket);
          const auto offset = mangled_function_name.rfind("+0x", last_right_parens);
          const auto last_left_parens = mangled_function_name.rfind('(', last_right_parens);
          if (last_left_parens + 1 < mangled_function_name.size()) {
            mangled_function_name = mangled_function_name.substr(last_left_parens + 1, offset - last_left_parens - 1);
          }
        }
#endif
 
        std::ostringstream oss;
        oss << prefix_ << "frame " << i << ": return address = " << stack_addrs[i] << std::endl
            << "  symbol = " << __demangle(mangled_function_name);
        frames_.push_back(oss.str());
      }
      free(frame_symbols);
#else  // !TTG_HAS_LIBUNWIND && !TTG_HAS_BACKTRACE
#if defined(SIMPLE_STACK)
      int bottom = 0x1234;
      void **topstack = (void **)0xffffffffL;
      void **botstack = (void **)0x70000000L;
      // signal handlers can put weird things in the return address slot,
      // so it is usually best to keep toptext large.
      void **toptext = (void **)0xffffffffL;
      void **bottext = (void **)0x00010000L;
#endif  // SIMPLE_STACK
 
#if (defined(linux) && defined(i386))
      topstack = (void **)0xc0000000;
      botstack = (void **)0xb0000000;
#endif
#if (defined(__OSF1__) && defined(i860))
      topstack = (void **)0x80000000;
      botstack = (void **)0x70000000;
#endif
 
#if defined(SIMPLE_STACK)
      // This will go through the stack assuming a simple linked list
      // of pointers to the previous frame followed by the return address.
      // It trys to be careful and avoid creating new exceptions, but there
      // are no guarantees.
      void **stack = (void **)&bottom;
 
      void **frame_pointer = (void **)stack[3];
      while (frame_pointer >= botstack && frame_pointer < topstack && frame_pointer[1] >= bottext &&
             frame_pointer[1] < toptext) {
        std::ostringstream oss;
        oss << prefix_ << "frame: " << (void *)frame_pointer;
        oss << "  retaddr: " << frame_pointer[1];
        frames_.push_back(oss.str());
 
        frame_pointer = (void **)*frame_pointer;
      }
#endif  // SIMPLE_STACK
#endif  // TTG_HAS_BACKTRACE
    }
 
    Backtrace::Backtrace(const Backtrace &other) : frames_(other.frames_), prefix_(other.prefix_) {}
 
    std::string Backtrace::str(size_t nframes_to_skip) const {
      std::ostringstream oss;
      std::copy(frames_.begin() + nframes_to_skip, frames_.end(), std::ostream_iterator<std::string>(oss, "\n"));
      return oss.str();
    }
 
    std::string Backtrace::__demangle(const std::string &symbol) {
      std::string dsymbol;
#ifdef TTG_HAS_CXA_DEMANGLE
      {
        int status;
        char *dsymbol_char = abi::__cxa_demangle(symbol.c_str(), 0, 0, &status);
        if (status == 0) {  // success
          dsymbol = dsymbol_char;
          free(dsymbol_char);
        } else  // fail
          dsymbol = symbol;
      }
#else
      dsymbol = symbol;
#endif
      return dsymbol;
    }
 
  }  // namespace detail
}  // namespace ttg