stack_trace.cpp

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// Copyright (c) 2011-2025  Made to Order Software Corp.  All Rights Reserved
//
// https://snapwebsites.org/
// contact@m2osw.com
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 
// self
//
#include    "libexcept/exception.h"
 
#include    "libexcept/demangle.h"
 
 
// C++
//
#include    <iostream>
#include    <memory>
#include    <vector>
 
 
// C
//
#include    <execinfo.h>
#include    <link.h>
#include    <unistd.h>
 
 
namespace libexcept
{
 
 
 
stack_trace_t collect_stack_trace(int stack_trace_depth)
{
    stack_trace_t stack_trace;
 
    if(stack_trace_depth > 0)
    {
        std::vector<void *> array;
        array.resize(std::max(stack_trace_depth, 1'000));
        int const size(backtrace(&array[0], stack_trace_depth));
 
        // save a copy of the system array in our class
        //
        std::unique_ptr<char *, decltype(&::free)> stack_string_list(backtrace_symbols(&array[0], size), &::free);
        for(int idx(0); idx < size; ++idx)
        {
            char const * stack_string(stack_string_list.get()[idx]);
            stack_trace.push_back(stack_string);
        }
    }
 
    return stack_trace;
}
 
 
stack_trace_t collect_stack_trace_with_line_numbers(int stack_trace_depth)
{
    stack_trace_t stack_trace;
 
    if(stack_trace_depth > 0)
    {
        std::vector<void *> array;
        array.resize(stack_trace_depth);
        int const size(backtrace(&array[0], stack_trace_depth));
 
        // save a copy of the system array in our class
        //
        std::unique_ptr<char *, decltype(&::free)> stack_string_list(backtrace_symbols(&array[0], size), &::free);
        for(int idx(0); idx < size; ++idx)
        {
            char const * raw_stack_string(stack_string_list.get()[idx]);
 
            // the raw stack string is expected to be composed of:
            //   <filename>(<function-name>+<offset>) [<addr>]
            //
            // we extract all those elements and use addr2line and c++filt
            // to convert that data to a usable function name and line number
            //
            std::string filename;
            std::string raw_function_name;
            std::string addr;
            std::string result;
 
            // go to end of filename
            //
            char const * s(raw_stack_string);
            char const * start(s);
            while(*s != '('
               && *s != '\0')
            {
                ++s;
            }
            if(*s == '(')
            {
                filename = std::string(start, s - start);
                ++s;
 
                start = s;
                while(*s != '+'
                   && *s != ')'
                   && *s != '\0')
                {
                    ++s;
                }
 
                if(*s == '+')
                {
                    raw_function_name = std::string(start, s - start);
                    ++s;
 
                    // skip the offset
                    //
                    while(*s != ')'
                       && *s != '\0')
                    {
                        ++s;
                    }
                }
                //else if(*s == ')') {} -- no function name
 
                if(*s == ')'
                && s[1] == ' '
                && s[2] == '['
                && s[3] == '0'
                && s[4] == 'x')
                {
                    s += 5;
 
                    start = s;
                    while(*s != ']'
                       && *s != '\0')
                    {
                        ++s;
                    }
 
                    if(*s == ']')
                    {
                        addr = std::string(start, s - start);
 
                        result.clear();
 
                        // here we have our info, use it to get sane data
                        //
                        // TODO: look into whether we could rewrite the
                        // eu-addr2line tool in C++ to avoid having to
                        // run it (because that would be faster)
                        //
                        // I first used the "... -e <filename> ..." option
                        // but with the --pid=..., it ought to be faster.
                        //
                        {
                            std::string addr2line("eu-addr2line --pid="
                                            + std::to_string(getpid())
                                            + " "
                                            + addr);
                            std::unique_ptr<FILE, int(*)(FILE *)> p(popen(addr2line.c_str(), "r"), &::pclose);
                            std::string line;
                            for(;;)
                            {
                                int const c(fgetc(p.get()));
                                if(c == EOF)
                                {
                                    break;
                                }
                                if(c != '\n')
                                {
                                    line += c;
                                }
                            }
                            if(line == "??:0")
                            {
                                // this means addr2line failed to find the
                                // debug info in your executable/.so
                                // we fallback to the default which may help
                                // if you have a version with debug info
                                //
                                result += filename
                                        + "["
                                        + addr
                                        + "]";
                            }
                            else
                            {
                                result = line;
                            }
                        }
 
                        if(!raw_function_name.empty())
                        {
                            result += " in ";
                            result += demangle_cpp_name(raw_function_name.c_str());
                        }
                        else
                        {
                            result += " <no function name>";
                        }
                    }
                }
            }
 
            if(result.empty())
            {
                // use the raw line as a fallback if we could not parse it
                // correctly or a conversion somehow fails...
                //
                stack_trace.push_back(std::string(raw_stack_string));   // LCOV_EXCL_LINE
            }
            else
            {
                stack_trace.push_back(result);
            }
        }
    }
 
    return stack_trace;
}
 
 
 
 
}
// namespace libexcept
// vim: ts=4 sw=4 et