Line data    Source code

       1             : // Copyright (c) 2019-2022  Made to Order Software Corp.  All Rights Reserved
       2             : //
       3             : // https://snapwebsites.org/project/libexcept
       4             : // contact@m2osw.com
       5             : //
       6             : // This program is free software; you can redistribute it and/or modify
       7             : // it under the terms of the GNU General Public License as published by
       8             : // the Free Software Foundation; either version 2 of the License, or
       9             : // (at your option) any later version.
      10             : //
      11             : // This program is distributed in the hope that it will be useful,
      12             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             : // GNU General Public License for more details.
      15             : //
      16             : // You should have received a copy of the GNU General Public License along
      17             : // with this program; if not, write to the Free Software Foundation, Inc.,
      18             : // 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
      19             : 
      20             : #include "./demangle.h"
      21             : 
      22             : // C++ includes
      23             : //
      24             : #include <cxxabi.h>
      25             : #include <memory>
      26             : 
      27             : 
      28             : /** \file
      29             :  * \brief Implementation of the demandler functions.
      30             :  *
      31             :  * This file includes functions we can use to demangle C++ names.
      32             :  */
      33             : 
      34             : 
      35             : 
      36             : namespace libexcept
      37             : {
      38             : 
      39             : 
      40             : 
      41             : /** \brief Demangle the specified type string.
      42             :  *
      43             :  * C++ offers a `typeid(\<type>).name()` function, only that does not
      44             :  * return a readable name in many cases. This function transforms that
      45             :  * name back to the original. This is particularly useful for C++ base
      46             :  * types. For example "unsigned short" becomes "t". To verify a type,
      47             :  * it is quite practical.
      48             :  *
      49             :  * This function demangles all names, including those we get when
      50             :  * building a stack trace.
      51             :  *
      52             :  * \note
      53             :  * This is similar to using the c++filt command line tool. If the
      54             :  * conversion fails, then the function returns the input string as is.
      55             :  *
      56             :  * \note
      57             :  * I found a piece of code snippet on Catch2 which is used to demangle a C++
      58             :  * name. It is one simple ABI call!
      59             :  *
      60             :  * \code
      61             :  * #include "catch.hpp"
      62             :  *
      63             :  * #include <cxxabi.h>
      64             :  * #include <typeinfo>
      65             :  *
      66             :  * CATCH_TRANSLATE_EXCEPTION(std::exception& e) {
      67             :  *   std::string s;
      68             :  *   int status;
      69             :  *
      70             :  *   const char* name = typeid(e).name();
      71             :  *   char* realname = abi::__cxa_demangle(name, 0, 0, &status);
      72             :  *   if(realname) {
      73             :  *     s.append(realname);
      74             :  *   } else {
      75             :  *     s.append(name);
      76             :  *   }
      77             :  *   s.append(": ");
      78             :  *   s.append(e.what());
      79             :  *   free(realname);
      80             :  *   return s;
      81             :  * }
      82             :  * \endcode
      83             :  *
      84             :  * Source: https://github.com/catchorg/Catch2/issues/539
      85             :  *
      86             :  * \param[in] type_id_name  The mangled C++ name.
      87             :  *
      88             :  * \return The converted name.
      89             :  *
      90             :  * \sa https://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.3/a01696.html
      91             :  */
      92          29 : std::string demangle_cpp_name(char const * type_id_name)
      93             : {
      94             : #if 1
      95          29 :     int status(0);
      96             : 
      97          29 :     std::unique_ptr<char, void(*)(void*)> res {
      98             :         abi::__cxa_demangle(type_id_name, nullptr, nullptr, &status),
      99             :         std::free
     100          58 :     };
     101             : 
     102          29 :     return status == 0
     103             :                 ? res.get()
     104          87 :                 : type_id_name;
     105             : #else
     106             :     // keeping the fallback in case the ABI stops working over time
     107             :     // this is "very" slow since it runs an external tool (c++filt)
     108             :     //
     109             :     std::string cppfilt("c++filt "
     110             :                       + raw_function_name);
     111             :     std::unique_ptr<FILE, decltype(&::pclose)> p(popen(cppfilt.c_str(), "r"), &::pclose);
     112             :     for(;;)
     113             :     {
     114             :         int const c(fgetc(p.get()));
     115             :         if(c == EOF)
     116             :         {
     117             :             break;
     118             :         }
     119             :         if(c != '\n')
     120             :         {
     121             :             result += c;
     122             :         }
     123             :     }
     124             : #endif
     125             : }
     126             : 
     127             : 
     128             : 
     129             : }
     130             : // namespace libexcept
     131             : // vim: ts=4 sw=4 et