Line data    Source code

       1             : // Copyright (c) 2019-2021  Made to Order Software Corp.  All Rights Reserved
       2             : //
       3             : // https://snapwebsites.org/
       4             : // contact@m2osw.com
       5             : //
       6             : // Permission is hereby granted, free of charge, to any person obtaining a
       7             : // copy of this software and associated documentation files (the
       8             : // "Software"), to deal in the Software without restriction, including
       9             : // without limitation the rights to use, copy, modify, merge, publish,
      10             : // distribute, sublicense, and/or sell copies of the Software, and to
      11             : // permit persons to whom the Software is furnished to do so, subject to
      12             : // the following conditions:
      13             : //
      14             : // The above copyright notice and this permission notice shall be included
      15             : // in all copies or substantial portions of the Software.
      16             : //
      17             : // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
      18             : // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
      19             : // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
      20             : // IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
      21             : // CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
      22             : // TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
      23             : // SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      24             : 
      25             : #include "./demangle.h"
      26             : 
      27             : // C++ includes
      28             : //
      29             : #include <cxxabi.h>
      30             : #include <memory>
      31             : 
      32             : 
      33             : /** \file
      34             :  * \brief Implementation of the demandler functions.
      35             :  *
      36             :  * This file includes functions we can use to demangle C++ names.
      37             :  */
      38             : 
      39             : 
      40             : 
      41             : namespace libexcept
      42             : {
      43             : 
      44             : 
      45             : 
      46             : /** \brief Demangle the specified type string.
      47             :  *
      48             :  * C++ offers a `typeid(\<type>).name()` function, only that does not
      49             :  * return a readable name in many cases. This function transforms that
      50             :  * name back to the original. This is particularly useful for C++ base
      51             :  * types. For example "unsigned short" becomes "t". To verify a type,
      52             :  * it is quite practical.
      53             :  *
      54             :  * This function demangles all names, including those we get when
      55             :  * building a stack trace.
      56             :  *
      57             :  * \note
      58             :  * This is similar to using the c++filt command line tool. If the
      59             :  * conversion fails, then the function returns the input string as is.
      60             :  *
      61             :  * \note
      62             :  * I found a piece of code snippet on Catch2 which is used to demangle a C++
      63             :  * name. It is one simple ABI call!
      64             :  *
      65             :  * \code
      66             :  * #include "catch.hpp"
      67             :  *
      68             :  * #include <cxxabi.h>
      69             :  * #include <typeinfo>
      70             :  *
      71             :  * CATCH_TRANSLATE_EXCEPTION(std::exception& e) {
      72             :  *   std::string s;
      73             :  *   int status;
      74             :  *
      75             :  *   const char* name = typeid(e).name();
      76             :  *   char* realname = abi::__cxa_demangle(name, 0, 0, &status);
      77             :  *   if(realname) {
      78             :  *     s.append(realname);
      79             :  *   } else {
      80             :  *     s.append(name);
      81             :  *   }
      82             :  *   s.append(": ");
      83             :  *   s.append(e.what());
      84             :  *   free(realname);
      85             :  *   return s;
      86             :  * }
      87             :  * \endcode
      88             :  *
      89             :  * Source: https://github.com/catchorg/Catch2/issues/539
      90             :  *
      91             :  * \param[in] type_id_name  The mangled C++ name.
      92             :  *
      93             :  * \return The converted name.
      94             :  *
      95             :  * \sa https://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.3/a01696.html
      96             :  */
      97          29 : std::string demangle_cpp_name(char const * type_id_name)
      98             : {
      99             : #if 1
     100          29 :     int status(0);
     101             : 
     102          29 :     std::unique_ptr<char, void(*)(void*)> res {
     103             :         abi::__cxa_demangle(type_id_name, nullptr, nullptr, &status),
     104             :         std::free
     105          58 :     };
     106             : 
     107          29 :     return status == 0
     108             :                 ? res.get()
     109          87 :                 : type_id_name;
     110             : #else
     111             :     // keeping the fallback in case the ABI stops working over time
     112             :     // this is "very" slow since it runs an external tool (c++filt)
     113             :     //
     114             :     std::string cppfilt("c++filt "
     115             :                       + raw_function_name);
     116             :     std::unique_ptr<FILE, decltype(&::pclose)> p(popen(cppfilt.c_str(), "r"), &::pclose);
     117             :     for(;;)
     118             :     {
     119             :         int const c(fgetc(p.get()));
     120             :         if(c == EOF)
     121             :         {
     122             :             break;
     123             :         }
     124             :         if(c != '\n')
     125             :         {
     126             :             result += c;
     127             :         }
     128             :     }
     129             : #endif
     130             : }
     131             : 
     132             : 
     133             : 
     134             : }
     135             : // namespace libexcept
     136             : // vim: ts=4 sw=4 et