Catch exception in boost::property_tree::read_xml

Question

I'm trying to catch exceptions that are raised by boost::property_tree::xml_parser::read_xml . Here is my example program:

 #include <iostream>
 #include <boost/property_tree/ptree.hpp>
 #include <boost/property_tree/xml_parser.hpp>
 int main(int argc, char** argv){
      boost::property_tree::ptree pt;
      std::cout<<"123123"<<std::endl;
      try{
        std::cout<<"Reading "<<argv[1]<<std::endl;
        read_xml(argv[1], pt);
      }
      catch(const boost::property_tree::xml_parser::xml_parser_error& ex){
        std::cout<<argv[1]<<" failed, reading "<<argv[2]<<std::endl;
        read_xml(argv[2], pt);
      }
 }

The output is:

123123
Reading 123.xml
[1]    97028 abort      ./a.out 123.xml 345.xml

What am I doing wrong? Obviously the exception isn't caught. I also tried to catch every thing via (...) and to catch std::exception as well as boost::exception . In all cases the result is the same. According to boost documentation a xml_parser_error should be thrown. My boost version is 1.54.

A Little update: When I don't try to just execute read_xml("notAValidFilePAth",pt), then I get

terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::property_tree::xml_parser::xml_parser_error> >'
  what():  123.xml: cannot open file

And when I run it with gdb I get:

Reading terminate called after throwing an instance of 
'boost::exception_detail::clone_impl<
       boost::exception_detail::error_info_injector<
           boost::property_tree::xml_parser::xml_parser_error> >'
  what():  PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/X11/bin:/usr/local/MacGPG2/bin:/opt/local/bin:/usr/texbin:/Users/weidenka/bin: 
 cannot open file
 Program received signal SIGABRT, Aborted.
    0x00007fff8a31b866 in __pthread_kill ()

#0  0x00007fff8a31b866 in __pthread_kill ()
#1  0x00007fff86c9f35c in pthread_kill ()
#2  0x00007fff86240b1a in abort ()
#3  0x00000001005547d5 in __gnu_cxx::__verbose_terminate_handler ()

Thanks in advance!

Best wishes, Peter

Answer 1

This is your problem:

    read_xml(argv[2], pt);

The fallback read operation is not guarded against throwing an exception, so when an exception occurs at this point your program terminates without flushing the iostreams buffers.