[Cppcms-users] [BUG] Custom 'syslog.id' and 'openlog'

[Nazım C. B. <naz...@ne...>]

Hi Artyom,

For any reason, if user needs to specify custom syslog.id value; CppCMS 
is calling 'openlog' function with id variable stored on the stack.

According to

  * man page at https://linux.die.net/man/3/openlog, and
  * this Debian bug report at
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=102350

'openlog' is free to use given 'ident' pointer as-is (without making a 
copy of it). Even on Ubuntu 16.04 system, it's not copying given ident.

In the following code excerpt, the pointer given at the line colored 
with red will point to invalid memory location at the moment code reach 
to end of active if block.

_service.cpp_

     if(settings.get("logging.syslog.enable",false)==true) {
         #ifndef CPPCMS_POSIX
             throw cppcms_error("Syslog is not availible on Windows");
         #else
         std::string id = settings.get("logging.syslog.id","");
         std::vector<std::string> vops = 
settings.get("logging.syslog.options",std::vector<std::string>());
         std::string sfacility = settings.get("logging.syslog.options","");
         int ops = 0;
         for(unsigned i=0;i<vops.size();i++) {
             std::string const &op=vops[i];
             if(op=="LOG_CONS") ops|=LOG_CONS;
             else if(op=="LOG_NDELAY") ops|=LOG_NDELAY;
             else if(op=="LOG_NOWAIT") ops|=LOG_NOWAIT;
             else if(op=="LOG_ODELAY") ops|=LOG_ODELAY;
             #ifdef LOG_PERROR
             else if(op=="LOG_PERROR") ops|=LOG_PERROR;
             #endif
             else if(op=="LOG_PID") ops|=LOG_PID;
         }
         if(id.empty())
             ::openlog(0,ops,0);
         else
             ::openlog(id.c_str(),ops,0);
logger::instance().add_sink(booster::shared_ptr<sink>(new sinks::syslog()));
         #endif
     }

     std::string log_file;

Regards,
Nazim Can.