src/Exception.cxx

   1 #include <libsex/Exception.hxx>
   2 #include <cstring> // strncpy()
   3
   4 namespace libsex {
   5
   6 Exception::Exception(const char* const message) throw()
   7 : _previous(0)
   8 {
   9         _initMessage(message);
  10 }
  11
  12 Exception::Exception(
  13         const char* const message,
  14         const Exception& previous) throw()
  15 : _previous(0)
  16 {
  17         _initMessage(message);
  18         try {
  19                 _previous = previous.clone();
  20         } catch (std::bad_alloc& e) {
  21                 // We need to know the amount of characters
  22                 // that can be put into _message.
  23
  24                 // Size to begin with:
  25                 unsigned int length = Exception::LENGTH;
  26                 // Substract characters written so far:
  27                 length -= strlen(_message);
  28                 // Substract nullbyte appended by strcat().
  29                 // Prevent underflow.
  30                 if (length > 0) --length;
  31
  32                 // Add notice to our original message:
  33                 strncat(_message, "\n"
  34                         "DOUBLE FAULT! "
  35                         "Caught std::bad_alloc in "
  36                         "constructor of an exception.",
  37                         length);
  38         }
  39 }
  40
  41 Exception::~Exception() throw()
  42 {
  43         if (_previous) delete _previous;
  44 }
  45
  46 void Exception::write(std::ostream& out) const throw(std::ios_base::failure)
  47 {
  48         out << what();
  49 }
  50
  51 void Exception::backtrace(std::ostream& out) const throw(std::ios_base::failure)
  52 {
  53         write(out);
  54         if (_previous != 0) {
  55                 out << "\n";
  56                 _previous->backtrace(out);
  57         }
  58 }
  59
  60 const Exception* Exception::clone() const
  61 throw(std::bad_alloc)
  62 {
  63         if (_previous) {
  64                 return new Exception(_message, *_previous);
  65         } else {
  66                 return new Exception(_message);
  67         }
  68 }
  69
  70 const char* Exception::what() const throw()
  71 {
  72         return _message;
  73 }
  74
  75 void Exception::_initMessage(const char* const message)
  76 {
  77         strncpy(_message, message, Exception::LENGTH);
  78         // if |message| < |_message|
  79         //      strncpy() will pad with 0
  80         // else
  81         //      strncpy() will NOT add a trailing 0!
  82         _message[Exception::LENGTH] = 0;
  83 }
  84
  85 } // namespace