libsex/Exception.cxx

   1 /**
   2  * @file
   3  *
   4  * Definition of @ref libsex::Exception.
   5  */
   6
   7 #include <libsex/Exception.hxx>
   8 #include <cstring> // strncpy()
   9
  10 libsex::Exception::Exception(const char* const message)
  11 throw()
  12 : _previous(0)
  13 {
  14         _initMessage(message);
  15 }
  16
  17 libsex::Exception::Exception(
  18         const char* const message,
  19         const Exception& previous)
  20 throw()
  21 : _previous(0)
  22 {
  23         _initMessage(message);
  24         try {
  25                 _previous = previous.clone();
  26         } catch (std::bad_alloc& e) {
  27                 // We need to know the amount of characters
  28                 // that can be put into _message.
  29
  30                 // Size to begin with:
  31                 unsigned int length = Exception::LENGTH;
  32                 // Substract characters written so far:
  33                 length -= strlen(_message);
  34                 // Substract nullbyte appended by strcat().
  35                 // Prevent underflow.
  36                 if (length > 0) --length;
  37
  38                 // Add notice to our original message:
  39                 strncat(_message, "\n"
  40                         "std::bad_alloc while cloning Exception!",
  41                         length);
  42         }
  43 }
  44
  45 libsex::Exception::~Exception()
  46 throw()
  47 {
  48         if (_previous) delete _previous;
  49 }
  50
  51 void libsex::Exception::write(std::ostream& out) const
  52 throw(std::ios_base::failure)
  53 {
  54         out << what();
  55 }
  56
  57 void libsex::Exception::backtrace(std::ostream& out) const
  58 throw(std::ios_base::failure)
  59 {
  60         write(out);
  61         if (_previous != 0) {
  62                 out << "\n";
  63                 _previous->backtrace(out);
  64         }
  65 }
  66
  67 const libsex::Exception* libsex::Exception::clone() const
  68 throw(std::bad_alloc)
  69 {
  70         if (_previous) {
  71                 return new Exception(_message, *_previous);
  72         } else {
  73                 return new Exception(_message);
  74         }
  75 }
  76
  77 const char* libsex::Exception::what() const
  78 throw()
  79 {
  80         return _message;
  81 }
  82
  83 void libsex::Exception::_initMessage(const char* const message)
  84 {
  85         strncpy(_message, message, Exception::LENGTH);
  86         // if |message| < |_message|
  87         //      strncpy() will pad with 0
  88         // else
  89         //      strncpy() will NOT add a trailing 0!
  90         _message[Exception::LENGTH] = 0;
  91 }