/home/ptr/dev/dev-libs/libsex/libsex/Exception.cxx

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/**
 * @file
 *
 * Definition of @ref libsex::Exception.
 */

#include <libsex/Exception.hxx>
#include <cstring> // strncpy()

libsex::Exception::Exception(const char* const message)
throw()
: _previous(0)
{
        _initMessage(message);
}

libsex::Exception::Exception(
        const char* const message,
        const Exception& previous)
throw()
: _previous(0)
{
        _initMessage(message);
        try {
                _previous = previous.clone();
        } catch (std::bad_alloc& e) {
                // We need to know the amount of characters
                // that can be put into _message.

                // Size to begin with:
                unsigned int length = Exception::LENGTH;
                // Substract characters written so far:
                length -= strlen(_message);
                // Substract nullbyte appended by strcat().
                // Prevent underflow.
                if (length > 0) --length;

                // Add notice to our original message:
                strncat(_message, "\n"
                        "std::bad_alloc while cloning Exception!",
                        length);
        }
}

libsex::Exception::~Exception()
throw()
{
        if (_previous) delete _previous;
}

void libsex::Exception::write(std::ostream& out) const
throw(std::ios_base::failure)
{
        out << what();
}

void libsex::Exception::backtrace(std::ostream& out) const
throw(std::ios_base::failure)
{
        write(out);
        if (_previous != 0) {
                out << "\n";
                _previous->backtrace(out);
        }
}

const libsex::Exception* libsex::Exception::clone() const
throw(std::bad_alloc)
{
        if (_previous) {
                return new Exception(_message, *_previous);
        } else {
                return new Exception(_message);
        }
}

const char* libsex::Exception::what() const
throw()
{
        return _message;
}

void libsex::Exception::_initMessage(const char* const message)
{
        strncpy(_message, message, Exception::LENGTH);
        // if |message| < |_message|
        //      strncpy() will pad with 0
        // else
        //      strncpy() will NOT add a trailing 0!
        _message[Exception::LENGTH] = 0;
}