C++ Exception-Handling Tricks for Linux
By Sachin O. Agrawal2005-04-12
Managing Signals
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Whenever a process performs an offending action such that the Linux™ kernel raises a signal, the signal must be handled. The signal handler generally releases the important resources and terminates the application. In this case, all the object instances on the stack are left un-destructed. On the other hand, if such signals are instead translated to C++ exceptions, you can gracefully invoke their destructors and program multiple levels of catch blocks to better deal with the signals.
SignalExceptionClass, defined in Listing 2, provides the abstraction of a C++ exception representing a signal that the kernel might rise. SignalTranslator is a template class based on SignalExceptionClass, which actually does the translation. There can be only one signal handler per signal per process active at any instant. Hence, SignalTranslator adopts a singleton design pattern. The whole concept is demonstrated using the SegmentationFault class for SIGSEGV and the FloatingPointException class for SIGFPE.
Listing 2. Translating signals to exceptions
templateclass SignalTranslator
{
private:
class SingleTonTranslator
{
public:
SingleTonTranslator()
{
signal(SignalExceptionClass::GetSignalNumber(), SignalHandler);
}
static void SignalHandler(int)
{
throw SignalExceptionClass();
}
};
public:
SignalTranslator()
{
static SingleTonTranslator s_objTranslator;
}
};
// An example for SIGSEGV
class SegmentationFault : public ExceptionTracer, public exception
{
public:
static int GetSignalNumber() {return SIGSEGV;}
};
SignalTranslatorg_objSegmentationFaultTranslator;
// An example for SIGFPE
class FloatingPointException : public ExceptionTracer, public exception
{
public:
static int GetSignalNumber() {return SIGFPE;}
};
SignalTranslatorg_objFloatingPointExceptionTranslator;
Tutorial Pages:
» Four Techniques for Dealing with Built-in Language Limitations
» Retaining exception source information
» Managing Signals
» Managing Exceptions in Constructors and Destructors
» Handling Exceptions in Multi-Threaded Programs
» Conclusion
» Resources
First published by IBM DeveloperWorks
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