Nuria::UnixSignalHandler Class Reference

Utility class to react to UNIX signals in a Qt fashion. More...

#include <unixsignalhandler.hpp>

Inheritance diagram for Nuria::UnixSignalHandler:

Signals
void	sigInterrupt ()
void	signalRaised (int signalId)
void	sigTerm ()
void	sigUser1 ()
void	sigUser2 ()

Public Member Functions
	~UnixSignalHandler () override
bool	ignoreUnixSignal (int signalId)
void	invokeOnSignal (int signalId, const Callback &callback)
bool	isListeningTo (int signalId)
bool	listenToUnixSignal (int signalId)

Static Public Member Functions
static UnixSignalHandler *	get ()

Detailed Description

Utility class to react to UNIX signals in a Qt fashion.

Usage

To install your own handler, all you have to do is to tell the class that it should install a signal handler itself using listenToUnixSignal(). After that, you can connect to the various Qt signals which are emitted when a UNIX signal was triggered.

To uninstall a UNIX handler use ignoreUnixSignal().

Note

Connected signals and callbacks don't have to be signal-safe as they're run outside the signal itself.

Restrictions

Please note that the UNIX signal system is quite fragile. Other code may replace the installed signal handlers without warning.

When unregistering, the class tries to restore the old handler. If the old handler is invalid at this point, the result will be undefined behaviour likely crashing the process.

If there is another UNIX signal handler at time of registration, the old one will not be called, which can potentionally break other code. Please note that Qt installs a handler on SIGCHLD for QProcess - Thus you should not install your own handler on that UNIX signal.

See also sigaction(3) for in-depth details.

Constructor & Destructor Documentation

Nuria::UnixSignalHandler::~UnixSignalHandler ( )

override

Destructor.

Member Function Documentation

static UnixSignalHandler* Nuria::UnixSignalHandler::get ( )

static

Returns the global instance.

bool Nuria::UnixSignalHandler::ignoreUnixSignal

(

int

signalId

)

Will unregister the handler of signalId. Returns true on success. Returns false when signalId is not listened to or if deregistration failed.

void Nuria::UnixSignalHandler::invokeOnSignal	(	int	signalId,
		const Callback &	callback
	)

Instructs the class to invoke callback when unixSignal has been caught. unixSignal may be AllSignals. callback will receive the signal identifier of type int as only argument.

Note

The method will try to register a handler for unixSignal if it's not already listened to by the class.

bool Nuria::UnixSignalHandler::isListeningTo

(

int

signalId

)

Returns true if signalId is currently listened to, that means, if the class has a registered handler for it.

bool Nuria::UnixSignalHandler::listenToUnixSignal

(

int

signalId

)

The class will attempt to register as signal handler for signalId. If registration fails, false is returned. When already listening to signalId, true is returned.

void Nuria::UnixSignalHandler::sigInterrupt ( )

signal

Emitted on SIGINT.

void Nuria::UnixSignalHandler::signalRaised ( int  signalId )

signal

Emitted when any signal has been raised.

See also

listenToUnixSignal

void Nuria::UnixSignalHandler::sigTerm ( )

signal

Emitted on SIGTERM.

void Nuria::UnixSignalHandler::sigUser1 ( )

signal

Emitted on SIGUSR1.

void Nuria::UnixSignalHandler::sigUser2 ( )

signal

Emitted on SIGUSR2.

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The documentation for this class was generated from the following file:

• unixsignalhandler.hpp