itgmania212121/stepmania/src/archutils/Unix/SignalHandler.cpp

#include "global.h"

#include "RageLog.h"
#include "SignalHandler.h"
#include "GetSysInfo.h"

#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>

static vector<SignalHandler::handler> handlers;
SaveSignals *saved_sigs;
static bool initted = false;

static int signals[] = {
	SIGALRM, SIGBUS, SIGFPE, SIGHUP, SIGILL, SIGINT, SIGABRT, SIGPIPE,
	SIGQUIT, SIGSEGV, SIGTRAP, SIGTERM, SIGVTALRM, SIGXCPU, SIGXFSZ,
#if defined(HAVE_DECL_SIGPWR) && HAVE_DECL_SIGPWR
	SIGPWR,
#endif
	-1
};

/*
 * Store signals and restore them.  This lets us clean up after libraries
 * that like to mess with our signal handler.  (Of course, if we undo
 * signal handlers for libraries, we need to be sure to handle whatever it
 * was cleaning up by hand.)
 */

SaveSignals::SaveSignals()
{
	/* Store the old signal handlers. */
	for(int i = 0; signals[i] != -1; ++i)
	{
		struct sigaction sa;
		sigaction(signals[i], NULL, &sa);
		old_handlers.push_back(sa);
	}
}

SaveSignals::~SaveSignals()
{
	/* Restore the old signal handlers. */
	for(unsigned i = 0; i < old_handlers.size(); ++i)
		sigaction(signals[i], &old_handlers[i], NULL);
}

static void SigHandler(int sig)
{
	for(unsigned i = 0; i < handlers.size(); ++i)
		handlers[i](sig);
}

/* Hook up events to fatal signals, so we can clean up if we're killed. */
void SignalHandler::OnClose(handler h)
{
	if(saved_sigs == NULL)
	{
		saved_sigs = new SaveSignals;

		/* Allocate a separate signal stack.  This makes the crash handler work
		 * if we run out of stack space. */
		/* Ugh.  Signal stack + pthreads + Linux 2.4 = crash or hang. */
		CString system;
		int version;
		GetKernel( system, version );
		void *p = NULL;
		const int AltStackSize = 1024*64;
		if( version > 20500 )
			p = mmap( NULL, AltStackSize, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 );

		if( p == (void *) -1 )
			p = malloc( AltStackSize );

		if( p != NULL )
		{
			stack_t ss;
			ss.ss_sp = p;
			ss.ss_size = AltStackSize;
			ss.ss_flags = 0;
			if( sigaltstack( &ss, NULL ) == -1 )
			{
				LOG->Info( "sigaltstack failed: %s", strerror(errno) );
				p = NULL; /* no SA_ONSTACK */
			}
		}
		
		/* Set up our signal handlers. */
		for(int i = 0; signals[i] != -1; ++i)
		{
			struct sigaction sa;

			sa.sa_handler = SigHandler;
			sa.sa_flags = p != NULL? SA_ONSTACK:0;
			sigemptyset(&sa.sa_mask);

			sigaction(signals[i], &sa, NULL);
		}
	}
	handlers.push_back(h);
}


/* Written by Glenn Maynard.  Public domain, copyrighting a simple signal handler
 * is dumb. */