Refactor signal handling in pvsprivinputd

Only use one socketpair and delegate the actual decision of what to do
when a specific signal is received to a special object.

6 files changed, 155 insertions, 18 deletions

diff --git a/src/input/CMakeLists.txt b/src/input/CMakeLists.txt
index 29c463a..fcb5ff5 100644
--- a/src/input/CMakeLists.txt
+++ b/src/input/CMakeLists.txt
@@ -18,6 +18,7 @@ if(UNIX)
 		pvsprivinputd.cpp
 		pvsPrivInputHandler.cpp
 		pvsCheckPrivileges.cpp
+		pvsPrivInputSignalHandler.cpp
 		rebootSystemHandler.cpp
 		killX11Handler.cpp
 		sayHelloHandler.cpp
@@ -26,6 +27,7 @@ if(UNIX)
 	set(pvsprivinputd_MOC_HDRS
 		pvsPrivInputHandler.h
 		pvsCheckPrivileges.h
+		pvsPrivInputSignalHandler.h
 	)
 
 	qt4_wrap_cpp(pvsprivinputd_MOC_SRCS
diff --git a/src/input/pvsPrivInputSignalHandler.cpp b/src/input/pvsPrivInputSignalHandler.cpp
new file mode 100644
index 0000000..b09c335
--- /dev/null
+++ b/src/input/pvsPrivInputSignalHandler.cpp
@@ -0,0 +1,69 @@
+/*
+ # Copyright (c) 2009 - OpenSLX Project, Computer Center University of Freiburg
+ #
+ # This program is free software distributed under the GPL version 2.
+ # See http://openslx.org/COPYING
+ #
+ # If you have any feedback please consult http://openslx.org/feedback and
+ # send your suggestions, praise, or complaints to feedback@openslx.org
+ #
+ # General information about OpenSLX can be found at http://openslx.org/
+ # --------------------------------------------------------------------------
+ # pvsPrivInputSignalHandler.cpp:
+ #  - Handle signals forwarded over a file descriptor - implementation
+ # --------------------------------------------------------------------------
+ */
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <signal.h>
+#include <cerrno>
+#include "pvsPrivInputSocket.h"
+#include "pvsPrivInputSignalHandler.h"
+
+void PVSPrivInputSignalHandler::signalReceived(int sigfd)
+{
+	int signum;
+
+	pid_t pid;
+	uid_t uid;
+	gid_t gid;
+	int err;
+	size_t siz = sizeof(signum);
+
+	if(!pvsPrivInputRecvMessage(sigfd, &signum, siz, pid, uid, gid, &err))
+	{
+		qWarning("Should have received a signal but could not read message: %s", strerror(err));
+		return;
+	}
+
+	if(siz != sizeof(signum))
+	{
+		qWarning("Sould have received a message of size %d bytes but got %d bytes instead. Discarding message.", (int)sizeof(signum), (int)siz);
+		return;
+	}
+
+	if(!_allowUnauthenticatedKilling && pid != getpid())
+	{
+		qCritical("SOMETHING STRANGE IS GOING ON!\nReceived signal %d from PID %d\nPlease kill me instead of sending me signal notifications.", signum, (int)pid);
+		return;
+	}
+
+	switch(signum)
+	{
+	case SIGINT:
+		qDebug("Caught SIGINT. Quitting.");
+		emit terminate();
+		break;
+	case SIGTERM:
+		qDebug("Caught SIGTERM. Quitting.");
+		emit terminate();
+		break;
+	case SIGHUP:
+		qDebug("Caught SIGHUP. Reloading configuration.");
+		emit reloadConfiguration();
+		break;
+	default:
+		qWarning("Received signal %d, but don't know how to handle it.", signum);
+	}
+}
diff --git a/src/input/pvsPrivInputSignalHandler.h b/src/input/pvsPrivInputSignalHandler.h
new file mode 100644
index 0000000..cb75c86
--- /dev/null
+++ b/src/input/pvsPrivInputSignalHandler.h
@@ -0,0 +1,47 @@
+/*
+ # Copyright (c) 2009 - OpenSLX Project, Computer Center University of Freiburg
+ #
+ # This program is free software distributed under the GPL version 2.
+ # See http://openslx.org/COPYING
+ #
+ # If you have any feedback please consult http://openslx.org/feedback and
+ # send your suggestions, praise, or complaints to feedback@openslx.org
+ #
+ # General information about OpenSLX can be found at http://openslx.org/
+ # --------------------------------------------------------------------------
+ # pvsPrivInputSignalHandler.h:
+ #  - Handle signals forwarded over a file descriptor - interface
+ # --------------------------------------------------------------------------
+ */
+
+#ifndef PVSPRIVINPUTSIGNALHANDLER_H_
+#define PVSPRIVINPUTSIGNALHANDLER_H_
+
+#include <QObject>
+
+class PVSPrivInputSignalHandler : public QObject
+{
+	Q_OBJECT
+public:
+	PVSPrivInputSignalHandler(QObject* parent = 0)
+		: QObject(parent)
+	{
+	}
+
+	void allowUnauthenticatedKilling(bool value)
+	{
+		_allowUnauthenticatedKilling = value;
+	}
+
+public slots:
+	void signalReceived(int sigfd);
+
+signals:
+	void terminate();
+	void reloadConfiguration();
+
+private:
+	bool _allowUnauthenticatedKilling;
+};
+
+#endif /* PVSPRIVINPUTSIGNALHANDLER_H_ */
diff --git a/src/input/pvsPrivInputSocket.cpp b/src/input/pvsPrivInputSocket.cpp
index c491dd9..df5dff5 100644
--- a/src/input/pvsPrivInputSocket.cpp
+++ b/src/input/pvsPrivInputSocket.cpp
@@ -60,6 +60,17 @@ QString pvsPrivInputGetSocketAddress()
 	return pvsPrivInputGetSettings()->value("socketpath", "/tmp/pvsprivinputd.sock").toString();
 }
 
+bool pvsPrivInputEnableReceiveCredentials(int sock)
+{
+	int passcred = 1;
+	if(setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &passcred, sizeof(passcred)) < 0)
+	{
+		return false;
+	}
+	else
+	{
+		return true;
+	}
 }
 
 int pvsPrivInputMakeClientSocket()
@@ -110,8 +121,7 @@ int pvsPrivInputMakeServerSocket()
 	}
 
 	// Announce that credentials are requested:
-	int passcred = 1;
-	if(setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &passcred, sizeof(passcred)) < 0)
+	if(!pvsPrivInputEnableReceiveCredentials(sock))
 	{
 		// We will not operate without credentials.
 		qCritical("Could not request peer credentials: %s", strerror(errno));
diff --git a/src/input/pvsPrivInputSocket.h b/src/input/pvsPrivInputSocket.h
index 879ca99..447360b 100644
--- a/src/input/pvsPrivInputSocket.h
+++ b/src/input/pvsPrivInputSocket.h
@@ -28,6 +28,7 @@ QSettings* pvsPrivInputGetSettings();
 QSettings* pvsPrivInputReopenSettings();
 QString pvsPrivInputGetSettingsPath();
 QString pvsPrivInputGetSocketAddress();
+bool pvsPrivInputEnableReceiveCredentials(int sock);
 int pvsPrivInputMakeClientSocket();
 int pvsPrivInputMakeServerSocket();
 bool pvsPrivInputSendMessage(int sock, void* buf, size_t len, int* err = 0);
diff --git a/src/input/pvsprivinputd.cpp b/src/input/pvsprivinputd.cpp
index 3a5e1a8..361bf9f 100644
--- a/src/input/pvsprivinputd.cpp
+++ b/src/input/pvsprivinputd.cpp
@@ -30,6 +30,7 @@
 #include <QSocketNotifier>
 #include "pvsPrivInputSocket.h"
 #include "pvsPrivInputHandler.h"
+#include "pvsPrivInputSignalHandler.h"
 
 using namespace std;
 
@@ -38,7 +39,7 @@ using namespace std;
 #endif
 
 QByteArray socketPath;
-int sigintFds[2];
+int signalFds[2];
 
 static void unlinkSocket()
 {
@@ -48,12 +49,9 @@ static void unlinkSocket()
 	}
 }
 
-static void onInterrupt(int)
+static void onCaughtSignal(int signum)
 {
-	char buf[] = { '!' };
-	char msg[] = "SIGINT caught. Quitting.\n";
-	write(sigintFds[0], buf, 1);
-	write(1, msg, sizeof(msg)-1);
+	pvsPrivInputSendMessage(signalFds[0], &signum, sizeof(signum), 0);
 }
 
 int main(int argc, char** argv)
@@ -103,28 +101,38 @@ int main(int argc, char** argv)
 	// the socket (access control is handled differently):
 	umask(0);
 
+	// Store the socket path before the signal handler is installed so it does not risk segfaulting
+	// due to bad timing.
+	socketPath = pvsPrivInputGetSocketAddress().toLocal8Bit();
+
 	// Ignore SIGPIPE. Connection errors are handled internally.
 	// According to signal(2), the only error is that the signal number
 	// is invalid. This cannot happen.
 	signal(SIGPIPE, SIG_IGN);
 
-	// set up signal handling:
-	if(socketpair(AF_UNIX, SOCK_STREAM, 0, sigintFds) < 0)
+	// Create our socket:
+	int sock = pvsPrivInputMakeServerSocket();
+	if(sock < 0)
 	{
-		qCritical("Could not set up signal handling. Giving up.");
 		exit(EXIT_FAILURE);
 	}
-	socketPath = pvsPrivInputGetSocketAddress().toLocal8Bit();
-	QSocketNotifier sigintWatcher(sigintFds[1], QSocketNotifier::Read);
-	QObject::connect(&sigintWatcher, SIGNAL(activated(int)), &app, SLOT(quit()));
-	signal(SIGINT, onInterrupt);
 
-	// Create our socket:
-	int sock = pvsPrivInputMakeServerSocket();
-	if(sock < 0)
+	// set up signal handling:
+	if(socketpair(AF_UNIX, SOCK_DGRAM, 0, signalFds) < 0)
 	{
+		qCritical("Could not set up signal handling. Giving up.");
 		exit(EXIT_FAILURE);
 	}
+	PVSPrivInputSignalHandler sigHandler;
+	QSocketNotifier sigintWatcher(signalFds[1], QSocketNotifier::Read);
+	sigHandler.allowUnauthenticatedKilling(!pvsPrivInputEnableReceiveCredentials(signalFds[1]));
+	QObject::connect(&sigintWatcher, SIGNAL(activated(int)), &sigHandler, SLOT(signalReceived(int)));
+	QObject::connect(&sigHandler, SIGNAL(terminate()), &app, SLOT(quit()));
+	QObject::connect(&sigHandler, SIGNAL(reloadConfiguration()), PVSCheckPrivileges::instance(), SLOT(updateCachedUserDatabase()));
+	QObject::connect(&sigHandler, SIGNAL(reloadConfiguration()), PVSCheckPrivileges::instance(), SLOT(rereadConfiguration()));
+	signal(SIGINT, onCaughtSignal);
+	signal(SIGTERM, onCaughtSignal);
+	signal(SIGHUP, onCaughtSignal);
 
 	// Our setup is complete.
 	if(!no_fork)