diff -r -u slim-1.3.6/log.cpp slim-1.3.6.new/log.cpp
--- slim-1.3.6/log.cpp	2013-10-02 00:38:05.000000000 +0200
+++ slim-1.3.6.new/log.cpp	2016-02-12 23:31:58.229257277 +0100
@@ -1,23 +1,37 @@
 #include "log.h"
 #include <iostream>
 
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
 bool
 LogUnit::openLog(const char * filename)
 {
-	if (logFile.is_open()) {
+	if ( closeLog() )
+	{
 		cerr << APPNAME
 			<< ": opening a new Log file, while another is already open"
 			<< endl;
-		logFile.close();
 	}
-	logFile.open(filename, ios_base::app);
+
+	// go through quite some trouble to get a close-on-exec file
+	// descriptor and wrapping it into an ostream object for easing
+	// logging
+
+	fileBuffer.open( filename, ios_base::app );
+	fcntl(fileBuffer.fd(), F_SETFD, FD_CLOEXEC);
+	logFile.rdbuf( &fileBuffer );
 
 	return !(logFile.fail());
 }
 
-void
+bool
 LogUnit::closeLog()
 {
-	if (logFile.is_open())
-		logFile.close();
+	if( ! fileBuffer.is_open() )
+		return false;
+
+	fileBuffer.close();
+	return true;
 }
diff -r -u slim-1.3.6/log.h slim-1.3.6.new/log.h
--- slim-1.3.6/log.h	2013-10-02 00:38:05.000000000 +0200
+++ slim-1.3.6.new/log.h	2016-02-12 23:31:09.797498557 +0100
@@ -8,16 +8,20 @@
 #include "PAM.h"
 #endif
 #include "const.h"
+#include <ext/stdio_filebuf.h>
 #include <fstream>
 
 using namespace std;
 
 static class LogUnit {
-	ofstream logFile;
+	typedef __gnu_cxx::stdio_filebuf<char> FileDescBuffer;
+	FileDescBuffer fileBuffer;
+	ostream logFile;
 public:
 	bool openLog(const char * filename);
-	void closeLog();
+	bool closeLog();
 
+	LogUnit() : logFile(&fileBuffer) { }
 	~LogUnit() { closeLog(); }
 
 	template<typename Type>