add contrib directory & contents

contrib/interface-demo2/util.h

@@ -0,0 +1,19 @@
+#include <stddef.h>
+
+void *xmalloc(size_t sz);
+void *xrealloc(void *p, size_t sz);
+
+#define new(p) ((p) = xmalloc(sizeof(*(p))))
+
+
+int kernel_version(void);
+#define KRELEASE(maj,min,patch) ((maj) * 10000 + (min)*1000 + (patch))
+
+
+int nstrcmp(const char *, const char *);
+
+char *safe_strncpy(char *dst, const char *src, size_t size); 
+
+
+#define netmin(a,b) ((a)<(b) ? (a) : (b))
+#define netmax(a,b) ((a)>(b) ? (a) : (b))