Add debugging constructs

util.cpp

@@ -1,8 +1,22 @@
 #include <cstdio>
 #include <string.h>
+#include <stdarg.h>
 
 #include "util.hpp"
 
+int debug;
+
+void do_debugf(int level, const char *format, ...)
+{
+    va_list args;
+    va_start(args, format);
+    if(debug >= level) {
+        vfprintf(stderr, format, args);
+        fflush(stderr);
+    }
+    va_end(args);
+}
+
 MsgException::MsgException(const std::string& msg, int code, bool is_perror)
     : _msg(msg), _code(code)
 {

util.hpp

@@ -3,6 +3,47 @@
 #include <exception>
 #include <string>
 
+/* Debugging -- taken from babeld */
+
+extern int debug;
+
+#if defined(__GNUC__) && (__GNUC__ >= 3)
+#define ATTRIBUTE(x) __attribute__ (x)
+#define LIKELY(_x) __builtin_expect(!!(_x), 1)
+#define UNLIKELY(_x) __builtin_expect(!!(_x), 0)
+#else
+#define ATTRIBUTE(x) /**/
+#define LIKELY(_x) !!(_x)
+#define UNLIKELY(_x) !!(_x)
+#endif
+
+#if defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901L
+#define debugf(...) \
+    do { \
+        if(UNLIKELY(debug >= 2)) do_debugf(2, __VA_ARGS__);     \
+    } while(0)
+#define kdebugf(...) \
+    do { \
+        if(UNLIKELY(debug >= 3)) do_debugf(3, __VA_ARGS__);     \
+    } while(0)
+#elif defined __GNUC__
+#define debugf(_args...) \
+    do { \
+        if(UNLIKELY(debug >= 2)) do_debugf(2, _args);   \
+    } while(0)
+#define kdebugf(_args...) \
+    do { \
+        if(UNLIKELY(debug >= 3)) do_debugf(3, _args);   \
+    } while(0)
+#else
+static inline void debugf(const char *format, ...) { return; }
+static inline void kdebugf(const char *format, ...) { return; }
+#endif
+
+void do_debugf(int level, const char *format, ...);
+
+
+
 /** MsgException -- an exception bearing a passed explanation message
  *
  * If `is_perror` is true, then the `strerror` corresponding message is appened