add log.c/log.h which contain all the log related macros and functions

include/log.h

@@ -0,0 +1,65 @@
+/*
+ * vim:ts=8:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ *
+ * © 2009 Michael Stapelberg and contributors
+ *
+ * See file LICENSE for license information.
+ *
+ */
+#ifndef _LOG_H
+#define _LOG_H
+
+#include <stdarg.h>
+
+/** ##__VA_ARGS__ means: leave out __VA_ARGS__ completely if it is empty, that
+   is, delete the preceding comma */
+#define LOG(fmt, ...) verboselog(fmt, ##__VA_ARGS__)
+#define ELOG(fmt, ...) errorlog("ERROR: " fmt, ##__VA_ARGS__)
+#define DLOG(fmt, ...) debuglog(LOGLEVEL, "%s:%s:%d - " fmt, __FILE__, __FUNCTION__, __LINE__, ##__VA_ARGS__)
+
+extern char *loglevels[];
+
+/**
+ * Enables the given loglevel.
+ *
+ */
+void add_loglevel(const char *level);
+
+/**
+ * Set verbosity of i3. If verbose is set to true, informative messages will
+ * be printed to stdout. If verbose is set to false, only errors will be
+ * printed.
+ *
+ */
+void set_verbosity(bool _verbose);
+
+/**
+ * Logs the given message to stdout while prefixing the current time to it,
+ * but only if the corresponding debug loglevel was activated.
+ *
+ */
+void debuglog(int lev, char *fmt, ...);
+
+/**
+ * Logs the given message to stdout while prefixing the current time to it.
+ *
+ */
+void errorlog(char *fmt, ...);
+
+/**
+ * Logs the given message to stdout while prefixing the current time to it,
+ * but only if verbose mode is activated.
+ *
+ */
+void verboselog(char *fmt, ...);
+
+/**
+ * Logs the given message to stdout while prefixing the current time to it.
+ * This is to be called by LOG() which includes filename/linenumber
+ *
+ */
+void slog(char *fmt, va_list args);
+
+#endif