Improved logging with various log levels

debug.c

@@ -6,10 +6,9 @@
  * README for terms of use. 
  */
 
-#ifndef NDEBUG
-
 #include "config.h"
 
+#include <assert.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <ctype.h>
@@ -25,6 +24,25 @@
 #include "debug.h"
 #include "net.h"
 
+static coap_log_t maxlog = LOG_WARN;	/* default maximum log level */
+
+coap_log_t 
+coap_get_log_level() {
+  return maxlog;
+}
+
+void
+coap_set_log_level(coap_log_t level) {
+  maxlog = level;
+}
+
+/* this array has the same order as the type log_t */
+static char *loglevels[] = {
+  "EMRG", "ALRT", "CRIT", "WARN", "NOTE", "INFO", "DEBG" 
+};
+
+#ifndef NDEBUG
+
 #ifdef HAVE_TIME_H
 
 static inline size_t
@@ -62,18 +80,27 @@ strnlen(unsigned char *s, size_t maxlen) {
   return n;
 }
 
-void debug(char *format, ...) {
-  static char timebuf[32];
-
+void 
+coap_log(coap_log_t level, char *format, ...) {
+  char timebuf[32];
   coap_tick_t now;
   va_list ap;
+  FILE *log_fd;
+
+  if (maxlog < level)
+    return;
+  
+  log_fd = level <= LOG_CRIT ? COAP_ERR_FD : COAP_DEBUG_FD;
 
   coap_ticks(&now);
   if (print_timestamp(timebuf,sizeof(timebuf), now))
-    fprintf(COAP_DEBUG_FD, "%s ", timebuf);
+    fprintf(log_fd, "%s ", timebuf);
+
+  if (level <= LOG_DEBUG)
+    fprintf(log_fd, "%s ", loglevels[level]);
 
   va_start(ap, format);
-  vfprintf(COAP_DEBUG_FD, format, ap);
+  vfprintf(log_fd, format, ap);
   va_end(ap);
   fflush(stdout);
 }
@@ -194,6 +221,4 @@ coap_show_pdu(const coap_pdu_t *pdu) {
   fflush(COAP_DEBUG_FD);
 }
 
-#else
-static inline void placeholder(void) {}
 #endif /* NDEBUG */

debug.h

@@ -9,13 +9,39 @@
 #ifndef _COAP_DEBUG_H_
 #define _COAP_DEBUG_H_
 
-#ifndef NDEBUG
-
 #ifndef COAP_DEBUG_FD
 #define COAP_DEBUG_FD stdout
 #endif
 
-void debug(char *,...);
+#ifndef COAP_ERR_FD
+#define COAP_ERR_FD stderr
+#endif
+
+/** Pre-defined log levels akin to what is used in \b syslog. */
+typedef enum { LOG_EMERG=0, LOG_ALERT, LOG_CRIT, LOG_WARN, 
+       LOG_NOTICE, LOG_INFO, LOG_DEBUG
+} coap_log_t;
+
+/** Returns the current log level. */
+coap_log_t coap_get_log_level();
+
+/** Sets the log level to the specified value. */
+void coap_set_log_level(coap_log_t level);
+
+/** 
+ * Writes the given text to @c COAP_ERR_FD (for @p level <= @c
+ * LOG_CRIT) or @c COAP_DEBUG_FD (for @p level >= @c LOG_WARN). The
+ * text is output only when @p level is below or equal to the log
+ * level that set by coap_set_log_level().
+ */
+void coap_log(coap_log_t level, char *format, ...);
+
+#ifndef NDEBUG
+
+/* A set of convenience macros for common log levels. */
+#define info(...) coap_log(LOG_INFO, __VA_ARGS__)
+#define warn(...) coap_log(LOG_WARN, __VA_ARGS__)
+#define debug(...) coap_log(LOG_DEBUG, __VA_ARGS__)
 
 #include "pdu.h"
 void coap_show_pdu(const coap_pdu_t *);
@@ -26,6 +52,9 @@ size_t coap_print_addr(const struct __coap_address_t *, unsigned char *, size_t)
 #else
 
 #define debug(...)
+#define info(...)
+#define warn(...)
+
 #define coap_show_pdu(x)
 #define coap_print_addr(...)