Allow plugins to call mosquitto_log_printf() (Linux only at the moment).

config.mk

@@ -120,7 +120,7 @@ LIB_LIBS:=
 PASSWD_LIBS:=
 
 ifeq ($(UNAME),Linux)
-	BROKER_LIBS:=$(BROKER_LIBS) -lrt
+	BROKER_LIBS:=$(BROKER_LIBS) -lrt -Wl,--dynamic-list=linker.syms
 	LIB_LIBS:=$(LIB_LIBS) -lrt
 endif
 

src/CMakeLists.txt

@@ -2,6 +2,16 @@ include_directories(${mosquitto_SOURCE_DIR} ${mosquitto_SOURCE_DIR}/src
 		${mosquitto_SOURCE_DIR}/lib ${OPENSSL_INCLUDE_DIR}
 		${STDBOOL_H_PATH} ${STDINT_H_PATH})
 
+if (UNIX)
+	set (CMAKE_EXE_LINKER_FLAGS "-Wl,--dynamic-list=${mosquitto_SOURCE_DIR}/src/linker.syms")
+	set (CMAKE_SHARED_LIBRARY_LINK_C_FLAGS "")
+endif (UNIX)
+
+# FIXME - something else needs fixing before this will work.
+#if (APPLE)
+#	set (CMAKE_EXE_LINKER_FLAGS "-Wl,-exported_symbols_list -Wl,${mosquitto_SOURCE_DIR}/src/linker-macosx.syms")
+#endif (APPLE)
+
 set (MOSQ_SRCS
 	conf.c
 	context.c

src/logging.c

@@ -81,9 +81,8 @@ int mqtt3_log_close(void)
 	return MOSQ_ERR_SUCCESS;
 }
 
-int _mosquitto_log_printf(struct mosquitto *mosq, int priority, const char *fmt, ...)
+int _mosquitto_log_vprintf(struct mosquitto *mosq, int priority, const char *fmt, va_list va)
 {
-	va_list va;
 	char *s;
 	char *st;
 	int len;
@@ -164,9 +163,7 @@ int _mosquitto_log_printf(struct mosquitto *mosq, int priority, const char *fmt,
 		s = _mosquitto_malloc(len*sizeof(char));
 		if(!s) return MOSQ_ERR_NOMEM;
 
-		va_start(va, fmt);
 		vsnprintf(s, len, fmt, va);
-		va_end(va);
 		s[len-1] = '\0'; /* Ensure string is null terminated. */
 
 		if(log_destinations & MQTT3_LOG_STDOUT){
@@ -221,3 +218,24 @@ int _mosquitto_log_printf(struct mosquitto *mosq, int priority, const char *fmt,
 	return MOSQ_ERR_SUCCESS;
 }
 
+int _mosquitto_log_printf(struct mosquitto *mosq, int priority, const char *fmt, ...)
+{
+	va_list va;
+	int rc;
+
+	va_start(va, fmt);
+	rc = _mosquitto_log_vprintf(mosq, priority, fmt, va);
+	va_end(va);
+
+	return rc;
+}
+
+void mosquitto_log_printf(int level, const char *fmt, ...)
+{
+	va_list va;
+
+	va_start(va, fmt);
+	_mosquitto_log_vprintf(NULL, level, fmt, va);
+	va_end(va);
+}
+

src/mosquitto_plugin.h

@@ -36,6 +36,48 @@ struct mosquitto_auth_opt {
  * gcc -I<path to mosquitto_plugin.h> -fPIC -shared plugin.c -o plugin.so
  */
 
+/* =========================================================================
+ *
+ * Utility Functions
+ *
+ * Use these functions from within your plugin.
+ *
+ * There are also very useful functions in libmosquitto.
+ *
+ * ========================================================================= */
+
+/*
+ * Function: mosquitto_log_printf
+ *
+ * Write a log message using the broker configured logging.
+ *
+ * Parameters:
+ * 	level -    Log message priority. Can currently be one of:
+ *
+ *             MOSQ_LOG_INFO
+ *             MOSQ_LOG_NOTICE
+ *             MOSQ_LOG_WARNING
+ *             MOSQ_LOG_ERR
+ *             MOSQ_LOG_DEBUG
+ *             MOSQ_LOG_SUBSCRIBE (not recommended for use by plugins)
+ *             MOSQ_LOG_UNSUBSCRIBE (not recommended for use by plugins)
+ *
+ *             These values are defined in mosquitto.h.
+ *
+ *	fmt, ... - printf style format and arguments.
+ */
+void mosquitto_log_printf(int level, const char *fmt, ...);
+
+
+
+/* =========================================================================
+ *
+ * Plugin Functions
+ *
+ * You must implement these functions in your plugin.
+ *
+ * ========================================================================= */
+
 /*
  * Function: mosquitto_auth_plugin_version
  *