+#include <ecoli_assert.h>
+
+enum ec_log_level {
+ EC_LOG_EMERG = 0, /* system is unusable */
+ EC_LOG_ALERT = 1, /* action must be taken immediately */
+ EC_LOG_CRIT = 2, /* critical conditions */
+ EC_LOG_ERR = 3, /* error conditions */
+ EC_LOG_WARNING = 4, /* warning conditions */
+ EC_LOG_NOTICE = 5, /* normal but significant condition */
+ EC_LOG_INFO = 6, /* informational */
+ EC_LOG_DEBUG = 7, /* debug-level messages */
+};
+
+/**
+ * Register a log type.
+ *
+ * This macro defines a function that will be called at startup (using
+ * the "constructor" attribute). This function register the named type
+ * passed as argument, and sets a static global variable
+ * "ec_log_local_type". This variable is used as the default log type
+ * for this file when using EC_LOG() or EC_VLOG().
+ *
+ * This macro can be present several times in a file. In this case, the
+ * local log type is set to the last registered type.
+ *
+ * On error, the function aborts.
+ *
+ * @param name
+ * The name of the log to be registered.
+ */
+#define EC_LOG_TYPE_REGISTER(name) \
+ static int name##_log_type; \
+ static int ec_log_local_type; \
+ __attribute__((constructor, used)) \
+ static void ec_log_register_##name(void) \
+ { \
+ ec_log_local_type = ec_log_type_register(#name); \
+ ec_assert_print(ec_log_local_type >= 0, \
+ "cannot register log type.\n"); \
+ name##_log_type = ec_log_local_type; \
+ }
+
+/**
+ * User log function type.
+ *
+ * It is advised that a user-defined log function drops all messages
+ * that are at least as critical as ec_log_level_get(), as done by the
+ * default handler.
+ *
+ * @param type
+ * The log type identifier.
+ * @param level
+ * The log level.
+ * @param opaque
+ * The opaque pointer that was passed to ec_log_fct_register().
+ * @param str
+ * The string to log.
+ * @return
+ * 0 on success, -1 on error (errno is set).
+ */
+typedef int (*ec_log_t)(int type, enum ec_log_level level, void *opaque,
+ const char *str);
+
+/**
+ * Register a user log function.
+ *
+ * @param usr_log
+ * Function pointer that will be invoked for each log call.
+ * If the parameter is NULL, ec_log_default_cb() is used.
+ * @param opaque
+ * Opaque pointer passed to the log function.
+ * @return
+ * 0 on success, -1 on error (errno is set).
+ */
+int ec_log_fct_register(ec_log_t usr_log, void *opaque);
+
+/**
+ * Register a named log type.
+ *
+ * Register a new log type, which is identified by its name. The
+ * function returns a log identifier associated to the log name. If the
+ * name is already registered, the function just returns its identifier.
+ *
+ * @param name
+ * The name of the log type.
+ * @return
+ * The log type identifier on success (positive or zero), -1 on
+ * error (errno is set).
+ */
+int ec_log_type_register(const char *name);
+
+/**
+ * Return the log name associated to the log type identifier.
+ *
+ * @param type
+ * The log type identifier.
+ * @return
+ * The name associated to the log type, or "unknown". It always return
+ * a valid string (never NULL).
+ */
+const char *ec_log_name(int type);
+
+/**
+ * Log a formatted string.
+ *
+ * @param type
+ * The log type identifier.
+ * @param level
+ * The log level.
+ * @param format
+ * The format string, followed by optional arguments.
+ * @return
+ * 0 on success, -1 on error (errno is set).
+ */
+int ec_log(int type, enum ec_log_level level, const char *format, ...)
+ __attribute__((format(__printf__, 3, 4)));
+
+/**
+ * Log a formatted string.
+ *
+ * @param type
+ * The log type identifier.
+ * @param level
+ * The log level.
+ * @param format
+ * The format string.
+ * @param ap
+ * The list of arguments.
+ * @return
+ * 0 on success, -1 on error (errno is set).
+ */
+int ec_vlog(int type, enum ec_log_level level, const char *format, va_list ap);
+
+/**
+ * Log a formatted string using the local log type.
+ *
+ * This macro requires that a log type is previously register with
+ * EC_LOG_TYPE_REGISTER() since it uses the "ec_log_local_type"
+ * variable.
+ *
+ * @param level
+ * The log level.
+ * @param format
+ * The format string, followed by optional arguments.
+ * @return
+ * 0 on success, -1 on error (errno is set).
+ */
+#define EC_LOG(level, args...) ec_log(ec_log_local_type, level, args)