Log to stderr by default

The logging we do use atm inside the library is largely
to spot application errors. Log that to stderr by default so
it doesn't get lost.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>

1 files changed, 27 insertions, 3 deletions

diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index dcf2beb..aa5cbd6 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -49,11 +49,32 @@ init_event_queue(struct libevdev *dev)
 }
 
 static void
-libevdev_noop_log_func(enum libevdev_log_priority priority,
+libevdev_dflt_log_func(enum libevdev_log_priority priority,
 		       void *data,
 		       const char *file, int line, const char *func,
 		       const char *format, va_list args)
 {
+	const char *prefix;
+	switch(priority) {
+		case LIBEVDEV_LOG_ERROR: prefix = "libevdev error"; break;
+		case LIBEVDEV_LOG_INFO: prefix = "libevdev info"; break;
+		case LIBEVDEV_LOG_DEBUG:
+					prefix = "libevdev debug";
+					break;
+		default:
+					break;
+	}
+	/* default logging format:
+	   libevev error in libevdev_some_func: blah blah
+	   libevev info in libevdev_some_func: blah blah
+	   libevev debug in file.c:123:libevdev_some_func: blah blah
+	 */
+
+	fprintf(stderr, "%s in ", prefix);
+	if (priority == LIBEVDEV_LOG_DEBUG)
+		fprintf(stderr, "%s:%d:", file, line);
+	fprintf(stderr, "%s: ", func);
+	vfprintf(stderr, format, args);
 }
 
 /*
@@ -61,7 +82,7 @@ libevdev_noop_log_func(enum libevdev_log_priority priority,
  */
 struct logdata log_data = {
 	LIBEVDEV_LOG_INFO,
-	libevdev_noop_log_func,
+	libevdev_dflt_log_func,
 	NULL,
 };
 
@@ -73,6 +94,9 @@ log_msg(enum libevdev_log_priority priority,
 {
 	va_list args;
 
+	if (!log_data.handler)
+		return;
+
 	va_start(args, format);
 	log_data.handler(priority, data, file, line, func, format, args);
 	va_end(args);
@@ -137,7 +161,7 @@ libevdev_set_log_handler(struct libevdev *dev, libevdev_log_func_t logfunc)
 LIBEVDEV_EXPORT void
 libevdev_set_log_function(libevdev_log_func_t logfunc, void *data)
 {
-	log_data.handler = logfunc ? logfunc : libevdev_noop_log_func;
+	log_data.handler = logfunc;
 	log_data.userdata = data;
 }