From e19994c34c4225185860cd9f2d2aab46a04347e6 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Thu, 30 May 2013 09:00:13 +1000
Subject: [PATCH] Add log func handling

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
---
 libevdev/libevdev-int.h |  2 ++
 libevdev/libevdev.c     | 26 ++++++++++++++++++++++++++
 libevdev/libevdev.h     | 18 ++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/libevdev/libevdev-int.h b/libevdev/libevdev-int.h
index c86a656..b231a81 100644
--- a/libevdev/libevdev-int.h
+++ b/libevdev/libevdev-int.h
@@ -41,6 +41,8 @@ struct libevdev {
 	libevdev_callback_proc sync_callback;
 	void *userdata;
 
+	libevdev_log_func_t log;
+
 	char name[MAX_NAME];
 	struct input_id ids;
 	unsigned long bits[NLONGS(EV_CNT)];
diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index 2b9dd17..2e74edd 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -25,6 +25,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <stdarg.h>
 
 #include "libevdev.h"
 #include "libevdev-int.h"
@@ -134,6 +135,21 @@ init_event_queue(struct libevdev *dev)
 	return 0;
 }
 
+static void
+_libevdev_log(struct libevdev *dev, const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	dev->log(format, args);
+	va_end(args);
+}
+
+static void
+libevdev_noop_log_func(const char *format, va_list args)
+{
+}
+
 struct libevdev*
 libevdev_new(int fd)
 {
@@ -141,6 +157,7 @@ libevdev_new(int fd)
 
 	dev = calloc(1, sizeof(*dev));
 	dev->num_slots = -1;
+	dev->log = libevdev_noop_log_func;
 
 	if (fd >= 0)
 		libevdev_set_fd(dev, fd);
@@ -155,6 +172,12 @@ libevdev_free(struct libevdev *dev)
 	free(dev);
 }
 
+void
+libevdev_set_log_handler(struct libevdev *dev, libevdev_log_func_t logfunc)
+{
+	dev->log = logfunc ? logfunc : libevdev_noop_log_func;
+}
+
 int
 libevdev_change_fd(struct libevdev *dev, int fd)
 {
@@ -171,6 +194,7 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	int i;
 
 	if (dev->fd == -1) {
+		libevdev_log_func_t log;
 		libevdev_callback_proc cb, scb;
 		void *userdata;
 
@@ -178,6 +202,7 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 		cb = dev->callback;
 		scb = dev->sync_callback;
 		userdata = dev->userdata;
+		log = dev->log;
 
 		memset(dev, 0, sizeof(*dev));
 
@@ -185,6 +210,7 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 		dev->callback = cb;
 		dev->sync_callback = scb;
 		dev->userdata = userdata;
+		dev->log = log;
 	}
 
 	rc = ioctl(fd, EVIOCGBIT(0, sizeof(dev->bits)), dev->bits);
diff --git a/libevdev/libevdev.h b/libevdev/libevdev.h
index a1787ee..7339c30 100644
--- a/libevdev/libevdev.h
+++ b/libevdev/libevdev.h
@@ -52,6 +52,24 @@ struct libevdev* libevdev_new(int fd);
  */
 void libevdev_free(struct libevdev *dev);
 
+/**
+ * Logging function called by library-internal logging.
+ * This function is expected to treat it's input like printf would.
+ *
+ * @param format printf-style format string
+ * @param args List of arguments
+ *
+ * @see libevdev_set_log_handler
+ */
+typedef void (*libevdev_log_func_t)(const char *format, va_list args);
+
+/**
+ * Set a printf-style logging handler for library-internal logging.
+ *
+ * @note This function may be called before libevdev_set_fd.
+ */
+void libevdev_set_log_handler(struct libevdev *dev, libevdev_log_func_t logfunc);
+
 /**
  * Grab or ungrab the device through a kernel EVIOCGRAB. This prevents other
  * clients (including kernel-internal ones such as rfkill) from receiving