diff --git a/libevdev/libevdev-int.h b/libevdev/libevdev-int.h
index 61c2454..e77db32 100644
--- a/libevdev/libevdev-int.h
+++ b/libevdev/libevdev-int.h
@@ -38,6 +38,7 @@
 #define ABS_MT_MAX ABS_MT_TOOL_Y
 #define ABS_MT_CNT (ABS_MT_MAX - ABS_MT_MIN + 1)
 #define LIBEVDEV_EXPORT __attribute__((visibility("default")))
+#define LIBEVDEV_PRINTF(_format, _args) __attribute__ ((format (printf, _format, _args)))
 
 #undef min
 #undef max
@@ -71,8 +72,6 @@ enum SyncState {
 
 struct libevdev {
 	int fd;
-	libevdev_log_func_t log;
-
 	char *name;
 	char *phys;
 	char *uniq;
@@ -109,6 +108,30 @@ struct libevdev {
 	struct timeval last_event_time;
 };
 
+struct logdata {
+	enum libevdev_log_priority priority;	/** minimum logging priority */
+	libevdev_log_func_t handler;		/** handler function */
+	void *userdata;				/** user-defined data pointer */
+};
+extern struct logdata log_data;
+
+#define log_msg_cond(priority, ...) \
+	do { \
+		if (libevdev_get_log_priority() >= priority) \
+			log_msg(priority, log_data.userdata, __FILE__, __LINE__, __func__, __VA_ARGS__); \
+	} while(0)
+
+#define log_error(...) log_msg_cond(LIBEVDEV_LOG_ERROR, __VA_ARGS__)
+#define log_info(...) log_msg_cond(LIBEVDEV_LOG_INFO, __VA_ARGS__)
+#define log_dbg(...) log_msg_cond(LIBEVDEV_LOG_DEBUG, __VA_ARGS__)
+#define log_bug(...) log_msg_cond(LIBEVDEV_LOG_ERROR, "BUG: "__VA_ARGS__)
+
+extern void
+log_msg(enum libevdev_log_priority priority,
+	void *data,
+	const char *file, int line, const char *func,
+	const char *format, ...) LIBEVDEV_PRINTF(6, 7);
+
 /**
  * @return a pointer to the next element in the queue, or NULL if the queue
  * is full.
@@ -194,11 +217,11 @@ static inline int
 queue_alloc(struct libevdev *dev, size_t size)
 {
 	if (size == 0)
-		return -ENOSPC;
+		return -ENOMEM;
 
 	dev->queue = calloc(size, sizeof(struct input_event));
 	if (!dev->queue)
-		return -ENOSPC;
+		return -ENOMEM;
 
 	dev->queue_size = size;
 	dev->queue_next = 0;
diff --git a/libevdev/libevdev-uinput.c b/libevdev/libevdev-uinput.c
index de2833e..af98fa4 100644
--- a/libevdev/libevdev-uinput.c
+++ b/libevdev/libevdev-uinput.c
@@ -226,10 +226,16 @@ fetch_syspath_and_devnode(struct libevdev_uinput *uinput_dev)
 
 		buf[len - 1] = '\0'; /* file contains \n */
 		if (strcmp(buf, uinput_dev->name) == 0) {
-			strcpy(buf, SYS_INPUT_DIR);
-			strcat(buf, namelist[i]->d_name);
-			uinput_dev->syspath = strdup(buf);
-			uinput_dev->devnode = fetch_device_node(buf);
+			if (uinput_dev->syspath) {
+				/* FIXME: could descend into bit comparison here */
+				log_info("multiple identical devices found. syspath is unreliable\n");
+				break;
+			} else {
+				strcpy(buf, SYS_INPUT_DIR);
+				strcat(buf, namelist[i]->d_name);
+				uinput_dev->syspath = strdup(buf);
+				uinput_dev->devnode = fetch_device_node(buf);
+			}
 		}
 	}
 
@@ -259,8 +265,10 @@ libevdev_uinput_create_from_device(const struct libevdev *dev, int fd, struct li
 			return fd;
 
 		new_device->fd_is_managed = 1;
-	} else if (fd < 0)
+	} else if (fd < 0) {
+		log_bug("Invalid fd %d\n", fd);
 		return -EBADF;
+	}
 
 	memset(&uidev, 0, sizeof(uidev));
 
@@ -300,6 +308,7 @@ libevdev_uinput_create_from_device(const struct libevdev *dev, int fd, struct li
 	new_device->fd = fd;
 
 	if (fetch_syspath_and_devnode(new_device) == -1) {
+		log_error("unable to fetch syspath or device node.\n");
 		errno = ENODEV;
 		goto error;
 	}
diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index 36160f6..aa5cbd6 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -49,18 +49,57 @@ init_event_queue(struct libevdev *dev)
 }
 
 static void
-_libevdev_log(struct libevdev *dev, const char *format, ...)
+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);
+}
+
+/*
+ * Global logging settings.
+ */
+struct logdata log_data = {
+	LIBEVDEV_LOG_INFO,
+	libevdev_dflt_log_func,
+	NULL,
+};
+
+void
+log_msg(enum libevdev_log_priority priority,
+	void *data,
+	const char *file, int line, const char *func,
+	const char *format, ...)
 {
 	va_list args;
 
-	va_start(args, format);
-	dev->log(format, args);
-	va_end(args);
-}
+	if (!log_data.handler)
+		return;
 
-static void
-libevdev_noop_log_func(const char *format, va_list args)
-{
+	va_start(args, format);
+	log_data.handler(priority, data, file, line, func, format, args);
+	va_end(args);
 }
 
 LIBEVDEV_EXPORT struct libevdev*
@@ -74,7 +113,6 @@ libevdev_new(void)
 	dev->fd = -1;
 	dev->num_slots = -1;
 	dev->current_slot = -1;
-	dev->log = libevdev_noop_log_func;
 	dev->grabbed = LIBEVDEV_UNGRAB;
 	dev->sync_state = SYNC_NONE;
 
@@ -89,7 +127,7 @@ libevdev_new_from_fd(int fd, struct libevdev **dev)
 
 	d = libevdev_new();
 	if (!d)
-		return -ENOSPC;
+		return -ENOMEM;
 
 	rc = libevdev_set_fd(d, fd);
 	if (rc < 0)
@@ -112,20 +150,42 @@ libevdev_free(struct libevdev *dev)
 	free(dev);
 }
 
+/* DEPRECATED */
 LIBEVDEV_EXPORT void
 libevdev_set_log_handler(struct libevdev *dev, libevdev_log_func_t logfunc)
 {
-	if (dev == NULL)
-		return;
+	/* Can't be backwards compatible to this yet, so don't even try */
+	fprintf(stderr, "libevdev: ABI change. Log function will not be honored.\n");
+}
 
-	dev->log = logfunc ? logfunc : libevdev_noop_log_func;
+LIBEVDEV_EXPORT void
+libevdev_set_log_function(libevdev_log_func_t logfunc, void *data)
+{
+	log_data.handler = logfunc;
+	log_data.userdata = data;
+}
+
+LIBEVDEV_EXPORT void
+libevdev_set_log_priority(enum libevdev_log_priority priority)
+{
+	if (priority > LIBEVDEV_LOG_DEBUG)
+		priority = LIBEVDEV_LOG_DEBUG;
+	log_data.priority = priority;
+}
+
+LIBEVDEV_EXPORT enum libevdev_log_priority
+libevdev_get_log_priority(void)
+{
+	return log_data.priority;
 }
 
 LIBEVDEV_EXPORT int
 libevdev_change_fd(struct libevdev *dev, int fd)
 {
-	if (dev->fd == -1)
+	if (dev->fd == -1) {
+		log_bug("device not initialized. call libevdev_set_fd() first\n");
 		return -1;
+	}
 	dev->fd = fd;
 	return 0;
 }
@@ -137,8 +197,10 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	int i;
 	char buf[256];
 
-	if (dev->fd != -1)
+	if (dev->fd != -1) {
+		log_bug("device already initialized.\n");
 		return -EBADF;
+	}
 
 	rc = ioctl(fd, EVIOCGBIT(0, sizeof(dev->bits)), dev->bits);
 	if (rc < 0)
@@ -152,7 +214,7 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	free(dev->name);
 	dev->name = strdup(buf);
 	if (!dev->name) {
-		errno = ENOSPC;
+		errno = ENOMEM;
 		goto out;
 	}
 
@@ -167,7 +229,7 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	} else {
 		dev->phys = strdup(buf);
 		if (!dev->phys) {
-			errno = ENOSPC;
+			errno = ENOMEM;
 			goto out;
 		}
 	}
@@ -182,7 +244,7 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	} else  {
 		dev->uniq = strdup(buf);
 		if (!dev->uniq) {
-			errno = ENOSPC;
+			errno = ENOMEM;
 			goto out;
 		}
 	}
@@ -662,11 +724,15 @@ libevdev_next_event(struct libevdev *dev, unsigned int flags, struct input_event
 {
 	int rc = 0;
 
-	if (dev->fd < 0)
-		return -ENODEV;
+	if (dev->fd < 0) {
+		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		return -EBADF;
+	}
 
-	if (!(flags & (LIBEVDEV_READ_NORMAL|LIBEVDEV_READ_SYNC|LIBEVDEV_FORCE_SYNC)))
+	if (!(flags & (LIBEVDEV_READ_NORMAL|LIBEVDEV_READ_SYNC|LIBEVDEV_FORCE_SYNC))) {
+		log_bug("invalid flags %#x\n.\n", flags);
 		return -EINVAL;
+	}
 
 	if (flags & LIBEVDEV_READ_SYNC) {
 		if (dev->sync_state == SYNC_NEEDED) {
@@ -748,8 +814,10 @@ libevdev_has_event_pending(struct libevdev *dev)
 	struct pollfd fds = { dev->fd, POLLIN, 0 };
 	int rc;
 
-	if (dev->fd < 0)
+	if (dev->fd < 0) {
+		log_bug("device not initialized. call libevdev_set_fd() first\n");
 		return -EBADF;
+	}
 
 	if (queue_num_elements(dev) != 0)
 		return 1;
@@ -1130,6 +1198,11 @@ libevdev_kernel_set_abs_info(struct libevdev *dev, unsigned int code, const stru
 {
 	int rc;
 
+	if (dev->fd < 0) {
+		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		return -EBADF;
+	}
+
 	if (code > ABS_MAX)
 		return -EINVAL;
 
@@ -1147,8 +1220,15 @@ libevdev_grab(struct libevdev *dev, enum libevdev_grab_mode grab)
 {
 	int rc = 0;
 
-	if (grab != LIBEVDEV_GRAB && grab != LIBEVDEV_UNGRAB)
+	if (dev->fd < 0) {
+		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		return -EBADF;
+	}
+
+	if (grab != LIBEVDEV_GRAB && grab != LIBEVDEV_UNGRAB) {
+		log_bug("invalid grab parameter %#x\n", grab);
 		return -EINVAL;
+	}
 
 	if (grab == dev->grabbed)
 		return 0;
@@ -1250,6 +1330,11 @@ libevdev_kernel_set_led_values(struct libevdev *dev, ...)
 	int rc = 0;
 	size_t nleds = 0;
 
+	if (dev->fd < 0) {
+		log_bug("device not initialized. call libevdev_set_fd() first\n");
+		return -EBADF;
+	}
+
 	memset(ev, 0, sizeof(ev));
 
 	va_start(args, dev);
diff --git a/libevdev/libevdev.h b/libevdev/libevdev.h
index 3d0b609..82142d6 100644
--- a/libevdev/libevdev.h
+++ b/libevdev/libevdev.h
@@ -202,7 +202,7 @@ extern "C" {
  *
  * dev = libevdev_new();
  * if (!dev)
- *         return ENOSPC;
+ *         return ENOMEM;
  *
  * err = libevdev_set_fd(dev, fd);
  * if (err < 0) {
@@ -349,28 +349,58 @@ int libevdev_new_from_fd(int fd, struct libevdev **dev);
  */
 void libevdev_free(struct libevdev *dev);
 
+enum libevdev_log_priority {
+	LIBEVDEV_LOG_ERROR = 10,	/** cricitical errors and application bugs */
+	LIBEVDEV_LOG_INFO  = 20,	/** informational messages */
+	LIBEVDEV_LOG_DEBUG = 30,	/** debug information */
+};
+
 /**
  * Logging function called by library-internal logging.
  * This function is expected to treat its input like printf would.
  *
+ * @param priority Log priority of this message
+ * @param data User-supplied data pointer (see libevdev_set_log_function())
+ * @param file libevdev source code file generating this message
+ * @param line libevdev source code line generating this message
+ * @param func libevdev source code function generating this message
  * @param format printf-style format string
  * @param args List of arguments
  *
- * @see libevdev_set_log_handler
+ * @see libevdev_set_log_function
  */
-typedef void (*libevdev_log_func_t)(const char *format, va_list args);
+typedef void (*libevdev_log_func_t)(enum libevdev_log_priority priority,
+				    void *data,
+				    const char *file, int line,
+				    const char *func,
+				    const char *format, va_list args);
 
 /**
  * Set a printf-style logging handler for library-internal logging. The default
- * logging function is a noop.
+ * logging function is to stdout.
  *
- * @param dev The evdev device
  * @param logfunc The logging function for this device. If NULL, the current
- * logging function is unset.
+ * logging function is unset and no logging is performed.
+ * @param data User-specific data passed to the log handler.
  *
  * @note This function may be called before libevdev_set_fd().
  */
-void libevdev_set_log_handler(struct libevdev *dev, libevdev_log_func_t logfunc);
+void libevdev_set_log_function(libevdev_log_func_t logfunc, void *data);
+
+/**
+ * Define the minimum level to be printed to the log handler.
+ * Messages higher than this level are printed, others are discarded. This
+ * is a global setting and applies to any future logging messages.
+ *
+ * @param priority Minimum priority to be printed to the log.
+ *
+ */
+void libevdev_set_log_priority(enum libevdev_log_priority priority);
+
+/**
+ * @return the current log level
+ */
+enum libevdev_log_priority libevdev_get_log_priority(void);
 
 
 enum libevdev_grab_mode {
@@ -1333,6 +1363,8 @@ int libevdev_get_repeat(struct libevdev *dev, int *delay, int *period);
 /* replacement: libevdev_kernel_set_abs_info */
 int libevdev_kernel_set_abs_value(struct libevdev *dev, unsigned int code, const struct input_absinfo *abs) LIBEVDEV_DEPRECATED;
 
+/* replacement: libevdev_set_log_function */
+void libevdev_set_log_handler(struct libevdev *dev, libevdev_log_func_t logfunc) LIBEVDEV_DEPRECATED;
 /**************************************/
 
 #ifdef __cplusplus
diff --git a/test/test-common-uinput.c b/test/test-common-uinput.c
index 7f3fe1f..32ecb89 100644
--- a/test/test-common-uinput.c
+++ b/test/test-common-uinput.c
@@ -75,7 +75,7 @@ uinput_device_new_with_events_v(struct uinput_device **d, const char *name, cons
 
 	dev = uinput_device_new(name);
 	if (!dev)
-		return -ENOSPC;
+		return -ENOMEM;
 	if (id != DEFAULT_IDS)
 		uinput_device_set_ids(dev, id);
 
diff --git a/test/test-int-queue.c b/test/test-int-queue.c
index e809048..a57eb93 100644
--- a/test/test-int-queue.c
+++ b/test/test-int-queue.c
@@ -34,10 +34,10 @@ START_TEST(test_queue_alloc)
 	int rc;
 
 	rc = queue_alloc(&dev, 0);
-	ck_assert_int_eq(rc, -ENOSPC);
+	ck_assert_int_eq(rc, -ENOMEM);
 
 	rc = queue_alloc(&dev, ULONG_MAX);
-	ck_assert_int_eq(rc, -ENOSPC);
+	ck_assert_int_eq(rc, -ENOMEM);
 
 	rc = queue_alloc(&dev, 100);
 	ck_assert_int_eq(rc, 0);
diff --git a/test/test-libevdev-init.c b/test/test-libevdev-init.c
index 344bbac..02dfa8b 100644
--- a/test/test-libevdev-init.c
+++ b/test/test-libevdev-init.c
@@ -93,27 +93,43 @@ START_TEST(test_init_and_change_fd)
 }
 END_TEST
 
-static void logfunc(const char *f, va_list args) {}
+
+static int log_fn_called = 0;
+static char *logdata = "test";
+static void logfunc(enum libevdev_log_priority priority,
+		    void *data,
+		    const char *file, int line, const char *func,
+		    const char *f, va_list args) {
+	ck_assert_int_eq(strcmp(logdata, data), 0);
+	log_fn_called++;
+}
 
 START_TEST(test_log_init)
 {
 	struct libevdev *dev = NULL;
 
-	libevdev_set_log_handler(NULL, logfunc);
-	libevdev_set_log_handler(NULL, NULL);
+	libevdev_set_log_function(logfunc, NULL);
+	libevdev_set_log_function(NULL, NULL);
 
 	dev = libevdev_new();
 	ck_assert(dev != NULL);
-	libevdev_set_log_handler(dev, logfunc);
-	libevdev_free(dev);
 
-	dev = libevdev_new();
-	ck_assert(dev != NULL);
-	libevdev_set_log_handler(dev, NULL);
-	libevdev_set_log_handler(dev, logfunc);
-	libevdev_free(dev);
-	/* well, we didn't crash. can't test this otherwise */
+	libevdev_set_log_function(logfunc, logdata);
+	libevdev_next_event(dev, LIBEVDEV_READ_NORMAL, NULL);
 
+	libevdev_set_log_function(NULL, NULL);
+	libevdev_next_event(dev, LIBEVDEV_READ_NORMAL, NULL);
+
+	libevdev_set_log_function(logfunc, logdata);
+	libevdev_next_event(dev, LIBEVDEV_READ_NORMAL, NULL);
+
+	/* libevdev_next_event(dev, LIBEVDEV_READ_NORMAL, NULL) should
+	   trigger a log message. We called it three times, but only twice
+	   with the logfunc set, thus, ensure we only called the logfunc
+	   twice */
+	ck_assert_int_eq(log_fn_called, 2);
+
+	libevdev_free(dev);
 }
 END_TEST