From 0ed0e7a18dd086540b455bdbfbd218460f131f20 Mon Sep 17 00:00:00 2001
From: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Date: Fri, 14 Aug 2015 16:09:29 -0400
Subject: [PATCH] Add logging mechanism

Copied from libinput

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
---
 src/libratbag-private.h | 17 +++++++++++++++
 src/libratbag.c         | 47 +++++++++++++++++++++++++++++++++++++++++
 src/libratbag.h         | 29 +++++++++++++++++++++++++
 3 files changed, 93 insertions(+)

diff --git a/src/libratbag-private.h b/src/libratbag-private.h
index d14b21c3..2069625f 100644
--- a/src/libratbag-private.h
+++ b/src/libratbag-private.h
@@ -25,6 +25,23 @@
 #define LIBRATBAG_PRIVATE_H
 
 #include "libratbag.h"
+void ratbag_device_init(struct ratbag *rb, int fd);
+
+void
+log_msg_va(struct libratbag *libratbag,
+	   enum libratbag_log_priority priority,
+	   const char *format,
+	   va_list args);
+void log_msg(struct libratbag *libratbag,
+	enum libratbag_log_priority priority,
+	const char *format, ...);
+
+#define log_debug(li_, ...) log_msg((li_), LIBRATBAG_LOG_PRIORITY_DEBUG, __VA_ARGS__)
+#define log_info(li_, ...) log_msg((li_), LIBRATBAG_LOG_PRIORITY_INFO, __VA_ARGS__)
+#define log_error(li_, ...) log_msg((li_), LIBRATBAG_LOG_PRIORITY_ERROR, __VA_ARGS__)
+#define log_bug_kernel(li_, ...) log_msg((li_), LIBRATBAG_LOG_PRIORITY_ERROR, "kernel bug: " __VA_ARGS__)
+#define log_bug_libratbag(li_, ...) log_msg((li_), LIBRATBAG_LOG_PRIORITY_ERROR, "libratbag bug: " __VA_ARGS__)
+#define log_bug_client(li_, ...) log_msg((li_), LIBRATBAG_LOG_PRIORITY_ERROR, "client bug: " __VA_ARGS__)
 
 #endif /* LIBRATBAG_PRIVATE_H */
 
diff --git a/src/libratbag.c b/src/libratbag.c
index 106aa4fc..de3620f3 100644
--- a/src/libratbag.c
+++ b/src/libratbag.c
@@ -23,6 +23,7 @@
 
 #include "config.h"
 #include <assert.h>
+#include <stdio.h>
 #include <stdlib.h>
 
 #include "libratbag-private.h"
@@ -30,8 +31,51 @@
 
 struct libratbag {
 	int refcount;
+	libratbag_log_handler log_handler;
+	enum libratbag_log_priority log_priority;
 };
 
+static void
+libratbag_default_log_func(struct libratbag *libratbag,
+			  enum libratbag_log_priority priority,
+			  const char *format, va_list args)
+{
+	const char *prefix;
+
+	switch(priority) {
+	case LIBRATBAG_LOG_PRIORITY_DEBUG: prefix = "debug"; break;
+	case LIBRATBAG_LOG_PRIORITY_INFO: prefix = "info"; break;
+	case LIBRATBAG_LOG_PRIORITY_ERROR: prefix = "error"; break;
+	default: prefix="<invalid priority>"; break;
+	}
+
+	fprintf(stderr, "libratbag %s: ", prefix);
+	vfprintf(stderr, format, args);
+}
+
+void
+log_msg_va(struct libratbag *libratbag,
+	   enum libratbag_log_priority priority,
+	   const char *format,
+	   va_list args)
+{
+	if (libratbag->log_handler &&
+	    libratbag->log_priority <= priority)
+		libratbag->log_handler(libratbag, priority, format, args);
+}
+
+void
+log_msg(struct libratbag *libratbag,
+	enum libratbag_log_priority priority,
+	const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	log_msg_va(libratbag, priority, format, args);
+	va_end(args);
+}
+
 LIBRATBAG_EXPORT struct libratbag *
 libratbag_create_context(void)
 {
@@ -43,6 +87,9 @@ libratbag_create_context(void)
 
 	libratbag->refcount = 1;
 
+	libratbag->log_handler = libratbag_default_log_func;
+	libratbag->log_priority = LIBRATBAG_LOG_PRIORITY_DEBUG;
+
 	return libratbag;
 }
 
diff --git a/src/libratbag.h b/src/libratbag.h
index 320599ed..e8ce75be 100644
--- a/src/libratbag.h
+++ b/src/libratbag.h
@@ -35,6 +35,15 @@ extern "C" {
 	__attribute__ ((format (printf, _format, _args)))
 #define LIBRATBAG_ATTRIBUTE_DEPRECATED __attribute__ ((deprecated))
 
+/**
+ * Log priority for internal logging messages.
+ */
+enum libratbag_log_priority {
+	LIBRATBAG_LOG_PRIORITY_DEBUG = 10,
+	LIBRATBAG_LOG_PRIORITY_INFO = 20,
+	LIBRATBAG_LOG_PRIORITY_ERROR = 30,
+};
+
 /**
  * @ingroup base
  * @struct libratbag
@@ -44,6 +53,26 @@ extern "C" {
  */
 struct libratbag;
 
+/**
+ * @ingroup base
+ *
+ * Log handler type for custom logging.
+ *
+ * @param libratbag The libratbag context
+ * @param priority The priority of the current message
+ * @param format Message format in printf-style
+ * @param args Message arguments
+ *
+ * @see libratbag_log_set_priority
+ * @see libratbag_log_get_priority
+ * @see libratbag_log_set_handler
+ */
+typedef void (*libratbag_log_handler)(struct libratbag *libratbag,
+				      enum libratbag_log_priority priority,
+				      const char *format, va_list args)
+	   LIBRATBAG_ATTRIBUTE_PRINTF(3, 0);
+
+
 /**
  * @defgroup base Initialization and manipulation of libratbag contexts
  * @defgroup device Querying and manipulating devices