Add a context for libratbag

This is useful to have some udev helpers, or the list of drivers.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>

src/Makefile.am

@@ -6,7 +6,8 @@ include_HEADERS =			\
 libratbag_la_SOURCES =			\
 	libratbag.c			\
 	libratbag.h			\
-	libratbag-private.h
+	libratbag-private.h		\
+	libratbag-util.h
 
 libratbag_la_LIBADD = $(LIBEVDEV_LIBS)
 

src/libratbag-util.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright © 2008 Kristian Høgsberg
+ * Copyright © 2013-2015 Red Hat, Inc.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#ifndef LIBRATBAG_UTIL_H
+#define LIBRATBAG_UTIL_H
+
+#define LIBRATBAG_EXPORT __attribute__ ((visibility("default")))
+
+static inline void *
+zalloc(size_t size)
+{
+	return calloc(1, size);
+}
+
+#endif /* LIBRATBAG_UTIL_H */

src/libratbag.c

@@ -22,3 +22,49 @@
  */
 
 #include "config.h"
+#include <assert.h>
+#include <stdlib.h>
+
+#include "libratbag-private.h"
+#include "libratbag-util.h"
+
+struct libratbag {
+	int refcount;
+};
+
+LIBRATBAG_EXPORT struct libratbag *
+libratbag_create_context(void)
+{
+	struct libratbag *libratbag;
+
+	libratbag = zalloc(sizeof(*libratbag));
+	if (!libratbag)
+		return NULL;
+
+	libratbag->refcount = 1;
+
+	return libratbag;
+}
+
+LIBRATBAG_EXPORT struct libratbag *
+libratbag_ref(struct libratbag *libratbag)
+{
+	libratbag->refcount++;
+	return libratbag;
+}
+
+LIBRATBAG_EXPORT struct libratbag *
+libratbag_unref(struct libratbag *libratbag)
+{
+	if (libratbag == NULL)
+		return NULL;
+
+	assert(libratbag->refcount > 0);
+	libratbag->refcount--;
+	if (libratbag->refcount > 0)
+		return libratbag;
+
+	free(libratbag);
+
+	return NULL;
+}

src/libratbag.h

@@ -35,6 +35,15 @@ extern "C" {
 	__attribute__ ((format (printf, _format, _args)))
 #define LIBRATBAG_ATTRIBUTE_DEPRECATED __attribute__ ((deprecated))
 
+/**
+ * @ingroup base
+ * @struct libratbag
+ *
+ * A handle for accessing libratbag. This struct is refcounted, use
+ * libratbag_ref() and libratbag_unref().
+ */
+struct libratbag;
+
 /**
  * @defgroup base Initialization and manipulation of libratbag contexts
  * @defgroup device Querying and manipulating devices
@@ -93,6 +102,41 @@ struct ratbag_profile;
  */
 struct ratbag_button;
 
+/**
+ * @ingroup base
+ *
+ * Create a new libratbag context.
+ *
+ * @return An initialized libratbag context or NULL on error
+ */
+struct libratbag *
+libratbag_create_context(void);
+
+/**
+ * @ingroup base
+ *
+ * Add a reference to the context. A context is destroyed whenever the
+ * reference count reaches 0. See @ref libratbag_unref.
+ *
+ * @param libratbag A previously initialized valid libratbag context
+ * @return The passed libratbag context
+ */
+struct libratbag *
+libratbag_ref(struct libratbag *libratbag);
+
+/**
+ * @ingroup base
+ *
+ * Dereference the libratbag context. After this, the context may have been
+ * destroyed, if the last reference was dereferenced. If so, the context is
+ * invalid and may not be interacted with.
+ *
+ * @param libratbag A previously initialized libratbag context
+ * @return NULL if context was destroyed otherwise the passed context
+ */
+struct libratbag *
+libratbag_unref(struct libratbag *libratbag);
+
 /**
  * @ingroup base
  *
@@ -100,7 +144,7 @@ struct ratbag_button;
  * point to a /dev/input/eventX event node and be opened in O_RDWR.
  */
 struct ratbag*
-ratbag_new_from_fd(int fd);
+ratbag_new_from_fd(struct libratbag *libratbag, int fd);
 
 /**
  * @ingroup device

src/libratbag.sym

@@ -1,6 +1,10 @@
 /* in alphabetical order! */
 
 LIBRATBAG_0.1.0 {
+global:
+	libratbag_create_context;
+	libratbag_ref;
+	libratbag_unref;
 local:
 	*;
 };