Add an open_restricted/close_restricted interface

Same as libinput. Since we need to open device files we need something that's
authorized to open them. So we punt that to the caller.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/libratbag-hidraw.c

@@ -40,11 +40,13 @@ ratbag_open_hidraw(struct ratbag *ratbag)
 {
 	struct hidraw_devinfo info;
 	int fd, res;
+	const char *devnode;
 
 	if (!ratbag->udev_hidraw)
 		return -EINVAL;
 
-	fd = open(udev_device_get_devnode(ratbag->udev_hidraw), O_RDWR);
+	devnode = udev_device_get_devnode(ratbag->udev_hidraw);
+	fd = ratbag_open_path(ratbag, devnode, O_RDWR);
 	if (fd < 0)
 		goto err;
 
@@ -67,7 +69,7 @@ ratbag_open_hidraw(struct ratbag *ratbag)
 
 err:
 	if (fd >= 0)
-		close(fd);
+		ratbag_close_fd(ratbag, fd);
 	return -errno;
 }
 

src/libratbag-private.h

@@ -39,6 +39,18 @@
 
 struct ratbag_driver;
 
+struct libratbag {
+	const struct libratbag_interface *interface;
+	void *userdata;
+
+	struct udev *udev;
+	struct list drivers;
+
+	int refcount;
+	libratbag_log_handler log_handler;
+	enum libratbag_log_priority log_priority;
+};
+
 struct ratbag {
 	char *name;
 	struct udev_device *udev_device;
@@ -102,6 +114,22 @@ struct ratbag_button {
 	enum ratbag_button_action_type action_type;
 };
 
+static inline int
+ratbag_open_path(struct ratbag *ratbag, const char *path, int flags)
+{
+	struct libratbag *libratbag = ratbag->libratbag;
+
+	return libratbag->interface->open_restricted(path, flags, libratbag->userdata);
+}
+
+static inline void
+ratbag_close_fd(struct ratbag *ratbag, int fd)
+{
+	struct libratbag *libratbag = ratbag->libratbag;
+
+	return libratbag->interface->close_restricted(fd, libratbag->userdata);
+}
+
 static inline void
 ratbag_set_drv_data(struct ratbag *ratbag, void *drv_data)
 {
@@ -126,6 +154,7 @@ ratbag_profile_get_drv_data(struct ratbag_profile *profile)
 	return profile->drv_data;
 }
 
+
 void
 log_msg_va(struct libratbag *libratbag,
 	   enum libratbag_log_priority priority,

src/libratbag.c

@@ -24,7 +24,6 @@
 #include "config.h"
 #include <assert.h>
 #include <errno.h>
-#include <fcntl.h>
 #include <libudev.h>
 #include <linux/hidraw.h>
 #include <stdbool.h>
@@ -35,15 +34,6 @@
 #include "libratbag-private.h"
 #include "libratbag-util.h"
 
-struct libratbag {
-	struct udev *udev;
-	struct list drivers;
-
-	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,
@@ -362,15 +352,23 @@ ratbag_register_driver(struct libratbag *libratbag, struct ratbag_driver *driver
 }
 
 LIBRATBAG_EXPORT struct libratbag *
-libratbag_create_context(void)
+libratbag_create_context(const struct libratbag_interface *interface,
+			 void *userdata)
 {
 	struct libratbag *libratbag;
 
+	if (interface == NULL ||
+	    interface->open_restricted == NULL ||
+	    interface->close_restricted == NULL)
+		return NULL;
+
 	libratbag = zalloc(sizeof(*libratbag));
 	if (!libratbag)
 		return NULL;
 
 	libratbag->refcount = 1;
+	libratbag->interface = interface;
+	libratbag->userdata = userdata;
 
 	list_init(&libratbag->drivers);
 	libratbag->udev = udev_new();

src/libratbag.h

@@ -132,6 +132,39 @@ struct ratbag_profile;
  */
 struct ratbag_button;
 
+/**
+ * @ingroup base
+ * @struct libratbag_interface
+ *
+ * libratbag does not open file descriptors to devices directly, instead
+ * open_restricted() and close_restricted() are called for each path that
+ * must be opened.
+ *
+ * @see libratbag_create_context
+ */
+struct libratbag_interface {
+	/**
+	 * Open the device at the given path with the flags provided and
+	 * return the fd.
+	 *
+	 * @param path The device path to open
+	 * @param flags Flags as defined by open(2)
+	 * @param user_data The user_data provided in
+	 * libratbag_create_context()
+	 *
+	 * @return The file descriptor, or a negative errno on failure.
+	 */
+	int (*open_restricted)(const char *path, int flags, void *user_data);
+	/**
+	 * Close the file descriptor.
+	 *
+	 * @param fd The file descriptor to close
+	 * @param user_data The user_data provided in
+	 * libratbag_create_context()
+	 */
+	void (*close_restricted)(int fd, void *user_data);
+};
+
 /**
  * @ingroup base
  *
@@ -140,7 +173,8 @@ struct ratbag_button;
  * @return An initialized libratbag context or NULL on error
  */
 struct libratbag *
-libratbag_create_context(void);
+libratbag_create_context(const struct libratbag_interface *interface,
+			 void *userdata);
 
 /**
  * @ingroup base

tools/ratbag-command.c

@@ -89,6 +89,29 @@ parse_args(int argc, char **argv, const char **path, int *verbose)
 	return 0;
 }
 
+static int
+open_restricted(const char *path, int flags, void *user_data)
+{
+	int fd = open(path, flags);
+
+	if (fd < 0)
+		fprintf(stderr, "Failed to open %s (%s)\n",
+			path, strerror(errno));
+
+	return fd < 0 ? -errno : fd;
+}
+
+static void
+close_restricted(int fd, void *user_data)
+{
+	close(fd);
+}
+
+const struct libratbag_interface interface = {
+	.open_restricted = open_restricted,
+	.close_restricted = close_restricted,
+};
+
 int
 main(int argc, char **argv)
 {
@@ -113,7 +136,7 @@ main(int argc, char **argv)
 		return 1;
 	}
 
-	libratbag = libratbag_create_context();
+	libratbag = libratbag_create_context(&interface, NULL);
 	if (!libratbag) {
 		fprintf(stderr, "Can't initilize libratbag\n");
 		return 1;