ntsync: Introduce NTSYNC_IOC_EVENT_READ.

This corresponds to the NT syscall NtQueryEvent().

This returns the signaled state of the event and whether it is manual-reset.

Signed-off-by: Elizabeth Figura <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/ntsync.c

···
 	return ret;
 }
 
+static int ntsync_event_read(struct ntsync_obj *event, void __user *argp)
+{
+	struct ntsync_event_args __user *user_args = argp;
+	struct ntsync_device *dev = event->dev;
+	struct ntsync_event_args args;
+	bool all;
+
+	if (event->type != NTSYNC_TYPE_EVENT)
+		return -EINVAL;
+
+	all = ntsync_lock_obj(dev, event);
+
+	args.manual = event->u.event.manual;
+	args.signaled = event->u.event.signaled;
+
+	ntsync_unlock_obj(dev, event, all);
+
+	if (copy_to_user(user_args, &args, sizeof(args)))
+		return -EFAULT;
+	return 0;
+}
+
 static int ntsync_obj_release(struct inode *inode, struct file *file)
 {
 	struct ntsync_obj *obj = file->private_data;
···
 		return ntsync_event_reset(obj, argp);
 	case NTSYNC_IOC_EVENT_PULSE:
 		return ntsync_event_set(obj, argp, true);
+	case NTSYNC_IOC_EVENT_READ:
+		return ntsync_event_read(obj, argp);
 	default:
 		return -ENOIOCTLCMD;
 	}

include/uapi/linux/ntsync.h

···
 #define NTSYNC_IOC_EVENT_PULSE		_IOR ('N', 0x8a, __u32)
 #define NTSYNC_IOC_SEM_READ		_IOR ('N', 0x8b, struct ntsync_sem_args)
 #define NTSYNC_IOC_MUTEX_READ		_IOR ('N', 0x8c, struct ntsync_mutex_args)
+#define NTSYNC_IOC_EVENT_READ		_IOR ('N', 0x8d, struct ntsync_event_args)
 
 #endif