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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _LINUX_WATCH_QUEUE_H
#define _LINUX_WATCH_QUEUE_H

#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/ioctl.h>

#define O_NOTIFICATION_PIPE \
	O_EXCL /* Parameter to pipe2() selecting notification pipe */

#define IOC_WATCH_QUEUE_SET_SIZE   _IO('W', 0x60) /* Set the size in pages */
#define IOC_WATCH_QUEUE_SET_FILTER _IO('W', 0x61) /* Set the filter */

enum watch_notification_type {
	WATCH_TYPE_META = 0,	   /* Special record */
	WATCH_TYPE_KEY_NOTIFY = 1, /* Key change event notification */
	WATCH_TYPE__NR = 2
};

enum watch_meta_notification_subtype {
	WATCH_META_REMOVAL_NOTIFICATION = 0, /* Watched object was removed */
	WATCH_META_LOSS_NOTIFICATION = 1,    /* Data loss occurred */
};

/*
 * Notification record header.  This is aligned to 64-bits so that subclasses
 * can contain __u64 fields.
 */
struct watch_notification {
	__u32 type : 24;   /* enum watch_notification_type */
	__u32 subtype : 8; /* Type-specific subtype (filterable) */
	__u32 info;
#define WATCH_INFO_LENGTH	    0x0000007f /* Length of record */
#define WATCH_INFO_LENGTH__SHIFT    0
#define WATCH_INFO_ID		    0x0000ff00 /* ID of watchpoint */
#define WATCH_INFO_ID__SHIFT	    8
#define WATCH_INFO_TYPE_INFO	    0xffff0000 /* Type-specific info */
#define WATCH_INFO_TYPE_INFO__SHIFT 16
#define WATCH_INFO_FLAG_0	    0x00010000 /* Type-specific info, flag bit 0 */
#define WATCH_INFO_FLAG_1	    0x00020000 /* ... */
#define WATCH_INFO_FLAG_2	    0x00040000
#define WATCH_INFO_FLAG_3	    0x00080000
#define WATCH_INFO_FLAG_4	    0x00100000
#define WATCH_INFO_FLAG_5	    0x00200000
#define WATCH_INFO_FLAG_6	    0x00400000
#define WATCH_INFO_FLAG_7	    0x00800000
};

/*
 * Notification filtering rules (IOC_WATCH_QUEUE_SET_FILTER).
 */
struct watch_notification_type_filter {
	__u32 type;		 /* Type to apply filter to */
	__u32 info_filter;	 /* Filter on watch_notification::info */
	__u32 info_mask;	 /* Mask of relevant bits in info_filter */
	__u32 subtype_filter[8]; /* Bitmask of subtypes to filter on */
};

struct watch_notification_filter {
	__u32 nr_filters; /* Number of filters */
	__u32 __reserved; /* Must be 0 */
	struct watch_notification_type_filter filters[];
};

/*
 * Extended watch removal notification.  This is used optionally if the type
 * wants to indicate an identifier for the object being watched, if there is
 * such.  This can be distinguished by the length.
 *
 * type -> WATCH_TYPE_META
 * subtype -> WATCH_META_REMOVAL_NOTIFICATION
 */
struct watch_notification_removal {
	struct watch_notification watch;
	__u64 id; /* Type-dependent identifier */
};

/*
 * Type of key/keyring change notification.
 */
enum key_notification_subtype {
	NOTIFY_KEY_INSTANTIATED = 0, /* Key was instantiated (aux is error code)
				      */
	NOTIFY_KEY_UPDATED = 1,	     /* Key was updated */
	NOTIFY_KEY_LINKED = 2,	 /* Key (aux) was added to watched keyring */
	NOTIFY_KEY_UNLINKED = 3, /* Key (aux) was removed from watched keyring
				  */
	NOTIFY_KEY_CLEARED = 4,	 /* Keyring was cleared */
	NOTIFY_KEY_REVOKED = 5,	 /* Key was revoked */
	NOTIFY_KEY_INVALIDATED = 6, /* Key was invalidated */
	NOTIFY_KEY_SETATTR = 7,	    /* Key's attributes got changed */
};

/*
 * Key/keyring notification record.
 * - watch.type = WATCH_TYPE_KEY_NOTIFY
 * - watch.subtype = enum key_notification_type
 */
struct key_notification {
	struct watch_notification watch;
	__u32 key_id; /* The key/keyring affected */
	__u32 aux;    /* Per-type auxiliary data */
};

#endif /* _LINUX_WATCH_QUEUE_H */