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