This is xnu-8019. See this file in:
 * Copyright (c) 2000-2021 Apple Inc. All rights reserved.
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * Please obtain a copy of the License at
 * and read it before using this file.
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * Please see the License for the specific language governing rights and
 * limitations under the License.
/* Copyright (c) 1998, 1999 Apple Computer, Inc. All Rights Reserved */
 *       @header kern_event.h
 *       This header defines in-kernel functions for generating kernel events as
 *       well as functions for receiving kernel events using a kernel event
 *       socket.


#include <sys/appleapiopts.h>
#include <sys/ioccom.h>
#include <sys/sys_domain.h>

#define KEV_SNDSPACE    (4 * 1024)
#define KEV_RECVSPACE   (32 * 1024)

#define KEV_ANY_VENDOR          0
#define KEV_ANY_CLASS           0
#define KEV_ANY_SUBCLASS        0

 * Vendor Code

 *       @defined KEV_VENDOR_APPLE
 *       @discussion Apple generated kernel events use the hard coded vendor code
 *       value of 1. Third party kernel events use a dynamically allocated vendor
 *       code. The vendor code can be found using the SIOCGKEVVENDOR ioctl.
#define KEV_VENDOR_APPLE        1

 * Definition of top-level classifications for KEV_VENDOR_APPLE

 *       @defined KEV_NETWORK_CLASS
 *       @discussion Network kernel event class.
#define KEV_NETWORK_CLASS       1

 *       @defined KEV_IOKIT_CLASS
 *       @discussion IOKit kernel event class.
#define KEV_IOKIT_CLASS         2

 *       @defined KEV_SYSTEM_CLASS
 *       @discussion System kernel event class.
#define KEV_SYSTEM_CLASS        3

 *       @defined KEV_APPLESHARE_CLASS
 *       @discussion AppleShare kernel event class.

 *       @defined KEV_FIREWALL_CLASS
 *       @discussion Firewall kernel event class.
#define KEV_FIREWALL_CLASS      5

 *       @defined KEV_IEEE80211_CLASS
 *       @discussion IEEE 802.11 kernel event class.
#define KEV_IEEE80211_CLASS     6

 *       @defined KEV_NKE_CLASS
 *       @discussion NKE kernel event class.
#define KEV_NKE_CLASS           7

#define KEV_NKE_ALF_SUBCLASS            1

 * The following struct is KPI, but it was originally defined with a trailing
 * array member of size one, intended to be used as a Variable-Length Array.
 * That's problematic because the compiler doesn't know that the array is
 * accessed out-of-bounds and can assume it isn't. This makes
 * -Warray-bounds-pointer-arithmetic sad. We can't just change the code because
 * it requires users to also change their uses of the class, at a minimum
 * because kern_event_msg's size changes when making the last member a VLA. This
 * macro allows users of this KPI to opt-in to the new behavior.
#define XNU_KERN_EVENT_DATA_SIZE /* nothing, it's a VLA */

 *       @struct kern_event_msg
 *       @discussion This structure is prepended to all kernel events. This
 *               structure is used to determine the format of the remainder of
 *               the kernel event. This structure will appear on all messages
 *               received on a kernel event socket. To post a kernel event, a
 *               slightly different structure is used.
 *       @field total_size Total size of the kernel event message including the
 *               header.
 *       @field vendor_code The vendor code indicates which vendor generated the
 *               kernel event. This gives every vendor a unique set of classes
 *               and subclasses to use. Use the SIOCGKEVVENDOR ioctl to look up
 *               vendor codes for vendors other than Apple. Apple uses
 *               KEV_VENDOR_APPLE.
 *       @field kev_class The class of the kernel event.
 *       @field kev_subclass The subclass of the kernel event.
 *       @field id Monotonically increasing value.
 *       @field event_code The event code.
 *       @field event_data Any additional data about this event. Format will
 *               depend on the vendor_code, kev_class, kev_subclass, and
 *               event_code. The length of the event_data can be determined
 *               using total_size - KEV_MSG_HEADER_SIZE.
struct kern_event_msg {
	u_int32_t       total_size;     /* Size of entire event msg */
	u_int32_t       vendor_code;    /* For non-Apple extensibility */
	u_int32_t       kev_class;      /* Layer of event source */
	u_int32_t       kev_subclass;   /* Component within layer */
	u_int32_t       id;             /* Monotonically increasing value */
	u_int32_t       event_code;     /* unique code */
	u_int32_t       event_data[XNU_KERN_EVENT_DATA_SIZE];   /* One or more data words */

 *       @defined KEV_MSG_HEADER_SIZE
 *       @discussion Size of the header portion of the kern_event_msg structure.
 *               This accounts for everything right up to event_data. The size
 *               of the data can be found by subtracting KEV_MSG_HEADER_SIZE
 *               from the total size from the kern_event_msg.
#define KEV_MSG_HEADER_SIZE (offsetof(struct kern_event_msg, event_data[0]))

 *       @struct kev_request
 *       @discussion This structure is used with the SIOCSKEVFILT and
 *               SIOCGKEVFILT to set and get the control filter setting for a
 *               kernel control socket.
 *       @field total_size Total size of the kernel event message including the
 *               header.
 *       @field vendor_code All kernel events that don't match this vendor code
 *               will be ignored. KEV_ANY_VENDOR can be used to receive kernel
 *               events with any vendor code.
 *       @field kev_class All kernel events that don't match this class will be
 *               ignored. KEV_ANY_CLASS can be used to receive kernel events with
 *               any class.
 *       @field kev_subclass All kernel events that don't match this subclass
 *               will be ignored. KEV_ANY_SUBCLASS can be used to receive kernel
 *               events with any subclass.
struct kev_request {
	u_int32_t       vendor_code;
	u_int32_t       kev_class;
	u_int32_t       kev_subclass;

 *       @defined KEV_VENDOR_CODE_MAX_STR_LEN
 *       @discussion This define sets the maximum length of a string that can be
 *               used to identify a vendor or kext when looking up a vendor code.

 *       @struct kev_vendor_code
 *       @discussion This structure is used with the SIOCGKEVVENDOR ioctl to
 *               convert from a string identifying a kext or vendor, in the
 *               form of a bundle identifier, to a vendor code.
 *       @field vendor_code After making the SIOCGKEVVENDOR ioctl call, this will
 *               be filled in with the vendor code if there is one.
 *       @field vendor_string A bundle style identifier.
#pragma pack(4)
struct kev_vendor_code {
	u_int32_t       vendor_code;
	char            vendor_string[KEV_VENDOR_CODE_MAX_STR_LEN];
#pragma pack()

 *       @defined SIOCGKEVID
 *       @discussion Retrieve the current event id. Each event generated will
 *               have a new id. The next event to be generated will have an id
 *               of id+1.
#define SIOCGKEVID      _IOR('e', 1, u_int32_t)

 *       @defined SIOCSKEVFILT
 *       @discussion Set the kernel event filter for this socket. Kernel events
 *               not matching this filter will not be received on this socket.
#define SIOCSKEVFILT    _IOW('e', 2, struct kev_request)

 *       @defined SIOCGKEVFILT
 *       @discussion Retrieve the kernel event filter for this socket. Kernel
 *               events not matching this filter will not be received on this
 *               socket.
#define SIOCGKEVFILT    _IOR('e', 3, struct kev_request)

 *       @defined SIOCGKEVVENDOR
 *       @discussion Lookup the vendor code for the specified vendor. ENOENT will
 *               be returned if a vendor code for that vendor string does not
 *               exist.
#define SIOCGKEVVENDOR  _IOWR('e', 4, struct kev_vendor_code)

#ifdef PRIVATE
struct xkevtpcb {
	u_int32_t       kep_len;
	u_int32_t       kep_kind;
	u_int64_t       kep_evtpcb;
	u_int32_t       kep_vendor_code_filter;
	u_int32_t       kep_class_filter;
	u_int32_t       kep_subclass_filter;

struct kevtstat {
	u_int64_t       kes_pcbcount __attribute__((aligned(8)));
	u_int64_t       kes_gencnt __attribute__((aligned(8)));
	u_int64_t       kes_badvendor __attribute__((aligned(8)));
	u_int64_t       kes_toobig __attribute__((aligned(8)));
	u_int64_t       kes_nomem __attribute__((aligned(8)));
	u_int64_t       kes_fullsock __attribute__((aligned(8)));
	u_int64_t       kes_posted __attribute__((aligned(8)));
#endif /* PRIVATE */

#ifdef KERNEL
 *       @define N_KEV_VECTORS
 *       @discussion The maximum number of kev_d_vectors for a kernel event.
#define N_KEV_VECTORS   5

 *       @struct kev_d_vectors
 *       @discussion This structure is used to append some data to a kernel
 *               event.
 *       @field data_length The length of data.
 *       @field data_ptr A pointer to data.
struct kev_d_vectors {
	u_int32_t       data_length;    /* Length of the event data */
	void            *data_ptr;      /* Pointer to event data */

 *       @struct kev_msg
 *       @discussion This structure is used when posting a kernel event.
 *       @field vendor_code The vendor code assigned by kev_vendor_code_find.
 *       @field kev_class The event's class.
 *       @field kev_class The event's subclass.
 *       @field kev_class The event's code.
 *       @field dv An array of vectors describing additional data to be appended
 *               to the kernel event.
struct kev_msg {
	u_int32_t vendor_code;          /* For non-Apple extensibility */
	u_int32_t kev_class;            /* Layer of event source */
	u_int32_t kev_subclass;         /* Component within layer */
	u_int32_t event_code;           /* The event code */
	struct kev_d_vectors dv[N_KEV_VECTORS]; /* Up to n data vectors */

 *       @function kev_vendor_code_find
 *       @discussion Lookup a vendor_code given a unique string. If the vendor
 *               code has not been used since launch, a unique integer will be
 *               assigned for that string. Vendor codes will remain the same
 *               until the machine is rebooted.
 *       @param vendor_string A bundle style vendor identifier(i.e.
 *       @param vendor_code Upon return, a unique vendor code for use when
 *               posting kernel events.
 *       @result May return ENOMEM if memory constraints prevent allocation of a
 *               new vendor code.
errno_t kev_vendor_code_find(const char *vendor_string, u_int32_t *vendor_code);

 *       @function kev_msg_post
 *       @discussion Post a kernel event message.
 *       @param event_msg A structure defining the kernel event message to post.
 *       @result Will return zero upon success. May return a number of errors
 *               depending on the type of failure. EINVAL indicates that there
 *               was something wrong with the kerne event. The vendor code of
 *               the kernel event must be assigned using kev_vendor_code_find.
 *               If the message is too large, EMSGSIZE will be returned.
errno_t kev_msg_post(struct kev_msg *event_msg);

#ifdef PRIVATE
 * Internal version of kev_msg_post. Allows posting Apple vendor code kernel
 * events.
int     kev_post_msg(struct kev_msg *event);
int     kev_post_msg_nowait(struct kev_msg *event);

LIST_HEAD(kern_event_head, kern_event_pcb);

struct kern_event_pcb {
	decl_lck_mtx_data(, evp_mtx);   /* per-socket mutex */
	LIST_ENTRY(kern_event_pcb) evp_link;    /* glue on list of all PCBs */
	struct socket *evp_socket;              /* pointer back to socket */
	u_int32_t evp_vendor_code_filter;
	u_int32_t evp_class_filter;
	u_int32_t evp_subclass_filter;

#define sotoevpcb(so)   ((struct kern_event_pcb *)((so)->so_pcb))

#endif /* PRIVATE */
#endif /* KERNEL */
#endif /* SYS_KERN_EVENT_H */