xserver/dix/resource_priv.h

/* SPDX-License-Identifier: MIT OR X11
 *
 * Copyright © 2024 Enrico Weigelt, metux IT consult <info@metux.net>
 */
#ifndef _XSERVER_DIX_RESOURCE_PRIV_H
#define _XSERVER_DIX_RESOURCE_PRIV_H

#include <X11/Xdefs.h>

#include "include/dix.h"
#include "include/resource.h"

#define SameClient(obj,client) \
        (CLIENT_BITS((obj)->resource) == (client)->clientAsMask)

/*
 * Resource IDs having that bit set still belonging to some client,
 * but are server-internal, thus invisible to clients.
 */
#define SERVER_BIT           (Mask)0x40000000        /* use illegal bit */

/* client field */
#define RESOURCE_CLIENT_MASK   (((1 << ResourceClientBits()) - 1) << CLIENTOFFSET)

/* bits and fields within a resource id */
#define RESOURCE_AND_CLIENT_COUNT   29  /* 29 bits for XIDs */
#define CLIENTOFFSET     (RESOURCE_AND_CLIENT_COUNT - ResourceClientBits())

/* extract the client mask from an XID */
#define CLIENT_BITS(id) ((id) & RESOURCE_CLIENT_MASK)

/* resource field */
#define RESOURCE_ID_MASK        ((1 << CLIENTOFFSET) - 1)

/*
 * @brief retrieve client that owns given window
 *
 * XIDs carry the ID of the client who created/owns the resource in upper bits.
 * (every client so is assigned a range of XIDs it may use for resource creation)
 *
 * @param WindowPtr to the window whose client shall be retrieved
 * @return pointer to ClientRec structure or NullClient (NULL)
 */
ClientPtr dixClientForWindow(WindowPtr pWin);

/*
 * @brief retrieve client that owns given grab
 *
 * XIDs carry the ID of the client who created/owns the resource in upper bits.
 * (every client so is assigned a range of XIDs it may use for resource creation)
 *
 * @param GrabPtr to the grab whose owning client shall be retrieved
 * @return pointer to ClientRec structure or NullClient (NULL)
 */
ClientPtr dixClientForGrab(GrabPtr pGrab);

/*
 * @brief retrieve client that owns InputClients
 *
 * XIDs carry the ID of the client who created/owns the resource in upper bits.
 * (every client so is assigned a range of XIDs it may use for resource creation)
 *
 * @param GrabPtr to the InputClients whose owning client shall be retrieved
 * @return pointer to ClientRec structure or NullClient (NULL)
 */
ClientPtr dixClientForInputClients(InputClientsPtr pInputClients);

/*
 * @brief retrieve client that owns OtherClients
 *
 * XIDs carry the ID of the client who created/owns the resource in upper bits.
 * (every client so is assigned a range of XIDs it may use for resource creation)
 *
 * @param GrabPtr to the OtherClients whose owning client shall be retrieved
 * @return pointer to ClientRec structure or NullClient (NULL)
 */
ClientPtr dixClientForOtherClients(OtherClientsPtr pOtherClients);

/*
 * @brief extract client ID from XID
 *
 * XIDs carry the ID of the client who created/owns the resource in upper bits.
 * (every client so is assigned a range of XIDs it may use for resource creation)
 *
 * This ID is frequently used as table index, eg. for client or resource lookup.
 *
 * @param XID the ID of the resource whose client is retrieved
 * @return index of the client (within client or resource table)
 */
static inline int dixClientIdForXID(XID xid) {
    return ((int)(CLIENT_BITS(xid) >> CLIENTOFFSET));
}

/*
 * @brief retrieve client pointer from XID
 *
 * XIDs carry the ID of the client who created/owns the resource in upper bits.
 * (every client so is assigned a range of XIDs it may use for resource creation)
 *
 * @param XID the ID of the resource whose client is retrieved
 * @return pointer to ClientRec structure or NullClient (NULL)
 */
static inline ClientPtr dixClientForXID(XID xid) {
    const int idx = dixClientIdForXID(xid);
    if (idx < MAXCLIENTS)
        return clients[idx];
    return NullClient;
}

/*
 * @brief check whether resource is owned by server
 *
 * @param XID the ID of the resource to check
 * @return TRUE if resource is server owned
 */
static inline Bool dixResouceIsServerOwned(XID xid) {
    return (dixClientForXID(xid) == serverClient);
}

/*
 * @brief hash a XID for using as hashtable index
 *
 * @param id the XID to hash
 * @param numBits number of bits in the resulting hash (>=0)
 * @result the computed hash value
 *
 * @note This function is really only for handling
 * INITHASHSIZE..MAXHASHSIZE bit hashes, but will handle any number
 * of bits by either masking numBits lower bits of the ID or by
 * providing at most MAXHASHSIZE hashes.
 */
int HashResourceID(XID id, unsigned int numBits);

/*
 * @brief scan for free XIDs for client
 *
 * @param pClient the client to scan
 * @param count maximum size of items to return
 * @param pids pointer to XID where to return found free XIDs
 * @result number of free XIDs
 */
unsigned int GetXIDList(ClientPtr pClient,
                        unsigned int count,
                        XID *pids);

/*
 * @brief retrieve a range of free XIDs for given client
 *
 * @param client the client to scan
 * @param server TRUE if scanning for free server XIDs
 * @param minp pointer to result buffer: minimum XID of found range
 * @param maxp pointer to result buffer: maximum XID of found range
 */
void GetXIDRange(int client,
                 Bool server,
                 XID *minp,
                 XID *maxp);

#endif /* _XSERVER_DIX_RESOURCE_PRIV_H */