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/* This file is part of the Project Athena Zephyr Notification System.
* It contains functions for the Zephyr server class manager subsystem.
*
* Created by: John T. Kohl
*
* $Source$
* $Author$
*
* Copyright (c) 1987 by the Massachusetts Institute of Technology.
* For copying and distribution information, see the file
* "mit-copyright.h".
*/
#include <zephyr/mit-copyright.h>
#ifndef lint
static char rcsid_cm_c[] = "$Header$";
#endif lint
#include <zephyr/zephyr.h>
#include "zserver.h"
/*
* Class manager subsystem.
*
*
* external functions are:
*
* Code_t cm_register(client, class)
*
* Code_t cm_deregister(client, class)
*
* ZClientList_t *cm_lookup(class)
* ZClientDesc_t *client;
* char *class;
*/
/* Private variables */
#define EMPTY_CLASS 2000
#define HASHSIZE 511
#define HASHMUL 243
static ZClass_t *class_bucket[511];
/* private routines */
static int hash(string)
char *string;
{
register int hval = 0;
register char *cp = string;
while (*cp)
hval = (hval + (*cp++) * HASHMUL) % HASHSIZE;
return(hval);
}
static ZClass_t *class_alloc(class)
char *class;
{
register ZClass_t *ptr;
if ((ptr = (ZClass_t *) malloc(sizeof(ZClass_t))) == NULLZCT)
return(NULLZCT);
if ((ptr->classname = strsave(class)) == NULL) {
free((char *) ptr);
return(NULLZCT);
}
return(ptr);
}
static void free_class(ptr)
ZClass_t *ptr;
{
free(ptr->classname);
free(ptr);
}
static ZClientList_t *client_alloc(client)
ZClientDesc_t *client;
{
register ZClientList_t *ptr;
if ((ptr = (ZClientList_t *) malloc(sizeof(ZClientList_t))) == NULLZCLT)
return(NULLZCLT);
ptr->client = client;
return(ptr);
}
static Code_t insert_client(ptr, client)
ZClass_t *ptr;
ZClientDesc_t *client;
{
register ZClientList_t *listp;
if ((listp = client_alloc(client)) == NULLZCLT)
return(ZERR_UNIX);
if (ptr->clientlist == NULLZCLT) {
listp->q_forw = listp;
listp->q_back = listp;
ptr->clientlist = listp;
} else
insque(listp, ptr->clientlist);
return(ZERR_NONE);
}
static Code_t remove_client(ptr, client)
ZClass_t *ptr;
ZClientDesc_t *client;
{
register ZClientList_t *listp = ptr->clientlist;
register ZClientList_t *listp2;
if (listp->client == client) { /* found him */
if (listp->q_forw == listp) { /* this is the only elem on this queue */
ptr->clientlist = NULLZCLT;
free(listp);
return(EMPTY_CLASS);
}
/* ok, remove him, being careful to reset the pointer to the queue */
ptr->clientlist = listp->q_forw;
remque(listp);
free(listp);
return(ZERR_NONE);
} else {
for (listp2 = listp->q_forw; listp2 != listp; listp2 = listp2->q_forw)
/* walk down list, looking for him */
if (listp2->client == client) {
remque(listp);
free(listp);
return(ZERR_NONE);
}
return(ZERR_S_BADASSOC);
}
}
/* */
/* public routines */
Code_t cm_register(client, class)
ZClientDesc_t *client;
char *class;
{
register ZClass_t *ptr, *ptr2;
int hashval = hash(class);
if ((ptr = class_bucket[hashval]) == NULLZCT) {
/* not registered */
if ((ptr = class_alloc(class)) == NULLZCT)
return(ZERR_UNIX);
ptr->q_forw = ptr;
ptr->q_back = ptr;
class_bucket[hashval] = ptr;
return(insert_client(ptr, client));
} else if (!strcmp(ptr->classname, class)) /* match! */
return(insert_client(ptr, client));
else {
for (ptr2 = ptr->q_forw; ptr2 != ptr; ptr2 = ptr2->q_forw)
/* walk down the list, looking for a match */
if (!strcmp(ptr2->classname, class))
return(insert_client(ptr2, client));
/* fell off the end, no match */
if ((ptr2 = class_alloc(class)) == NULLZCT)
return(ZERR_UNIX);
insque(ptr2, ptr); /* insert new class into hash bucket */
return(insert_client(ptr2, client));
}
}
Code_t cm_deregister(client, class)
ZClientDesc_t *client;
char *class;
{
register ZClass_t *ptr, *ptr2;
int retval = -1;
int hashval = hash(class);
if ((ptr = class_bucket[hashval]) == NULLZCT)
/* no such class to deregister */
return(ZERR_S_BADASSOC);
if (!strcmp(ptr->classname, class)) { /* match! */
if (remove_client(ptr, client) == EMPTY_CLASS) {
/* careful here, we need to remove it and adjust the pointer to
the next element unless this is the only one */
if (ptr = ptr->q_forw) {
/* garbage collect this bucket */
free_class(ptr);
class_bucket[hashval] = NULLZCT;
} else {
/* adjust pointer and garbage collect */
class_bucket[hashval] = ptr->q_forw;
remque(ptr);
free_class(ptr);
}
}
return(ZERR_NONE);
}
else {
for (ptr2 = ptr->q_forw; ptr2 != ptr; ptr2 = ptr2->q_forw) {
/* walk down the list, looking for a match */
if (!strcmp(ptr2->classname, class)) {
if ((retval = remove_client(ptr2, client)) == EMPTY_CLASS) {
/* here ptr2 is never pointing to class_bucket[hashval],
so we don't worry about freeing the bucket */
remque(ptr2);
free_class(ptr2);
return(ZERR_NONE);
}
/* if not EMPTY_CLASS, it's either ZERR_S_BADASSOC (not found)
or ZERR_NONE (found and removed), so break */
break;
}
}
/* fell off: either client not found or client found
and removed, retval contains the result */
return(retval);
}
}
ZClientList_t *cm_lookup(class)
char *class;
{
register ZClass_t *ptr, *ptr2;
int hashval = hash(class);
if ((ptr = class_bucket[hashval]) == NULLZCT)
return(NULLZCLT); /* no such class */
else if (!strcmp(ptr->classname, class))
return(ptr->clientlist);
else { /* go search the list for the class */
for (ptr2 = ptr->q_forw; ptr2 != ptr; ptr2 = ptr2->q_forw) {
/* walk down the list, looking for a match */
if (!strcmp(ptr2->classname, class))
return(ptr2->clientlist);
}
/* fell off the end */
return(NULLZCLT);
}
}
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