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conditions.c
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/* conditions.c
* Implementation for condition handler.
*
* $Id: conditions.c,v 1.2 2002/05/04 09:19:09 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include "conditions.h"
/* container for condition classes */
static GHashTable* classes = NULL;
/* condition data structure declaration */
struct condition{
char* class_id;
void* user_data;
_cnd_eval eval_func;
_cnd_reset reset_func;
};
/* structure used to store class functions in GHashTable */
typedef struct _cnd_class{
_cnd_constr constr_func;
_cnd_destr destr_func;
_cnd_eval eval_func;
_cnd_reset reset_func;
} _cnd_class;
/* helper function prototypes */
static void _cnd_init();
static void _cnd_find_hash_key_for_class_id(gpointer, gpointer, gpointer);
condition* cnd_new(const char* class_id, ...){
va_list ap;
condition *cnd = NULL, *cnd_ref = NULL;
_cnd_class *cls = NULL;
char* id = NULL;
/* check if hash table is already initialized */
_cnd_init();
/* get class structure for this id */
if((cls = (_cnd_class*)g_hash_table_lookup(classes, class_id)) == NULL)
return NULL;
/* initialize the basic structure */
if((cnd_ref = (condition*)malloc(sizeof(condition))) == NULL) return NULL;
cnd_ref->user_data = NULL;
cnd_ref->eval_func = cls->eval_func;
cnd_ref->reset_func = cls->reset_func;
/* copy the class id */
if((id = (char*)malloc(strlen(class_id)+1)) == NULL){
free(cnd_ref);
return NULL;
}
strcpy(id, class_id);
cnd_ref->class_id = id;
/* perform class specific initialization */
va_start(ap, class_id);
cnd = (cls->constr_func)(cnd_ref, ap);
va_end(ap);
/* check for successful construction */
if(cnd == NULL){
free(cnd_ref);
free(id);
}
return cnd;
} /* END cnd_new() */
void cnd_delete(condition *cnd){
_cnd_class *cls = NULL;
const char* class_id = cnd->class_id;
/* check for valid pointer */
if(cnd == NULL) return;
/* check if hash table is already initialized */
_cnd_init();
/* get the condition class */
cls = (_cnd_class*)g_hash_table_lookup(classes, class_id);
/* call class specific destructor */
if(cls != NULL) (cls->destr_func)(cnd);
/* free memory */
free(cnd->class_id);
/* free basic structure */
free(cnd);
} /* END cnd_delete() */
gboolean cnd_eval(condition *cnd, ...){
va_list ap;
gboolean ret_val = FALSE;
/* validate cnd */
if(cnd == NULL) return FALSE;
/* call specific handler */
va_start(ap, cnd);
ret_val = (cnd->eval_func)(cnd, ap);
va_end(ap);
return ret_val;
} /* END cnd_eval() */
void cnd_reset(condition *cnd){
if(cnd != NULL) (cnd->reset_func)(cnd);
} /* END cnd_reset() */
void* cnd_get_user_data(condition *cnd){
return cnd->user_data;
} /* END cnd_get_user_data() */
void cnd_set_user_data(condition *cnd, void* user_data){
cnd->user_data = user_data;
} /* END cnd_set_user_data() */
gboolean cnd_register_class(const char* class_id,
_cnd_constr constr_func,
_cnd_destr destr_func,
_cnd_eval eval_func,
_cnd_reset reset_func){
char* key = NULL;
_cnd_class *cls = NULL;
/* check for valid parameters */
if((constr_func == NULL) || (destr_func == NULL) ||
(eval_func == NULL) || (reset_func == NULL) || (class_id == NULL))
return FALSE;
/* check if hash table is already initialized */
_cnd_init();
/* check for unique class id */
if((cls = (_cnd_class*)g_hash_table_lookup(classes, class_id)) != NULL)
return FALSE;
/* GHashTable keys need to be persistent for the lifetime of the hash
table. Allocate memory and copy the class id which we use as key. */
if((key = (char*)malloc(strlen(class_id)+1)) == NULL) return FALSE;
strcpy(key, class_id);
/* initialize class structure */
if((cls = (_cnd_class*)malloc(sizeof(_cnd_class))) == NULL){
free(key);
return FALSE;
}
cls->constr_func = constr_func;
cls->destr_func = destr_func;
cls->eval_func = eval_func;
cls->reset_func = reset_func;
/* insert new class */
g_hash_table_insert(classes, key, cls);
return TRUE;
} /* END cnd_register_class() */
static char* pkey = NULL;
void cnd_unregister_class(const char* class_id){
char *key = (char*)class_id;
_cnd_class *cls = NULL;
/* check if hash table is already initialized */
_cnd_init();
/* find the key for this class id and store it in 'pkey' */
g_hash_table_foreach(classes,
_cnd_find_hash_key_for_class_id,
key);
/* find the class structure for this class id */
cls = (_cnd_class*)g_hash_table_lookup(classes, class_id);
/* remove constructor from hash table */
g_hash_table_remove(classes, class_id);
/* free the key */
free(pkey);
pkey = NULL;
/* free the value */
free(cls);
} /* END cnd_unregister_class() */
/*
* Initialize hash table.
*/
static void _cnd_init(){
if(classes != NULL) return;
/* create hash table, we use strings as keys */
classes = g_hash_table_new(g_str_hash, g_str_equal);
} /* END _cnd_init() */
/*
* Callback for function 'g_hash_table_foreach()'.
* We don't keep references to hash table keys. Keys have memory allocated
* which must be freed when they are not used anymore. This function finds
* the reference to a key corresponding to a particular class id. The reference
* to the key is stored in a global variable.
*/
void _cnd_find_hash_key_for_class_id(gpointer key,
gpointer value _U_,
gpointer user_data){
char* class_id = (char*)user_data;
char* key_value = (char*)key;
if(strcmp(class_id, key_value) == 0) pkey = key;
} /* END _cnd_find_hash_key_for_class_id() */