conditions.c

   1 /* conditions.c
   2  * Implementation for condition handler.
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 #include "config.h"
  26
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <stdarg.h>
  30 #include "conditions.h"
  31
  32 /* container for condition classes */
  33 static GHashTable* classes = NULL;
  34
  35 /* condition data structure declaration */
  36 struct condition{
  37   char* class_id;
  38   void* user_data;
  39   _cnd_eval eval_func;
  40   _cnd_reset reset_func;
  41 };
  42
  43 /* structure used to store class functions in GHashTable */
  44 typedef struct _cnd_class{
  45   _cnd_constr constr_func;
  46   _cnd_destr destr_func;
  47   _cnd_eval eval_func;
  48   _cnd_reset reset_func;
  49 } _cnd_class;
  50
  51 /* helper function prototypes */
  52 static void _cnd_init(void);
  53 static void _cnd_find_hash_key_for_class_id(gpointer, gpointer, gpointer);
  54
  55 condition* cnd_new(const char* class_id, ...){
  56   va_list ap;
  57   condition *cnd = NULL, *cnd_ref = NULL;
  58   _cnd_class *cls = NULL;
  59   char* id = NULL;
  60
  61   /* check if hash table is already initialized */
  62   _cnd_init();
  63
  64   /* get class structure for this id */
  65   if((cls = (_cnd_class*)g_hash_table_lookup(classes, class_id)) == NULL) {
  66     g_warning("cnd_new: Couldn't find class ID \"%s\"", class_id);
  67     return NULL;
  68   }
  69
  70   /* initialize the basic structure */
  71   if((cnd_ref = (condition*)g_malloc(sizeof(condition))) == NULL) return NULL;
  72   cnd_ref->user_data = NULL;
  73   cnd_ref->eval_func = cls->eval_func;
  74   cnd_ref->reset_func = cls->reset_func;
  75
  76   cnd_ref->class_id = g_strdup(class_id);
  77
  78   /* perform class specific initialization */
  79   va_start(ap, class_id);
  80   cnd = (cls->constr_func)(cnd_ref, ap);
  81   va_end(ap);
  82
  83   /* check for successful construction */
  84   if(cnd == NULL){
  85     g_free(cnd_ref);
  86     g_free(id);
  87   }
  88   return cnd;
  89 } /* END cnd_new() */
  90
  91 void cnd_delete(condition *cnd){
  92   _cnd_class *cls = NULL;
  93   const char* class_id;
  94   /* check for valid pointer */
  95   if(cnd == NULL) return;
  96
  97   class_id = cnd->class_id;
  98   /* check if hash table is already initialized */
  99   _cnd_init();
 100   /* get the condition class */
 101   cls = (_cnd_class*)g_hash_table_lookup(classes, class_id);
 102   /* call class specific destructor */
 103   if(cls != NULL) (cls->destr_func)(cnd);
 104   /* free memory */
 105   g_free(cnd->class_id);
 106   /* free basic structure */
 107   g_free(cnd);
 108 } /* END cnd_delete() */
 109
 110 gboolean cnd_eval(condition *cnd, ...){
 111   va_list ap;
 112   gboolean ret_val = FALSE;
 113   /* validate cnd */
 114   if(cnd == NULL) return FALSE;
 115   /* call specific handler */
 116   va_start(ap, cnd);
 117   ret_val = (cnd->eval_func)(cnd, ap);
 118   va_end(ap);
 119   return ret_val;
 120 } /*  END cnd_eval() */
 121
 122 void cnd_reset(condition *cnd){
 123   if(cnd != NULL) (cnd->reset_func)(cnd);
 124 } /* END cnd_reset() */
 125
 126 void* cnd_get_user_data(condition *cnd){
 127   return cnd->user_data;
 128 } /* END cnd_get_user_data() */
 129
 130 void cnd_set_user_data(condition *cnd, void* user_data){
 131   cnd->user_data = user_data;
 132 } /* END cnd_set_user_data() */
 133
 134 gboolean cnd_register_class(const char* class_id,
 135                             _cnd_constr constr_func,
 136                             _cnd_destr destr_func,
 137                             _cnd_eval eval_func,
 138                             _cnd_reset reset_func){
 139   char* key = NULL;
 140   _cnd_class *cls = NULL;
 141   /* check for valid parameters */
 142   if((constr_func == NULL) || (destr_func == NULL) ||
 143      (eval_func == NULL) || (reset_func == NULL) || (class_id == NULL))
 144     return FALSE;
 145   /* check if hash table is already initialized */
 146   _cnd_init();
 147   /* check for unique class id */
 148   if(g_hash_table_lookup(classes, class_id) != NULL) {
 149     g_warning("cnd_register_class: Duplicate class ID \"%s\"", class_id);
 150     return FALSE;
 151   }
 152   /* GHashTable keys need to be persistent for the lifetime of the hash
 153      table. Allocate memory and copy the class id which we use as key. */
 154   key = g_strdup(class_id);
 155   /* initialize class structure */
 156   if((cls = (_cnd_class*)g_malloc(sizeof(_cnd_class))) == NULL){
 157     g_free(key);
 158     return FALSE;
 159   }
 160   cls->constr_func = constr_func;
 161   cls->destr_func = destr_func;
 162   cls->eval_func = eval_func;
 163   cls->reset_func = reset_func;
 164   /* insert new class */
 165   g_hash_table_insert(classes, key, cls);
 166   return TRUE;
 167 } /* END cnd_register_class() */
 168
 169 static char* pkey = NULL;
 170 void cnd_unregister_class(const char* class_id){
 171   const char *key = (const char*)class_id;
 172   _cnd_class *cls = NULL;
 173   /* check if hash table is already initialized */
 174   _cnd_init();
 175   /* find the key for this class id and store it in 'pkey' */
 176   g_hash_table_foreach(classes,
 177                        _cnd_find_hash_key_for_class_id,
 178                        (gpointer)key);
 179   /* find the class structure for this class id */
 180   cls = (_cnd_class*)g_hash_table_lookup(classes, class_id);
 181   /* remove constructor from hash table */
 182   g_hash_table_remove(classes, class_id);
 183   /* free the key */
 184   g_free(pkey);
 185   pkey = NULL;
 186   /* free the value */
 187   g_free(cls);
 188 } /* END cnd_unregister_class() */
 189
 190 /*
 191  * Initialize hash table.
 192  */
 193 static void _cnd_init(void){
 194   if(classes != NULL) return;
 195   /* create hash table, we use strings as keys */
 196   classes = g_hash_table_new(g_str_hash, g_str_equal);
 197 } /* END _cnd_init() */
 198
 199 /*
 200  * Callback for function 'g_hash_table_foreach()'.
 201  * We don't keep references to hash table keys. Keys have memory allocated
 202  * which must be freed when they are not used anymore. This function finds
 203  * the reference to a key corresponding to a particular class id. The reference
 204  * to the key is stored in a global variable.
 205  */
 206 void _cnd_find_hash_key_for_class_id(gpointer key,
 207                                      gpointer value _U_,
 208                                      gpointer user_data){
 209   char* class_id = (char*)user_data;
 210   char* key_value = (char*)key;
 211   if(strcmp(class_id, key_value) == 0) pkey = key_value;
 212 } /* END _cnd_find_hash_key_for_class_id() */
 213
 214 /*
 215  * Editor modelines
 216  *
 217  * Local Variables:
 218  * c-basic-offset: 2
 219  * tab-width: 8
 220  * indent-tabs-mode: nil
 221  * End:
 222  *
 223  * ex: set shiftwidth=2 tabstop=8 expandtab:
 224  * :indentSize=2:tabSize=8:noTabs=true:
 225  */