epan/wslua/wslua_file_common.c

   1 /*
   2  * wslua_file_common.c
   3  *
   4  * Wireshark's interface to the Lua Programming Language
   5  * for file handling related source file internal functions.
   6  *
   7  * (c) 2014, Hadriel Kaplan <hadrielk@yahoo.com>
   8  *
   9  * Wireshark - Network traffic analyzer
  10  * By Gerald Combs <gerald@wireshark.org>
  11  * Copyright 1998 Gerald Combs
  12  *
  13  * SPDX-License-Identifier: GPL-2.0-or-later
  14  */
  15
  16 /************
  17  * The following is for handling private data for the duration of the file
  18  * read_open/read/close cycle, or write_open/write/write_close cycle.
  19  * In other words it handles the "priv" member of wtap and wtap_dumper,
  20  * but for the Lua script's use. A Lua script can set a Lua table
  21  * to CaptureInfo/CaptureInfoConst and have it saved and retrievable this way.
  22  * We need to offer that, because there needs to be a way for Lua scripts
  23  * to save state for a given file's operations cycle. Since there can be
  24  * two files opened at the same time for the same Lua script (due to reload
  25  * and other such events), the script can't just have one file state.
  26  */
  27 #include "config.h"
  28
  29 #include "wslua_file_common.h"
  30
  31
  32 /* create and set the wtap->priv private data for the file instance */
  33 void create_wth_priv(lua_State* L, wtap *wth) {
  34     file_priv_t *priv = g_new(file_priv_t, 1);
  35
  36     if (wth->priv != NULL) {
  37         g_free(priv);
  38         luaL_error(L, "Cannot create wtap private data because there already is private data");
  39         return;
  40     }
  41     priv->table_ref = LUA_NOREF;
  42     wth->priv = (void*) priv;
  43 }
  44
  45 /* gets the private data table from wtap */
  46 int get_wth_priv_table_ref(lua_State* L, wtap *wth) {
  47     file_priv_t *priv = (file_priv_t*) wth->priv;
  48
  49     if (!priv) {
  50         /* shouldn't be possible */
  51         luaL_error(L, "Cannot get wtap private data: it is null");
  52         return LUA_NOREF;
  53     }
  54
  55     /* the following might push a nil, but that's ok */
  56     lua_rawgeti(L, LUA_REGISTRYINDEX, priv->table_ref);
  57
  58     return 1;
  59 }
  60
  61 /* sets the private data to wtap - the table is presumed on top of stack */
  62 int set_wth_priv_table_ref(lua_State* L, wtap *wth) {
  63     file_priv_t *priv = (file_priv_t*) wth->priv;
  64
  65     if (!priv) {
  66         /* shouldn't be possible */
  67         luaL_error(L, "Cannot get wtap private data: it is null");
  68         return 0;
  69     }
  70
  71     if (lua_isnil(L, -1)){
  72         /* user is setting it nil - ok, de-ref any previous one */
  73         luaL_unref(L, LUA_REGISTRYINDEX, priv->table_ref);
  74         priv->table_ref = LUA_NOREF;
  75         return 0;
  76     }
  77
  78     if (!lua_istable(L, -1)) {
  79         luaL_error(L, "The private_table member can only be set to a table or nil");
  80         return 0;
  81     }
  82
  83     /* if we had a table already referenced, de-ref it first */
  84     if (priv->table_ref != LUA_NOREF) {
  85         luaL_unref(L, LUA_REGISTRYINDEX, priv->table_ref);
  86     }
  87
  88     priv->table_ref = luaL_ref(L, LUA_REGISTRYINDEX);
  89
  90     return 0;
  91 }
  92
  93 /* remove, deref, and free the wtap->priv data */
  94 void remove_wth_priv(lua_State* L, wtap *wth) {
  95     file_priv_t *priv = (file_priv_t*) wth->priv;
  96
  97     if (!priv) {
  98         /* shouldn't be possible */
  99         luaL_error(L, "Cannot remove wtap private data: it is null");
 100         return;
 101     }
 102
 103     luaL_unref(L, LUA_REGISTRYINDEX, priv->table_ref);
 104
 105     g_free(wth->priv);
 106     wth->priv = NULL;
 107 }
 108
 109 /* create and set the wtap_dumper->priv private data for the file instance */
 110 void create_wdh_priv(lua_State* L, wtap_dumper *wdh) {
 111     file_priv_t *priv = g_new(file_priv_t, 1);
 112
 113     if (wdh->priv != NULL) {
 114         g_free(priv);
 115         luaL_error(L, "Cannot create wtap_dumper private data because there already is private data");
 116         return;
 117     }
 118     priv->table_ref = LUA_NOREF;
 119     wdh->priv = (void*) priv;
 120 }
 121
 122 /* get the private data from wtap_dumper */
 123 int get_wdh_priv_table_ref(lua_State* L, wtap_dumper *wdh) {
 124     file_priv_t *priv = (file_priv_t*) wdh->priv;
 125
 126     if (!priv) {
 127         /* shouldn't be possible */
 128         luaL_error(L, "Cannot get wtap_dumper private data: it is null");
 129         return LUA_NOREF;
 130     }
 131
 132     /* the following might push a nil, but that's ok */
 133     lua_rawgeti(L, LUA_REGISTRYINDEX, priv->table_ref);
 134
 135     return 1;
 136 }
 137
 138 /* sets the private data to wtap - the table is presumed on top of stack */
 139 int set_wdh_priv_table_ref(lua_State* L, wtap_dumper *wdh) {
 140     file_priv_t *priv = (file_priv_t*) wdh->priv;
 141
 142     if (!priv) {
 143         /* shouldn't be possible */
 144         luaL_error(L, "Cannot get wtap private data: it is null");
 145         return 0;
 146     }
 147
 148     if (lua_isnil(L, -1)){
 149         /* user is setting it nil - ok, de-ref any previous one */
 150         luaL_unref(L, LUA_REGISTRYINDEX, priv->table_ref);
 151         priv->table_ref = LUA_NOREF;
 152         return 0;
 153     }
 154
 155     if (!lua_istable(L, -1)) {
 156         luaL_error(L, "The private_table member can only be set to a table or nil");
 157         return 0;
 158     }
 159
 160     /* if we had a table already referenced, de-ref it first */
 161     if (priv->table_ref != LUA_NOREF) {
 162         luaL_unref(L, LUA_REGISTRYINDEX, priv->table_ref);
 163     }
 164
 165     priv->table_ref = luaL_ref(L, LUA_REGISTRYINDEX);
 166
 167     return 0;
 168 }
 169
 170 /* remove and deref the wtap_dumper->priv data */
 171 void remove_wdh_priv(lua_State* L, wtap_dumper *wdh) {
 172     file_priv_t *priv = (file_priv_t*) wdh->priv;
 173
 174     if (!priv) {
 175         /* shouldn't be possible */
 176         luaL_error(L, "Cannot remove wtap_dumper private data: it is null");
 177         return;
 178     }
 179
 180     luaL_unref(L, LUA_REGISTRYINDEX, priv->table_ref);
 181     /* we do NOT free wtap_dumper's priv member - wtap_dump_close() free's it */
 182 }
 183
 184
 185 /*
 186  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 187  *
 188  * Local variables:
 189  * c-basic-offset: 4
 190  * tab-width: 8
 191  * indent-tabs-mode: nil
 192  * End:
 193  *
 194  * vi: set shiftwidth=4 tabstop=8 expandtab:
 195  * :indentSize=4:tabSize=8:noTabs=true:
 196  */