Mon Oct 8 12:39:02 2012

Asterisk developer's documentation


func_config.c

Go to the documentation of this file.
00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2008, Digium, Inc.
00005  *
00006  * Russell Bryant <russell@digium.com>
00007  * Tilghman Lesher <func_config__200803@the-tilghman.com>
00008  *
00009  * See http://www.asterisk.org for more information about
00010  * the Asterisk project. Please do not directly contact
00011  * any of the maintainers of this project for assistance;
00012  * the project provides a web site, mailing lists and IRC
00013  * channels for your use.
00014  *
00015  * This program is free software, distributed under the terms of
00016  * the GNU General Public License Version 2. See the LICENSE file
00017  * at the top of the source tree.
00018  */
00019 
00020 /*! \file
00021  *
00022  * \brief A function to retrieve variables from an Asterisk configuration file
00023  *
00024  * \author Russell Bryant <russell@digium.com>
00025  * \author Tilghman Lesher <func_config__200803@the-tilghman.com>
00026  * 
00027  * \ingroup functions
00028  */
00029 
00030 /*** MODULEINFO
00031    <support_level>core</support_level>
00032  ***/
00033 
00034 #include "asterisk.h"
00035 
00036 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 328209 $")
00037 
00038 #include "asterisk/module.h"
00039 #include "asterisk/channel.h"
00040 #include "asterisk/pbx.h"
00041 #include "asterisk/app.h"
00042 
00043 /*** DOCUMENTATION
00044    <function name="AST_CONFIG" language="en_US">
00045       <synopsis>
00046          Retrieve a variable from a configuration file.
00047       </synopsis>
00048       <syntax>
00049          <parameter name="config_file" required="true" />
00050          <parameter name="category" required="true" />
00051          <parameter name="variable_name" required="true" />
00052       </syntax>
00053       <description>
00054          <para>This function reads a variable from an Asterisk configuration file.</para>
00055       </description>
00056    </function>
00057 
00058 ***/
00059 
00060 struct config_item {
00061    AST_RWLIST_ENTRY(config_item) entry;
00062    struct ast_config *cfg;
00063    char filename[0];
00064 };
00065 
00066 static AST_RWLIST_HEAD_STATIC(configs, config_item);
00067 
00068 static int config_function_read(struct ast_channel *chan, const char *cmd, char *data, 
00069    char *buf, size_t len) 
00070 {
00071    struct ast_config *cfg;
00072    struct ast_flags cfg_flags = { CONFIG_FLAG_FILEUNCHANGED };
00073    const char *val;
00074    char *parse;
00075    struct config_item *cur;
00076    AST_DECLARE_APP_ARGS(args,
00077       AST_APP_ARG(filename);
00078       AST_APP_ARG(category);
00079       AST_APP_ARG(variable);
00080       AST_APP_ARG(index);
00081    );
00082 
00083    if (ast_strlen_zero(data)) {
00084       ast_log(LOG_ERROR, "AST_CONFIG() requires an argument\n");
00085       return -1;
00086    }
00087 
00088    parse = ast_strdupa(data);
00089    AST_STANDARD_APP_ARGS(args, parse);
00090 
00091    if (ast_strlen_zero(args.filename)) {
00092       ast_log(LOG_ERROR, "AST_CONFIG() requires a filename\n");
00093       return -1;
00094    }
00095 
00096    if (ast_strlen_zero(args.category)) {
00097       ast_log(LOG_ERROR, "AST_CONFIG() requires a category\n");
00098       return -1;
00099    }
00100    
00101    if (ast_strlen_zero(args.variable)) {
00102       ast_log(LOG_ERROR, "AST_CONFIG() requires a variable\n");
00103       return -1;
00104    }
00105 
00106    if (!(cfg = ast_config_load(args.filename, cfg_flags)) || cfg == CONFIG_STATUS_FILEINVALID) {
00107       return -1;
00108    }
00109 
00110    if (cfg == CONFIG_STATUS_FILEUNCHANGED) {
00111       /* Retrieve cfg from list */
00112       AST_RWLIST_RDLOCK(&configs);
00113       AST_RWLIST_TRAVERSE(&configs, cur, entry) {
00114          if (!strcmp(cur->filename, args.filename)) {
00115             break;
00116          }
00117       }
00118 
00119       if (!cur) {
00120          /* At worst, we might leak an entry while upgrading locks */
00121          AST_RWLIST_UNLOCK(&configs);
00122          AST_RWLIST_WRLOCK(&configs);
00123          if (!(cur = ast_malloc(sizeof(*cur) + strlen(args.filename) + 1))) {
00124             AST_RWLIST_UNLOCK(&configs);
00125             return -1;
00126          }
00127 
00128          strcpy(cur->filename, args.filename);
00129 
00130          ast_clear_flag(&cfg_flags, CONFIG_FLAG_FILEUNCHANGED);
00131          if (!(cfg = ast_config_load(args.filename, cfg_flags)) || cfg == CONFIG_STATUS_FILEINVALID) {
00132             ast_free(cur);
00133             AST_RWLIST_UNLOCK(&configs);
00134             return -1;
00135          }
00136 
00137          cur->cfg = cfg;
00138          AST_RWLIST_INSERT_TAIL(&configs, cur, entry);
00139       }
00140 
00141       cfg = cur->cfg;
00142    } else {
00143       /* Replace cfg in list */
00144       AST_RWLIST_WRLOCK(&configs);
00145       AST_RWLIST_TRAVERSE(&configs, cur, entry) {
00146          if (!strcmp(cur->filename, args.filename)) {
00147             break;
00148          }
00149       }
00150 
00151       if (!cur) {
00152          if (!(cur = ast_malloc(sizeof(*cur) + strlen(args.filename) + 1))) {
00153             AST_RWLIST_UNLOCK(&configs);
00154             return -1;
00155          }
00156 
00157          strcpy(cur->filename, args.filename);
00158          cur->cfg = cfg;
00159 
00160          AST_RWLIST_INSERT_TAIL(&configs, cur, entry);
00161       } else {
00162          ast_config_destroy(cur->cfg);
00163          cur->cfg = cfg;
00164       }
00165    }
00166 
00167    if (!(val = ast_variable_retrieve(cfg, args.category, args.variable))) {
00168       ast_log(LOG_ERROR, "'%s' not found in [%s] of '%s'\n", args.variable, 
00169          args.category, args.filename);
00170       AST_RWLIST_UNLOCK(&configs);
00171       return -1;
00172    }
00173 
00174    ast_copy_string(buf, val, len);
00175 
00176    /* Unlock down here, so there's no chance the struct goes away while we're using it. */
00177    AST_RWLIST_UNLOCK(&configs);
00178 
00179    return 0;
00180 }
00181 
00182 static struct ast_custom_function config_function = {
00183    .name = "AST_CONFIG",
00184    .read = config_function_read,
00185 };
00186 
00187 static int unload_module(void)
00188 {
00189    struct config_item *current;
00190    int res = ast_custom_function_unregister(&config_function);
00191 
00192    AST_RWLIST_WRLOCK(&configs);
00193    while ((current = AST_RWLIST_REMOVE_HEAD(&configs, entry))) {
00194       ast_config_destroy(current->cfg);
00195       ast_free(current);
00196    }
00197    AST_RWLIST_UNLOCK(&configs);
00198 
00199    return res;
00200 }
00201 
00202 static int load_module(void)
00203 {
00204    return ast_custom_function_register(&config_function);
00205 }
00206 
00207 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Asterisk configuration file variable access");

Generated on Mon Oct 8 12:39:02 2012 for Asterisk - The Open Source Telephony Project by  doxygen 1.4.7