Asterisk - The Open Source Telephony Project  GIT-master-b7027de
func_config.c
Go to the documentation of this file.
1 /*
2  * Asterisk -- An open source telephony toolkit.
3  *
4  * Copyright (C) 2008, Digium, Inc.
5  *
6  * Russell Bryant <russell@digium.com>
7  * Tilghman Lesher <func_config__200803@the-tilghman.com>
8  *
9  * See http://www.asterisk.org for more information about
10  * the Asterisk project. Please do not directly contact
11  * any of the maintainers of this project for assistance;
12  * the project provides a web site, mailing lists and IRC
13  * channels for your use.
14  *
15  * This program is free software, distributed under the terms of
16  * the GNU General Public License Version 2. See the LICENSE file
17  * at the top of the source tree.
18  */
19 
20 /*! \file
21  *
22  * \brief A function to retrieve variables from an Asterisk configuration file
23  *
24  * \author Russell Bryant <russell@digium.com>
25  * \author Tilghman Lesher <func_config__200803@the-tilghman.com>
26  *
27  * \ingroup functions
28  */
29 
30 /*** MODULEINFO
31  <support_level>core</support_level>
32  ***/
33 
34 #include "asterisk.h"
35 
36 #include "asterisk/module.h"
37 #include "asterisk/channel.h"
38 #include "asterisk/pbx.h"
39 #include "asterisk/app.h"
40 
41 /*** DOCUMENTATION
42  <function name="AST_CONFIG" language="en_US">
43  <synopsis>
44  Retrieve a variable from a configuration file.
45  </synopsis>
46  <syntax>
47  <parameter name="config_file" required="true" />
48  <parameter name="category" required="true" />
49  <parameter name="variable_name" required="true" />
50  <parameter name="index" required="false">
51  <para>If there are multiple variables with the same name, you can specify
52  <literal>0</literal> for the first item (default), <literal>-1</literal> for the last
53  item, or any other number for that specific item. <literal>-1</literal> is useful
54  when the variable is derived from a template and you want the effective value (the last
55  occurrence), not the value from the template (the first occurrence).</para>
56  </parameter>
57  </syntax>
58  <description>
59  <para>This function reads a variable from an Asterisk configuration file.</para>
60  </description>
61  </function>
62 
63 ***/
64 
65 struct config_item {
67  struct ast_config *cfg;
68  char filename[0];
69 };
70 
72 
73 static int config_function_read(struct ast_channel *chan, const char *cmd, char *data,
74  char *buf, size_t len)
75 {
76  struct ast_config *cfg;
77  struct ast_flags cfg_flags = { CONFIG_FLAG_FILEUNCHANGED };
78  char *parse;
79  struct config_item *cur;
80  int index = 0;
81  struct ast_variable *var;
82  struct ast_variable *found = NULL;
83  int ix = 0;
85  AST_APP_ARG(filename);
86  AST_APP_ARG(category);
87  AST_APP_ARG(variable);
88  AST_APP_ARG(index);
89  );
90 
91  if (ast_strlen_zero(data)) {
92  ast_log(LOG_ERROR, "AST_CONFIG() requires an argument\n");
93  return -1;
94  }
95 
96  parse = ast_strdupa(data);
98 
99  if (ast_strlen_zero(args.filename)) {
100  ast_log(LOG_ERROR, "AST_CONFIG() requires a filename\n");
101  return -1;
102  }
103 
104  if (ast_strlen_zero(args.category)) {
105  ast_log(LOG_ERROR, "AST_CONFIG() requires a category\n");
106  return -1;
107  }
108 
109  if (ast_strlen_zero(args.variable)) {
110  ast_log(LOG_ERROR, "AST_CONFIG() requires a variable\n");
111  return -1;
112  }
113 
114  if (!ast_strlen_zero(args.index)) {
115  if (!sscanf(args.index, "%d", &index)) {
116  ast_log(LOG_ERROR, "AST_CONFIG() index must be an integer\n");
117  return -1;
118  }
119  }
120 
121  if (!(cfg = ast_config_load(args.filename, cfg_flags)) || cfg == CONFIG_STATUS_FILEINVALID) {
122  return -1;
123  }
124 
125  if (cfg == CONFIG_STATUS_FILEUNCHANGED) {
126  /* Retrieve cfg from list */
129  if (!strcmp(cur->filename, args.filename)) {
130  break;
131  }
132  }
133 
134  if (!cur) {
135  /* At worst, we might leak an entry while upgrading locks */
138  if (!(cur = ast_calloc(1, sizeof(*cur) + strlen(args.filename) + 1))) {
140  return -1;
141  }
142 
143  strcpy(cur->filename, args.filename);
144 
146  if (!(cfg = ast_config_load(args.filename, cfg_flags)) || cfg == CONFIG_STATUS_FILEINVALID) {
147  ast_free(cur);
149  return -1;
150  }
151 
152  cur->cfg = cfg;
154  }
155 
156  cfg = cur->cfg;
157  } else {
158  /* Replace cfg in list */
161  if (!strcmp(cur->filename, args.filename)) {
162  break;
163  }
164  }
165 
166  if (!cur) {
167  if (!(cur = ast_calloc(1, sizeof(*cur) + strlen(args.filename) + 1))) {
169  return -1;
170  }
171 
172  strcpy(cur->filename, args.filename);
173  cur->cfg = cfg;
174 
176  } else {
177  ast_config_destroy(cur->cfg);
178  cur->cfg = cfg;
179  }
180  }
181 
182  for (var = ast_category_root(cfg, args.category); var; var = var->next) {
183  if (strcasecmp(args.variable, var->name)) {
184  continue;
185  }
186  found = var;
187  if (index == -1) {
188  continue;
189  }
190  if (ix == index) {
191  break;
192  }
193  found = NULL;
194  ix++;
195  }
196 
197  if (!found) {
198  ast_debug(1, "'%s' not found at index %d in [%s] of '%s'. Maximum index found: %d\n",
199  args.variable, index, args.category, args.filename, ix);
201  return -1;
202  }
203 
204  ast_copy_string(buf, found->value, len);
205 
206  /* Unlock down here, so there's no chance the struct goes away while we're using it. */
208 
209  return 0;
210 }
211 
213  .name = "AST_CONFIG",
214  .read = config_function_read,
215 };
216 
217 static int unload_module(void)
218 {
219  struct config_item *current;
220  int res = ast_custom_function_unregister(&config_function);
221 
223  while ((current = AST_RWLIST_REMOVE_HEAD(&configs, entry))) {
224  ast_config_destroy(current->cfg);
225  ast_free(current);
226  }
228 
229  return res;
230 }
231 
232 static int load_module(void)
233 {
234  return ast_custom_function_register(&config_function);
235 }
236 
237 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Asterisk configuration file variable access");
const char * name
Definition: pbx.h:119
struct ast_variable * next
Main Channel structure associated with a channel.
static struct ast_custom_function config_function
Definition: func_config.c:212
#define AST_MODULE_INFO_STANDARD(keystr, desc)
Definition: module.h:567
Asterisk main include file. File version handling, generic pbx functions.
#define AST_RWLIST_HEAD_STATIC(name, type)
Defines a structure to be used to hold a read/write list of specified type, statically initialized...
Definition: linkedlists.h:332
char buf[BUFSIZE]
Definition: eagi_proxy.c:66
#define AST_RWLIST_WRLOCK(head)
Write locks a list.
Definition: linkedlists.h:51
#define AST_STANDARD_APP_ARGS(args, parse)
Performs the &#39;standard&#39; argument separation process for an application.
#define CONFIG_STATUS_FILEINVALID
#define AST_RWLIST_UNLOCK(head)
Attempts to unlock a read/write based list.
Definition: linkedlists.h:150
Structure for variables, used for configurations and for channel variables.
#define var
Definition: ast_expr2f.c:614
const char * args
#define NULL
Definition: resample.c:96
int ast_custom_function_unregister(struct ast_custom_function *acf)
Unregister a custom function.
#define AST_RWLIST_RDLOCK(head)
Read locks a list.
Definition: linkedlists.h:77
struct ast_variable * ast_category_root(struct ast_config *config, char *cat)
returns the root ast_variable of a config
Definition: main/config.c:1162
#define ast_debug(level,...)
Log a DEBUG message.
Definition: logger.h:444
#define ast_log
Definition: astobj2.c:42
#define ast_config_load(filename, flags)
Load a config file.
General Asterisk PBX channel definitions.
Data structure associated with a custom dialplan function.
Definition: pbx.h:118
#define AST_RWLIST_TRAVERSE
Definition: linkedlists.h:493
void ast_config_destroy(struct ast_config *config)
Destroys a config.
Definition: extconf.c:1290
#define ast_strdupa(s)
duplicate a string in memory from the stack
Definition: astmm.h:300
Core PBX routines and definitions.
#define CONFIG_STATUS_FILEUNCHANGED
#define LOG_ERROR
Definition: logger.h:285
static int len(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t buflen)
#define ast_strlen_zero(a)
Definition: muted.c:73
static void parse(struct mgcp_request *req)
Definition: chan_mgcp.c:1872
#define ast_free(a)
Definition: astmm.h:182
static int load_module(void)
Definition: func_config.c:232
#define ast_calloc(num, len)
A wrapper for calloc()
Definition: astmm.h:204
#define AST_RWLIST_REMOVE_HEAD
Definition: linkedlists.h:843
Structure used to handle boolean flags.
Definition: utils.h:199
#define ast_clear_flag(p, flag)
Definition: utils.h:77
#define AST_RWLIST_ENTRY
Definition: linkedlists.h:414
static int config_function_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
Definition: func_config.c:73
#define AST_RWLIST_INSERT_TAIL
Definition: linkedlists.h:740
static int unload_module(void)
Definition: func_config.c:217
void ast_copy_string(char *dst, const char *src, size_t size)
Size-limited null-terminating string copy.
Definition: strings.h:401
Definition: search.h:40
#define ASTERISK_GPL_KEY
The text the key() function should return.
Definition: module.h:46
Asterisk module definitions.
#define AST_DECLARE_APP_ARGS(name, arglist)
Declare a structure to hold an application&#39;s arguments.
Application convenience functions, designed to give consistent look and feel to Asterisk apps...
#define ast_custom_function_register(acf)
Register a custom function.
Definition: pbx.h:1508
#define AST_APP_ARG(name)
Define an application argument.