funcs/func_shell.c

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 2006, Digium, Inc.
   5  *
   6  * See http://www.asterisk.org for more information about
   7  * the Asterisk project. Please do not directly contact
   8  * any of the maintainers of this project for assistance;
   9  * the project provides a web site, mailing lists and IRC
  10  * channels for your use.
  11  *
  12  * This program is free software, distributed under the terms of
  13  * the GNU General Public License Version 2. See the LICENSE file
  14  * at the top of the source tree.
  15  */
  16
  17 /*! \file
  18  *
  19  * SHELL function to return the value of a system call.
  20  *
  21  * \note Inspiration and Guidance from Russell! Thank You!
  22  *
  23  * \author Brandon Kruse <bkruse@digium.com>
  24  *
  25  * \ingroup functions
  26  */
  27
  28 #include "asterisk.h"
  29
  30 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
  31
  32 #include "asterisk/module.h"
  33 #include "asterisk/channel.h"
  34 #include "asterisk/pbx.h"
  35 #include "asterisk/utils.h"
  36 #include "asterisk/app.h"
  37
  38 static int shell_helper(struct ast_channel *chan, const char *cmd, char *data,
  39                                          char *buf, size_t len)
  40 {
  41         if (ast_strlen_zero(data)) {
  42                 ast_log(LOG_WARNING, "Missing Argument!  Example:  Set(foo=${SHELL(echo \"bar\")})\n");
  43                 return -1;
  44         }
  45
  46         if (chan)
  47                 ast_autoservice_start(chan);
  48
  49         if (len >= 1) {
  50                 FILE *ptr;
  51                 char plbuff[4096];
  52
  53                 ptr = popen(data, "r");
  54                 while (fgets(plbuff, sizeof(plbuff), ptr)) {
  55                         strncat(buf, plbuff, len - strlen(buf) - 1);
  56                 }
  57                 pclose(ptr);
  58         }
  59
  60         if (chan)
  61                 ast_autoservice_stop(chan);
  62
  63         return 0;
  64 }
  65
  66 static struct ast_custom_function shell_function = {
  67         .name = "SHELL",
  68         .synopsis = "Executes a command as if you were at a shell.",
  69         .syntax = "SHELL(<command>)",
  70         .read = shell_helper,
  71         .desc =
  72 "Returns the value from a system command\n"
  73 "  Example:  Set(foo=${SHELL(echo \"bar\")})\n"
  74 "  Note:  When using the SHELL() dialplan function, your \"SHELL\" is /bin/sh,\n"
  75 "  which may differ as to the underlying shell, depending upon your production\n"
  76 "  platform.  Also keep in mind that if you are using a common path, you should\n"
  77 "  be mindful of race conditions that could result from two calls running\n"
  78 "  SHELL() simultaneously.\n",
  79 };
  80
  81 static int unload_module(void)
  82 {
  83         return ast_custom_function_unregister(&shell_function);
  84 }
  85
  86 static int load_module(void)
  87 {
  88         return ast_custom_function_register(&shell_function);
  89 }
  90
  91 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Returns the output of a shell command");
  92