Add function to execute a shell command and return the output (Issue 8676)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@49785 65c4cc65-6c06-0410-ace0-fbb531ad65f3

funcs/func_shell.c

+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2006, Digium, Inc.
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \SHELL function to return the value of a system call.
+ * 
+ * \ Inspiration and Guidance from Russell! Thank You! 
+ *
+ * \author Brandon Kruse <bkruse@digium.com>
+ */
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include "asterisk/module.h"
+#include "asterisk/channel.h"
+#include "asterisk/pbx.h"
+#include "asterisk/logger.h"
+#include "asterisk/utils.h"
+#include "asterisk/app.h"
+
+static int shell_helper(struct ast_channel *chan, char *cmd, char *data,
+		                         char *buf, size_t len)
+{
+	if (ast_strlen_zero(data)) {
+		ast_log(LOG_WARNING, "Missing Argument!  Example:  Set(foo=${SHELL(echo \"bar\")})\n");
+		return -1;
+	}
+
+	if (len >= 1) {
+		FILE *ptr;
+		char plbuff[4096];
+
+		ptr = popen(data, "r");
+		while (fgets(plbuff, sizeof(plbuff), ptr)) {
+			strncat(buf, plbuff, len - strlen(buf) - 1);
+		}
+		pclose(ptr);
+	}
+
+	return 0;
+}
+
+static struct ast_custom_function shell_function = {
+	.name = "SHELL",
+	.synopsis = "Executes a command as if you were at a shell.",
+	.syntax = "SHELL(<command>)",
+	.read = shell_helper,
+	.desc =
+"Returns the value from a system command\n"
+"  Example:  Set(foo=${SHELL(echo \"bar\")})\n"
+"  Note:  When using the SHELL() dialplan function, your \"SHELL\" is /bin/sh,\n"
+"  which may differ as to the underlying shell, depending upon your production\n"
+"  platform.  Also keep in mind that if you are using a common path, you should\n"
+"  be mindful of race conditions that could result from two calls running\n"
+"  SHELL() simultaneously.\n",
+};
+
+static int unload_module(void)
+{
+	return ast_custom_function_unregister(&shell_function);
+}
+
+static int load_module(void)
+{
+	return ast_custom_function_register(&shell_function);
+}
+
+AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "SHELL dialplan function");
+