/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * backticks Application For Asterisk
 *
 * Copyright (C) 2005, Anthony Minessale II
 *
 * Anthony Minessale II <anthmct@yahoo.com>
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 */
#include <asterisk.h>
#include <stdio.h> 
#include <asterisk/file.h>
#include <asterisk/logger.h>
#include <asterisk/channel.h>
#include <asterisk/pbx.h>
#include <asterisk/module.h>
#include <asterisk/lock.h>
#include <asterisk/app.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#define AST_MODULE "app_backticks"

static char *tdesc = "backticks";
static char *app = "BackTicks";
static char *synopsis = "Execute a shell command and save the result as a variable.";
static char *desc = ""
"  Backticks(<VARNAME>|<command>)\n\n"
"Be sure to include a full path!\n"

;

static char *do_backticks(char *command, char *buf, size_t len) 
{
	int fds[2], pid = 0;
	char *ret = NULL;

	memset(buf, 0, len);

	if (pipe(fds)) {	
		ast_log(LOG_WARNING, "Pipe/Exec failed\n");
	} else { /* good to go*/
		
		pid = fork();

		if (pid < 0) { /* ok maybe not */
			ast_log(LOG_WARNING, "Fork failed\n");
			close(fds[0]);
			close(fds[1]);
		} else if (pid) { /* parent */
			close(fds[1]);
			read(fds[0], buf, len);
			close(fds[0]);
			ret = buf;
		} else { /*  child */
			char *argv[255] = {0};
			int argc = 0;
			char *p;
			char *mycmd = ast_strdupa(command);
			
			close(fds[0]);
			dup2(fds[1], STDOUT_FILENO);
			argv[argc++] = mycmd;

			do {
				if ((p = strchr(mycmd, ' '))) {
					*p = '\0';
					mycmd = ++p;
					argv[argc++] = mycmd;
				}
			} while (p);

			close(fds[1]);			
			execv(argv[0], argv); 
			/* DoH! */
			ast_log(LOG_ERROR, "exec of %s failed\n", argv[0]);
			exit(0);
		}
	}

	return buf;
}

static int backticks_exec(struct ast_channel *chan, void *data)
{
	int res = 0;
	const char *usage = "Usage: Backticks(<VARNAME>|<command>)";
	char buf[1024], *argv[2], *mydata;
	int argc = 0;
	
	
	if (!data) {
		ast_log(LOG_WARNING, "%s\n", usage);
		return -1;
	}

	
	/* Do our thing here */

	if (!(mydata = ast_strdupa(data))) {
		ast_log(LOG_ERROR, "Memory Error!\n");
		res = -1;
	} else {
		if((argc = ast_app_separate_args(mydata, '|', argv, sizeof(argv) / sizeof(argv[0]))) < 2) {
			ast_log(LOG_WARNING, "%s\n", usage);
			res = -1;
		}
		
		if (do_backticks(argv[1], buf, sizeof(buf))) {
			pbx_builtin_setvar_helper(chan, argv[0], buf);
		} else {
			ast_log(LOG_WARNING, "No Data!\n");
			res = -1;
		}
	}
	return res;
}


static char *function_backticks(struct ast_channel *chan, char *cmd, char *data, char *buf, size_t len)
{
	char *ret = NULL;

	if (do_backticks(data, buf, len)) {
		ret = buf;
	}

	return ret;
}

static struct ast_custom_function backticks_function = {
	.name = "BACKTICKS", 
	.desc = "Executes a shell command and evaluates to the result.", 
	.syntax = "BACKTICKS(<command>)", 
	.synopsis = "Executes a shell command.", 
	.read = function_backticks
};


int unload_module(void)
{
   ast_module_user_hangup_all();
	ast_custom_function_unregister(&backticks_function);
	return ast_unregister_application(app);
}

int load_module(void)
{
	ast_custom_function_register(&backticks_function);

   int res;
	res = ast_register_application(app, backticks_exec, synopsis, desc);
   printf("Return value from register: %d\n", res);
   return res;
}

char *description(void)
{
	return tdesc;
}

int usecnt(void)
{
	int res;
	return res;
}

char *key()
{
	return ASTERISK_GPL_KEY;
}

AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Execute command and return output");