//===============================
string& Pipe::exec_filter(const string& path, string& iobuf)
{
	pid_t pid;
	int nb, status;
	fd_set read_fds;

	// check access mode
	if(::access(path.c_str(), X_OK) == -1)
		throw general_exception("Pipe::exec_filter:" + string(strerror(errno)));
		
	if(::pipe(fds1_) < 0 || ::pipe(fds2_) < 0 || (pid = ::fork()) < 0)	
		throw general_exception("Pipe::exec_filter:" + string(strerror(errno)));
	
	else if(pid > 0) { // Parent		
		
		close(fds1_[0]);
		close(fds2_[1]);

		// write
		write(fds1_[1], iobuf.c_str(), iobuf.length());
		close(fds1_[1]);
		
		// wait for something to read
		FD_ZERO(&read_fds);
		FD_SET(fds2_[0], &read_fds);
		int e = select(fds2_[0] + 1, &read_fds, NULL, NULL, &read_timeout_);
		if(e == -1) throw general_exception("Pipe::exec_filter: parent: " + string(strerror(errno)));
		else if(!e) throw general_exception("Pipe::exec_filter: parent: " + string(strerror(errno=ETIMEDOUT)) + " [" + path + "]");
		
		// read
		char buffer[256+1];
		iobuf = "";
		while((nb = read(fds2_[0], buffer, 256)) > 0) {
			*(buffer+nb) = '\0';
			iobuf += buffer;
		}

		// Wait for child exit 
		if((e = wait(&status)) == -1)
			throw general_exception("Pipe::exec_filter: parent: " + string(strerror(errno)));

		// process any child errors
		if(status) 
			throw general_exception("Pipe::exec_filter: child: " + string(strerror(status)) + " [" + path + "]");
	}		
	else {	// Child	
		
		// dup stdin/stdout 
		close(fds1_[1]);
		close(fds2_[0]);
		if(fds1_[0] != STDIN_FILENO && dup2(fds1_[0], STDIN_FILENO) != STDIN_FILENO)
			_exit(errno);	
		if(fds2_[1] != STDOUT_FILENO && dup2(fds2_[1], STDOUT_FILENO) != STDOUT_FILENO)
			_exit(errno);

		// set nice 
		errno = 0;
		if(nice_inc_ && ::nice(nice_inc_) == -1 && errno)
			_exit(errno);			
		
		::execv(path.c_str(), NULL);
		_exit(1);
	}

	return iobuf;
}
//===============================