/*
Copyright 2014 CoreOS Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package activation

import (
	"net"
)

// Listeners returns a slice containing a net.Listener for each matching socket type
// passed to this process.
//
// The order of the file descriptors is preserved in the returned slice.
// Nil values are used to fill any gaps. For example if systemd were to return file descriptors
// corresponding with "udp, tcp, tcp", then the slice would contain {nil, net.Listener, net.Listener}
func Listeners(unsetEnv bool) ([]net.Listener, error) {
	files := Files(unsetEnv)
	listeners := make([]net.Listener, 0)

	for i := 0; i < len(files); i++ {
		if pc, err := net.FileListener(files[i]); err == nil {
			listeners = append(listeners, pc)
			continue
		} else {
			listeners = append(listeners, nil)
		}
	}
	return listeners, nil
}
