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// Copyright 2015 CoreOS, Inc.
// Copyright 2015-2016 Luke Shumaker
//
// 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 sd
import (
"os"
"strconv"
"strings"
"syscall"
)
///*#include <systemd/sd-daemon.h>*/
//#define SD_LISTEN_FDS_START 3
import "C"
// ListenFds returns a list of file descriptors passed in by the
// service manager as part of the socket-based activation logic.
//
// If unsetEnv is true, then (regarless of whether the function call
// itself succeeds or not) it will unset the environmental variables
// LISTEN_FDS and LISTEN_PID, which will cause further calls to this
// function to fail.
//
// In the case of an error, this function returns nil.
func ListenFds(unsetEnv bool) []*os.File {
if unsetEnv {
defer func() {
_ = os.Unsetenv("LISTEN_PID")
_ = os.Unsetenv("LISTEN_FDS")
_ = os.Unsetenv("LISTEN_FDNAMES")
}()
}
pid, err := strconv.Atoi(os.Getenv("LISTEN_PID"))
if err != nil || pid != os.Getpid() {
return nil
}
nfds, err := strconv.Atoi(os.Getenv("LISTEN_FDS"))
if err != nil || nfds < 1 {
return nil
}
names := strings.Split(os.Getenv("LISTEN_FDNAMES"), ":")
files := make([]*os.File, 0, nfds)
for i := 0; i < nfds; i++ {
fd := i+C.SD_LISTEN_FDS_START
syscall.CloseOnExec(fd)
name := "unknown"
if i < len(names) {
name = names[i]
}
files = append(files, os.NewFile(uintptr(fd), name))
}
return files
}
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