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// Copyright 2015 CoreOS, Inc.
// Copyright 2015 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"
"syscall"
)
//#include <systemd/sd-daemon.h>
import "C"
// 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 os.Unsetenv("LISTEN_PID")
defer os.Unsetenv("LISTEN_FDS")
}
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 == 0 {
return nil
}
files := make([]*os.File, 0, nfds)
for fd := C.SD_LISTEN_FDS_START; fd < C.SD_LISTEN_FDS_START+nfds; fd++ {
syscall.CloseOnExec(fd)
files = append(files, os.NewFile(uintptr(fd), "LISTEN_FD_"+strconv.Itoa(fd)))
}
return files
}
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