github.com/blixtra/rkt@v0.8.1-0.20160204105720-ab0d1add1a43/stage1/common/run.go (about) 1 // Copyright 2015 The rkt Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package common 16 17 import ( 18 "errors" 19 "fmt" 20 "io/ioutil" 21 "os" 22 "path/filepath" 23 24 "github.com/coreos/rkt/pkg/sys" 25 "github.com/hashicorp/errwrap" 26 ) 27 28 // WithClearedCloExec executes a given function in between setting and unsetting the close-on-exit flag 29 // on the given file descriptor 30 func WithClearedCloExec(lfd int, f func() error) error { 31 err := sys.CloseOnExec(lfd, false) 32 if err != nil { 33 return err 34 } 35 defer sys.CloseOnExec(lfd, true) 36 37 return f() 38 } 39 40 // WritePpid writes the pid's parent pid to $PWD/ppid 41 func WritePpid(pid int) error { 42 // write ppid file as specified in 43 // Documentation/devel/stage1-implementors-guide.md 44 out, err := os.Getwd() 45 if err != nil { 46 return errwrap.Wrap(errors.New("cannot get current working directory"), err) 47 } 48 // we are the parent of the process that is PID 1 in the container so we write our PID to "ppid" 49 err = ioutil.WriteFile(filepath.Join(out, "ppid"), 50 []byte(fmt.Sprintf("%d\n", pid)), 0644) 51 if err != nil { 52 return errwrap.Wrap(errors.New("cannot write ppid file"), err) 53 } 54 return nil 55 }