89 lines
1.7 KiB
Go
89 lines
1.7 KiB
Go
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// +build linux
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package overlay2
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import (
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"bytes"
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"encoding/json"
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"flag"
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"fmt"
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"os"
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"runtime"
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"syscall"
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"github.com/containers/storage/pkg/reexec"
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)
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func init() {
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reexec.Register("docker-mountfrom", mountFromMain)
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}
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func fatal(err error) {
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fmt.Fprint(os.Stderr, err)
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os.Exit(1)
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}
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type mountOptions struct {
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Device string
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Target string
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Type string
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Label string
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Flag uint32
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}
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func mountFrom(dir, device, target, mType, label string) error {
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options := &mountOptions{
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Device: device,
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Target: target,
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Type: mType,
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Flag: 0,
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Label: label,
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}
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cmd := reexec.Command("docker-mountfrom", dir)
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w, err := cmd.StdinPipe()
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if err != nil {
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return fmt.Errorf("mountfrom error on pipe creation: %v", err)
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}
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output := bytes.NewBuffer(nil)
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cmd.Stdout = output
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cmd.Stderr = output
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if err := cmd.Start(); err != nil {
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return fmt.Errorf("mountfrom error on re-exec cmd: %v", err)
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}
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//write the options to the pipe for the untar exec to read
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if err := json.NewEncoder(w).Encode(options); err != nil {
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return fmt.Errorf("mountfrom json encode to pipe failed: %v", err)
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}
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w.Close()
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if err := cmd.Wait(); err != nil {
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return fmt.Errorf("mountfrom re-exec error: %v: output: %s", err, output)
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}
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return nil
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}
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// mountfromMain is the entry-point for docker-mountfrom on re-exec.
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func mountFromMain() {
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runtime.LockOSThread()
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flag.Parse()
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var options *mountOptions
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if err := json.NewDecoder(os.Stdin).Decode(&options); err != nil {
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fatal(err)
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}
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if err := os.Chdir(flag.Arg(0)); err != nil {
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fatal(err)
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}
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if err := syscall.Mount(options.Device, options.Target, options.Type, uintptr(options.Flag), options.Label); err != nil {
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fatal(err)
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}
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os.Exit(0)
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}
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