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Don't fchown when inheriting io #1354

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merged 1 commit into from
Mar 3, 2017
Merged

Don't fchown when inheriting io #1354

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18 changes: 4 additions & 14 deletions tty.go
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,6 @@ import (
"io"
"os"
"sync"
"syscall"

"github.com/docker/docker/pkg/term"
"github.com/opencontainers/runc/libcontainer"
Expand All @@ -28,9 +27,9 @@ func (t *tty) copyIO(w io.Writer, r io.ReadCloser) {
r.Close()
}

// setup standard pipes so that the TTY of the calling runc process
// is not inherited by the container.
func createStdioPipes(p *libcontainer.Process, rootuid, rootgid int) (*tty, error) {
// setup pipes for the process so that advanced features like c/r are able to easily checkpoint
// and restore the process's IO without depending on a host specific path or device
func setupProcessPipes(p *libcontainer.Process, rootuid, rootgid int) (*tty, error) {
i, err := p.InitializeIO(rootuid, rootgid)
if err != nil {
return nil, err
Expand Down Expand Up @@ -62,19 +61,10 @@ func createStdioPipes(p *libcontainer.Process, rootuid, rootgid int) (*tty, erro
return t, nil
}

func dupStdio(process *libcontainer.Process, rootuid, rootgid int) error {
func inheritStdio(process *libcontainer.Process) error {
process.Stdin = os.Stdin
process.Stdout = os.Stdout
process.Stderr = os.Stderr
for _, fd := range []uintptr{
os.Stdin.Fd(),
os.Stdout.Fd(),
os.Stderr.Fd(),
} {
if err := syscall.Fchown(int(fd), rootuid, rootgid); err != nil {
return err
}
}
return nil
}

Expand Down
12 changes: 4 additions & 8 deletions utils_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -110,19 +110,15 @@ func setupIO(process *libcontainer.Process, rootuid, rootgid int, createTTY, det
process.Stderr = nil
return &tty{}, nil
}

// When we detach, we just dup over stdio and call it a day. There's no
// requirement that we set up anything nice for our caller or the
// container.
// when runc will detach the caller provides the stdio to runc via runc's 0,1,2
// and the container's process inherits runc's stdio.
if detach {
if err := dupStdio(process, rootuid, rootgid); err != nil {
if err := inheritStdio(process); err != nil {
return nil, err
}
return &tty{}, nil
}

// XXX: This doesn't sit right with me. It's ugly.
return createStdioPipes(process, rootuid, rootgid)
return setupProcessPipes(process, rootuid, rootgid)
}

// createPidFile creates a file with the processes pid inside it atomically
Expand Down