73 lines
2 KiB
Go
73 lines
2 KiB
Go
//go:build linux || freebsd
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// +build linux freebsd
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package initlayer // import "github.com/docker/docker/daemon/initlayer"
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import (
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"os"
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"path/filepath"
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"strings"
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"github.com/docker/docker/pkg/idtools"
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"golang.org/x/sys/unix"
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)
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// Setup populates a directory with mountpoints suitable
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// for bind-mounting things into the container.
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//
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// This extra layer is used by all containers as the top-most ro layer. It protects
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// the container from unwanted side-effects on the rw layer.
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func Setup(initLayerFs string, rootIdentity idtools.Identity) error {
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// Since all paths are local to the container, we can just extract initLayerFs.Path()
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initLayer := initLayerFs
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for pth, typ := range map[string]string{
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"/dev/pts": "dir",
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"/dev/shm": "dir",
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"/proc": "dir",
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"/sys": "dir",
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"/.dockerenv": "file",
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"/etc/resolv.conf": "file",
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"/etc/hosts": "file",
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"/etc/hostname": "file",
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"/dev/console": "file",
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"/etc/mtab": "/proc/mounts",
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} {
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parts := strings.Split(pth, "/")
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prev := "/"
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for _, p := range parts[1:] {
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prev = filepath.Join(prev, p)
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unix.Unlink(filepath.Join(initLayer, prev))
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}
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if _, err := os.Stat(filepath.Join(initLayer, pth)); err != nil {
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if os.IsNotExist(err) {
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if err := idtools.MkdirAllAndChownNew(filepath.Join(initLayer, filepath.Dir(pth)), 0755, rootIdentity); err != nil {
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return err
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}
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switch typ {
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case "dir":
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if err := idtools.MkdirAllAndChownNew(filepath.Join(initLayer, pth), 0755, rootIdentity); err != nil {
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return err
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}
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case "file":
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f, err := os.OpenFile(filepath.Join(initLayer, pth), os.O_CREATE, 0755)
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if err != nil {
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return err
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}
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f.Chown(rootIdentity.UID, rootIdentity.GID)
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f.Close()
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default:
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if err := os.Symlink(typ, filepath.Join(initLayer, pth)); err != nil {
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return err
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}
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}
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} else {
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return err
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}
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}
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}
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// Layer is ready to use, if it wasn't before.
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return nil
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}
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