131 lines
2.9 KiB
Go
131 lines
2.9 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package rootfs
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import (
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"os"
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"path/filepath"
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"syscall"
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)
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const (
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defaultInitializer = "linux-init"
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)
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func init() {
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initializers[defaultInitializer] = initFS
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}
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func createDirectory(name string, uid, gid int) initializerFunc {
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return func(root string) error {
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dname := filepath.Join(root, name)
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st, err := os.Stat(dname)
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if err != nil && !os.IsNotExist(err) {
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return err
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} else if err == nil {
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if st.IsDir() {
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stat := st.Sys().(*syscall.Stat_t)
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if int(stat.Gid) == gid && int(stat.Uid) == uid {
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return nil
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}
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} else {
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if err := os.Remove(dname); err != nil {
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return err
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}
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if err := os.Mkdir(dname, 0755); 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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if err := os.Mkdir(dname, 0755); err != nil {
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return err
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}
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}
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return os.Chown(dname, uid, gid)
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}
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}
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func touchFile(name string, uid, gid int) initializerFunc {
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return func(root string) error {
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fname := filepath.Join(root, name)
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st, err := os.Stat(fname)
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if err != nil && !os.IsNotExist(err) {
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return err
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} else if err == nil {
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stat := st.Sys().(*syscall.Stat_t)
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if int(stat.Gid) == gid && int(stat.Uid) == uid {
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return nil
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}
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return os.Chown(fname, uid, gid)
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}
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f, err := os.OpenFile(fname, os.O_CREATE, 0644)
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if err != nil {
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return err
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}
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defer f.Close()
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return f.Chown(uid, gid)
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}
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}
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func symlink(oldname, newname string) initializerFunc {
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return func(root string) error {
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linkName := filepath.Join(root, newname)
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if _, err := os.Stat(linkName); err != nil && !os.IsNotExist(err) {
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return err
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} else if err == nil {
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return nil
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}
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return os.Symlink(oldname, linkName)
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}
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}
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func initFS(root string) error {
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st, err := os.Stat(root)
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if err != nil {
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return err
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}
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stat := st.Sys().(*syscall.Stat_t)
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uid := int(stat.Uid)
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gid := int(stat.Gid)
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initFuncs := []initializerFunc{
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createDirectory("/dev", uid, gid),
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createDirectory("/dev/pts", uid, gid),
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createDirectory("/dev/shm", uid, gid),
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touchFile("/dev/console", uid, gid),
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createDirectory("/proc", uid, gid),
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createDirectory("/sys", uid, gid),
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createDirectory("/etc", uid, gid),
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touchFile("/etc/resolv.conf", uid, gid),
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touchFile("/etc/hosts", uid, gid),
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touchFile("/etc/hostname", uid, gid),
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symlink("/proc/mounts", "/etc/mtab"),
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}
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for _, fn := range initFuncs {
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if err := fn(root); err != nil {
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return err
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}
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}
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return nil
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}
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