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package container
import (
"encoding/gob"
"fmt"
"os"
"path"
. "syscall"
)
func init() { gob.Register(new(AutoRootOp)) }
// Root appends an [Op] that expands a directory into a toplevel bind mount mirror on container root.
// This is not a generic setup op. It is implemented here to reduce ipc overhead.
func (f *Ops) Root(host, prefix string, flags int) *Ops {
*f = append(*f, &AutoRootOp{host, prefix, flags, nil})
return f
}
type AutoRootOp struct {
Host, Prefix string
// passed through to bindMount
Flags int
// obtained during early;
// these wrap the underlying Op because BindMountOp is relatively complex,
// so duplicating that code would be unwise
resolved []Op
}
func (r *AutoRootOp) early(params *Params) error {
if !path.IsAbs(r.Host) {
return msg.WrapErr(EBADE, fmt.Sprintf("path %q is not absolute", r.Host))
}
if d, err := os.ReadDir(r.Host); err != nil {
return wrapErrSelf(err)
} else {
r.resolved = make([]Op, 0, len(d))
for _, ent := range d {
name := ent.Name()
if IsAutoRootBindable(name) {
op := &BindMountOp{
Source: path.Join(r.Host, name),
Target: "/" + name,
Flags: r.Flags,
}
if err = op.early(params); err != nil {
return err
}
r.resolved = append(r.resolved, op)
}
}
return nil
}
}
func (r *AutoRootOp) apply(params *Params) error {
for _, op := range r.resolved {
msg.Verbosef("%s %s", op.prefix(), op)
if err := op.apply(params); err != nil {
return err
}
}
return nil
}
func (r *AutoRootOp) Is(op Op) bool {
vr, ok := op.(*AutoRootOp)
return ok && ((r == nil && vr == nil) || (r != nil && vr != nil &&
r.Host == vr.Host && r.Prefix == vr.Prefix && r.Flags == vr.Flags))
}
func (*AutoRootOp) prefix() string { return "setting up" }
func (r *AutoRootOp) String() string {
return fmt.Sprintf("auto root %q prefix %s flags %#x", r.Host, r.Prefix, r.Flags)
}
// IsAutoRootBindable returns whether a dir entry name is selected for AutoRoot.
func IsAutoRootBindable(name string) bool {
switch name {
case "proc":
case "dev":
case "tmp":
case "mnt":
case "etc":
default:
return true
}
return false
}
|
