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package hst
import (
"encoding/gob"
"strings"
"hakurei.app/container"
)
func init() { gob.Register(new(FSOverlay)) }
// FilesystemOverlay is the type string of an overlay mount point.
const FilesystemOverlay = "overlay"
// FSOverlay represents an overlay mount point.
type FSOverlay struct {
// mount point in container
Target *container.Absolute `json:"dst"`
// any filesystem, does not need to be on a writable filesystem, must not be nil
Lower []*container.Absolute `json:"lower"`
// the upperdir is normally on a writable filesystem, leave as nil to mount Lower readonly
Upper *container.Absolute `json:"upper,omitempty"`
// the workdir needs to be an empty directory on the same filesystem as Upper, must not be nil if Upper is populated
Work *container.Absolute `json:"work,omitempty"`
}
func (o *FSOverlay) Valid() bool {
if o == nil || o.Target == nil {
return false
}
for _, a := range o.Lower {
if a == nil {
return false
}
}
if o.Upper != nil { // rw
return o.Work != nil && len(o.Lower) > 0
} else { // ro
return len(o.Lower) >= 2
}
}
func (o *FSOverlay) Path() *container.Absolute {
if !o.Valid() {
return nil
}
return o.Target
}
func (o *FSOverlay) Host() []*container.Absolute {
if !o.Valid() {
return nil
}
p := make([]*container.Absolute, 0, 2+len(o.Lower))
if o.Upper != nil && o.Work != nil {
p = append(p, o.Upper, o.Work)
}
p = append(p, o.Lower...)
return p
}
func (o *FSOverlay) Apply(z *ApplyState) {
if !o.Valid() {
return
}
if o.Upper != nil && o.Work != nil { // rw
z.Overlay(o.Target, o.Upper, o.Work, o.Lower...)
} else { // ro
z.OverlayReadonly(o.Target, o.Lower...)
}
}
func (o *FSOverlay) String() string {
if !o.Valid() {
return "<invalid>"
}
lower := make([]string, len(o.Lower))
for i, a := range o.Lower {
lower[i] = container.EscapeOverlayDataSegment(a.String())
}
if o.Upper != nil && o.Work != nil {
return "w*" + strings.Join(append([]string{
container.EscapeOverlayDataSegment(o.Target.String()),
container.EscapeOverlayDataSegment(o.Upper.String()),
container.EscapeOverlayDataSegment(o.Work.String())},
lower...), container.SpecialOverlayPath)
} else {
return "*" + strings.Join(append([]string{
container.EscapeOverlayDataSegment(o.Target.String())},
lower...), container.SpecialOverlayPath)
}
}
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