zrepl/zfs/mapping.go
2017-04-26 20:29:54 +02:00

145 lines
2.3 KiB
Go

package zfs
import (
"bufio"
"errors"
"fmt"
"io"
"os/exec"
)
type DatasetMapping interface {
Map(source DatasetPath) (target DatasetPath, err error)
}
type GlobMapping struct {
PrefixPath DatasetPath
TargetRoot DatasetPath
}
var NoMatchError error = errors.New("no match found in mapping")
func (m GlobMapping) Map(source DatasetPath) (target DatasetPath, err error) {
if len(source) < len(m.PrefixPath) {
err = NoMatchError
return
}
target = make([]string, 0, len(source)+len(m.TargetRoot))
target = append(target, m.TargetRoot...)
for si, sc := range source {
target = append(target, sc)
if si < len(m.PrefixPath) {
if sc != m.PrefixPath[si] {
err = NoMatchError
return
}
continue
}
}
return
}
type ComboMapping struct {
Mappings []DatasetMapping
}
func (m ComboMapping) Map(source DatasetPath) (target DatasetPath, err error) {
for _, sm := range m.Mappings {
target, err = sm.Map(source)
if err == nil {
return target, err
}
}
return nil, NoMatchError
}
type DirectMapping struct {
Source DatasetPath
Target DatasetPath
}
func (m DirectMapping) Map(source DatasetPath) (target DatasetPath, err error) {
if m.Source == nil {
return m.Target, nil
}
if len(m.Source) != len(source) {
return nil, NoMatchError
}
for i, c := range source {
if c != m.Source[i] {
return nil, NoMatchError
}
}
return m.Target, nil
}
type ExecMapping struct {
Name string
Args []string
}
func NewExecMapping(name string, args ...string) (m *ExecMapping) {
m = &ExecMapping{
Name: name,
Args: args,
}
return
}
func (m ExecMapping) Map(source DatasetPath) (target DatasetPath, err error) {
var stdin io.Writer
var stdout io.Reader
cmd := exec.Command(m.Name, m.Args...)
if stdin, err = cmd.StdinPipe(); err != nil {
return
}
if stdout, err = cmd.StdoutPipe(); err != nil {
return
}
resp := bufio.NewScanner(stdout)
if err = cmd.Start(); err != nil {
return
}
go func() {
err := cmd.Wait()
if err != nil {
fmt.Printf("error: %v\n", err) // TODO
}
}()
if _, err = io.WriteString(stdin, source.ToString()+"\n"); err != nil {
return
}
if !resp.Scan() {
err = errors.New(fmt.Sprintf("unexpected end of file: %v", resp.Err()))
return
}
t := resp.Text()
switch {
case t == "NOMAP":
return nil, NoMatchError
}
target = toDatasetPath(t) // TODO discover garbage?
return
}